Distribution Restriction Statement...DEPARTMENT OF THE ARMY EM 1110-2-2703 U.S. Army Corps of...

CECW-EE

Engineer Manual1110-2-2703

Department of the ArmyU.S. Army Corps of Engineers

Washington, DC 20314-1000

EM 1110-2-2703

30 June 1994

Engineering and Design

LOCK GATES AND OPERATINGEQUIPMENT

Distribution Restriction StatementApproved for public release; distribution is

unlimited.

EM 1110-2-270330 June 1994

US Army Corpsof Engineers

ENGINEERING AND DESIGN

Lock Gates andOperating Equipment

ENGINEER MANUAL

DEPARTMENT OF THE ARMY EM 1110-2-2703U.S. Army Corps of Engineers

CECW-EE Washington, DC 20314-1000

ManualNo. 1110-2-2703 30 June 1994

Engineering and DesignLOCK GATES AND OPERATING EQUIPMENT

1. Purpose. This manual provides guidance in the structural, mechanical, and electrical design oflock gates and operating equipment at navigation projects.

2. Applicability. This manual applies to all HQUSACE elements, major subordinate commands,districts, laboratories, and field operating activities having responsibilities for the design and construc-tion of civil works projects.

FOR THE COMMANDER:

WILLIAM D. BROWNColonel, Corps of EngineersChief of Staff

____________________________________________________________________________________This manual supersedes EM 1110-2-2703, dated 29 February 1984.

DEPARTMENT OF THE ARMY EM 1110-2-2703U.S. Army Corps of Engineers

CECW-EE Washington, D.C. 20314

ManualNo. 1110-2-2703 30 June 1994

Engineering and DesignLOCK GATES AND OPERATING EQUIPMENT

Table of Contents

Subject Paragraph Page

Chapter 1IntroductionPurpose . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-1Applicability . . . . . . . . . . . . . . . . . . . . 1-2 1-1References . . . . . . . . . . . . . . . . . . . . . 1-3 1-1Applicable Computer Programs. . . . . . . 1-4 1-1Plates . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 1-1General. . . . . . . . . . . . . . . . . . . . . . . . 1-6 1-1Materials and Working Stresses. . . . . . . 1-7 1-3Basic Dimensions . . . . . . . . . . . . . . . . 1-8 1-4Loads . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 1-4Fatigue and Fracture Control. . . . . . . . . 1-10 1-5Operating Machinery General Design

Criteria . . . . . . . . . . . . . . . . . . . . . . . 1-11 1-5

Chapter 2Miter GatesMiter Gates, Horizontally Framed. . . . . 2-1 2-1Miter Gates, Horizontally Framed-

Arch Type . . . . . . . . . . . . . . . . . . . . 2-2 2-19Miter Gates, Vertically Framed. . . . . . . 2-3 2-19Erection and Testing, Miter Gates. . . . . 2-4 2-22Operating Machinery. . . . . . . . . . . . . . 2-5 2-23

Chapter 3Diagonal Design, Miter GatesDiagonal Design . . . . . . . . . . . . . . . . . 3-1 3-1Definitions of Terms and Symbols. . . . . 3-2 3-1Introduction . . . . . . . . . . . . . . . . . . . . 3-3 3-2Geometry . . . . . . . . . . . . . . . . . . . . . . 3-4 3-2Example 1, Horizontally Framed Gate . . 3-5 3-15Example 2, Vertically Framed Gate. . . . 3-6 3-21Vertical Paneling of Leaf . . . . . . . . . . . 3-7 3-27Derivation of Equation 3-11’. . . . . . . . . 3-8 3-30Temporal Hydraulic Loads. . . . . . . . . . 3-9 3-30Procedure for Prestressing

Diagonals . . . . . . . . . . . . . . . . . . . . . 3-10 3-32


New Information onDiagonal Design . . . . . . . . . . . . . . . . 3-11 3-32

Chapter 4Sector GatesSector Gates. . . . . . . . . . . . . . . . . . . . 4-1 4-1Operating Machinery. . . . . . . . . . . . . . 4-2 4-4

Chapter 5Vertical-Lift GatesVertical-Lift Gates . . . . . . . . . . . . . . . . 5-1 5-1Operating Machinery. . . . . . . . . . . . . . 5-2 5-7

Chapter 6Submergible Tainter GatesDesign Analysis. . . . . . . . . . . . . . . . . . 6-1 6-1Seal and Gate Deicing. . . . . . . . . . . . . 6-2 6-1Operating Machinery. . . . . . . . . . . . . . 6-3 6-1

Chapter 7Corrosion ControlCorrosive Environment of Lock Gates . . 7-1 7-1Corrosion and Corrosion Control. . . . . . 7-2 7-1Painting Structures. . . . . . . . . . . . . . . . 7-3 7-1Type of Cathodic Protection. . . . . . . . . 7-4 7-2Cathodic-Protection Operation. . . . . . . . 7-5 7-2Anode Concepts . . . . . . . . . . . . . . . . . 7-6 7-2Flooding and Emergency

Maintenance. . . . . . . . . . . . . . . . . . . 7-7 7-2Cathodic-Protection Tests, Adjustments,

and Reports . . . . . . . . . . . . . . . . . . . 7-8 7-3Measurement of Existing Cathodic-

Protection Systems. . . . . . . . . . . . . . . 7-9 7-3Cathodic Protection for Miter and

Quoin Blocks . . . . . . . . . . . . . . . . . . 7-10 7-3

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Appendix AReferences . . . . . . . . . . . . . . . . . . . . A-1

Appendix BIllustrative Plates . . . . . . . . . . . . . . . B-1

Appendix CSample Computations . . . . . . . . . . . C-1

Appendix DAir Bubbler GateRecess Flusher . . . . . . . . . . . . . . . . D-1

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Chapter 1Introduction

1-1. Purpose

This manual provides guidance in the structural, mechan-ical, and electrical design of lock gates and operatingequipment at navigation projects.

1-2. Applicability

This manual applies to all HQUSACE elements, majorsubordinate commands, districts, laboratories, and fieldoperating activities having responsibilities for the designand construction of civil works projects.

1-3. References

References are listed in Appendix A.

1-4. Applicable Computer Programs

CMITER, Computer Aided Structural Engineering,U.S. Army Engineer Waterways Experiment Station,3909 Halls Ferry Road, Vicksburg, MS 39180-6199.

1-5. Plates

Illustrative plates containing general information, typicaldetails, mechanical design data, and sample computationsare included in Appendix B, and are referred to herein asPlate B-1, B-2, etc.

1-6. General

a. Function of gates. Lock gates serve a number ofdifferent functions, depending on location and conditions.While the major use of lock gates is to form thedamming surface across the lock chamber, they may alsoserve as guard gates, for filling and emptying the lockchamber, for passing ice and debris, to unwater the lockchamber, and to provide access from one lock wall to theother by means of walkways or bridgeways installed ontop of the gates. A navigation lock requires closure gatesat both ends of the lock so that the water level in thelock chamber can be varied to coincide with the upperand lower approach channels. The sequence of “locking”a vessel upstream is: first, lower the water level in thelock to the downstream water level; second, open thelower gate and move the vessel into the lock chamber;third, close the lower gate and fill the lock chamber tothe level of the upper pool; and finally, open the

upstream gate and move the vessel out of the lock.Lockage of a vessel downstream involves a similarsequence in reverse order.

b. Types of gates covered.

(1) Miter gates. A very large percentage of thelocks in the United States are equipped with double-leafmiter gates which are used for moderate- and high-liftlocks. These gates are fairly simple in construction andoperation and can be opened or closed more rapidly thanany other type of gate. Maintenance costs generally arelow. A disadvantage of this gate is that it cannot be usedto close off flow in an emergency situation with anappreciable unbalanced head.

(a) Miter gates fit into recesses in the wall in theopen position. The bottom of the recess should extendbelow the gate bottom to preclude operating difficultiesfrom silt and debris collection. Enlarged recesses aresometimes used to facilitate the removal of accumulatedice. An air bubbler system is recommended to help clearice and debris from gate recesses. (See Appendix D fortypical air bubbler recess flusher.)

(b) Miter gates are framed either horizontally orvertically. The skin plate of a horizontally framed gate issupported by horizontal members which may be eitherstraight girders acting as beams, or circular arches. Eachsuch horizontal member is supported by the verticalquoin post at one end and the miter post at the other.All water load is transmitted through the girders andquoin blocking into the gate monoliths. A verticallyframed gate resists the water pressure by a series ofvertical girders more or less uniformly spaced throughoutthe length of the gate, and supported at top and bottomby horizontal girders transmitting the loads to miter andquoin at the top of the leaf, and directly to the sill at thebottom.

(c) The relative costs of the two types of gates (hori-zontally and vertically framed) depend largely upon threemain factors:

- Overall weight of the gate;

- Simplicity of design and ease of fabrication anderection;

- Cost of that part of the lock walls and sills influ-enced by the design of the gates.

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(d) When the ratio of the height of a leaf to its widthis greater than about 0.7, the horizontally framed gatewill weigh less. For long, shallow gates, vertical framingrequires less material.

(e) The overturning moment carried to the lock wallby a horizontally framed gate is greater about all pointsbelow the sill than that caused by a vertically framedgate, unless the entire sill load is transmitted to the wall.Hence, the latter type requires less masonry in a thrustwall of gravity section, but the heavier sill necessary tosupport the bottom girder into which the verticals areframed may counterbalance this saving.

(f) Due to the greater rigidity and resistance to boatimpact of the horizontally framed gate and the insignifi-cant difference in cost, the vertically framed gate will nolonger be used except for unusual applications and uponspecial approval.

(2) Sector gates. A sector gate is similar in shape toa tainter gate except it is oriented to rotate about a verti-cal axis and is supported at the top and bottom in a man-ner similar to a miter gate. Like miter gates, sector gatesare used in pairs, meeting at the center of the lock whenin the closed position and swinging into recesses in thelock walls for the open position. The trunnions arelocated in the lock walls, and the skin plates face in thedirection of the normally higher pool level.

(a) Sector gates are used at both ends of locks thatare located in tidal reaches of rivers or canals where thelifts are low and where the gates may be subjected toreversal of heads. Since these gates can be opened andclosed under head, they can be used to close off flow inan emergency. The gates swing apart and water flowsinto or out of the lock through the center openingbetween the gates. In some cases, flow is admittedthrough culverts to improve filling characteristics orwhere ice or drift may not permit adequate flow betweenthe gates.

(b) Because the turbulence area at the upper end of alock filled by a sector gate is not effective for lockage ofvessels, the length of the lock chambers must beincreased proportionately. Model tests indicate that about100 feet (ft) of additional length is required. Like otherend-filling systems, sector gates cannot be used for fillingand emptying high-lift locks unless the filling and empty-ing rates are greatly reduced. The practical lift limitationis usually about 10 ft, although gates with higher liftshave been built.

(c) The disadvantages of the sector gates are highconstruction cost, long opening and closing times, andlarger wall recesses.

(3) Vertical-lift gates. Vertical-lift gates may beused at both ends of a lock, or at only one end in combi-nation with a miter gate at the other end. They can beraised or lowered under low to moderate heads but arenot used when there is reversed head. Their operationtime is much slower for older gates and maintenancecosts are higher than those of miter gates, but they canbe used in emergency closure. The newer gates, how-ever, are capable of achieving operating speeds equal to,or even faster than, miter gates.

(a) A vertical-lift gate installation at the upstreamend of a lock normally consists of a single-leaf submerg-ible gate, which rises vertically to close off the lockchamber from the upper pool. When the lock is filled,the gate is opened by sliding the leaf vertically down-ward until the top of the leaf is at or below the top of theupper sill.

(b) In some cases, a double-leaf vertical-lift gatemay be used. The upper leaf can be provided with acurved crest which permits overflow to supplement flowfrom the primary filling system when the lock chamber isnearly full. This type of gate can also be used for skim-ming ice and debris.

(c) When a vertical-lift gate is used at the down-stream end of a lock, it is raised vertically to a heightabove the lower pool level so that vessels can passunderneath. The gate leaf is suspended from towers onthe lock walls and may be equipped with counterweightsto reduce the power hoist size. Lock gates of this typeare practical only for very high locks and where requiredvertical clearance can be provided under the gate in itsraised position.

(4) Submergible tainter gates. The locks of theDalles Dam, some Lower Snake River projects, and theUpper and Lower St. Anthony Falls Locks have sub-mergible tainter gates. This type of gate is raised toclose the lock chamber and lowered into the lock cham-ber to open it. The end frames are recessed into the lockwall so no part of the end frame projects into the pas-sageway. This type of gate was chosen because it isstructurally efficient and was estimated to be lighter inweight and less costly than a double-leaf miter gate forthese applications. Also, the tainter gate permitted thelength of the approach channel to be reduced by the leaf

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width of the miter gate. There are two potential problemareas in the operation of this type of gate: skewing ofgate during opening and closing, and vulnerability todamage if hit by lock traffic. However, with gooddesign practices and lock management, these problemswill be minimal.

1-7. Materials and Working Stresses

a. Materials. This manual serves only as a guideand the following list should not be considered as acomplete listing of materials that may be used.

(1) Structural steel. Lock gates are usually con-structed of structural grade carbon steel having a yieldpoint of 36,000 pounds per square inch (psi). Low-alloysteel, with a yield point up to 50,000 psi, is quite fre-quently used as skin plate in conjunction with structuralgrade girders. In some cases for the larger gates, otherthan miter gates, low-alloy steel may be economical forthe complete gate. The deflection of members fabricatedof high-strength low-alloy steel should always be investi-gated as it will always be more severe than if the mem-bers were of structural grade carbon steel. For mitergates, structural grade carbon steel should be usedregardless of the gate height in the interest of providing amore rigid gate, except for the skin plate and diagonalswhich may be of high-strength, low-alloy steel wheneverwarranted.

(2) Corrosion-resistant steel. Corrosion-resistantsteel normally should only be used in locations wherecorrosion is expected to be severe or where corrosionwill impair the normal efficiency of gate operation.Under most conditions, seal contact surfaces of lockgates are not required to be corrosion resistant but underadverse conditions corrosion-resistant clad or solid stain-less steel plates may be desirable. For some lock loca-tions and conditions it may also be desirable to clad thecontact surfaces of miter and quoin blocks with corro-sion-resistant steel or to use solid stainless or corrosion-resistant steel miter and quoin contact blocks. Flamespraying of corrosion-resisting steel particles to surfacessubject to severe corrosion may be advantageous whereusing solid or clad corrosion-resisting steel is not practi-cal or not economical. The new guide specificationCW-05036 covers the requirements for surface prepara-tion and applications of metalizing/flame sprayingcoatings.

(3) Cast steel. The operating strut pin bearingcollars, pintle sockets, and pintle shoes are normallyfabricated of cast steel, utilizing mild-strength to

medium-strength carbon steel castings. For items that aresubjected to higher stresses than medium-strength cast-ings are capable of carrying, such as the miter guideroller and pintle balls, high-strength, low-alloy steelcastings should be used.

(4) Forged steels. Gudgeon pins, operating strutconnecting pins, anchor link pins, parts of the anchoragelinks, and guide roller pins should be made of carbonsteel forgings rated for general industrial use. Forgingsmay be untreated or heat-treated depending on intendeduse and requirements. The pintle ball of most gates ismade of an alloy steel forging containing nickel, givingthe forging a good allowable bearing value as well as afair degree of corrosion resistance. Corrosion-resistantweld overlays may also be used on pintle balls in highlycorrosive environments.

(5) Bronze. Bushings for all lock gate componentsare normally made of bronze. Usually bearings are madeof a bronze designated for general purpose applications.Where stresses are encountered that are higher than desir-able for the general purpose bronze, aluminum bronzemay be used.

(6) Bolts. Where bolted connections are used forparts of the gate that may have to be removed for main-tenance or repair, a copper-nickel alloy, usually referredto as monel, or an equally corrosion-resistant steel shouldbe considered, especially if corrosive elements are pres-ent. The 300 series stainless steel and bronze bolts, nuts,washers, and setscrews have been used with good resultsin highly corrosive environments. Ordinarily, bolts, nuts,and washers should all be made from the same type ofmaterial; however, if salvage and reuse is intended differ-ent alloy combinations for bolts and nuts should be usedto minimize seizing. Normal applications of this type ofconnection are pintle socket to gate connection, quoinand miter water seal bolts, and bolts for the bottom seal.Where bolts are used and corrosion is not a factor,ASTM A307 or A325 bolts should be used, with boltstrength dictated by load and conditions.

(7) Fabrication. Fabrication of all lock gates shouldbe by welding, with bolts being used only for those partsthat may have to be removed for maintenance or repair.The application of welding generally results in lighterand stronger gates. All welding should be done in accor-dance with the current Structural Welding Code of theAmerican Welding Society, Section 9, Design of NewBridges.

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b. Design strength. Structural steel gate membersshall be designed in accordance with the requirements ofEM 1110-2-2105. For general purpose bronze bushings,the allowable bearing should be below 1,500 psi with amaximum concentrated bearing of not more than5,000 psi (this refers to a bushing with an eccentricload). Where a higher allowable bearing is desirable,aluminum bronze may be used with working stresses upto 5,000 psi and a concentrated bearing of not more than10,000 psi as described above. Working stresses for bothforgings and castings should be based on yield strengthand for normal applications should be no more than0.50Fy.

1-8. Basic Dimensions

a. Miter gates. A miter gate is a three-hinged archwhen the leaves are mitered. Gate geometry is a func-tion of the angle the work line of the leaf makes with aline normal to the lock walls, with the gate in a miteredposition. Past study and design have determined that formiter gates a slope of 1L on 3T gives the best results(L = longitudinal, T = transverse). In general, verticallyframed gates have been used where the height-to-lengthratio of the leaf was less than 0.5. The approximate ratioof height to length, where the weight of a verticallyframed leaf is essentially the same as a horizontallyframed leaf, is somewhere between 0.70 and 1.0 (seeparagraph 1-6b(1)). However, vertically framed gates arenot recommended for new construction. Even with aslight increase in cost, the greater rigidity of the horizon-tally framed gates makes them more desirable.

(1) The pintle is located so that the leaf, whenrecessed, is completely within the lock wall and so thatthe pintle is eccentric (upstream) with respect to thecenter of curvature of the bearing face of the quoin con-tact block. The center of curvature of the bearing face isalways located on the line tangent to the thrust line at thequoin contact point. The pintle eccentricity, whichmakes the quoin block approach the contact point tangen-tially, should be approximately 7 in., thereby reducingthe possibility of metal interference (see paragraph 2-1h).

(2) The arch-type miter gate is a horizontally framedstructural system of curved members with a compositeacting skin plate. Except for the curvature, the gate sizeand other components are similar to or the same as hori-zontally framed straight gates.

b. Sector gates. Sector gates are generally laid outwith the frames forming an equilateral triangle. Thenormal layout is for 60 degrees (deg) or greater interior

angles, formed by the frames and a chord line behind theskin plates. One strut is parallel to the lock wall in theclosed position, thereby causing the other strut to form anangle equal to the interior angle, with the lock wall.The pintle is located so that the gate is completely in therecess in the open position.

c. Vertical-lift gates. Dimensions for vertical-liftgates are based solely on lock width and girder depthsrequired by the head. Recesses in lock walls for uppergates are determined by load, girder depth, and detailrequirements. Towers for downstream gates are alsodetermined by load, counterweights, and related details.

d. Submergible tainter gates. As with spillwaytainter gates, the controlling dimensions are the lockwidth, gate radius, and end frame and trunnion hublocation. Plates B-45 and B-46 show typical end frameand cross section of the gate.

1-9. Loads

The loads applicable to lock gate design are dead, hydro-static, hydraulic, temporal, and boat impact. Miter gatesare also subject to torsion. Dead load is the weight ofthe structure plus mud and ice; hydrostatic load is thewater load on the gate produced by the pool differential;boat impact is the dynamic force applied to the gate bythe barge impact; temporal load is the water surge forcesfrom wave loads or overfilling of the lock; and torsionon miter gates is the result of a twisting action from theoperating strut force and the water resistance caused bythe leaf moving. For more specific lock gate loads, seethe gate type’s respective section herein.

a. The controlled upper and lower pools cause thenormal loading, and greater water forces, such asunwatering the lock, are considered emergency condi-tions, with an increase in allowable stress of 33 percent.

b. The force of impact usually is limited by localfailure in the region of impact. For design purposes, thisforce, supported by past designs, is converted into anequivalent water load of 10- to 15-ft head below the topgirder and of 6- to 10-ft head above the top girder forvertical-lift gates if horizontally framed. An impact loadof 250,000 or 400,000 pounds (lb), according to locationof load, is applied above the pool to horizontally framedmiter gates. (See paragraph 2-1b(1)(d).) Barge orimpact force is generally not applied to vertical framingmembers. Greater impact forces or the use of barriersmay be justified based on the importance of the water-way or type of traffic.

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c. On sector gates a design withstanding a concen-trated impact force of 125,000 lb applied to the top hori-zontal girder is recommended, with vertical framingmembers designed for no impact loading.

d. The quoin end of a miter gate leaf is held verticalby the pintle and gudgeon pin, leaving the miter end freeto twist out of vertical alignment. The deadweight of theleaf, along with ice or mud, also causes the leaf to twist.To keep the leaf in vertical alignment while stationary,and to eliminate excessive deflection during operation,diagonals are provided on the downstream faces of hori-zontally framed miter gates and on both upstream anddownstream faces of vertically framed miter gates.These diagonals act as tension members for all normalgate operations. (See USAED, Chicago 1960.)

1-10. Fatigue and Fracture Control

All possible modes of failure should be considered whendesigning lock gates. Possible failure modes are:1) general yielding or excessive plastic deformation,2) buckling or general instability, 3) subcritical crackgrowth leading to loss of cross section or unstable crackgrowth, and 4) unstable crack extension leading to failureof a member. Failure modes 1 and 2 are addressed byLoad and Resistance Factor Design (LRFD) and Allow-able Stress Design (ASD) principles whereas failuremodes 3 (fatigue) and 4 (brittle fracture) can beaddressed using fatigue and fracture mechanics princi-ples. Welded construction with its emphasis on mono-lithic structural members has led to the increaseddesirability of including fracture criterion in addition tostrength and buckling criteria when designing a structure.Stress range, detailing, and the number and frequency ofload cycles control fatigue while geometry, toughness,and stress levels control fracture. For further guidance,see EM 1110-2-2105.

a. Fatigue requirements. Fatigue can be controlledby stress range, detailing, and the number and frequencyof load cycles. While the number and frequency of loadcycles are usually controlled by the structure’s purpose,the designer can control the stress range and the choiceof detail. Refer to AISC (Current Edition), Appendix K,for guidance in design and detailing.

b. Fracture control requirements. The designershould set limits on tensile stress levels, enforce controlson quality fabrication and inspection procedures to mini-mize initial defects and residual stresses, designate theappropriate temperature zone, and specify the relatedminimum fracture toughness for critical members and/or

components. For lock gates, fracture critical membersshall be defined as “members and their associated con-nections subjected to tensile stresses and whose failurewould cause the structure to be inoperable.” Forminimum Charpy V-notch impact test values seeEM 1110-2-2105.

1-11. Operating Machinery General DesignCriteria

a. Machinery components. All components of thegate operating or hoisting machinery except compressionmembers which may fail by buckling should be designedfor loads or forces produced by an effective cylinderoperating pressure or normal full load torque of an elec-tric motor with a minimum safety factor of five based onthe ultimate tensile strength of the material involved. Inaddition, each part or component should be designed fora unit stress not to exceed 75 percent of the yieldstrength of the material for the maximum load, maximumcylinder pressure obtainable, or overload torque from anelectric motor.

b. Piston rods. Piston rods and other compressionmembers in which failure may be caused by bucklingshould be designed in accordance with either the Johnsonor Euler equation, whichever applies. A factor of safetyof at least 2.5 should be provided based on the maximumload to be imposed on the member and the critical buck-ling load. In almost all cases the end fixity coefficientfor pin-ended columns should be used.

c. Shafting. Shafting should be designed for therated loads, increased by applicable shock and fatiguefactors, with a factor of safety of five based upon theultimate strength of the materials, provided the stressesproduced by the maximum torque of the motor do notexceed 75 percent of the yield point of the materialsinvolved. Stress concentration factors should be usedwhere applicable. A combined shock and fatigue factorof 1.25 should be used. Shafting should be amply sup-ported, and provided with adequate means to preventlongitudinal movement. The distance between bearingson shafting subject to bending, except that due to its ownweight, should be such that the maximum shaft deflectionwill not exceed 0.01 in./ft of length at rated load. Tor-sional shaft deflection should not exceed 0.08 deg/ft ofshaft length at rated load. If spur gears are mounted onthe shafts it is necessary to limit the relative slope of theshafts containing the gear and pinion. It has generallybeen found acceptable to limit the slope of the shaft atthe center line of the gear mesh to one-third the backlashdivided by the gear face width. The usual range of

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backlash for spur gears is 0.03/D.P. to 0.05/D.P. in.,where D.P. is the diametral pitch.

d. Speed reducers. Speed reducers should be worm,helical, or herringbone type in accordance with the appli-cable American Gear Manufacturers Association(AGMA, Current Edition) standards with antifrictionbearings. If possible, an oil meeting the requirements forthe ambient temperatures that will be encountered shouldbe used. Where ambient temperature range will exceedthat recommended for the oil, a thermostatically con-trolled heater should be provided in the reducer case tokeep the oil at the temperature recommended by the oilmanufacturer. Where heaters are used, the surface areaof the heater should be as large as possible to preventcharring of the oil. The watt density of elements selectedshould not exceed 10 watts per square inch. In the inter-est of energy conservation, consideration should be givento insulating the reducer case to minimize heat loss.Another alternative would be the use of a synthetic gearlubricant with a minus 40° Fahrenheit (F) pour point ifacceptable to the reducer manufacturer. Reducer selec-tion should be based on manufacturer’s published ratingsfor the required service conditions.

e. Couplings. Flexible couplings should be of thegear type. Couplings should have flanged sleeve hous-ings and integral lips at each end to house the seals andretain the sleeves. Selection normally should be basedon manufacturer’s published rating. Sleeves should befastened so that they cannot work loose or slip off.Couplings with sleeves held in place with snap ringsshould not be permitted.

f. Brakes. Brakes should be of the shoe type, springset, with D-C magnet operated release and should becompletely enclosed in a watertight and dusttight enclo-sure. The brake should have a torque rating not less than150 percent of the full load torque of the motor whenreferred to the shaft on which the brake wheel ismounted, efficiency not being considered. The torquerating should be based on continuous duty. Fuses shouldnot be used in the brake control circuit.

g. Bearings.

(1) Antifriction bearings should be selected in accor-dance with manufacturer’s published catalog ratings.Life expectancy should be based on 10,000 hours B-10life with loads assumed equal to 75 percent of maximum.

(2) Bronze sleeve bearings should have allowableunit bearing pressures not exceeding the following:

(a) Sheave bushings, slow speed, Federal Specifica-tion QQ-C-390B, Alloy C90500, 3,500 psi.

(b) Main pinion shaft bearings and other slow-moving shafts, hardened steel on bronze Federal Specifi-cation QQ-C-390B, Alloy C90500, 1,000 psi.

(c) Bearings moving at ordinary speeds, steel orbronze Federal Specification QQ-C-390B, Alloy C93400,750 psi.

h. Open gearing. Open gearing should have spurteeth of the involute form, to comply with AGMA201.02, ANSI Standard System, “Tooth Proportions forCoarse-Pitch Involute Spur Gears” (InformationSheet A). Strength should be based on static load fromthe Lewis equation modified for pitch line velocity by thefactor (600 + velocity in feet per minute (fpm)) dividedby 600.

i. Efficiency. In computing losses in a lock-gate-operating machine the following should be used as aguide:

(1) Silent chain (includes oil-retainingand dust-tight case) 97%

(2) V-belt (includes both drive anddriven sheave) 90-96%

(3) Spur gear reduction unit up to16:1 ratio 88%16:1 to 40:1 ratio 84%14:1 to 150:1 ratio 78%

(4) Herringbone gear reduction unitSingle reduction 97%Double reduction 95%Triple reduction 90%

(5) Planetary or helical reduction unitSingle reduction 97%Double reduction 95%Triple reduction 90%

(6) Pair of spurgears (Gears only) 97%

(7) Pair of bevelgears (Gears only) 95%

(8) Worm gear reduction unit

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Since worm gears are the most controversialclass of all gearing, the manufacturers shouldfurnish the certified starting and running effi-ciency of the unit, particularly if the unit is oper-ated at other than standard speeds.

(9) BearingsBall and roller 98%Intermediate horizontal

shafts, bronze bushings 95%Very slow speed shafts,

bronze bushings 93%

j. Hydraulic systems and components.

(1) System types. Two basic types of lock hydraulicsystems are currently in use. One is the central pumpingunit type where the system pumps are all located in onecentral location with supply and return extending to thegate and valve operating machinery location on the lock.The other type consists of pumping unit assemblies com-plete with reservoir, valves, and necessary system com-ponents located at each individual operating cylinder, orat each of the four corners of the lock. A pumping unitat each corner could then operate a gate leaf and a taintervalve. If local pump systems are used at each operatingcylinder, they could also be piped to a near valve or gatecylinder for backup hydraulic power.

(a) Central pumping system. Many of the centralpumping systems of the past have used constant displace-ment screw pumps with system operating pressures of900 psi to as high as 1,500 psi. Usually, three mainsupply pumps and one smaller capacity holding pumpwere used. The capacity of the main pumps was suchthat for normal operation two pumps would supply therequired flow. Operation was alternated between thethree pumps so as to equalize wear, while also maintain-ing standby capability. The smaller capacity pressureholding pump was used to build and maintain systempressure and allow the larger pumps to start unloadedand operate unloaded when the gates were not beingmoved. With this system, flow control and decelerationvalves were used to control the speed of the valves orgates. Experience has shown this system to be simple,reliable, and fairly economical. In recent years variabledisplacement piston pumps have been used with thecentral pumping system. Pumps with three to five presetdelivery positions have been used, with one position setat zero delivery so that the pumps can start or idleunloaded. Systems using these pumps rely on the presetvariable displacement to control valve and gate speeds.With these types of pumps, two pumps are required for

each lock so that each miter gate leaf cylinder can besupplied by one pump. With a double lock, the fourrequired pumps provide adequate standby capacitythrough interconnecting valving. On a single lock a thirdstandby pump should be considered; however, if eco-nomics or space requirements preclude installation of thethird pump, the two pumps should be interconnected toprovide standby operational capability at reduced speed,if one unit should malfunction. The variable displace-ment capability makes these pumps very well suited forcontrolling gate speed.

(b) Local pumping system. The local pumping sys-tem is usually used on locks that are not subject to flood-ing (overtopping); however, local pumping systems canbe used with success on locks subject to inundation withspecial attention paid to lock design. Local hydraulicpumping units and controls should not be located in thegalleries on locks which are subject to overtopping.Where galleries are used the galleries should be sealedwith watertight doors; the piping should penetrate thewalls through sealed sleeves; and a sump pump shouldbe provided to handle any leakage incurred. Localpumping systems can utilize any of the conventionaltypes of pumps, with operating pressures in the 2,000- to3,000-psi range acceptable. Large system pressure dropsand high system shock pressures are reduced by theabsence of long hydraulic line runs. Variable displace-ment piston pumps may be best suited for this applica-tion due to their high pressure capabilities, efficiency,and variable flow capabilities.

(2) System operating pressure. Many factors mustbe considered in the selection of the system operatingpressure. Among the most predominate of these factorsare reliability, serviceability, efficiency, safety, and eco-nomics. Also among these factors are pump type, pres-sure rating and capacity, cylinder size and pressurerating, pipe size, friction loss, bursting pressure, andsystem shock. In Europe, operating pressures as high5,000 psi have been used for several years on locks anddams with good success, whereas in the United Statesthese pressures are still not as common with hydraulicequipment manufacturers. System operating pressuresshould be as follows:

(a) Central pumping system operating pressure of900 psi to as high as 3,000 psi should be satisfactory.

(b) Local pumping system operating pressure of1,500 psi to 3,000 psi should be satisfactory anddesirable.

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(3) System components. The manufacturer’s pub-lished pressure rating should be used for the selection ofall system components. All published ratings should beequal to twice the system’s operating design pressure,thus establishing a high level of quality for theequipment.

(a) Cylinders. The types of hydraulic cylinders thathave been used on locks in the past include the speciallydesigned, the tie-rod type, and the mill type. Manufac-turers’ standard mill type is the preferred, as it is knownas the extra heavy duty type. These, however, should bedesigned with a factor of safety of five based on theultimate strength of the material involved. Tie rod cylin-ders have also been used with good success. Wherespecially designed cylinders are required, they may beconstructed of seamless steel tubes on flat plates rolledinto cylinders; forged in one piece with integral flanges;or centrifugally cast steel. Fittings for supply and returnlines to hydraulic cylinders should be mounted on the topor sides of the cylinders. These connections should befor “SAE four-bolt flange” or “SAE straight threadO-ring” connections for installation and maintenanceconvenience. Cylinders should be fitted with air bleedvents and drains at each end of the cylinders. Anotheroptional feature which may be beneficial under certaincircumstances is the adjustable cushion which is used fordeceleration control at stroke limits. Piston rods areusually chrome plated for wear resistance and may behigh strength stainless steel where corrosion is a concern.Ceramic coated rods, which have been used for severalyears in Europe but are relatively new in the U.S., maybe considered for corrosive and abrasive service. Oncylinders that are foot mounted, wedges should be pro-vided between cylinder feet and shear plates to assure atight fit. Specifications should indicate that cylindersshall be shipped with piston rod retracted and restrainedfrom movement. Cylinders should be filled with newhydraulic fluid (the same type as that specified for thesystem) after manufacture to prevent corrosion during thestorage period prior to use. An accumulator charged to100 psi connected to the rod end port to allow for fluidexpansion and contraction is a good method to do this.

(b) Pumps. Several different types of pumps havebeen used in locks in the past; these include gear, vane,and piston (both axial and radial) pumps. The gear pumpis simple in design, rugged, has a large capacity for asmall size, is low in cost, and has a high tolerance forcontaminants in hydraulic fluids. The gear pumps’ lowvolumetric efficiency, high wear characteristics, noise,fixed volume, and relatively short life expectancy makethem undesirable for main pressure pumps. Variable

volume vane pumps are efficient and durable if a cleanhydraulic system is maintained. They are generallyquiet, but may whine at higher speeds, and they arecompact in relation to their output. The piston-typepump is the one recommended for main hydraulic power,as it has the highest volumetric and overall efficiencies,is capable of high output pressures, readily lends itself tovariable displacement, and generally has long life expec-tancy. In order to reduce noise and increase life expec-tancy the pump speed should be 900 to 1,800 rpm. Avariable delivery radial piston type, three to five adjust-able delivery rate pump with solenoid control for selec-tion of pumping rates is a desirable pump for mainhydraulic pressure supply. One of the delivery rates onthe pump should be set at neutral or zero delivery so asto start the pump motor under a no-load condition. Theindividual controls on each pump should be adjustablefrom zero to full flow capacity at each control setting sothat flow rates can be varied in the field to suit minorvariations in operating conditions. The pump shall beequipped with an auxiliary gear pump for pilot pressure,internal pressure relief valves, and an adjustable flowcontrol device to control the speed of shifting betweenpumping rates. Variable volume axial piston pumps withthe swiveling barrel, rather than swashplate, have alsobeen used with good success. These tend to be a highergrade pump with less noise, vibration, and wear than theswashplate design. If an axial piston pump is used, thenan additional auxiliary pump will be required for pilotpressure.

(c) Directional control valves. The directionalvalves normally used are four-way, three-position,blocked center solenoid-controlled pilot operated, spring-centered type. Where the solenoid control is selected,the valve should be equipped with adjustable orifices toslow the action of the spool when changing spool posi-tions. The edges of the valve spools should be groovedto provide a throttling effect when moving from oneposition to another. The tandem center-type spool hasbeen used in the past; however, system diversity islimited by this type of valve. Lever-operated directionalcontrol valves have also been used in the past; but theywill not lend themselves to interlock logic control, sothey should be considered on only the most basic appli-cation. The directional control valve could be the singlegreatest pressure loss point in a hydraulic circuit and,therefore, should be given a great deal of design atten-tion. If practical, the directional control valves should bedesigned for 1.5 to 2.0 times the maximum flow raterequired in order to minimize pressure loss. There areseveral companies that manufacture high quality mani-folds for mounting cartridge-type control valves. This

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type of system can be used to mount directional control,relief valves, counterbalance valves, proportional valves,and other types of control valves. The manifold systemis economical, minimizes pipe fabrication, possibility ofleaks, and space requirements and, therefore, should beused wherever possible. The solenoid-control valve forthe main directional control valve should be providedwith manual operating pins for emergency operationduring solenoid malfunction or failure.

(d) Relief valves. Relief valves that are normallyused on pressure lines are the balanced piston type, inter-nally operated with an adjustable operating range. Thesevalves have been used with good success and haveproven to be rugged and reliable. The manifold andcartridge valve system should be considered as it mayprove to be advantageous because it offers space and costsavings and easy maintenance. The cartridge valvesshould be the pilot-operated poppet type with adjustablepressure relief range. Response times are very quick oncartridge valves, usually in the 10-millisecond range, sothe designer must decide how much slower the poppetshould respond to eliminate the operational shocks.

(e) Flow control valves. Flow control valves, ifrequired, should be of the adjustable orifice type, allow-ing controlled flow in one direction, free flow in theother direction. Where inertia loads such as miter gatesare being controlled by hydraulic cylinders, the flowcontrol valve should be placed to control the oil leavingthe cylinder. When used in conjunction with a counter-balance valve, or in an element moving vertically, theflow control valve should control the oil entering thecylinder. Here again the manifold and cartridge valvesystem should be considered.

(f) Reservoirs. Hydraulic fluid reservoirs shouldhave a minimum capacity in gallons of about three timesthe maximum pump capacity in gallons per minute(gpm). There are other factors also that must beconsidered in sizing of a reservoir. If the reservoir iscross-connected to another system to serve as an emer-gency backup, then an analysis of the potential “overfill”or “overempty” of the reservoir must be accomplished.This is due to the increase or decrease in the volume ofthe operating cylinder to which it is cross-connected.Long line runs and thermal expansion of the fluid mustalso be taken into consideration when sizing the reser-voir. In any case, the reservoir should have a capacity toalways provide a flooded suction to the pump. Theinterior of the reservoir should be coated with a goodepoxy coating system suited for hydraulic service. Thereservoir top, sides, and bottom should be fabricated of

heavy steel plate, 1/4 in. to 3/8 in. thick, annealed andpickled. Internal reinforcing should be provided toensure sturdy mounting for the pump unit, with verticaloil baffles to separate oil return from the pump inlet, andto provide a nonturbulent flow of oil to the pump suc-tion. Consideration should be given to providing vibra-tion isolation between the pump base and the oilreservoir to minimize noise transmission. Reservoiraccessories such as suction filter, oil level gage, lowlevel shutoff switch, magnetic particle unit, drain valve,removable clean-out plates (both ends), reservoir heaters(if required), and replaceable filter breather cap should beprovided. Where reservoir heaters are used, the wattdensity should not exceed 10 watts per square inch.When a free-standing reservoir is used with a centralsystem, it should be of such size as to promote coolingand contaminant separation and allow thermal expansionof the fluid and changes of fluid level due to systemoperation. The design minimum fluid level should behigh enough to prevent vortex formation at the pumpinlet opening. Adequate pump suction submergenceshould be available from the pump manufacturer. Manycentral systems have been built with free-standing tanksof approximately 1,000-gallon (gal) capacity.

(g) Filters. To provide initial cleanup and continu-ous filtering of the hydraulic oil, a full flow, removable-cartridge-type oil filter should be provided in the returnline. Pressure gages should be installed on the filter tankto indicate pressure drop across the filter. Also, a filtercartridge replacement indicator would be beneficial tomaintenance personnel. A system should be provided toindicate when oil is bypassing the filter. Filter elementsshould be capable of removing particulate matter of10 micrometers, with a filtration ratio (Beta) of B10 = 75.The Beta (Bn) is the ratio of the number of particlesgreater than a given size (n) in the influent fluid to thenumber of particles greater than the same size (n) in theeffluent fluid. ANSI B93.30M should be referenced forthe B10 filtration ratio test procedure. Since proper oper-ation of the control valves, relief valves, and pumpsdepends on the cleanliness of the oil used, it is a veryimportant consideration in the design of the hydraulicsystem. Very rigorous specifications should be preparedrequiring recirculation of all oil in the system through thesystem filter before the unit is put into operation. Whena separate pilot pressure pumping system is provided, anin-line, system pressure filter with a replaceable cartridgeshould be furnished in the pump discharge line.

(h) Accumulators. Accumulators should be used insystems with long lines to minimize the effect of systemshock pressures.

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(i) Piping. Piping for hydraulic systems which arefree from appreciable shock, vibration, and external loadshould be designed for a safety factor of six based on theoperating pressure. Where severe shock, mechanicalabuse, or vibration are likely to occur, then a safetyfactor of eight should be used. Where flexible hoses areused they should be designed with a minimum safetyfactor of eight. Also, exposure to the elements, anyabnormal equipment hazard, and chafing are elements tobe considered in the design of flexible hoses. Normally,piping should be seamless, black steel pipe, pickled andoiled with forged steel weld fittings. Piping 2 in. andsmaller should use socket-weld-type fittings, and over2-in. piping should use butt-weld type. Where pipingcrosses under the lock chamber, or other applicationssubject to very corrosive conditions, stainless steel pipeand fittings should be used. Hydraulic tubing with flare-or swage-type fittings may be used with package-typepump units. Expansion joints are normally not required,or recommended; however, every piping system shouldbe analyzed and adequate provisions made for pipeexpansion and movement. Pipe hangers should be of atype that are not rigidly connected, in order to preventbreakage from line shock or pipe movement within thehanger. Some desirable features that should be consid-ered for maintainability of a hydraulic piping system are:

(1) Piping should be pitched a minimum of 1/2 in.per 50 ft in order to provide high and low points.

(2) Air bleed valves should be provided at highpoints in the system.

(3) Drain valves should be provided at low points inthe system.

(4) Periodic shutoff valves should be provided, espe-cially in long runs, to facilitate maintenance withoutcomplete system drainage.

(5) Periodic pressure gage ports with gage cocksshould be considered for installation of gages for systemtroubleshooting.

With the central pumping system, supply and return linesat the ends of long runs of piping should have a valvedcross-connection to permit start-up, or periodic flushing.Piping for hydraulic systems should be hydrostaticallytested at 150 percent of system design pressure.

(j) Fluid velocity and pressure drops. The selectionof fluid velocity for the computation of pipe friction is,in general, a compromise between limitations of pressure

drop and limitations of line size. The following para-graphs indicate the general range of velocities acceptable.

(k) Pressure supply lines. The velocity in supplylines is generally held between 10 and 15 feet per second(fps), although for very short lines, as used in thepackage-type unit, velocities up to 20 fps are not consid-ered excessive.

(l) Return lines. Generally the velocity in returnlines is kept basically the same or slightly less than thevelocity in supply lines.

(m) Pump suction. Velocities in pump suction linesnormally are in the range of 2 to 5 fps. Pump suctionlines deserve special attention to velocity since the pres-sure drop in the line together with the pressure dropthrough a suction filter, if used, can be detrimental topump performance, especially during cold start-up.Excessive pressure drop in the pump suction line is afrequent cause of pump cavitation.

(n) Drain lines. Although flow in the drain linesfrom the valves is normally very small, velocity must bekept low to avoid pressure drop which is reflected asback pressure on the drain port of the component beingdrained. Excessive back pressure in draining can resultin malfunctioning of valves and damage to seals. Com-ponent manufacturer’s limitations on maximum allowableback pressure on drain ports should be followed in allcases. If the component being drained is located belowthe level of the fluid in the reservoir, the pressure due tostatic head must be added to the pressure drop to deter-mine the total back pressure. In computing the velocityin drain lines, the fluid flow should be based upon themaximum allowable drain flow at which replacement oroverhaul is required, rather than the flow from a newcomponent, and should be based upon the viscosity ofthe fluid at operating temperature.

(o) Pilot lines. Normally the flow through pilot linesis small enough so that velocities will be low. In anyevent velocities should not exceed 10 to 15 fps.

(p) Hydraulic fluid. A petroleum oil with a highviscosity index should be selected to minimize thechange in pipe friction between winter and summermonths. The oil selected must have a viscosity rangesuitable for the system components and their expectedoperating temperature range. Generally, the maximumviscosity range is between 4,000 Saybolt Universal sec-onds (SSU) at start-up and 70 SSU at maximum operat-ing temperature. However, this range will vary between

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manufacturers and types of equipment. In the case of asystem containing a large quantity of fluid, rust andoxidation inhibitors should be added. An alternate to theabove-recommended hydraulic fluid is a relatively newbiodegradable and nontoxic fluid. This fluid usesvegetable-based oils and synthetic additives to providespecific properties which are required in hydraulic fluids.

This fluid meets some pump manufacturers’ require-ments, but it does not meet all manufacturers’ require-ments, as of this date, so care must be exercised inselecting this fluid. Also, there is only one manufacturerwhich produces this fluid at present. This fluid, whileclear when new, turns amber with age and usage. Thismay or may not be a problem.

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Chapter 2Miter Gates

2-1. Miter Gates, Horizontally Framed

a. Stress analysis. The primary structural elementsof a single gate leaf consist of a series of horizontalgirders, connected vertically by a skin plate, two enddiaphragms, and a number of intermediate diaphragms.(See Plate B-1.) The horizontal girders are in effect aseries of three-hinged arches which transmit the waterpressures to the lock walls through the quoin hinges.They are subjected to combined bending and directstresses. The system of vertical diaphragms forms aseries of vertical continuous beams supported by theelastic horizontal girders.

(1) In the following general solution for a three-hinged arch, the vertical stiffness of the gate leaf isneglected. Figure 2-1 shows a horizontal girder (half ofa three-hinged arch) acted upon by water pressure due todifferential head varying in magnitude with the depth ofthe girder below the water surface and the panel widthwhich it supports. The following symbols are usedthroughout to describe reactions in the mitered position.

R = reaction of the girder at the wall quoin andmiter blocks

N = component of R perpendicular to work line ofleaf

P1 = component of R parallel to work line of leaf

P2 = the corresponding water force on the end ofeach girder, determined from the water pressureon the surface extending from the contact pointto the upstream side of the skin plate

W = total corresponding water force on each girder,determined by the pressure and the length ofthe leaf, adjusted by the effective width ofdamming surface. (See Figure 2-1 andPlate B-3 for the relation of R, N, P1, and P2 tothe total force W.)

(2) The three-hinged arch formed by the two leavesis symmetrical about the center line of the lock, and,therefore, the miter end reaction R is perpendicular tothis center line. If R is extended to intersect the resultantwater load W, and from this point of intersection a line isdrawn to the point of contact at the quoin end, this line

will give the work line which connects the quoin and themiter contact points. The angleθ is the complement ofone-half of the miter angle. Referring to Figure 2-1, thebending moment at x distance from the contact point:

(2-1)Mx

w2

[L(x) L(a) cot θ

(t a)2 a 2 x 2]

Bending moment at center of span x = L/2

(2-1a)Mc

w2

[L 2/4 L(a) cot θ

(t a)2 a 2]

Bending stress in upstream extreme girder fiber:

(2-2)fb1

w(t a)2 I

[L(x) L(a) cot θ

(t a)2 a 2 x 2]

where

I = moment of inertia of the girder

Bending stress in downstream extreme girder fiber:

(2-3)fb2

w(d t a)2 I

[L(x) L(a) cot θ

(t a)2 a 2 x 2]

Axial stress in the girder:

(2-4)fa

wA

[L/2 cot θ t]

where

A = cross-sectional area of girder

Combined axial and bending stresses:

Upstream flange:

fc1 = fa + fb1

or

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(2-5)fc1 fa

w(t a)2 I

[L(x) L(a) cot θ

(t a)2 a 2 x 2]

Downstream flange:

fc2 = fa - fb2

or

(2-6)fc2 fa

w(d t a)2 I

[L(x) L(a) cot θ

(t a)2 a 2 x 2]

(3) For small values ofx, the downstream flange willbe generally in compression. Asx is increased towardthe midpoint of the leaf, bending stresses will increase sothe downstream flange will be generally in tension.Hence, by moving the work line downstream, a saving inweight may be achieved in the center portions of the leafwhere the upstream flange is in compression and thedownstream flange is in tension or less compression.Considering the girder as a whole, then, the work lineshould be as far downstream from the neutral axis as ispracticable.

(4) The foregoing analysis of the statically deter-minate forces and stresses affecting the horizontal girdersof a gate will serve to indicate approximate dimensions.Common practice is to design the lower girders of thegate for full hydrostatic loads, and to assign loads greaterthan the hydrostatic to upper girders. These additionalloads give greater vertical stiffness to the leaf andapproximate tow impact loads.

(5) Initial approximate dimensions may be taken asfollows (see Figures 2-1 and 2-2).

(a) A common value forθ is arc tan 1/3 = 18 deg,26 min, 6 sec, which gives an exact bevel of 1L on 3T(L = longitudinal, T = transverse).

(b) The length of the leaf then becomes 0.527 timesthe distance between quoin contact points of the gate.

(c) A first trial value, for gates of moderate height,for the depthd may be taken as 0.07 times the length ofthe leaf, but a minimum depth of 48 in. Refer to para-graph 2-1d(3) for additional guidance.

(d) The distance from the downstream girder flangeface to the work line (d - t) may be set at a practicalminimum of 4 in.

b. Loads and reactions. The following loading con-ditions represent various combinations of loads andforces to which the gate structure may be subjected:

(1) Loading condition I. Working stresses specifiedin paragraph 1-7b will be applied to loads listed below:

(a) Dead load (including ice, mud, etc., on leaf).

(b) Live load (bridgeway and walkway live loadswithout impact).

(c) Water pressure (hydrostatic load due to pooldifferential).

(d) Barge impact load (point of load applied abovepool at miter point (symmetric impact), and anywhere towithin 35 ft, the standard barge width, of either lock wall(unsymmetric)).

Impact, I = 250 kips (symmetric)I = 400 kips (unsymmetric)

(e) Gate diagonal prestress loads.

(f) Operating strut loads on gudgeon pin assembly,eye bars, and embedded anchorage. Normal submer-gence and obstruction are assumed with gate leaf in therecessed and mitered positions.

(2) Loading condition II. When the loading includesin addition to condition I loads any of the loads listedbelow, a 1/3 overstress of working stresses specified inparagraph 1-7b will apply:

(a) Earthquake loads (inertia force of gate mass plusdynamic water load).

(b) Water loads (increased hydrostatic loads due todewatering for maintenance).

(c) Thermal stresses.

(d) Wave loads, including reverse head due to tem-poral loads (overfill, overempty, etc.)

(e) Wind loads.

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(3) The loads causing gate leaf deflection and torsionduring operation of the miter gate are determined asfollows: The bottom edge of the leaf is assumed to beheld (zero deflection) by water and/or submergedobstruction, the vertical quoin edge is supported by thegudgeon pin and the pintle assembly. Maximum machin-ery load is applied to the top of the leaf under the above-described edge support conditions. This machinery loaddeflects the leaf causing an increase or decrease in ten-sion in the prestressed diagonals and torsional stresses inthe horizontal girders.

(4) Gate reactions are basically divided into twocategories: one, with the gate in the open or intermediateposition with no water load; or two, with the leavesmitered and supporting the full hydrostatic load. Withthe gate in the unmitered (intermediate or open) position,the leaf reactions are couple-forces, applied at the gud-geon pin at the top and the pintle at the bottom. The topcouple-force is made up of the gudgeon pin reactionforce combined with the operating strut force, while thebottom or pintle force results from the leaf reaction onthe pintle. Leaf reaction and strut forces due to all load-ing conditions defined above will be considered in deter-mining the governing force combinations for design ofthe gudgeon pin and pintle assemblies. (See Plate B-8.)With the gate adhering and the full hydrostatic loadapplied, each horizontal girder carries a portion of thewater force to the wall monoliths.

c. Skin plate, intercostals, and diaphragms.

(1) Skin plate. The skin plate is located on theupstream face of the girders and is designed for the waterload, with the edges of panels assumed fixed at the cen-ter line of intercostals and the edge of girder flanges,except that where the flanges are greater than 12 in. widethe skin plate is assumed fixed at a point 6 in. from thecenter line of the web. The skin plate is also consideredan effective part of the upstream girder flange. When asection has a skin plate of a higher yield than the rest ofthe girder, the effective width of skin plate shall be deter-mined by the higher yield point. Due to the combinedloading the skin plate shall be checked for biaxial stress,composed of skin plate action and beam action. TheHuber-Mises formula is convenient for checking biaxialstresses.

(2-6)S2 S 2x SxSy S 2

y

where

S = combined stress≤ 0.75 Fy

Sx = normal stress inx direction

Sy = normal stress iny direction

Fy = minimum yield stress of steel being used

The most effective panel shape for a skin plate is asquare, but due to maintaining a uniform intercostalspacing from top to bottom of the leaf, and the variablegirder spacing, the panels are usually rectangles, with aratio of the short side to the long side of the panel,varying from about ± 0.45 at the upper panels to approxi-mately 1.0 on the more critical lower panels. Assuminga rectangular panel with all edges fixed, the followingsymbols and formulas are used to determine stress in theskin plate from water force only. (See Roark and Young1975.)

w = unit load at the center line of the panel (averagehead)

a = greater dimension of the panel

b = smaller dimension of the panel

q = ratio of b to a

t = thickness of plate

Stress at the center line of the long edge =

0.5wb2

t 2(1 0.623q 6)

Stress at the center line of the short edge =

0.25wb2

t 2

(2) Intercostals. Intercostals are designed as verticalfixed end beams supported at the center line of girderwebs.

(a) An effective section of skin plate is assumed asacting with the intercostal, the effective width determinedin accordance with the AISC Specifications. (Unstif-fened elements under compression.)

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(b) An average water pressure (head at the center ofthe panel supported by the intercostal) is used for designof the intercostal, with the loading extending from edgeto edge of flanges (maximum of 6 in. from center line ofgirder web).

(c) When the skin plate is of low-alloy steel and theintercostal is of structural grade steel, the acting compos-ite section of skin plate and intercostal shall be governedby the allowable stress for the lower strength material.(See Figure 2-3 for additional information onintercostals.)

(3) Diaphragms. The end diaphragms are designedas panels acting as skin plate, with the effective panelbeing between the stiffener angle and the next lowergirder. The stiffener is located at midpoint betweengirders. The head at the center of the effective panel isused as the design pressure. Intermediate diaphragmsshould be spaced and sized as follows:

(a) To provide adequate supports for horizontalgirders (weight and lateral buckling).

(b) For shear forces resulting from the diaphragmstending to equalize differential deflections between adja-cent horizontal girders due to variation of hydrostatic andimpact loads.

(c) For operating machinery, jacking support, anddiagonal tension-related loads.

The critical buckling stress should be kept below 70 per-cent of the yield stress of the diaphragm material. Onsmaller gates the intermediate diaphragms are made aminimum of 3/8 in., while the minimum for larger gatesis 1/2 in. Generally the end diaphragms are made aminimum of 1/2 in. for all sizes of gates. Diaphragmsare made as deep as the girder webs, and stiffeners thesame size as the longitudinal web stiffeners are used asvertical stiffeners on the intermediate diaphragms. Fordetermining critical buckling stresses in flat plates inedge compression and shear and establishing allowablediaphragm panel sizes refer to Timoshenko (1936),Bleich (1952), and Priest (1954).

d. Horizontal girders. Horizontal girders lie along achord of the thrust line curve, with the resulting eccen-tricity of thrust producing bending stress in addition tothe axial stress.

(1) The girders are so spaced that variation in thegirder flange sizes and skin plate thicknesses are held to

a minimum. The spacing usually varies from a maxi-mum of 6 ft at the top to a minimum of 4 ft at the bot-tom of the leaf. Each girder should be equal to orsmaller than the one immediately below, with the excep-tion of the top girder. Girder spacing also influences thesize of intercostals.

(2) The loads on each girder are determined bytaking the average water load per linear foot of girder.While this gives slight variation from the exact loadingfor some girders, (generally two girders per leaf) theaverage is considered to be more than accurate enoughfor the usual gate loading. Consideration should begiven to any special loading condition to determine if theactual loading should be used instead of the averagedescribed above. The boat impact loads are usuallygoverning for the uniformly spaced upper girders.

(3) The ratio of the depth of girder web to the lengthof leaf varies from 1/8 to 1/15 for most gates, the greatervalue occurring on gates having the higher heads.Deeper girders make the leaf torsionally stiffer but mayrequire web stiffeners. The appropriate sections of theAISC specifications shall be used to check for webbuckling and web crippling. Horizontal girder websshould be stiffened with horizontal stiffeners to meet thecriteria for web buckling for axial loaded columns usingthe diaphragm spacing as the effective column length.Minimum horizontal stiffeners are generally used ongirder webs even though not required by web buckling.The minimum width of stiffeners shall be 3-7/8 in., usedwhere the minimum flange width of 8 in. is used.

(4) Minimum thickness of material shall be 3/8 in.for webs and stiffeners and 1/2 in. for flanges. Theminimum width of flange plates shall be 8 in. for theupstream flange and 12 in. for the downstream flange,with the exception of the bottom girder. The down-stream flange of the bottom girder can be a minimum of9 in. wide, with 3 in. below the center line of the web toprovide additional clearance between bottom girder andsill. For the end sections of the bottom girder, where thedownstream flange is heavier, the upper portion of theflange can be made a maximum width of 15t above thecenter line of the web, maintaining the 3 in. below theweb center line and limiting the overall width of theflange to 1 ft 3 in. For all other flanges the maximumoverall width should be limited to 24t, thereby reducingthe possibility of flanges being undesirably wide andthin. The use of cover plates is not recommended for theusual gate design. (See Plates B-3 and B-5.)

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(5) The maximum extension of skin plate above thecenter line of the top girder is 8 in., to prevent interfer-ence with the operating strut. The maximum extensionof skin plate above the top flange should not be over1/2 in., limiting the maximum width of the upstreamflange for the top girder to 1 ft 3 in.

(6) Buckling of the girder about the major axis is nota concern since the skin plate provides lateral support toeach girder. However, lateral stability of the downstreamflange should be checked where that flange is in com-pression near the end diaphragms.

(7) The girder should be checked for buckling aboutthe minor axis. The length shall be taken as the distancebetween quoin and miter bearings, with K = 1. Theradius of gyration to be used may be calculated for thecenter part of the girder. However, this may be slightlyoverconservative. If this calculation shows that bucklingstrength is a controlling condition, use the followingmore realistic value for the radius of gyration.

(2-7)rx (L1 x rx2)2(L2 x rx1)

L1 2(L2)

where

rx1 and rx2 = major axis radius of gyration ofrespective sections

L1 andL2 = lengths of respective sections

For additional information, see USAEWES (1987).

(8) The web depth-to-thickness ratio should be suchthat no reduction in flange stress is necessary. See theAISC specifications for the maximum ratio.

(9) Transition of flange widths at butt joints shall begoverned by the applicable provisions of Structural Weld-ing Code, AWSD1.1. The maximum change in flangewidth, on the same edge of a girder web, shall be 6 in.,with a 3-in. differential on each edge of the flange, withthe exception of the downstream flange of the bottomgirder, where the total 6-in. differential may be on theupper edge of the flange. This applies between the sec-tion at the center line of a girder, where the upstreamflange is a maximum width and the downstream flange isa minimum width, and a section at the end of a girderwhere the upstream flange is a minimum width and thedownstream flange is a maximum width. A taperedflange transition is also preferred where all horizontaland vertical flanges connect to gusset plates with themaximum change being as previously described.

(10) The flanges of the bottom girder are offset fromthe center line of the girder web as indicated by thepreceding paragraphs. The downstream flange shouldextend 3 in. below the center line of the girder web, fromend to end of girder, to allow for clearance between theflange and the sill. The upstream flange should extend6 in. below the center line of the girder web, from end toend of girder, with the skin plate 1/2 in. above the loweredge of the flange. A minimum of 4 in. should be usedabove the center line of the web, thereby making a mini-mum width of 10 in. for the upstream flange of the lowergirder. (See Plate B-5.)

(11) The load in the diagonal is resisted by membersconnected to the gusset plate. The horizontal componentof this load is distributed among several girders. Thedesign of all girders attached to the gusset plate shallinclude provisions for this additional eccentric axial load.A discussion of the distribution of this load among thegirders may be found in Technical Report ITL-87-4,Report 7 (USAEWES 1987).

(12) Drain holes shall be provided in all girder websexcept the top girder where the drain holes shall beplaced in the upstream flange, since the web of the topgirder forms part of the damming surface during highwater.

(13) The critical point for the tapered end sectionsoccurs at a distance Z’ from the center line of bearing.

Z span 16t2

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where the span is the smaller span adjacent to the webunder consideration andt is the thickness of the thrustdiaphragm. (See Figure 2-4.) Due to the short lengthsinvolved, Fa and Fb are equal to the basic stress of0.50 Fy.

(14) The moment is determined by assuming a canti-lever section equal in length to Z’ with a water loadequal to w, plus the moment created by R being eccentricfrom the centroid of the section. See paragraph 2-1e onthe thrust diaphragm for more information relating to thedistribution of stress from the end plates to the webs.

(15) The web thickness of the tapered section isincreased to keep the stress within the allowable limits.If a thicker tapered end web is required, this thickness iscarried 12 in. past the end diaphragm. This may vary onthe bottom girder where the stiffeners for the jackingsupport may interfere. A check should be made forconcentrated stresses in the web just inside the end dia-phragm. This stress is caused by the thrust diaphragmending, transferring its load into the web. It is recom-mended that 20 percent of the thrust diaphragm load andan area of 40 percent of the web depth and correspond-ing thickness, including any stiffeners in the area, beconsidered for the check. The bottom girder web thick-ness over the pintle is 3/4 in. minimum and machined toa 250 finish or match the machine finish to the top of thepintle socket casting. (See Figure 2-5.) The top andbottom webs are wider at the quoin end to accommodatethe gudgeon pin and pintle. (See Plates B-3, B-4, andB-5 for additional information on girders.)

e. Thrust diaphragms. The thrust diaphragm is tan-gent to the thrust curve at the contact point and isapproximately in line with the thrust curve between thecontact point and the end diaphragm, which is the limitof the thrust diaphragm. The thrust diaphragm serves todistribute the reaction of the girders from the quoin blockinto the girder webs. It also acts as the damming surfacebetween the end plate and the end diaphragm. Part ofthe thrust diaphragm is also considered effective in thequoin post, making it subject to bearing, skin plate, andcolumn action stresses. Shear between the web andthrust diaphragm is to be checked also, but is not com-bined with the above-listed forces. The allowable stressfor the combined bearing and skin plate action, occurringadjacent to the end plate, is limited by the elastic limit or0.70 Fy, whichever is the lesser value. The stress in thethrust diaphragm is assumed to follow a 45-deg anglefrom a point midway between girders, up to the effective

web section. The effective section consists of the web,flanges, and a portion of the thrust diaphragm. SeeFigure 2-4 for the layout of this stress pattern for thetapered end section. The elastic limit may be determinedby assuming the panel under consideration to be clampedon all edges and equal uniform compression on twoopposite edges, with the critical stress equal toK[E/(1 - v2)](t/b)2

where

a = longer dimension of panel

b = shorter dimension of panel

v = Poisson’s ratio

t = thickness

K = 7.7 for a ratio of a/b = 1.0



See Roark and Young (1975) for additional informationon elastic stability.

f. Quoin post. A section of the thrust diaphragms,vertically from top to bottom girders, forms a column tosupport the dead weight of the leaf. The end plate andtwo vertical stiffeners form one flange of the column; aplate perpendicular to the thrust diaphragm, with verticalstiffeners on the outside edges, form the other flange.See Plate B-5 for a typical layout of the quoin post. Theaxial load on the quoin post consists of the dead weightof the leaf plus ice and mud load. Due to the eccentric-ity of the pintle and gudgeon pin with respect to thecentroid of the quoin post, the quoin post is subjected toan axial stress and bending stresses, plus the skin plateaction of the thrust plate.

The maximum combined stress may occur at the center

(2-8)Stress PI

PecIx

PecIy

skin plate stress

of the lower edge of the thrust diaphragm panel, shownas point C or at any of the extreme corners of the quoinpost cross section shown as points A, B, E, and F inPlate B-5. The allowable stress for the combined loadingis limited to the basic stress of 0.50 Fy.

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g. Gudgeon pin hood and anchorage.

(1) Gudgeon pin and hood. The gudgeon pin hoodis an arrangement of plates forming the hinge connectionat the top of the miter gate leaf. (See Plate B-6.) Thecommended distance between the center line of the topweb and the center line of the top pin plate is 1 ft6-3/4 in. This is with a 1-in. top pin plate and 1-1/4 in.pin plate welded to the top girder web. The top pin platehas sections of it sloping from the 1 ft 6-3/4 in. heightdown to the girder web. The downstream edge of thetop pin plate is attached to the 1/2-in. section of thebulkhead plate with a weld. The upstream part of thehood is formed by a vertical plate, normally 3/4-in. mini-mum thickness, that overlaps the upstream girder flange,with the edge of the vertical hood plate being welded onthe center line of the horizontal girder web.

(a) The top pin plate should be designed as a curvedbeam with a uniform load rather than assume the plate tobe an eye bar. Formulas from Seely and Smith (1952),are shown in Plate B-7. The basic stress of 0.50 Fy

should control.

(b) The pin is generally made a minimum of 12 in.in diameter, to give an additional factor of safety and tostandardize the barrel and hood arrangement.

(c) The pin is usually made of forged alloy steel,ASTM A668, normalized and tempered, with the allow-able stresses as referenced in paragraph 1-7b.

(d) The bushing is normally of bronze with the bear-ing pressure kept below 1,500 psi.

(e) Rings of ASTM A36 steel varying in thicknessfrom 1/16 in. to 1/4 in. are used to adjust the verticalclearance between the gudgeon pin barrel and the pinhood.

(2) Anchorage. The anchorage system supportingthe miter gate leaves is divided into four basic catego-ries: (a) gudgeon pin barrel, (b) anchorage links,(c) embedded anchorage, (d) pintle and pintle base.While these components act together as a unit, each isdesigned as an individual unit. The force applied to eachof these units is the resultant force of the combined strutforce and the dead weight of the leaf, increased 10 per-cent for impact. The governing loads usually occur atthe recessed (open) or mitered (closed) positions of thegate leaf. In order to develop maximum operating strutforces the leaf is assumed obstructed near its miter end.The anchorage system is also checked for temporal loads.

(See Plates B-11 and B-15 for the layout of typicalanchorage systems.)

(a) Gudgeon pin barrel. The gudgeon pin barrel, ofwelded carbon steel plates or forged alloy steel plates, isdesigned as a continuous beam supported by verticalstiffeners, and at the same time as a curved beam, madeup of a horizontal plate and an effective section of theplate cylinder which forms the pin barrel. The minimumthickness of the barrel or horizontal plate should not beless than 1-1/2 in. See Plate B-9 for a typical barrelarrangement and formulas. The alternate method ofanalysis shown in Plate B-10 may be used in lieu of themore precise method beginning in Plate B-9. While thealternate method stresses vary from the more accuratemethod, the variations are on the conservative side. Dueto the barrel being a critical item the design stressesshould be kept low, in the range of approximately0.33 Fy, using the yield point of the lowest grade steelused in the composite barrel unit. This stress should bethe combined stress due to bending and direct stress.

(b) Anchorage links. The links are made up ofpinned ends connecting to the embedded anchorage witha threaded section between the embedded anchorage andthe gudgeon pin. Each link is designed as a tension orcompression member individually, and the two links arechecked as a unit, as shown in Plate B-11. An alternatetop anchorage is shown in Plate B-15. This assembly ismade up of two anchor arms and two gudgeon links.The links are welded to the arm which is normal to theface of the lock wall. Adjustment of this anchorageassembly is accomplished by means of wedges. Thedesign procedure is as described above. The designtension force is the tension load plus 10 percent impact,and the design compression force is the compression loadplus 10 percent impact. The links acting as a unit areassumed to have a maximum misalignment of 2-1/2 in. atpoint B, shown in Plate B-11. This introduces a bendingstress in conjunction with the axial load. Allowabletension and compression stresses should be determined inaccordance with fatigue criteria of ASSHTO StandardSpecifications for Highway Bridges or in accordancewith paragraph 1-7b of this manual, whichever governs.The threaded section of each link, made up of a forgedsteel section a minimum of 6 in. in diameter, and a hex-agonal sleeve nut are used for adjustment of the gateleaf. Right- and left-hand threads, giving a turnbuckleeffect, are recommended, with 1/2-in. square threadsbeing used for the sleeve nuts. After all adjustments tothe gate leaf have been made, a channel may be weldedbetween the sleeve nuts to lock them in place. The out-side diameter of the section threaded for the sleeve nut

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should be the same as the largest dimension of the rect-angular section. The rectangular section of the link, aminimum of 6 in. by 4 in., is also made of forged steel.The pin-connected ends of the rectangular sections aredesigned as eye bars, with the allowable stresses being83 percent of those shown in AISC. Pins should bedesigned for both bending and bearing, with the allow-able stresses determined as indicated in paragraph 1-7b.The dimensions and sizes shown in Plate B-11 arerecommended as a minimum unless special conditions orloadings warrant a variation in some dimensions.

(c) Embedded anchorage. In order to distribute thetop reaction of the leaf into a larger segment of concrete,the embedded anchorage is designed as a triangular unit,composed of a heavy member for the hypotenuse andvertical side and a secondary member for the horizontalside. The vertical and horizontal sides of the triangle arenormally 9 ft with the hypotenuse forming a 45-degtriangle. The hypotenuse and vertical member aredesigned as a column or tension member, depending onthe direction of the gate reaction. The horizontal orsecondary member is for fabrication and construction andis assumed to carry no design load. The reactions of thetriangular unit are applied to the concrete through platesor pads on the lower points of the triangle. Bolts areused in conjunction with the bearing plates, with thebolts prestressed so that bearing on the concrete willnever be completely relieved by the loads from the gateleaf. See Plates B-12 and B-15 for typical layout ofembedded anchorage. The prestressed bolts should havean anchor at the ends to carry the full load, assuming noload transfer through bond and using mastic to preventbond on the bolts. Bolts should be sized according toload, and the length should be sufficient to extend into atleast two lifts of concrete. The use of strain gages or anultrasonic bolt stress monitor is recommended for deter-mining the desirable loads in the prestressed bolts, as thenuts sometimes bind on one edge and thereby distorttorque readings and make the turn of the nut methoddifficult.

h. Pintle assembly. The pintle and related compo-nents support the dead weight of each leaf of the mitergate. The unit is made up of four major components:(1) pintle socket, (2) pintle, (3) pintle shoe, and (4) pintlebase. (See Plates B-13 and B-14.)

(1) The pintle socket is made of cast steel and isconnected to the bottom of the lower girder web withturned monel or stainless steel bolts. The bolts are sizedto carry the gate leaf reaction in shear, but, as an addedsafety factor, a thrust plate should be welded to the

underside of the bottom girder web, with a milled contactsurface between the plate and pintle socket. The mini-mum plate size should be 1-1/4 in. in thickness and12 in. wide, with a length as required by the girder web.The socket encloses the bronze bushing which fits overthe pintle ball. An allowable bearing stress of 1,500 psiis desirable but may not always be practical. The auto-matic greasing system allows a higher bearing stress butshould not exceed 2,500 psi. See Plate B-13 for addi-tional information.

(2) The pintle, generally made of cast alloy steelwith a nickel content of 3 to 5 percent, is usually 10 in.to 20 in. in diameter, with the top bearing surface in theshape of a half sphere and a cylindrical shaped bottomshaft. For salt or brackish water locations, pintles shouldbe of forged alloy steel with bearing surfaces ofcorrosion-resisting steel deposited in weld passes to athickness of not less than 1/8 in. and machined to therequired shape. The pintle ball and bushing are finishedto a 16-microinch finish where the two come in contact.

(3) Pintle assemblies used for horizontally framedmiter gates are generally two types: fixed and floating.

(a) Fixed pintle. This type of pintle is recommendedfor new construction and major gate rehabilitation. Thepintle fits into the pintle shoe, which is bolted to theembedded pintle base. The degree of fixity of the pintledepends on the shear capacity of the pintle shoe bolts.The pintle should be designed so that after relieving theload on the pintle by jacking, the pintle assembly iseasily removable. See Plate B-16 for typical fixed pintle.The pintle base, made of cast steel, is embedded in con-crete, with the shoe fitting into a curved section of theupper segment of the base. The curved section, of thesame radius as the pintle shoe, is formed so that undernormal operation the reaction between the shoe and baseis always perpendicular to a line tangent to the curve ofboth shoe and base at the point of reaction.

(b) Floating pintle. This type of pintle is not recom-mended for new construction. The pintle is fitted into acast steel shoe, with a shear key provided to prevent thepintle from turning in the shoe. The shoe is not fastenedto the base, thereby allowing the gate leaf to move out-ward in case of debris between the quoin and wall quoinpreventing the leaf from seating properly. SeePlate B-13 for typical floating pintle. Damage to thepintle bearing has occurred frequently with this type ofpintle due to the relative movement between the pintleshoe and base. The movement can consist of the shoesliding on the base during leaf operation from either the

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mitered or recessed position, until the leaf reachesapproximately the midposition, at which time the shoeslides back against the flange on the base. This type ofmovement is generally visually detectable and causesserious wear. However, an alternative to the floatingcircular shoe is to make the shoe three sided with onecorner having the same radius as the circular shoe, andattach a steel keeper bar to the embedded base in front ofthe shoe. This would prevent the shoe from rotating onthe embedded base and prevent the pintle from movingout of pocket. Again, the degree of fixity would dependon the shear capacity of the bolts in the keeper bar. Thisalternative will meet the requirements of the fixed pintleas well as the capacity to minimize damage in case ofemergency.

(4) The pintle base is designed so that there will be acompressive force under all parts of the base. The valueof the compressive force on the concrete will vary from amaximum on one edge to a minimum on the oppositeedge. Computations are based on that portion of thepintle above the point under consideration acting as acomposite unit. The overturning moment can be foundfrom the horizontal force on the pintle and will beresisted by the reaction on the section being investigated.The eccentricity of the vertical force can be determinedby the angle the resultant makes with the horizontal andthe distance between the horizontal force on the pintleand reaction on the pintle base.

(5) The center line of the pintle (vertical axis ofrotation) is located eccentric (upstream) relative to thecenter of curvature of the bearing face of the quoin con-tact block. This center of curvature is on the thrust line.The center line of pintle should be located on the pointof intersection of the bisector of the angle formed by themitered and recessed gate leaf work lines and the perpen-dicular line from the bisector to the quoin contact pointresulting in an offset of approximately 7 in. as in thedetails shown in Plate B-4. Studies and experience showthat eccentricities arrived at by the above-describedmethod will reduce the contact time between the fixedwall quoin and the contact block of the moving gate leafsufficiently to minimize interference and binding betweenthe bearing blocks. The 7-in. offset will be exact andconstant for all gates with the same miter angle anddistance from the face of lock chamber to the recessedwork line (1 ft 2-1/2 in.) as shown in Plate B-4 and inthe example in Appendix C.

i. Operating strut connection. The operating strutconnection for horizontally framed gates is generally oneof three types, the basic types being the hood, vertical

shaft, and direct acting cylinder. Each type has itsadvantages and disadvantages, and the selection of whicho use can only be made after considering all pertinentfactors. The different types are described below withsome of the main characteristics given for each one.

(1) Hood-type connection. This connection, com-monly used with the Panama, Modified Ohio, or theOhio type machine is attached to the top girder on a linethrough the center of the pintle and parallel to the workline of the leaf. Three vertical diaphragms, usually oneof the regular intermediate diaphragms and two additionaldiaphragms, spanning between girders one and two,support the connection in the vertical direction. Thehood is designed for both moment and shear with a stan-dard rolled tee, under the center of the pin, and spanningbetween the vertical diaphragms. The stem of the tee iswelded to the underside of the top girder web and theends of the tee are welded to the three verticaldiaphragms. The strut is connected to the hood by twopins, one larger vertical pin and a smaller horizontal pinthrough the vertical pin, forming a universal joint tominimize moment in the strut. The vertical pin isdesigned for both moment and shear, with the pin sup-ported by bearing collars and bushings at the upper andlower ends. The bearing collars are attached to the sup-porting horizontal plates by turned bolts, which are sizedfor shear. Shear normally will determine the size of thehorizontal pin. Plate B-33 shows typical details for thehood-type connection.

(2) Vertical-shaft-type connection. This connectionconsists of a vertical cylindrical shaft extending throughthe web of the top girder down to the web of the secondgirder. It has generally been used with a cylindrical ortubular strut utilizing ring springs. As the shaft is free torotate in its supporting bearings it is designed for simplemoment and shear, with the restraining forces supplied tothe shaft by the webs of the first and second girder webs.This arrangement is similar to the vertical pin in thehood type with the exception that the shaft is taperedbetween the first and second girders. The pin is designedas a cantilever above the top girder. The vertical-shaft-type connection is similar to the vertical pin of the hood-type connection; therefore the details of the vertical shaftconnection are not shown in the plates in Appendix B.

(3) Direct-acting-type connection. This connection,while not restricted to them, has normally been used onlyfor direct-acting-cylinder machines. It is bolted directlyto a section of the upstream flange of the top girderwhich is increased in width and thickness and supportedby transverse stiffeners on each side of the girder web.

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The flange section is designed as a simple beam sup-ported by the stiffeners. The length of the increasedsection is determined by fabrication requirements andshear between the section and the web. The operatingstrut, connected by the same universal-type joint as thehood type, consisting of vertical and horizontal pins,applies no moment about the weak axis of the pin platesand eliminates any force except direct forces beingapplied to the girder flange. See Plate B-33 for typicalarrangement of this type of connection.

(4) Comparison of types. The hood-type connection,located on a line through the center of the pintle, avoidsincreased anchorage forces created by a moment armfrom the upstream flange to the center of the pintle.This keeps Rb, as shown in Plate B-8, to a minimumforce. The fabrication cost for the hood type will gener-ally be higher than for the other types of connections.

(a) The vertical shaft system is a simpler type ofconnection than the hood type, and it is also located on aline through the center of the pintle, thereby keepingforce Rb to a minimum. The cantilevered length of theshaft above the top girder may be prohibitive for thehelical coil spring and wide-flange-type strut.

(b) The direct-acting-type connection is the simplestof the three connections, but as the pin plate assembly isbolted to the upstream flange of the type girder it will, ingeneral, require a wider wall recess if used with machin-ery other than the direct-acting cylinder, due to having tomove the machine back from the face of the lock wall.If the machine is kept in the same position as for thehood- or vertical-shaft-type connections, the strut wouldhave to be reduced in length, thereby creating potentialinterference between parts of the strut.

(c) As was previously stated, each type of connectionhas its advantages and disadvantages and final selectionof the type to use can only be made after carefully evalu-ating all aspects of each individual gate, weighing costagainst efficiency, maintenance, and effect on other seg-ments of the gate or anchorage.

j. Diagonals. Each leaf of a miter gate is similar toa cantilever beam. The skin plate has such a great verti-cal stiffness that the diagonals are necessary only tocounteract the torsional or twisting action on the leaf.(See Plate B-17.)

(1) The basic formulas and information for thedesign of diagonals are covered in “Torsional Deflectionof Miter-Type Lock Gates and Design of the Diagonals”

(USAED Chicago 1960). (See Chapter 3 of this manualfor additional information.)

(2) The stiffness of welded miter gates appears to beconsiderably greater in most cases than the manual indi-cates. While this does not affect the overall pattern ofdiagonal design, it should be kept in mind when selectingthe values for deflection of the leaf.

(3) The diagonals may be pin connected or weldedto the gusset plates. Turnbuckles or brackets on the endof the diagonals are recommended for prestressing thediagonals. Brackets are generally located on the lowerend of the diagonals. However, the brackets on thenewer locks in the Ohio River Division are located onthe upper end of the diagonals for better surveillance.An advantage of the brackets is that no compression canbe placed in the diagonal during prestressing. It is notedthat the fatigue strength of the welded connection maygovern the design when welding instead of pinning thediagonals to the gusset plates. Studies have shown thatthe most important factors which govern the fatiguestrength of cyclically loaded members are the stressrange and the type of details used. The AASHTO Stan-dard Specifications for Highway Bridges, Section 10.3,allows only a stress range of 13,000 psi and 8,000 psi for500,000 and 2,000,000 cycles, respectively, for filletweld Category E.

(4) Strain gages installed with instant-setting cementor strain transducers should be used for determining thestress in each diagonal.

(5) The maximum stress, for temporary conditions,should not exceed 0.75 Fy. See Plate 17 for typicalinformation on diagonals.

k. Miter and wall quoins.

(1) Miter blocks. Miter blocks are usually 8-in. by5-1/2 in. rectangular blocks with one miter block havinga concave surface with a radius of 1 ft 6 in. and the otherhaving a convex surface with a radius of 1 ft 4-1/2 in.located at the miter ends of the leaves. These blocks aremade up of 15- to 20-ft-long sections with transversejoints occurring at the center lines of horizontal girderwebs. Together with the thrust diaphragms and endplates the miter blocks distribute the axial load from thehorizontal girders in the vertical direction and form acontact bearing surface between the miter ends of theleaves. Jacking and holding bolts are used for temporarysupports and adjustment of the miter blocks to assure fullcontact between leaves in the mitered position.

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(2) Wall quoin. The quoin block on the lock wall isessentially the same as the miter block with the wallquoin having the concave surface with a 1-ft-6-in. radiusand the quoin block on each leaf having a convex surfacewith a 1-ft-4-1/2-in. radius. There are two recommendedtypes of wall quoin systems. The first system, an adjust-able type, consists of a 10-in. by 3-1/2-in. bar, welded toa 1-1/4-in. by 1-ft-5-in. base plate. The base plate isattached to a vertical beam with jacking and holdingbolts to facilitate adjustment and replacement. The verti-cal beam is embedded in second-pour concrete and trans-mits the quoin reaction forces into the wall. The spacebetween the base plate and the embedded beam is filledwith an epoxy filler after final adjustments have beenmade. The second system, a fixed type, consists of a10-in. by 3-1/2-in. bar, welded to a vertical beam whichwas described previously. This type is more desirablewhen using zinc as a backing material because the hightemperatures involved may damage the concrete.

(3) Material for quoins. Adjustable and replaceablecorrosion-resisting clad steel or solid corrosion-resistingsteel blocks are recommended for both miter and wallquoins. The minimum size bolts used for installation andadjustment should be 3/4 in. in diameter. Plate B-18shows typical quoin and miter block details.

(4) Backing material. After final adjustments havebeen made to the miter and quoin blocks, a gap of about1/2 in. between the end or backing plate and the blocksis filled with zinc or an approved epoxy filler. The fillerlayer assures a uniform transfer of the loads from the leafinto the blocks. Although epoxy is now more widelyused, the contractor may be given the option of usingeither zinc or epoxy or the district may wish to dictatewhich is to be used based on their past success. In thepast, epoxy was easier and safer to work with but newtypes of equipment for heating zinc and preheating theends of the gate leaves have greatly reduced many objec-tions to its use. The initial investment in the equipmentneeded in using zinc is expensive and the placement maybe slightly more expensive, but with the life expectancyof zinc being 2 to 4 times that of epoxy, the use of zincwill be less expensive during the life of a project. Pre-cautions should be taken to prevent leakage of eitherfiller, and to prevent air entrapment. Application of abond-breaking material to jacking bolts, holding bolts,and contact surfaces should be made, and the manufac-turer’s installation instructions should be followed explic-itly. Where zinc is used, a seal weld is needed at theend joints of the blocks after cooling. Welds should beground smooth to prevent interference with bearing sur-faces. Where epoxy is used, fresh, properly stored epoxy

filler material mixed under clean and dry conditionsshould assure its functional performance.

(5) Cathodic protection for quoins. When carbonsteel quoin and miter blocks are installed, they are boltedto the gate with zinc or Nordback in back of them. Theblocks and the zinc can be protected with cathodic pro-tection. As a minimum, the sides of the blocks can andshould be painted. The miter and quoin faces are pro-tected with protective potentials in the same manner asthe gates.

l. Seals. Rubber seals should be installed on thebottom of each leaf to seal the gate to the miter sill.Various types of seals have been used by the differentdistricts and divisions with varying degrees of success.The seal should give a reasonable degree of watertight-ness but some leakage is to be expected. Excessiveleakage is objectionable when the lower portion of thegate is exposed.

(1) Where a large temperature range is encounteredthe 4-in. round rubber seal appears to be satisfactory.This type of seal allows for the effective shortening orlengthening of the leaf, which causes the leaf to changepositions with respect to the sill. This seal allows theupper pool to force it against the gate leaf, eliminatingpossible vibration. The curved section around the pintlegenerally utilizes the J-type seal, the shape and size ofthe 4-in. diameter rubber seal not being conducive tosharp bends. The sill concrete is second pour around theembedded portion of the seal. See Plate B-21 for details.

(2) Where the temperature range is such that thevariations in leaf length are small, the so called “Pork-chop” type seal has been used. The sill angle for thistype of seal is in second-pour concrete, with all adjust-ments made before placing the second pour. This type ofseal also reduces the probability of vibration encounteredwith the J-type seal. See Plate B-21 for details.

(3) Although the seal arrangements described abovehave provided satisfactory service in the past, they aresubject to vibration and damage from debris and are notrecommended for new construction.

(4) The seal detail, Section A-A, shown inPlate B-22, eliminates vibration problems caused bychanges in the length of the leaves due to temperaturefluctuations. Inherent in its higher location and orienta-tion, it is also less susceptible to damage from debris andprovides positive sealing under unbalanced head

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conditions. Therefore, this type of seal is recommendedfor new construction.

(5) Where there are large amounts of debris, drift,and large rocks tumbling along the bottom, such as in theshallow rivers of the Upper Mississippi River System, asuccessful method of sealing has been attaching theJ-seal to the embedded metal in the sill. This method ofsealing is not easily damaged, is reliable, and can beeasily replaced. See Plate B-22 for details.

(6) Above the top girder, J-type seals are used toseal the leaf to the top of the bulkhead plate. SeePlate B-23 for a typical detail.

m. Miter guide. The miter guide is used to bringboth leaves of the gate into the mitered position simulta-neously, thereby facilitating seating of the miter blocks.The guide assembly may be located on the upstream sideof the top girders or on top of the top girder web of eachleaf. The miter guide is made up of two major compo-nents, the roller, mounted on an adjustable bracket, andthe two-piece, adjustable, v-shaped contact block with itssupport. The roller bracket and the contact block areconnected to their supports with a series of push-pullbolts to permit field adjustment. Steel shims or epoxyfiller may be used to secure the miter guide componentsin their final positions. The height of the contact blockshould be greater than the length of the roller. The rollershould be equipped with a bronze bushing and a suitablegreasing arrangement. (See Plates B-19 and B-20 fortypical details.)

n. Walkway. Each leaf of all miter gates should beequipped with a walkway such that when the gate ismitered a continuous walkway is formed across the topof the gate. The walkway should have a width of4 ft 0 in. back-to-back of support angles, with the top ofthe walkway flush with the top of the lock wall. Thevertical legs of the support angles will act as a toe boardfor the walkway. (See Plate B-19.)

(1) The angle is supported by vertical stiffeners andthe bulkhead plate on the downstream side and by struc-tural tees acting as columns on the upstream side. Thetees should be placed above the vertical diaphragms andgirder web stiffeners as far as practical. The design loadfor the walkway should be 100 pounds per square foot(psf).

(2) Steel grating shall be type II and hot dippedgalvanized after fabrication, with a minimum depth of1-1/4 in. The ends of all grating shall be banded with

bars the same size as the bearing bars. Panels shall bemade in convenient sizes for installation and removal,with a minimum of four clips per panel.

(3) Other materials may be used for the walkwaysurface on top of or in place of grating with an ade-quately designed support system. These materials shouldhave adequate load-carrying capacity if used in place ofsteel.

(4) The end of the walkway adjacent to the lockwall should be made on a radius, usually 4 ft 5 in., fromthe center line of the gudgeon pin to the outside edge.This section should be hinged at the edge of the bulkheadplate. The outer edge of the radius is supported by anangle on the lock wall and an angle that is an integralpart of the grating system over the anchorage recess.

(5) Handrail should be designed to meet OSHAStandards which require it to support a 200-pound (lb)concentrated load applied at any point in any direction.For normal installations and post spacing, 2-in.-diameterextra strong pipe post with 2-in. standard pipe rail, orequivalent aluminum if economy dictates aluminum forthe lock walls, will be required. The railing should beremovable and made in convenient size panels, withhandrail located on both sides of the walkway. For addi-tional information and guidance on railing design see theASSHTO Standard Specifications for Highway Bridges.

o. Bridgeway. Instead of a walkway, a maintenancebridgeway may be provided over and supported by thelower miter gates to accommodate a mobile crane,thereby eliminating the frequent need for a floating plantfor many maintenance and repair operations. The road-way and supports may be designed for the wheel loads ofa 20-ton-capacity mobile crane without impact. Theallowable working stresses will be in accordance withcurrent AASHTO specifications.

p. Fenders and gate stops. All miter gates shouldbe equipped with a system of bumpers and fenders toprotect the gate from impact and to prevent damage bypassing tows when the gate is in the recess. Four basictypes of fender systems have been used on gates in thepast, with the systems consisting of wood, rubber, metal,and a combination of rubber and metal.

(1) The all-metal type, normally made of pipe, tub-ing, or curved plates, offers the advantages of ruggednessand minimum damage while in use but has the disadvan-tage of having very little energy-absorbing capacity.Where welded directly to the girder flanges, impact is

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transferred through the girder web to the operating strut,anchorage, and pintle.

(2) A combination fender, made of pipe or a curvedplate, mounted with rubber pads between the metal con-tact surface and the girder flanges gives a more desirableenergy-absorbing capacity but is a more complex andexpensive system.

(3) The all-rubber fender system offers the highestdegree of impact protection for the gate but has somedisadvantages such as passing tows tending to tear therubber fender from the gate and the increased cost of thesystem; however, low-friction butyl rubber fenders arebeing used successfully and may prove to be a viablealternative to timber based on a life-cycle cost.

(4) When all aspects of the basic system are consid-ered, timber fender systems appear to be the most desir-able. Timber offers a reasonable degree of resiliency forgate protection, is rigid enough to resist the sliding forcesfrom passing tows, and is normally readily available, andin most cases, is considerably more economical than theother systems. When timber is used, white oak is gener-ally the more desirable species if available locally.When white oak is unavailable, pine timber is an accept-able substitute. The size of timber of either white oak orpine should generally be 10 in. by 10 in. (S4S), pressuretreated with creosote if pine and untreated if white oak.

(5) The fender system should be installed on thedownstream flanges of all horizontal girders subject to animpact loading. Generally, this extends from a point ator slightly below the minimum pool up to a pointapproximately 6 ft above the maximum pool to be in thelock during operation. Consideration should be given toplacing fenders 2 ft on center vertically in areas whereheavier tows are likely to cause considerable damage togates. Vertical beams spanning between horizontal gird-ers should be used to support the extra fenders. Fendersshould be fastened to the flanges of horizontal girderswith a minimum of 3/4-in.-diameter bolts, 2 ft on centerand alternating sides, vertically, of the flange, with thehead of all bolts recessed a minimum of 1 in. to preventpassing barges and boats from catching the bolt heads. Ifrubber fenders are used, bolt heads should be recessed asmuch as practical to allow for compression of the fenderand prevent the bolts from being caught by passing tows.

(6) Bumpers are selected by applying the same crite-ria as those for fenders. Where ice buildup in therecesses is not a problem, bumpers are fastened to thewall of the recess to cushion any impact between the

gate leaf and the wall. If ice buildup in the recess is aproblem, bumpers can be mounted on the gate leaf.Timber bumpers are generally made of 12-in. by 12-in.(S2S) white oak. Bumpers are placed so as to strike theleaf near the end vertical diaphragm at the miter end, onthe center line of the horizontal girders. The minimumnumber of bumpers used should be one for each of thetop two girders and one for each of the bottom two gird-ers. On high gates, it may be desirable to also placebumpers for some of the intermediate girders. Thelength of the bumpers should be approximately 2 ft onthe impact face. Each bumper should be fastened to thewall of the recess with a minimum of two 3/4-in.-diame-ter bolts, with the ends of the bolts recessed a minimumof 1 in. to prevent the bolts from striking the gate.

q. Gate latches. Latches should be provided to holdeach gate leaf in the recess against temporal hydraulicloads and in case of an emergency. Due to the verticalstiffness of the leaf a latch at the top of the leaf is nor-mally sufficient. Where the lock is used as a floodwayduring high flows and where required by temporalhydraulic loads, additional latches, located near the centerof the leaf, vertically, or near the lower miter corner ofthe leaf, may be required. Latches should be so con-structed that the leaf is held snug against the bumpers sothe potential vibration is kept to a minimum. Also seeautomatic gate latches, paragraph 2-5f(3). A latch or tieshould also be provided to tie the leaves in the miterposition, again with the ability to pull the leaves togetherso as to reduce the probability of vibration. SeePlates B-24, B-25, and B-26 for suggested latch details.

r. Embedded metals. The items normally includedas embedded metals are miter sill angle, pintle base, wallquoin and support members, embedded anchorage, andgate tieback. With the exception of the pintle base, allitems are usually made of structural steel, with someitems, such as the wall quoin block, having a corrosion-resisting surface in some instances. All items have beendiscussed previously except the sill angle. The sill angleis placed in second-pour concrete, with provision foradjustment to the gate leaf, with all adjustments beingmade before the second pour is placed. See Plates B-21,B-22, and B-32 for a suggested plan of a sill anglearrangement.

s. Cathodic protection. Two basic methods ofcathodic protection are the sacrificial anode method andthe impressed current method with the impressed currentsystem being the most efficient. Impressed current isrequired to protect the large areas between the horizontalgirders and the skin plate of the gate. The anodes of the

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system are placed between the horizontal girders, withthe vertical wiring passing through holes in the girderwebs. This makes the system much less susceptible todamage from traffic or debris. In most cases, metallicconduit and some angle iron are required to protect thecathodic protection anodes. (See CW-16643 for impactprotection.) See Chapter 7 of this manual for additionalinformation.

2-2. Miter Gates, Horizontally Framed-Arch Type

The analysis of the arch gate is similar to that of thestraight horizontally framed type gate. As with thestraight gate, the general analysis for the arch neglectsthe vertical stiffness of the gate leaf and skin plate.Plate B-27 shows the geometry and forces on the archrib. The longitudinal axis of the horizontal rib girderapproximates the “pressure or thrust line” from the load-ing conditions; thus the magnitude of the bendingmoment in the ribs, determined from the eccentricity ofthe axial load to the ribs’ axis, is a minimal value. Theskin plate for this gate is designed as a continuous mem-ber. The intercostals of the gate shown in Plate B-28 donot come in contact with the skin plate. The primaryfunction of the intercostals is to serve as vertical dia-phragms. Design of the other elements of the arch gateleaf and anchorages is covered under paragraph 2-1.Plates B-28 and B-29 show horizontal rib girder anddiaphragm layout.

2-3. Miter Gates, Vertically Framed

Horizontally framed gates provide a more rigid structureand are usually economically comparable to verticallyframed gates. While vertically framed gates should notbe used for new construction, this manual covers verti-cally framed gates to provide information because oftheir use in existing structures.

a. Reactions. Due to the basic framing plan of avertically framed gate, with the horizontal girder support-ing the upper end of all vertical members, the reaction ofthe horizontal girder is similar to the reaction of a girderin a horizontally framed gate. The girder in each type ofgate acts as a segment of a three-hinged arch, with theend reactions and related forces being the same in bothcases. The designations R, N, P1, and P2 are the samefor both horizontally and vertically framed gates. Thelower ends of all vertical members are supported directlyby the sill, with the bottom girder acting to transfer theconcentrated loads into a uniform reaction on the sill.

b. Skin plate and vertical beams.

(1) Skin plate. Existing vertically framed gates mayhave either the conventional-type skin plate, generallylocated on the downstream side of the leaf, or a skinplate composed of buckle plates fastened to the upstreamflanges of the vertical beams and framing into the websof the vertical girders. Although buckle plates are still inuse on existing gates, they are no longer used for newconstruction. In determining the location of the skinplate for a vertically framed gate, consideration should begiven to the problems of uplift and silting. While theskin plate located on the downstream face of the gateeliminates uplift, the maximum area is exposed for siltaccumulation. The reverse is true for the skin platelocated on the upstream face of the gate. The moredesirable skin plate location will have to be determinedfor each site, weighing the problem of uplift against theproblem of silting.

(a) The analysis of flat panels of skin plate is thesame as discussed for horizontally framed gates, with thedesirable panel shape being approximately square. (SeePlate B-2 for additional information.)

(b) Intercostals are required for flat skin plates,spanning horizontally between vertical beams andbetween vertical beams and vertical girders. The criteriafor intercostal spacing and design are essentially thesame as those for horizontally framed gates. See Fig-ure 2-3 for additional information on design.

(2) Vertical beams. Vertical beams span betweenthe top and bottom girders, supporting the buckle plateson their upstream flange or the flat skin plate on thedownstream flange. The vertical beams are assumed tobe simply supported top and bottom, with simple momentand shear dictating beam size. Spacing of the verticalbeams is determined largely by load and support require-ments for the skin plate system with a normal locationbeing at the quarter points between vertical girders.

(3) Vertical girders. Vertical girders are verticalmembers that function as vertical beams and at the sametime serve as support members for the top and bottomgirders. The vertical girders are spaced so thatpractically all vertical forces caused by the diagonals arecarried by the vertical girders. The most effective panelfor diagonals is when the height is no more than1.50 times the width. The vertical girders and thebottom girder are normally the same depth so as to

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simplify framing and make the bottom girder flangesmore directly effective in taking the components of thediagonals. The stability of the girder flanges under thesecomponents should be verified, assuming the flanges toact as columns. Webs of the girders are normally deter-mined by minimum thickness rather than by shearrequirements (the minimum thickness of all materialshould be 3/8 in.) and should be checked for stiffenerrequirements.

c. Horizontal girders.

(1) Top horizontal girder. The top horizontal girderis designed to withstand a simultaneous load of waterforce and boat impact. The water force is applied asconcentrated loads by the vertical beams and girders; theboat impact load is as described in paragraph 2-1b(1),acting directly on the top girder. The top girder design isessentially the same as that for the girders in ahorizontally framed gate; the symbols W, N, R, P1, andP2 are the same for both types. The reaction of the topgirder is transmitted through steel bearing blocks at eachend of the girder. These blocks are similar to the bear-ing arrangement for horizontally framed gates, having thesame convex and concave faces and the same adjustment.The bearing blocks may be of cast steel or a built-upweldment; the weldment has the advantage of being moreeasily obtained in the event replacement is necessary.The girders should be designed to withstand water loadand basic stress or the combined water and boat impactwith an allowable 1/3 overstress.

(2) Bottom horizontal girder. Under normal condi-tions, the bottom girder does not function as a girder butrather as a member to transfer the concentrated verticalbeam and girder loads into a uniformly distributed hori-zontal force on the sill. For most gates, the bottomgirder center line is located approximately 4 in. belowthe top of the sill to provide sufficient bearing surfacebetween the girder and the embedded metal. The girderis also checked for sufficient capacity to carry the reac-tion from any vertical beam or girder to adjacent beam orgirder points if irregularities or obstructions between thesill and bottom girder prevent bearing at a vertical beamlocation. The minimum effective length for this shouldbe twice the vertical beam spacing. When the leaf is notin the mitered position, the bottom girder acts as a col-umn, having an axial load created by the dead weight ofthe leaf. The downstream flange of the bottom girder isdesigned to distribute vertically the bearing load on thesill, which may require stiffener plates to support theflange. If the skin plate is not a flat plate on the down-stream face of the leaf, the downstream flange of the

bottom girder is subjected to vertical bending due to thehydrostatic uplift on the bottom of the leaf with the webof the girder acting similar to a skin plate. Adjacent tothe pintle, the bottom girder should be checked for thehorizontal reaction of the pintle. The depth of the bot-tom girder also influences the depth of the vertical gird-ers and has a direct relation to the stiffness of the leaf,this being determined by the distance between sets ofdiagonals or, in the case of a flat skin plate, the distancebetween the skin plate and diagonals.

d. Diagonals. Design of the diagonals for a verti-cally framed gate is essentially the same as that for ahorizontally framed gate (see USAED, Chicago 1960).Most existing vertically framed gates have diagonals onboth the upstream and downstream faces, with buckleplates located between the two sets. If a flat skin plate isused on the downstream face of the leaf, diagonals arerequired only on the upstream face, with the skin platetaking all the vertical shear from dead load. The numberof panels of diagonals used on vertically framed gatesdepends on the spacing of vertical girders. The panelsize of height equals 1.50 times the width is desirable,but should not in itself be the only consideration forvertical girder spacing, which sets the panels for diago-nals. Usually leaf dimensions are such that three sets ofdiagonals on a leaf face are commonly used. Due toflexibility of a vertically framed gate turnbuckles arerecommended on all diagonals to allow for easier adjust-ment at a later time. See Chapter 3 and Plate B-17 foradditional information on design of diagonals.

e. Wall quoin. The wall quoin of a vertically framedgate, similar to the wall quoin of a horizontally framedgate, serves to distribute the girder reaction of the hori-zonal girder. The main difference in the two types is thevertical height of the reaction bearing area. The wallquoin of a vertically framed gate is normally in the orderof 2 ft-0 in. high and 1 ft-8 in. wide. The quoin blockmay be made of cast steel or a built-up weldment, withweldment generally being more readily available in thecase of replacement. The block is made to fit the quoinblock of the girder and is attached to an embedded beamto distribute the force to the concrete. The beam shouldbe of sufficient size to maintain bearing on the concreteto approximately 600 psi or less, so that cracks in theconcrete around the corner of the gate recess will be keptto a minimum. The beam is generally placed horizon-tally in first-pour concrete with the bearing being detach-able with provisions for adjustment.

f. Top anchorage and gudgeon. The design of theanchorage elements is similar to the design of the

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anchorage for horizontally framed gates. Frequently thesame anchorage is used for both types when a lock hasan upper gate vertically framed and a lower gate horizon-tally framed, where the small difference in materialsgenerally is not enough to offset the savings of makingtwo identical sets. The gudgeon pin and hood are bothsimilar to those for horizontally framed gates, with theexception that the pin hood of the vertically framed gateincreases the moment on the vertical beam adjacent tothe quoin girder. This gives a combined loading of waterplus the forces from the pin hood on this particular verti-cal beam.

g. Strut connection. The strut connection for verti-cally framed gates is essentially the same as that forhorizontally framed gates, with the exception that thehorizontal girder for vertically framed gates carries allthe strut force whereas vertical diaphragms on horizon-tally framed gates distribute the load to the first two andsometimes the first three horizontal girders.

h. Pintle and pintle anchorage. The design of thepintle for vertically framed gates is the same as that forhorizontally framed gates, using the same procedures andmaterials. The design of the pintle base for verticallyframed gates is essentially as described for horizontallyframed gates, with similar bases being required for hori-zontally framed leaves consisting of five or six girdersand vertically framed leaves. Relatively speaking, hori-zontal forces on the pintle base are greater for the verti-cally framed gates and the smaller horizontally framedgates. Unlike horizontally framed gates, the pintlesocket, or center of pintle, is generally located on thecenter line of the bottom girder. See Plate B-30 forinformation relating to the seal between leaf and pintlebase.

i. Bottom sill. The bottom sill for vertically framedgates, unlike the sill of horizontally framed gates,receives a significant amount of water force applied tothe gate. The embedded metal segment of the sill shouldprovide an adequate bearing and sealing area and limitbearing on the concrete to approximately 300 psi or less.Anchor bolts to hold the embedded metal are set in first-pour concrete with the embedded metal placed in second-pour concrete. See Plate B-32 for a typical sill layout.

j. Seals.

(1) Wall seals. The wall seal of a vertically framedgate consists of an embedded channel with a cladding ofcorrosion-resisting material on the exposed sealing sur-face. This channel is embedded in first-pour concrete,

with the rubber J seal on the leaf being adjusted to thesealing surface of the channel. (See Plate B-30.) Theseal on the gate leaf is composed of a rubber J sealattached to a vertical plate which is an extension of theweb of the vertical quoin girder. The flange of the quoingirder is made of one plate, with the web extensionwelded to the outside of the flange. An angle betweenthe rubber seal and the web extension allows for adjust-ment of the seal.

(2) Miter seal. The miter seal consists of a verticalplate on one leaf and a conventional J seal on the otherleaf, placed so that the water pressure forces the rubberseal against the vertical plate. Below the web of thebottom girder two rectangular rubber blocks, one on eachleaf, form the seal between the vertical J seal and the sill.

(3) Bottom seal. The bottom seal of verticallyframed gates is formed by the contact between the bot-tom girder and the embedded metal of the gate sill. Ametal bearing plate is attached to the downstream flangeof the bottom girder and this also acts as a seal plate. Atthe end of the leaf adjacent to the pintle, a solid rubberblock seal attached to the leaf is used between the leafand pintle base. (See Plates B-30 through B-32 for addi-tional information.)

k. Mitering device. The mitering device is essen-tially the same for both vertically and horizontallyframed gates with the same basic dimensions and materi-als used for both types. See Plates B-19 and B-20 for atypical mitering arrangement.

l. Walkways. Walkways for vertically framed andhorizontally framed gates are essentially the same, usingthe same basic dimensions and design criteria. See para-graph 2-1n on walkways for horizontally framed gatesand Plate B-19 for additional information.

m. Fenders and gates stops. The same protectionsystem and gate stops are used for both vertically andhorizontally framed gates. See paragraph 2-1p for moreinformation.

n. Gate latches. Gate latches for both vertically andhorizontally framed gates are essentially the same. Whilethere may need to be a slight variation in the method ofattaching the latching unit to the leaf the same generalmethod should be used for the vertically and horizontallyframed gates.

o. Embedded metals. The normal items included inthe category of embedded metals are the embedded top

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anchorage, quoin bearing, pintle base, and miter sillembedded metal. All items are essentially the same asthose for horizontally framed gates except the miter sillembedded metal. All other items have been discussed inthe paragraphs on horizontally framed gates and in previ-ous sections for vertically framed gates. While the sillembedded metal is similar for both horizontally andvertically framed gates, the sill for vertically framedgates is designed to receive the gate reaction and distrib-ute this force to the concrete. As previously stated, thesill embedded metal serves two functions, acting as abearing surface and as a sealing surface. The embeddedmetal is placed in second-pour concrete; the supportinganchor bolts are set in first pour. All adjustmentsbetween gate and sill are made before placing thesecond-pour concrete. See Plate B-32 for a suggestedsill layout.

p. Cathodic protection. The cathodic protectionsystems of both vertically and horizontally framed gatesare essentially the same. The location and number ofanodes may vary but the method and components are thesame for both types of gates. For further information,see Chapter 7.

2-4. Erection and Testing, Miter Gates

a. Miter gates, both horizontally and verticallyframed, should be completely shop assembled, if sizepermits, with adjoining pieces fitted together to ensuresatisfactory field connections. The tolerances should notexceed 1/16 in. for individual members up to 30 ft inlength and not more than 1/8 in. for members over 30 ftin length. Structures made from two (2) or more mem-bers should not deviate from the overall dimension bymore than the tolerance for any one member. Rubberseals should be fitted and assembled to the gate leaf inthe shop, with holes drilled to match the seal supports onthe gate leaf and then removed for shipment. Beforedisassembly of the leaf each piece should be match-marked to facilitate erection in the field.

b. The bottom pintle casting shall be adjusted toproper elevation and position and then properly concretedin place before erection of the leaf. The bearing surfaceof the pintle and bushing should be thoroughly cleanedand lubricated before setting in place. Considerationshould be given to using temporary concrete pedestals tosupport the leaf, with a minimum of two pedestals perleaf and allowing the pintle to support the quoin end ofthe gate leaf.

c. Care should be taken to ensure that the parts ofthe gate leaves are in correct alignment before any fieldwelding is commenced. All necessary precautions shouldbe taken to prevent distortion of the leaf as a whole or ofany of its components. Each unit should be accuratelyaligned so that no binding in any moving parts or distor-tion of any members occurs before final connections aremade.

d. After completion of the leaf, the top anchoragelinks should be installed and adjusted so that the centerof the gudgeon pin is in vertical alignment with the cen-ter of the pintle.

e. After diagonals have been prestressed and finaladjustments have been made to the anchorage, the leavesshall be mitered and securely held in this position whilethe contact blocks at the quoin and miter ends arebrought into firm contact by adjusting the bolts behindthe blocks. After adjustment of the blocks, the leavesshould be swung out and zinc or epoxy filler pouredbetween the seal blocks and the end plates of the leaves.If zinc is the option selected by the contractor, blocksand plates adjacent to the zinc shall be preheated to atemperature between 200 and 250 deg F, immediatelypreceding the pouring to prevent the zinc from coolingbefore it can fill the area behind the blocks. The pouringtemperature of the zinc shall be maintained between810 and 900 deg F to avoid volatilizing or oxidizing themetal and to ensure that it will fill the area behind theblocks. Pouring holes should be located 2 to 3 ft apart.If the alternate backing of epoxy is selected, the materialshould meet the properties set forth in paragraph 2-1k(4).

f. After a gate leaf is erected, diagonals prestressed,and miter and quoin blocks adjusted and set, each leafshould swing without interference of the quoin blocksuntil, as the gate is mitered, the quoin block on each leafmakes tight contact with the one on the lock wall. Afterfinal adjustment of blocks and seals, the gate leaf shouldswing freely and any point on the moving structureshould remain in a horizontal plane throughout the entirerange of movement. Past experience indicates that1/16 in. on the smaller locks to 1/8 in. on the 110-ft orlarger locks can be allowed as maximum variance fromthe horizontal plane and not have any adverse effect onthe gate, although every effort should be made to keepingthe leaves in a horizontal plane.

g. After completion of the gate, including prestress-ing of the diagonals, installation of all seals, and all

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adjustment, the gate leaves should be swung through asufficient number of opening and closing operations toassure that the leaves are in true alignment and that nec-essary clearances have been provided. After this trialoperation the leaves should be swung out and the second-pour concrete placed in the sill and wall quoins.

h. The miter guide should be installed after the trialoperation and second-pour concreting has been com-pleted. The guide bracket and roller bracket assembliesshould be mounted on their respective leaves with thegate in the mitered position. Adjustments should bemade to the brackets so that either leaf may be miteredor opened without disturbing the other leaf.

i. The final test on the gate should consist of operat-ing the gate under power, by means of the permanentoperating machinery, first during the unwatered conditionand then using available headwater and tailwater. Theleaves should be operated through their entire travel asufficient number of times to indicate that all parts andequipment are in proper operating condition. Theworkmanship in fabrication and erection of the gatesshall be such that, when mitered, they will form a water-tight barrier across the lock under all ranges of head,except for minor negligible leakage at the miter, sill, orquoin.

2-5. Operating Machinery

a. General description of linkages and components.Four different types of miter gate operating machineshave been frequently used. The Panama Canal linkage,which has no angularity between the strut and sectorarms at either the open or closed positions of the gate, isshown in Figure 2-6. The Ohio River linkage, havingangularity between the strut and sector arms at both theopen and closed positions, is shown in Figure 2-7. TheModified Ohio River linkage has angularity between thestrut and sector arms at the recess or open position andno angularity at the mitered or closed position. Thislinkage is shown in Figure 2-8. A direct connected cyl-inder has been used on some 84-ft-wide locks and con-sists of a hydraulic cylinder and rod connected to a pinon the gate and a pin on the lock wall, the piston forcebeing transmitted directly from the piston rod to the gate.This linkage is shown in Figure 2-9.

(1) Panama Canal linkage. The Panama Canal link-age has been used primarily where electric motor opera-tion was feasible, that is, at locations where high waterwill not overtop the lock wall. The operating machineryfor this linkage generally consists of a high torque, high

slip a-c motor driving the gate through two enclosedspeed reducers, bull gear, sector arm, and spring-typestrut. This linkage will permit the gate to be uniformlyaccelerated from rest to the midpoint of its travel andthen uniformly decelerated through the remainder of itstravel, thus eliminating the need for elaborate motorspeed control. This is accomplished by locating theoperating arm and strut on “dead center” when the gateleaf is in both the open and closed positions. The strutmust be located at a higher elevation than the sector armin order to pass over the arm and become aligned fordead center position when the gate is fully open. Specialconsideration should be given to the design of this eccen-tric connection between the strut and sector arm. Anassembly layout of the Panama-type linkage is shown inPlate B-47.

(2) Modified Ohio linkage. The Modified Ohiolinkage is similar to the Panama type except that thedead center alignment is attained only in the gate fullyclosed position. With the Modified Ohio linkage, thestrut and sector gear are located at the same elevation,thus eliminating the eccentric strut connection but pre-venting the linkage from attaining the dead center posi-tion with the gate recessed. The operating machinery forthis linkage has been built either for electric motor driveas with the Panama linkage or hydraulic operation aswith the Ohio River machine. An assembly layout of theModified Ohio linkage with electric motor drive is shownin Plate B-48.

(3) Ohio linkage. The Ohio linkage consists of ahydraulic cylinder, piston rod, toothed rack meshed witha sector gear, and a sector arm, the spring-type strutbeing connected to the gate leaf and sector arm. A typi-cal machine is shown in Plate B-49.

(4) Direct connected linkage. Another type ofmachine is the “Direct Connected Type.” It consists of acylinder mounted in a gimbal bracket and located in arecess on the lock wall with the piston rod connecteddirectly to a bracket on the gate. The kinematics of thislinkage is such that it is necessary to control the acceler-ation of the gate by use of a variable volume pumpingunit instead of relying on the mechanical advantage ofthe linkage to accomplish this. Since the piston rod isused as a strut, it is generally a little larger in diameterthan the rod of the Ohio-type machine. This larger rodincreases the ratio of time of opening to time of closingsince the net effective cylinder volume on the rod end issmaller than the volume on the head end. This variationin opening and closing times can be eliminated by use of

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Figure 2-6. Panama Canal linkage (USAEWES 1964)

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Figure 2-7. Ohio River linkage (USAEWES 1964)

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Figure 2-8. Modified Ohio River linkage (USAEWES 1964)

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Figure 2-9. Direct connected linkage

variable volume flow control valves or by use of a regen-erative circuit along with a cylinder in which the rod areais about one-half the piston area. The arrangement of thedirect connected type machine is shown in Plate B-50.The direct connected type of machine has been usedsatisfactorily on 84-ft-wide locks in the U.S. with locksup to nearly 100 ft and 110 ft wide in Europe. The useof the direct connected cylinder on locks 110 ft widenow appears to be a viable option; however, an in-depthdesign analysis should be made for each applicationconsidered. Experience has shown that the direct con-nected machine costs approximately 30 percent less thanthe conventional Ohio-type machine when used on locksup to 84 ft wide.

(5) Recommended linkage. The Ohio River or directconnected linkage is probably the most satisfactory typeto use with hydraulic cylinder operation. With the OhioRiver and Direct Connected linkages, load analysis for all

components is possible. Overloads due to surges orobstructions are carried through the piston and convertedto oil pressure which is released through a relief valve.In this way, all machinery component loads can be deter-mined based on the relief valve setting. This is also truefor the Modified Ohio linkage except at the miteredposition. As this linkage approaches the mitered posi-tion, the sector arm and strut approach the dead centerposition. Should an obstruction be encountered at thistime, the force in the strut becomes indeterminate.Although this linkage provides restraint against condi-tions of reverse head in the dead center position, it mustbe designed with an easily repaired “weak link” to limitthe maximum loads that can be placed on the machinerycomponents. The Modified Ohio River linkages on somelocks have yielded unsatisfactory results, and these havebeen converted to Ohio River linkages. The Ohio Riverlinkage offers several obvious advantages due to itsunique geometric configuration relating to the

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acceleration and deceleration of the miter gates. Thedisadvantages of this system are wear, bearing forces,and mechanical inefficiencies associated with the gearedrack, sector gear, sector arm, and strut. Ohio Riverlinkages have recorded a service life of over 50 years onmany locks, with good reliability and a minimum ofmaintenance.

(6) Struts. Two types of struts have been used forthe above-mentioned machines. One type utilizes severalnests of helical coil springs installed into a cartridge andattached to a wide flange structural steel fabricated mem-ber. The springs, when compressed, act as a shockabsorber to soften the loads transmitted to the operatingmachinery. In the case of electric-motor-operatedmachines, the compression in the springs permits theoperation of a limit switch to cut off current to the motorwhen the gates are mitered or recessed. The switch alsoserves as a limit switch to protect the machinery againstthe possibility of extremely high loads which might occurif an obstruction is encountered when the strutapproaches dead center in either direction. The limitswitch is set to open the motor circuit at a point immedi-ately preceding the maximum spring compression in thestrut. This type of strut is shown in Plate B-51. Anothertype of strut utilizes a spring cartridge housing and tubu-lar steel strut. Ring springs are used in the spring car-tridge to provide the necessary deflection. Excessivemaintenance and repair costs have occurred with the useof this type of strut. In addition, ring springs are avail-able only from one manufacturer. Use of the ring-spring-type strut is not recommended. Recently,Belleville springs have been utilized in struts and appearto function satisfactorily. The Belleville spring strut isshown in Plates B-52 and B-53.

(7) Sector gear anchorage. The sector gear supportand anchorage is one of the more critical items to beconsidered in the design of miter gate machinery. Forproper machine operation and long component life, thesector gear must be maintained in rigid and proper align-ment. The recommended arrangement consists of asector base anchorage, sector base support, and a sectorbase. The sector base anchorage is a welded steel frameembedded deep in the concrete which provides anchorageand alignment for post-tension rods. The sector basesupport is a heavy, rigid, welded steel member which isanchored to the concrete by the post-tension rods. Thesector base is a heavy steel casting which is bolted to thesector base support and contains the sector pin on whichthe sector gear turns. The sector gear pin should berestrained to prevent rotation in the sector base. Thedesign is such that the final post-tension rod force is

enough to resist the horizontal sector pin load by frictionbetween the concrete and sector base support. Inaddition, compression blocks are welded to the bottom ofthe sector base support to provide additional resistance tohorizontal motion. Details of this anchorage are shownin Plate B-49.

b. Design criteria.

(1) Design loads.

(a) Normal loads. Gate operating machinery shouldnormally be designed to conform to the following crite-ria: Operating loads on the miter gate machinery shouldbe derived by hydraulic similarity from test data obtainedfrom model studies. The model study available fordesign is included in Technical Report 2-651 (USACE-WES 1964). (This was the last study made by WES onthis subject.) This report includes data on the OhioRiver, Modified Ohio River, and Panama Canal typelinkages. The study contains necessary data for conver-sion to prototype torque for all three of the differenttypes of linkages. For direct connected type machines,prototype tests were made at Claiborne Locks and resultsof the tests are included herein for the determination ofgate torque for any proposed direct connected lockmachine of similar proportions. A curve of gate torqueplotted against percentage of gate closure has beenincluded so that torque at any other submergence or timeof operation can be computed by application of Froude’slaw, adjusting the submergence and time to suit the newconditions.

(b) Temporal loads. In addition to the above-normalloads, the miter gate machinery should be designed towithstand the forces produced by a 1.25-ft (exceeding30-sec duration) surge load acting on the submergedportion of the miter gate. For this case, the machinerymust be designed to maintain control over the miter gatewhen the gate is in the miter position. In the recessposition, control of the gate may be accomplished byautomatically latching the gate in the recess. Normalmachinery operating loads govern the machinery designfor the intermediate positions.

(2) Operating time. A time of operation should beselected and should be based on the size of gate. Forsmaller gates (84-ft lock) an average time of 90 secshould be used and for the larger gates (110-ft locks) anaverage time of 120 sec would be suitable.

(3) Submergence. The design of the gate operatingmachinery should be based on the submergence of the

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upper or lower gate, whichever is greater. The designshould be the same for all four gate machines since therewould be no savings in designing and building two dif-ferent size machines. The increased design cost wouldoffset the reduced cost of the material used in construct-ing the smaller machine.

(a) The submergence of the gate is the difference inelevation of the tailwater on the gate and the elevation ofthe bottom of the lower seal protruding below the gate.A submergence selected for design of the gate machineryshould be the tailwater on the gate that would not beexceeded more than 15 to 20 percent of the time.

(b) The operating cylinder size should be selected toprovide a force to operate the gate under these conditionsutilizing approximately 900 to 3,000 psi effective pres-sure where a central pumping system is used. If higherthan 1,000 psi is selected for the operating pressure, thenmeasures to eliminate hydraulic shock should be consid-ered because of the long hydraulic lines. Where localpumping units are used, an operating pressure of 1,500 to3,000 psi will be satisfactory.

(c) The time of gate operation will automatically belengthened when the required gate torque exceeds theavailable gate torque. This condition may occur duringstarting peaks or periods of higher submergence. Thiscondition causes the pressure in the hydraulic cylinder torise above the relief valve setting, which in turn reducesoil flow to the cylinder slowing down the gate and reduc-ing the required pintle torque. This increases the totaltime of operation; however, this slower operation will beexperienced for only 15 to 20 percent of the lock totalyearly operating time.

(d) Peak torque can be reduced by nonsynchronousoperation of the gate leaves. A considerable reduction inpeak torque can be obtained by having one leaf lead theother by approximately 12.5 percent of the operatingtime. The time of opening would be increased by theamount of time one gate leads the other. It has beenfound that in actual practice very few gates are operatedin this manner.

(4) Under gate clearance. Model tests revealed anincrease in gate torque values as the bottom clearancedecreased, regardless of the length of operating time.When using model similarity to compute gate loads, anadjustment should be made in accordance with modelexperience. Normally 2.5-ft to 3.5-ft clearance under thegate should be satisfactory.

(5) Machine components. General design criteriaapplicable to the various machine components are pre-sented in paragraph 1-9. Allowable stresses may beincreased one-third for temporal loading conditions.

c. Load analysis.

(1) Normal loads. Normal operating hydraulic loadson miter gates are primarily caused by submergence,speed of gate, and clearance under gate.

(a) Technical Report 2-651 (USAEWES 1964) indi-cates that the maximum torque recorded as the gateleaves entered the mitered position (closing) varied as the1.5 power of the submergence; and the maximum torquerecorded as the gate leaves left the mitered position(opening) varied as the 2.1 power of the submergence forthe Ohio Linkage.

(b) For the Modified Ohio linkage, TechnicalReport 2-651 indicates that the maximum torque recordedas the gate leaves entered the mitered position (closing)varied as the 1.9 power of the submergence; and themaximum torque recorded as the gate leaves left themitered position (opening) varied as the 2.2 power of thesubmergence.

(c) For the Panama-Type linkage, TechnicalReport 2-651 indicates that the maximum torque recordedas the gate leaves entered the mitered position (closing)varied as the 1.5 power of the submergence; and themaximum torque recorded as the leaves left the miteredposition (opening) varied as the 1.7 power of thesubmergence.

(d) The report indicates that the maximum torquerecorded decreased as the 1.0 power of the operatingtime for both the closing and opening cycles when usingthe Ohio Linkage.

(e) For the Modified Ohio linkage, the report indi-cates that the maximum torque recorded decreased, as the1.1 power of the operating time for the closing cycle andas the 1.5 power for the opening cycle.

(f) The report indicates for the Panama-Type linkagethat the torque decreased as the 1.1 power of the operat-ing time for the closing cycle and as the 1.3 power forthe opening cycle.

(g) Tests reveal that an increase in gate torqueoccurs when the clearance under the gate leaf is

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decreased regardless of the length of operating time.Data from these tests are presented in Figure 2-10 andindicate the percentage increase in model torque forvarious bottom clearances relative to the torque observedwith a 3-in. bottom clearance. These data can be used toadjust the observed torque values determined for a modelbottom clearance of 3 in. when gate length is 3 ft.

(h) Nonsynchronous operation of miter gates resultsin slightly lower forces on the leading leaf. Forces onthe lagging gate leaf are greater during most of the clos-ing cycle and less during the opening cycle than similarforces recorded for synchronous operation of the gateleaves. The greatest reduction in torque appears to bewhen one gate is leading the other by approximately12.5 percent of the total operating time.

(i) Barges in the lock chambers are found to havenegligible effect on gate operating forces.

(j) The chamber length affects the gate torque in thatthe longer the chamber, the less the torque. As thelength of time is increased, the less the chamber lengthaffects the gate torque. Insufficient data are available toset up any definite adjustment factors for correcting forchamber length.

(k) Torque caused by gate pintle friction is of smallmagnitude and should not be considered in loadcalculations.

(l) When computing operating torque for a directconnected type miter gate drive, the curves shown inPlate B-87, Sheets 5 and 7, may be used. The curves areresults of prototype tests made on Claiborne Lock andshow gate torque plotted against percentage “closed.”The torque from these curves may be adjusted to suitnew conditions by the application of Froude’s law asdescribed in detail in paragraph 2-5d below. Since thecurves were based on the use of a three-speed pump toslow the gate travel at beginning and end of cycle, it willbe necessary to make similar assumptions on the pro-posed lock. Assuming a fast delivery rate of the pump at1.0, the medium delivery rate should be 0.8 and the slowrate adjusted to 0.3 of the fast rate. A normal cyclewould be to operate 10 percent of the gate angular travelat 0.3 capacity, 10 percent at 0.8 capacity, 60 percent at1.0 capacity, 10 percent at 0.8 capacity, and 10 percent at0.3 capacity. A comparison study made between thistype of operation and the Panama-type linkage indicatesthat the direct connected machine, if operated as statedabove, will compare favorably with the Panama machinein angular gate velocity (degrees per second) at all

positions. If one assumes that the angular velocitiescompare with the Panama-type machine, the maximumtorque will vary as the 1.5 power of the submergence(closing) and 1.7 power of the submergence (opening).The operating time should vary as the 1.1 power forclosing and the 1.3 power for the opening cycle.

(2) Temporal loads. Temporal hydraulic loads orsurges are temporary changes in water level resulting in adifferential water level on opposite sides of a lock gate.These surges or differential heads may be caused byovertravel of water in the valve culvert during filling oremptying, wind waves, ship waves, propeller wash, etc.Depending on the circumstances, this differential hasbeen observed to vary from 1 to 2 ft. These forces donot affect the machinery power requirements, but they doaffect the design of the gate machine components whenthe gate is at the recess or mitered position. Theseforces have been known to fracture gate struts and shearsector pins. See paragraph 2-5b(1)(b) for the descriptionof these loads.

d. Determination of machinery loads.

(1) Normal loads. Normal miter gate operatingmachinery loads are difficult to determine and should,whenever possible, be determined from model or proto-type tests. Data compiled by the Special EngineeringDivision of the Panama Canal Zone taken from testsmade on the existing locks and a model for the thirdlocks and model studies included in TechnicalReport 2-651 (USAEWES 1964) appear to be the mostreliable sources for obtaining miter gate machinery loadsavailable at this time. When using data from the modeltests, it will be necessary to adjust the data on the basisof the scalar ratio between the model and the proposedlock. The length of the gate leaf is normally used fordetermining the scalar ratio. From the scalar ratio,Froude’s law comparing prototype to model would be asfollows:

Scalar ratio = length of prototype leaf= LR (2-9)length of model leaf

Volume, weight, and force = (LR)3:1

Time and velocity =LR:1

Torque = (LR)4:1

When using machines having the Ohio linkage, the Mod-ified Ohio linkage, or the Panama-type linkage, theforces on any size miter gate may be obtained from

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curves shown in Plates B-83 through B-86 which areplotted from the results of the WES and Panama CanalModel Tests. Readings from the curves must be factoredaccording to Froude’s law for submergence, time ofoperation, and clearance under gate. Curves are based onlock lengths of 600 ft or greater. Forces for shorterlengths would be slightly greater; however very few, ifany, locks would be built with chamber lengths less than600 ft.

(a) Computation of pintle torque for Panama Canaland Ohio-type linkage. If the proposed lock gate is inthe same scalar ratio with respect to length of gate andthe submergence and time of operation as shown oncurves and the type of linkage are the same, the pintletorque would equal the pintle torque at each positionindicated on the curves multiplied by the ratio of gateleaf lengths to the 4th power.

P1 = P(L1/L)4 (2-10)

where

P1 = pintle torque of proposed lock gate at selectedposition

P = pintle torque shown on curve of model study atselected position

L1 = leaf length, pintle to miter end, proposed lockgates

L = leaf length, pintle to miter end for curves thathave been plotted on model study

In the event the ratios of gate lengthsL1/L, submergenceS1/S, and the square of the time of operationT1/T are notof the same scalar ratio, the formula should be expandedas follows:

(2-11)P1 P(L1/L)4(S1/2)x(T2/T1)y

where

P1, P, L1, andL = same as in Equation 2-10

S1 = submergence of proposed lock gate

S = actual submergence of model gate upon whichcurves are based

S2 = adjusted submergence of model lock gate= S(L1/L)

T1 = time of operation of proposed lock gate (Seearc of travel adjustment below.)

T = actual time of operation of model gate uponwhich curves are based

T2 = adjusted time of operation of model lock gate =

T L1 /L

x = power to which submergence must be raised,for particular type linkage

y = power to which time must be raised, forparticular type linkage

NOTE: If only one ratio for either submergenceor the square of the operating time is not of thesame ratio as gate leaf lengthL1/L, then only theratio not in agreement withL1/L need be consid-ered in the equation.

If the arcs of gate travel differ from that shown on modelcurves, it will be necessary to adjust the operating timeof the proposed lockT1 to use in Equation 2-11 asfollows:

Let TA = adjusted operating time

or

TA = T1( arc of travel, proposed lock ) (2-12)(arc of travel, on model curves)

= T1(K1/K)

TA must be substituted in equation forT1

Use of Equations 2-10 through 2-12 results in a pintletorque which makes no allowance for motor slip since allof the model curves were based on uniform speed ofhydraulic cylinder or constant rpm of the motor. If aportion of the required gate torque curve overloads themotor, the resulting time of gate operation would beslower, which in turn would result in lower gate torqueduring this period. The same would occur when operat-ing the gates with a hydraulic cylinder. Overloading thecylinder would result in some of the oil being bypassed

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through relief valves which in turn would slow down thegate during the overload period. When using the Ohio-type linkages and torque data from TechnicalReport 2-651, the pintle torqueP1 should be adjusted forundergate clearance in addition to submergence and time.The percentage increase can be obtained from curves inFigure 2-10. Where a proposed lock is not subjected toflooding, electric motor operation with Panama-type orModified-Ohio-type linkage may be considered. A high-torque, high-slip motor should be used and should beselected so that the normal full load torque availablewould not be exceeded by the required torque of themachine more than 15 to 20 percent of the time. Peaktorque during the overload period should not exceed150 percent of full load torque. This can be determinedby plotting the required torque based on curves computedfrom model tests described above and by plotting avail-able motor torque curves at various degrees of slip andsuperimposing these curves over the required curves.Typical calculations for determining loads using theOhio-type linkage (hydraulic operation) are shown inPlate B-79. Calculations for determining loads using thePanama-Canal-type linkage (electric motor operation) forthe same design conditions are shown in Plate B-80.

(b) Computation of pintle torque for direct connectedlinkages. The kinematics of this type of machine shouldbe developed so as to provide the shortest practicablepiston stroke. This will require the gate pin connectionto be located out from the pintle a distance of 20 to25 percent of the gate length, and the center line of thecylinder gimbal bracket to be located so as to give thebest effective operating arm about the pintle at eachposition throughout the entire stroke of the piston. Withuse of this linkage and a uniform traveling piston, gateangular velocity will be greatest at the extreme closed oropen position of the gate. Uniform travel of the piston istherefore undesirable, and it will be necessary to slowdown the speed of the piston near the closed and openpositions by use of a variable volume pump in the oilcircuit. By slowing the travel near open or closed posi-tion of the gate, angular travel rates will be comparablewith the Panama Canal linkage. Figure 2-11 showscomparison curves for angular velocity of gate plottedagainst percent “closed” for Panama Canal Third Lockslinkage and for Claiborne Lock direct connected linkagewith and without variable speed control. Time of opera-tion should be selected for the proposed lock that willgive angular gate velocities approximately equal to thevelocities shown on the curve for Panama Canal. Gatepintle torque should then be taken from the prototypecurves shown in Plate B-87, Sheets 3 and 5, and adjustedby means of Froude’s Law of Similarity to the

submergence and time requirements of the proposed lockusing the same exponents as used for the Panama Canallinkage. Load computations for a direct connectedmachine are shown in Plate B-87, Sheets 1-10.

(2) Temporal loads. The resulting machinery loadsfor the case of temporal loading are based on a 1.25-ftdifferential head superimposed on the normal gate sub-mergence. These loads are considered applicable onlywhen the gate is at either the miter or recess position. Inoperation, these forces are resisted by a hydraulic loadbrake rather than by pumped oil pressure at the miterposition. This is done by automatically engaging a highpressure hydraulic relief valve at the position of travelwhere these loads occur. For this load condition, a33.33 percent overstress is allowed for componentdesign. In the recess position, this load is resisted byautomatically latching the gate. Only the sample compu-tations for the Ohio-River-type machine shown inPlate B-79, Sheets 1-12, include the temporal loadcomputations.

e. Operating machinery control.

(1) Hydraulically operated machines. A completedescription of the two basic types of hydraulic systemsfor locks along with pertinent hydraulic system designcriteria are presented in paragraph 1-11j. Control ofthese systems has utilized manual, solenoid controlled,pilot operated, and cartridge valves.

(a) With manual control, a small control stand islocated over a recess on one lock wall near the gatemachinery and is equipped with control valve operatinglevers. A schematic piping diagram of a manually con-trolled “central pumping” system is shown in Plate B-61.This diagram includes the connections for the taintervalves and shows the complete lock operating hydraulicsystem.

(b) Recent control systems utilize solenoid-controlledpilot-operated four-way and solenoid-controlled cartridgevalves to control the flow of oil to cylinders. This makesthe system more flexible and enables the inclusion of anelectrical interlock between the miter gates and lock filland empty valves so that the lock chamber water levelcannot be changed before all gates are closed. Changingthe water level in the lock chamber before the gates areclosed creates a swell head on the partially closed gateswhich could cause them to slam shut damaging the gateand/or gate machinery. This type of control is recom-mended rather than the manual control. A schematic

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piping diagram of this control system is shown inPlate B-62. (See also Plate B-63.)

(c) The majority of locks using electrically operateddirectional control valves have two points of lock control(one located near each gate in a control booth). Somerecently designed locks have utilized a single point ofcontrol located in the control building. Each controlpoint consists of a control console with all the controlfeatures associated with a normal lockage. These fea-tures include valve control, bubbler system, lock lighting,navigational signal, maintain pressure, and alarms. Atsome projects with dual control points, the control con-soles may become inundated during high water and,therefore, should be designed so that they are locatedabove the anticipated high water (by elevating the controlbooths) or so that they can easily be removed. A controlconsole layout is shown in Plate B-69.

(d) Locks with single points of control have theirgate and valve control console located in the controlbuilding near the upstream gate. So that the operatorscan view the downstream gate during opening and miter-ing, a multicamera closed circuit television system is alsoprovided. A simplified control stand is provided near thedownstream gate for the operation of the gate if thetelevision system becomes inoperative or during periodsof maintenance. Means for disconnecting or transferringcontrol from this control stand when not in use should beprovided.

(e) Whether single or dual control points are utilized,the control features are the same. This system providestwo speeds for miter gates and two speeds for culvertvalves. This scheme also provides a high degree ofautomation and protection against misoperation. Electri-cal interlocks are used in the control circuit to producethe desired operating sequence. Limit switches located atthe miter point of the gates, in the gate machineryrecesses and the culvert valve recesses, are used to pre-vent the upstream culvert valve from being opened whenthe downstream gate and/or valves are open and viceversa. These interlocks are also used to prevent slam-ming of the gates or changing the lock chamber waterlevel when gates are mismitered. One miter limit switchis located near the top of the gate and two miter limitswitches are located near the bottom of the gate. (Seemiter gate limit switch locations shown in Plate B-67.)Since the gate’s bottom seal resistance will prevent thelower portion of the gate from closing properly eventhough the top is mitered, only the top miter limit switchand the rack-mounted gate-mitered limit switches mustbe actuated before the corresponding filling or emptying

sequence can be started. If, after the valves are openedand at least one of the lower gate mounted miterswitches is not actuated, the valve being opened willautomatically close. A logic diagram for this system isshown in Figure 2-12. A manual backup system shouldbe provided for gate and valve control should theautomatic control system fail. The manual control sys-tem is independent of the automatic control system andbypasses all gate-valve interlocks.

(f) The electrical controls systems utilize either elec-tro-mechanical relays or solid state controllers. Theelectro-mechanical relay system for the valve/gate inter-lock system is shown in Plate B-66, Sheets 1-5. Thesame type of diagram can be used if solid state control-lers are to be used. Miscellaneous power and controldiagrams are shown in Plate B-65.

(g) In case of a control system failure that couldshut down the lock, a backup system should be provided.One backup system used on several locks is indicated inPlate B-70. The manual backup panel is connected to areceptacle located under each console. When connectedand a transfer switch is placed in the “backup” position,the operator has direct electrical control of the solenoid-operated directional control valve. When in use, thepanel bypasses all automatic control and electrical inter-lock features.

(2) Electrically operated machines. At projectswhere floodwaters will not overtop the lock wall ormachinery recesses, a modified Ohio machine with elec-tric motor drive may be economical and desirable. Atthese projects, control equipment consists of the combi-nation of full voltage magnetic controllers, limit switches,and control switches arranged to produce the desiredoperating sequence. The limit switches used in previousdesigns were of the traveling-nut type in NEMA fourenclosures with heaters. Due to the unavailability oftravel nut limits switches, cam-operated switches arebeing used. Control consoles similar to that describedabove for the hydraulic system are usually used. Electri-cal valve-gate interlock features should be similar to thatdescribed above for the hydraulic system. Strut stresslimit switches are used to cut off the motor if the strutstresses in either tension or compression beyond a presetpoint. This will protect the strut and machinery if anobstruction is encountered. A typical electrical schematicof a control system using a single-speed motor is shownin Plate B-71. Control for a two-speed motor is shownin Plate B-72.

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Figure 2-12. Lock filling sequence. (Lock emptying sequence is similar.)

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f. Miscellaneous equipment and systems.

(1) Machinery stops. In order to deal with ordinaryconstruction tolerances, a means must be provided toadjust the miter gate machinery linkage at installation. Ithas usually been found satisfactory to provide approxi-mately 2 in. of overtravel at each end of the hydrauliccylinder and rack to allow for adjustment. With thelinkage connected and the miter and recess positionsestablished for the gate, stops are installed and adjustedto limit the machinery motion to these extreme positions.One stop is placed so as to stop the rack when the gate ismitered; another is placed to stop the sector arm whenthe gate is recessed. Details of this arrangement areshown in Plate B-49.

(2) Automatic greasing. A system should beprovided to automatically grease each miter gate pintlebushing and gudgeon pin as shown in Figure 2-13. Thesystem should dispense a measured amount of grease toeach location automatically during gate movement. Anautomatic grease system is available with a built-in pro-grammable controller, which will allow variations ingrease cycles and quantity of grease provided. Since thegrease systems have to be field-tuned, for a particularlock application, the programmable controller should be adesirable option. The pintle bushing should be designedto permit the installation of an O-ring seal and a greasereturn line which can be monitored to ensure greasedelivery to the pintle bushing. The system shouldinclude automatic monitoring equipment to warn of amalfunction. Special consideration should be given tothe layout and sizing of the grease lines to ensure properoperation and minimum pressure loss. Grease linesshould be stainless steel pipe of adequate wall thicknessfor the anticipated pressures. Grease lines should belocated in areas of the gate that afford the greatest degreeof protection from damage due to ice and drift. Thepumping unit should be located near the gate to minimizegrease line length. Provisions should be made to removethe pumping unit if flooding is likely. For more details,see Plate B-13, Detail A.

(3) Automatic gate latches. Latches should be pro-vided for holding the gates in the recess. The latchesshould be designed to automatically latch the gate whenit comes into the recess. Release of the latches should beaccomplished automatically each time a “gate close”function is initiated. A recess latch is shown inPlate B-68. The system should be provided with latchedand unlatched position indication.

(4) Maintain pressure system.

(a) A maintain pressure system should be providedto hold miter gates closed with hydraulic pressure. Thepresent system (as indicated in Plate B-66) is designed tohold the gate leaves together against wind loading orsmall water surges prior to changing the chamber waterlevel. Upstream gate maintain pressure is used duringlock pit emptying, and downstream gate maintain pres-sure is used during lock pit filling operation. This main-tain pressure system is activated by the lock operatordepressing a pushbutton on operator console. This sys-tem can be deactivated manually by the operator or isautomatically deactivated when the gate under maintainpressure is opened or after the valves are opened for apredetermined time to allow an adequate head of wateron the gates to keep them mitered. The maintain pres-sure system should utilize the valve “slow” or the lowestpumping rate available.

(b) The tandem center hydraulic system is not pre-ferred but, if used, or if retrofitting a tandem center sys-tem, the maintain pressure system will provide pressureto the miter gate cylinder in the gate closed positionthrough the use of a standard bladder-type accumulator.This accumulator, located in each miter gate machineryrecess, will be charged and pressure maintained through apilot-operated check valve installed in series with eachmiter gate cylinder. A pressure switch, sensing accumu-lator pressure, will ensure adequate pressure through atime delay circuit. An indicator lamp on the controlconsole will be illuminated when pressure in the maintainpressure system is adequate. At the same time the gatefour-way valve will be automatically shifted from “close”to “neutral” position.

(5) Fire protection system. In addition to therequirements of EM 1110-2-2608, a fire-protection sys-tem may be provided for miter gates. In operation, thissystem provides a dense spray of water on the miter gatesurface between the gate and barges which may be onfire in the lock chamber. This spray would keep thegates cool and minimize distortion in the event of a fire.The system consists of a series of water spray nozzleslocated along the top of each miter gate leaf discharginginto the lock chamber. These spray nozzles are fed byhigh capacity raw water pumps. One pump is providedfor each lock chamber. Control stations are located neareach gate with controls for starting and stopping the rawwater pump and also for opening and closing the motor-ized valve in the supply line to each set of gate nozzles.

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Figure 2-13. Automatic lubrication system schematic

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The decision to include the gate spray system should beevaluated on a case-by-case basis depending upon theconsequences of the loss of the gate.

(6) Overfill and overempty control system. Theoverfill and overempty system should be evaluated on acase-by-case basis and should be considered mainly onhigh lift locks or locks with long narrow approaches. Acontrol system has been developed to eliminate overfill-ing and overemptying of the lock chamber. This systemmeasures water levels by sensing the back pressure ofcompressed air constantly bubbling through tubes extend-ing below the surface of the water. This system

compares the level of water in the lock chamber withthat of the upper pool when filling and the lower poolwhen emptying and at a predetermined time begins clos-ing the fill or empty valves, respectively. This actiondissipates the energy of flowing water in the culverts,thereby eliminating lock overfill or overempty. Theoperators at locks which utilize the gate-mounted limitswitches have developed an operating technique whicheliminates or greatly reduces overfill or overempty. Asthe lock fills or empties, the operator watches the indicat-ing lights controlled by the gate-mounted limit switches.When the lights start going off the operator opens theappropriate gate.

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Chapter 3Diagonal Design, Miter Gates

3-1. Diagonal Design

The following information is applicable to open framegates and is essentially the same as that presented in“Torsional Deflection of Miter-Type Lock Gates andDesign of the Diagonals” (USAED, Chicago, 1960) withonly minor modifications.

3-2. Definitions of Terms and Symbols

Deviations from these symbols are noted at the places ofexception.

∆ - Total torsional deflection of the leaf measured, atthe miter end, by the movement of the top girderrelative to the bottom girder. (See Figure 3-1.)The deflection is positive if the top of the miterend is moved upstream relative to the bottom.

Positive diagonal: A diagonal which decreased inlength with a positive deflection of the leaf. (SeeFigure 3-4.)

a - The cross-sectional area of that part of a hori-zontal girder which lies outside the midpointbetween the skin and the flange. (SeeFigure 3-6.)

A - Cross-sectional area of diagonal.

A′- Stiffness of the leaf in deforming the diagonal.Until more test data are available, it is suggestedthat A′ be taken as the sum of the average cross-sectional areas of the two vertical and two hori-zontal girders which bound a panel times:

1/8 for welded horizontally framed leaveswith skin of flat plates,

1/20 for riveted vertically framed leaveswith skin of buckle plate. (Seeparagraph 3-4i(1).)

b - Distance from the center line of the skin plate tothe flange of a horizontal girder. (SeeFigure 3-6.)

c - The smaller dimension of a rectangular crosssection.

d - Pitch diameter of the threaded portion of thediagonals.

D - Prestress deflection for a diagonal.D is thedeflection of the leaf required to reduce thestress in a diagonal to zero.D is always positivefor positive diagonals and negative for negativediagonals.

E - Bending modulus of elasticity.

Es- Shearing modulus of elasticity.

h - Height of panel enclosing diagonal.

H - Vertical height over whichH is measured, usu-ally distance between top and bottom girders.

I - Moment of inertia about the vertical axis of anyhorizontal girder.

Ix- Moment of inertia, about the horizontal centroi-dal axis, of a vertical section through a leaf.(See Figure 3-5.)

J - Modified polar moment of inertia of the horizon-tal and vertical members of the leaf.

K - A constant, taken equal to 4. (See para-graph 3-4i(2).)

l - The larger dimension of a rectangular crosssection.

L - Length of a diagonal, center to center of pins.

M - Torque required to turn the sleeve nut to pre-stress diagonal. (Refer to Equation 3-28.)

n - Number of threads per inch in sleeve nut ofdiagonal.

N - Number of turns of nut to prestress diagonal.(Refer to Equation 3-27.)

Qo- Elasticity constant of a leaf without diagonals.(See paragraph 3-4i(2).)

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EM 1110-2-270330 Jun 94

Q - Elasticity constant of diagonal defined byEquation 3-18.

Ro - Ratio of change in length of diagonal to deflec-tion of leaf when diagonal offers no resistance.(Refer to Equation 3-11.) Ro is positive forpositive diagonals and negative for negativediagonals.

R - Ratio of actual change in length of diagonal todeflection of leaf. (Refer to Equation 3-13.)Ris positive for positive diagonals and negativefor negative diagonals.

s - Unit stress in diagonal.

S - Total force in diagonal.

t - Distance from center line of skin plate to centerline of diagonal. (For curved skin plate, seeparagraph 3-4h.)

Tz - Torque area. Product of the torqueT of anapplied load and the distancez to the load fromthe pintle. z is measured horizontally along theleaf. Tz is positive if the load produces a posi-tive deflection.

v - Distance from center line of pintle to extrememiter end of leaf.

w - Width of panel. (Refer to Figure 3-1.)

X - Distance from center line of skin plate to verti-cal shear center axis of leaf. (Refer toEquation 3-30.)

y - Distance to any horizontal girder from the hori-zontal centroidal axis of a vertical sectionthrough a leaf.

yn- Distance to any horizontal girder from the hori-zontal shear center axis of a vertical sectionthrough a leaf.

Y - Distance to horizontal shear center axis fromthe horizontal centroidal axis of a vertical sec-tion through a leaf. (Refer to Equation 3-29.)

3-3. Introduction

A lock-gate leaf is a very deep cantilever girder with arelatively short span. The skin plate is the web of this

girder. If the ordinary equations for the deflection of acantilever under shearing and bending stresses areapplied, the vertical deflection of the average leaf will befound to be only a few hundredths of an inch. Becausethe skin plate imparts such a great vertical stiffness to theleaf, the stresses in the diagonals are a function of onlythe torsional (twisting) forces acting upon the leaf.These forces produce a considerable torsional deflectionwhen the gate is being opened or closed. It is thistorsional deflection and the accompanying stresses in thediagonals with which this chapter is concerned.

a. The shape of the twisted leaf is determined geo-metrically. Then the work done by the loads is equatedto the internal work of the structure. From this, theresistance which each diagonal offers to twisting of theleaf is computed as a function of the torsional deflectionof the leaf and the dimensions of the structure. Equa-tions for torsional deflection of the leaf and stresses inthe diagonals are derived.

b. Experiments were made on a model of the pro-posed gates for the MacArthur Lock at Sault Ste. Marie.Tests were also conducted in the field on the lower gatesof the auxiliary lock at Louisville, KY. Both experi-ments indicate that the behavior of a gate leaf is accu-rately described by the torsional deflection theory.

c. Examples of the application of the theory arepresented together with alternate methods for prestressingthe diagonals of a leaf.

3-4. Geometry

In order to make a torsional analysis of a lock gate, thegeometry of the deflected structure must be known. Thechange in length of the diagonal members will be deter-mined as a function of the torsional deflection of the leaf.For the present, the restraint offered by the diagonals willnot be considered.

a. Diagonal deformation. In Figures 3-2 and 3-3,the panel ak of Figure 3-1 is considered separately. Asthe leaf twists the panel ak twists as indicated by thedotted lines. In Figure 3-3, movements of all points arecomputed relative to the three reference axes gf, gb, andgk shown in Figure 3-2. The girders and skin plate arefree to twist, but they remain rectangles, except forsecond-order displacements. Therefore, the three refer-ence axes are always mutually perpendicular. Letδo

equal the change in length of either diagonal ofFigure 3-3.

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Figure 3-1. Schematic drawing of a typical miter-type lock-gate leaf

(3-1)

δo

dw

t cos α

dh

t sin α

dtw

w

(w 2 h 2)1/2

dth

h

(w 2 h 2)1/2

2dt

(w 2 h 2)1/2

b. Sign convention. For the necessary sign conven-tion, let the deflectiond be positive when the top of theleaf moves upstream in relation to the bottom. With apositive deflection, those diagonals that decrease inlength are considered positive diagonals. With negativedeflection, where the top of the gate moves downstreamin relation to the bottom, those diagonals that decrease inlength are considered negative diagonals.

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Figure 3-2. Schematic drawing of panel ak

c. Ratio of diagonal deformation to panel deflection.In the following information a decrease in any diagonallength, either positive or negative diagonal, is designatedas a positive change in length. Letro be defined asfollows:

(3-2)ro

δd

o

which from Equation 3-1 becomes

(3-3)ro ± 2t

(w 2 h 2)1/2

ro is positive for positive diagonals and negative fornegative diagonals. Figure 3-4 illustrates the positive andnegative diagonals of a typical leaf.

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Figure 3-3. Displacements of points of panel ak

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Figure 3-4. Positive and negative diagonals of a typical leaf

d. Diagonal restraint. Up to this point, the restraintoffered by the diagonal members has not been consid-ered. Equation 3-1 gives the change in length of a diag-onal if the diagonal offers no resistance. However,unless a diagonal is slack, it does offer resistance tochange in length. Therefore, when a deflection d isimposed upon the panel, the length of the diagonal doesnot change an amountδo. The actual deformation isδwhich is less thanδo by some amountδ′.

(3-4)δ δo δ

(1) It is evident thatδ is inversely proportional to theresistance of the diagonal and thatδ′ is inversely propor-tional to the ability of the panel to elongate the diagonal.Let the resistance of the diagonal be measured by itscross-sectional areaA. Then

(3-5)δδ1

AA

in which A′ is a measure of the stiffness of the panel indeforming the diagonal. The significance ofA′ and themethod of determining its magnitude will be discussedlater. Let it be assumed for the present, however, thatA′is known.

(2) Solving Equation 3-4 forδ′ and substituting itsvalue in Equation 3-5,

(3-6)δδo δ

AA

(3) Let r be defined as the ratio of the actual defor-mation of the diagonal to the deflection of the panel.

(3-7)rδd

(4) Using Equations 3-2 and 3-7, Equation 3-6 canbe written

rdrod rd

AA

and solving forr

(3-8)rA

A Aro

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It will be noted that when the diagonal offers no restraint(that is to say thatA = o), r = r o.

(5) Let ∆ be defined as the torsional deflection of thewhole leaf; see Figure 3-1. It is evident that the relativedeflectiond from one end of a panel to the other is pro-portional to the width of the panel

(3-9)dw ∆

v

(6) Let Ro be defined as follows:

(3-10)Ro

δo

∆

Substituting the values ofδo and ∆ from Equations 3-2and 3-9, respectively

Ro

rod

(v/w)d

wro

v

which, from Equation 3-3, becomes

(3-11)Ro ±

2wt

v(w 2 h 2)1/2

Let R be defined by

(3-12)Rδ∆

Substituting in Equation 3-12 the values ofδ and ∆obtained from Equations 3-7 and 3-9, respectively

Rrd

(v/w)dwv

r

which, from Equation 3-8 becomes

(3-13)Rwv

ro

A

A ARo

A

A A

e. Deflection of leaf and stresses in diagonals. Ingeneral, the diagonals of any lock-gate leaf will have, asa result of adjustments, an initial tension which is herecalled a prestress. The prestress in all diagonals is notthe same. However, for any diagonal the leaf can bedeflected by some amount∆, such that the stress in thatdiagonal is reduced to zero. The magnitude of thisdeflection is a measure of the initial tension in thediagonal and will be called the prestress deflectionD forthat diagonal. By selecting the value ofD, the designercan establish a definite prestress in any diagonal (seeexamples 1 and 2 in this chapter). It can be seen fromthe definition of a positive diagonal thatD is positive forpositive diagonals and negative for negative diagonals.

(1) Referring to Equation 3-12, it is seen that theprestress in any diagonal results from a change in lengthequal toR (-D). If an additional deflection∆ is imposedupon the leaf, the total change in length will be

(3-14)δ R ( D) R (∆) R (∆ D)

and similarly

δo = Ro(∆ - D) (3-14a)

Since a positive value ofδ represents a decrease inlength, the elongation of a diagonal is (-δ) and the totalforce is

S( δ) EA

L

which from Equation 3-14 becomes

(3-15)SREAL

(∆ D)

(2) If the diagonal offered no resistance to change inlength, its deformation would be, from Equation 3-4,δo

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EM 1110-2-270330 Jun 94

= δ + δ′. The force in the diagonal, therefore, not onlyelongates the diagonal an amountδ′. The total workdone by the forceS in the diagonal is, therefore

WD

12

(δ δ ) 12

Sδo

which, by adapting Equation 3-14a, becomes

(3-15a)WD

12

SRo (∆ D)

Substituting the value ofS from Equation 3-15

(3-16)WD

RRoEA

2L(∆ D)2

(3) The forceS in the diagonal is produced by someexternal torqueT. The work done is

WT

12

Tθ

It is evident from Figure 3-1 that the angle of rotationθof any section of the leaf is proportional to the distancezfrom the pintle. If the leaf is twisted an amount (∆-D),the angle of rotation at the end is (∆-D)/h. Therefore, atany section

θ (∆ D)h

zv

Making this substitution for 0 in the equation forWT

(3-17)WT

(∆ D)2hv

Tz

The term Tz is the area of the torque diagram for thetorque T. Tz will hereinafter be called “torque-area.”(See definitions.)

(4) Equating the sum ofWD and WT as given byEquations 3-16 and 3-17, respectively, to zero andsimplifying

Tz

RRoEAhv

L(∆ D) 0

Let

(3-18)QRRoEAhv

L

Then(3-19)Tz Q (D ∆) 0

SinceTz is the torque-area of the external load, the quan-tity Q(D-∆) may be called the resisting torque-area of thediagonal. All factors ofQ are constant for any diagonal.Q, therefore, is an elasticity constant of the diagonal.Even if there were no diagonals on a leaf, the structurewould have some resistance to twisting. Let the resistingtorque-area of the leaf without diagonals be defined asQo(∆). A prestress deflectionD is not included in thisdefinition since the leaf does not exert any torsionalresistance when it is plumb. In other words,D for theleaf is zero. Qo will be evaluated later. For the present,let it be assumed thatQo is known.

(5) The total torque-area of all external loads plusthe torque-area of all resisting members must equal zero.Therefore, Equation 3-19 may be written as follows:

(3-20)Σ (Tz) Qo∆ Σ [Q (D ∆)] 0

in which ∑[Q(D-∆)] includes all diagonals of the leaf.

(6) Since∆ is a constant for any condition of load-ing, Equation 3-20 may be solved for∆.

(3-21)∆Σ (Tz) Σ (QD)

Q0 ΣQ

which is the fundamental equation for deflection.

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(7) If the leaf is to hang plumb (∆ = 0) under deadload, the numerator of the right-hand member of Equa-tion 3-21 must equal zero.

(3-22)Σ(Tz)D.L. Σ(QD) 0

Equation 3-22 represents the necessary and sufficientcondition that a leaf hang plumb under dead load.

(8) If the live-load and dead-load torque-areas areseparated, Equation 3-21 may be written

∆Σ (Tz)L.L. Σ (Tz)D.L. Σ (QD)

Qo ΣQ

But if Equation 3-22 is satisfied,∑(Tz)D.L. + ∑(QD) = 0

Therefore

(3-23)∆Σ (Tz)L.L.

Qo ΣQ

which is the fundamental equation for deflection of a leafwith all diagonals prestressed. Equation 3-23 shows thatthe live load deflection of a leaf is independent of theprestress deflectionD for any diagonal.

(9) The unit stress in a diagonal is obtained bydividing Equation 3-15 by A,

(3-24)sREL

(D ∆)

which is the fundamental equation for unit stress in adiagonal.

(10) If the maximum allowable unit stress is substi-tuted for s in Equation 3-24, the maximum allowablenumerical value of (D-∆) will be obtained. Since themaximum values of∆ are known from Equation 3-23,the maximum numerical value ofD for any diagonal canbe determined.

(11) The diagonals of a gate leaf should be pre-stressed so that all of them are always in tension (seeparagraph 3-4j). If this is to be so, the quantity (D-∆)must always represent an elongation of the diagonal.Therefore, for positive diagonals,D must be positive and

greater than the maximum positive value of∆. Fornegative diagonals,D must be negative and numericallygreater than the maximum negative deflection. Thesethen are the minimum numerical values ofD.

(12) Values of D shall be selected such that theysatisfy Equation 3-22 and lie within the limits specifiedabove. If this is done, the leaf will hang plumb underdead load, and none of the diagonals will ever becomeoverstressed or slack. In addition, the deflection of theleaf will be held to a minimum since a prestressed ten-sion diagonal is in effect a compression diagonal as well.

f. Preliminary area of diagonals. In the design ofdiagonals, it is desirable to have a direct means of deter-mining their approximate required areas. With theseareas, the deflection and stresses can then be found and,if considered unacceptable, the areas could be revisedand the process repeated. A close approximation to therequired area can be found by equating Equations 3-15aand 3-17.

12

SRo (∆ D) (∆ D)2hv

Tz

TreatingRo as equal for all diagonals, substitutingsA forS, and taking∑ for all diagonals in a set,

(3-25)AΣ Tz

Rohv

With the above, the maximum positive∑Tz will give thetotal area required in the set of negative diagonals andthe maximum negative∑Tz, the area for the positivediagonals.

g. Vertical paneling of leaf. By differentiating Qwith respect toh, it has been found that the most effec-tive slope for a diagonal exists withh = w(2)1/2. If happroaches 2.5w, it will be desirable to subdivide thepanel vertically to reduce the area of the diagonals or,possibly, to reduce their total cost. The example in para-graph 3-6i shows the slight modification necessary toapply this method of design to panels subdividedvertically. In general, diagonals are most effective inpanels having the ratio of

Greater dimensionLesser dimension

≈ (2)1/2

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EM 1110-2-270330 Jun 94

h. Curved skin plate. The geometric relationshipsderived herein apply equally well to a leaf with curved orstepped skin plating and the more general value oft isthe plan view divided by the width. The plan-view areais the area bounded by the skin plate, the center line ofthe diagonals, and the side boundaries of the panel.

i. Discussion.

(1) The constantA′: Except for the constantsA′ andQo′ all properties of the gate leaf are known, and thedeflection of the leaf and the stresses in the diagonalscan be determined.A′ appears in the equations for bothR andQ as follows:

(3-13)RA

A ARo

(3-18)QRRoEAhv

L

Ro2EAhv

L× A

A A

(a) Measurements were made on the 1/32-size cellu-loid model of the gates for the MacArthur Lock at SaultSte. Marie (Soo). Field measurements were also madeon the lower gate at Louisville, KY, and 29 gate leavesin the Rock Island District on the Mississippi River. TheSoo and Louisville gates are horizontally framed andhave flat skin plates and the Mississippi gates are verti-cally framed and have buckle skin plates. In all cases,δwas determined from strain gage readings on the diago-nal and∆ was measured directly as the leaf was twisted.Equation 3-12 gave the value ofR. A′ was then cal-culated from Equation 3-12 in which the theoretical valueof Ro, obtained from Equation 3-11 was substituted.1

Values ofA′ obtained are:

Sault Ste.Marie A′ = 0.025 in.2 (model)

= 0.025 x (32)2 = 26 in.2 (prototype)

Louisville = 13 in.2

MississippiRiver Gates = 10 in.2

(b) It seems reasonable to suppose that the size ofthe horizontal and vertical girders to which the diagonal

_____________________________1 In the model test, the experimental value of Ro wasalso determined and was found to agree with the theoreti-cal value within 1 percent.

is attached can be used as a measure ofA′. At Sault Ste.Marie, A′ is 0.14 of the sum of the cross-sectional areasof the girders which bound the diagonal. At Louisvillethe factor is 0.07 and for the Mississippi River gates,0.045. Additional experiments are desirable. However,until more data are obtained, it is believed that a conser-vative value ofA′ for the average diagonal is the sum ofthe average cross-sectional areas of the girders whichbound the diagonals times 1/8 for the heavier, welded,horizontally framed leaves with flat skin plate and 1/20for the lighter, riveted, vertically framed leaves withbuckle plates.

(c) It is believed that for any gate leaf diagonal,A′will usually be as large or larger thanA. Therefore, alarge error inA′ will result in a much smaller error in thefraction A′/(A + A′). Hence, it is necessary to know theapproximate value of A′ in order to apply the foregoingtheory. This is especially true of the diagonal stress, ascan be seen from Equation 3-24 where an error inA′produces an errorR which is opposite to that produced in(D - ∆). Thus, stress is nearly independent ofA′.

(2) The constantQo: Qo is an elasticity constantwhich is a measure of the torsional stiffness of a leafwithout diagonals. Qo is a function of many propertiesof the leaf. However, it seems reasonable that the tor-sional work done upon the typical main members of theleaf, as the leaf twists, might be used as a measure ofQo.

(a) When a leaf twists, the horizontal and verticalmembers rotate through angles of∆/h and ∆/v, respec-tively. The work done in any member is

W12

EsJ

v(∆)2

h 2, for horizontal members

W12

EsJ

h(∆)2

v 2, for vertical members

Es = shearing modulus of elasticity

J = modified polar moment of inertia

The work done by an external torque is, fromEquation 3-17

WT

∆2hv

Tz

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In this case the value ofD in Equation 3-17 is zero sincethe members are not supplying a resisting torque whenthe deflection is zero. EquatingWT to W and solvingTz,

Tz = EsJ ∆ , for horizontal membersh

Tz = EsJ ∆ , for vertical membersv

The quantitiesEsJ/h and EsJ/v might be called the valuesof Qo for

horizontal and vertical members, respectively, hence,

(3-26)Qo K Es Σ (J/h J/V)

where the value ofK as determined experimentally forthe Sault Ste. Marie model and the Louisville prototypeis approximately 4. Until additional measurements canbe made, this value should be used.

(b) Nearly all members of a leaf subject to torsionare made up of narrow rectangles. For these, the valueof J is

Σ l (3)3

3

Where plates are riveted or welded together, with theirsurfaces in contact, they are considered to act as a unitwith c equal to their combined thickness.

(c) Using Equation 3-26,Qo can be evaluated veryeasily, as will be demonstrated in the examples. How-ever, in many casesQo can be neglected entirely withoutbeing overly conservative. In neglectingQo, the stiffnessof the leaf itself, without diagonals, is neglected. Anexperiment has shown this stiffness to be small. Further-more, anyone who has seen structural steel shapes han-dled knows how easily they twist. Unless closed sectionsare formed, the total stiffness of a leaf is just the arith-metic sum of the stiffness of all members taken individu-ally and this sum can be shown to be small. The lack oftorsional stiffness is also illustrated by a known case inwhich a leaf erected without diagonals twisted severalfeet out of plumb under its own dead weight.Qo isincluded in examples 1 and 2 but its values are only5 percent and 3 percent, respectively, of the total stiff-nesses,Q, contributed by the diagonals.

(3) Load torque-areas. By definition, a load appliedthrough the shear center of a section will cause no twist-ing of the section. In computing dead load torque-areathe moment arm of the dead load is, therefore, the dis-tance from the vertical plane through the shear center tothe center of gravity of the leaf. The method of locatingthe shear center of a lock-gate leaf is given in para-graph 3-4k. The water offers resistance against the sub-merged portion of the leaf as it is swung. There is alsoan inertial resistance to stopping and starting. Since theresultant of these resistances is located near or below thecenter height of leaf and the operating force is near thetop of the leaf, a live load torsion results. From testsperformed to determine operating machinery designloads, the maximum value of the above-mentioned resis-tances was found to be equivalent to a resistance of30 psf on the submerged portion of the leaf. Until addi-tional data become available, it is recommended that thisvalue be generally used in computing the live loadtorque-area. However, in the case of locks accommodat-ing deep-draft vessels, water surges are created duringlockages that appear to exceed the above-mentionedequivalent load. Until more data are obtained, it is rec-ommended that for these cases, 45 psf or higher beused.2 The diagonals will also be checked for obstruc-tion loads and temporal hydraulic loads and the govern-ing loading condition will be used for diagonal design.For definition of obstruction and temporal hydraulicloads, refer to paragraphs 2-1b and 3-8, respectively.

(4) Skin plate consisting of buckle plates. Thetheory is based upon the assumption that the skin plateremains rectangular at all times. If the skin consistsentirely of buckle plates and if the shear in the skin islarge, this assumption may be in error. However, if thediagonals extending downward toward the miter end aremade larger or prestressed higher than the others, theprestress in them can be made to carry a large part, if notall, of the dead load shear. Although the action ofbuckle plates in shear is not understood, it is recom-mended that they be treated as flat plates. As a precau-tion, however, the diagonals should be prestressed tocarry as much of the dead load as possible within therestrictions imposed uponD (see paragraph 3-4e). Thereader is referred to example 2, paragraph 3-6.

j. Methods for prestressing diagonals. It is essentialthat all diagonals be prestressed. With all diagonals

_____________________________2 The operating strut mechanism should also then bedesigned for these larger forces.

3-11

EM 1110-2-270330 Jun 94

prestressed, none will ever alternately bow out and thensnap back into position during operation of the leaf. It iscertain that this buckling was responsible for some of thefailures of diagonals which occurred in the past. Pre-stressing also reduces the torsional deflection of the leafto a minimum, since all diagonals are always acting.There are two general methods of prestressing diagonals.In one method, the leaf is twisted a precomputed amountand the slack in the diagonals is removed. In the other,the sleeve nut on the diagonal is turned a precomputedamount. Caution should be taken when using the twistof the leaf method where the leaf has top and bottomtorque tubes. Due to the increased leaf stiffness, there isthe need for a higher jack capacity (150+ tons), and apossibility that damage could be caused to the leaf orother gate components. The high jacking loads couldcause damage such as localized buckling of plates, exces-sive deflection in the quoin post, damage to the greaseseals, pintle, and pintle socket, etc. These two methodsare discussed below:

(1) Twist-of-the-leaf-method. The quoin end of theleaf is made plumb and the miter end is anchored toprevent horizontal movement in either direction. This isdone by either tying the miter end to the sill or tying thetop miter end to the lock wall and using a hydraulic jackat the bottom. Then with a power-operated cableattached to the top of the miter end, the leaf is twistedthe computedD for one set of diagonals and the slack isremoved from this set. During this operation, the otherset of diagonals must be maintained slack. The leaf isthen twisted in the opposite direction the computedD forthe other set of diagonals, and the slack is removed fromthem. (See example 2, paragraph 3-6.) It is importantthat all the slack be removed without introducing anysignificant tension in the diagonal. This can best beaccomplished by lubricating the nut and manually turningit with a short wrench. Since the turning resistanceincreases abruptly with the removal of the slack, thepoint of removal can be felt. As a further precaution, astrain gage is recommended on the diagonal being tight-ened. The maintained deflection of the leaf should alsobe watched, since more than a slight tension in the diago-nal will cause a change in deflection of the leaf. Onexisting gates in which the diagonals were not designedby this method, it may be necessary to overstress somediagonals during the prestress operation. A stress of0.67Fy for this one-time load is considered permissiblewhere Fy is the yield strength of the diagonal material.The prestressing force required (normal to the leaf, at theupper miter corner) is obtained from Equation 3-21 as

p∆ (Qo ΣQ) ΣQ (ΣTz) D.L.

hv

where Q includes only the active diagonals. (See theexample, paragraph 3-6i.)

(2) Turn-of-the-nut-method. In this method, it isessential that the nut be very well lubricated with a heavylubricant. Initially, all diagonals must be slack and,during the prestressing operation, each diagonal must bemaintained slack until it is reached in the prestressingsequence. Then the slack is removed from the first diag-onal to be prestressed and the diagonal is clamped to theleaf, as close to both ends of the nut as possible, toprevent twisting of the diagonal during the nut-turningoperation. The clamping should restrain twisting of thediagonal without preventing elongation of the full length.In removing the slack, the same precautions should beobserved as in the previous method. The nut is thenturned the precomputedN for the diagonal. This proce-dure is repeated for each succeeding diagonal. (Seeexample 1, paragraph 3-5.) The large torque required tofully tighten the nut can be provided by a mechanicallysupplied force at the end of a long wrench. The nutmust be turned to shorten the diagonal an amountδo =Ro (D-∆). Therefore, ifn is the number of threads perinch, the number of turns required is

(3-27)NnRo(D ∆)

2

in which ∆ is the initial deflection measured in the field.From textbooks on machine design, the torqueMrequired to turn the nut to obtain the desired prestress,sA, is

M sA tan (θ α)d

where d is the pitch diameter of the threads,θ is thefriction angle which from tests may be taken equal to tan-1(0.15) = 8o30′, and α is the helix angle which, withinthe size range that would be used on diagonals, may betaken as a constant angle of 1o30′. Further the maximumunit stress s is given by Equation 3-24.

Therefore

(3-28)M 0.18 sAd0.18 REAd(D ∆)

L

3-12

EM 1110-2-270330 Jun 94

in which ∆ is determined from Equation (3-21), withonly the active diagonals included.

(3) Comparison of methods. The twist-of-the-leafmethod has been used, with excellent results, consider-ably more than the turn-of-the-nut method. While theturn-of-the-nut method appears to have some merit, suchas reduction in setup time, the elimination of overstress-ing any diagonal during prestressing, and the eliminationof strain gages, this method is not recommended due tothe difficulties encountered during prestressing. Thediagonal bar tends to twist and it is extremely difficult toprovide sufficient torque to the sleeve nut or turnbucklewithout first deflecting the leaf. The turn-of-the-nutmethod is included for information but for normal instal-lations the twist-of-the-leaf method should be used.

k. General method for locating shear center of a lockgate leaf. The shear center of a gate leaf is the pointthrough which loads must be applied if the leaf is not totwist.

(1) Horizontal shear center axis. Consider the leafrestrained against rotation about the hinge. To preventtwisting of the leaf due to horizontal forces, the resultantof these forces must be located so that the load to eachhorizontal girder is proportional to their relative stiff-nesses. This is equivalent to saying that the resultantmust be located along the horizontal gravity axis of thegirder stiffnesses. This gravity axis is then the horizontalshear center axis and is located a distance from the cen-troidal axis equal to

(3-29)YΣ (In Y)

Σ In

in which In is the moment of inertia of any horizontalgirder about its vertical centroidal axis.

(2) Vertical shear center axis. A lock-gate leaf is acantilever beam supported by the pintle gudgeon. Avertical load on the leaf causes tension above and com-pression below the centroidal axis. Therefore, longitudi-nal shearing stresses exist in the structure and shearingstresses of equal magnitude and at right angles to thelongitudinal shearing stresses exist in the plane of anyvertical cross section.

(a) A shear diagram with arrows to indicate thedirection of the shear is shown in Figure 3-5. Since theshears of the flanges of the top and bottom girders are

small and since the shear on one side of a flange is usu-ally equal and opposite to the shear on the other side ofthe same flange, these shears will be neglected. Thehorizontal shears in the webs of the top and bottom gird-ers produce a torsional moment on the section whichmust be balanced by the torsional momentVX of thevertical forces if the leaf is not to twist.

(b) The shear diagram for the web of the right-handpart of the top girder is redrawn to a larger scale in Fig-ure 3-6. The trapezoidal shape of this diagram is basedupon the assumption that the thickness of the web isconstant within the limits of the diagram. The ordinateof the diagram at any point isVQ/I. The area of theshear diagram is the total horizontal shearS on this partof the girder. This area is (VQ/I)b in which VQ/I is theordinate at the center of the diagram. Therefore,Q is thestatical moment, about the centroidal axis of the wholesection, of that part of the section lying within the circleof Figure 3-6. Ifa is the area of this part of the section,thenQ = ay, and

SVay

Ib

The torsional moment of all these horizontal shearingforces about the horizontal shear center axis is

T Σ VayI

byn

VI

Σ (aybyn)

If the leaf is not to twist, the sum of the moments of thevertical and horizontal forces must equal zero.

VXVI

Σ (aybyn) 0

and solving

(3-30)X

Σ(aybyn)

I

which is the horizontal distance from the center line ofthe skin to the shear center of the section. In this equa-tion, a is always positive andb and X are positive whenmeasured to the right of the skin and negative whenmeasured to the left.

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EM 1110-2-270330 Jun 94

Figure 3-5. Shear diagram for typical vertically framed lock-gate leaf

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Figure 3-6. Shear diagram for web of the right-handpart of the top girder

c. Equations 3-29 and 3-30 are general expressions,independent of the number of horizontal girders, and assuch apply equally well to horizontally framed gates.

3-5. Example 1, Horizontally Framed Gate

Lower operating gates, MacArthur Lock, Sault Ste. Marie(See Figure 3-7).

a. Evaluation of A′. The bottom and top girders andthe vertical end girders are W36X150 with a cross-sectional area of 44.16in2. Therefore,A′ is (see para-graph 3-4i(1))

A′ = 1/8 (4 × 44.16) = 22 in.2

b. Evaluation of Qo. (See paragraph 3-4i(2) andTable 3-1.)

(3-26)

Qo K Es Σ ( j/h j/v)

Qo 4 × 12 × 106 4320.03 × 684.0

5903 × 529

120.0 × 106in. lb.

c. Location of shear center. (See Figure 3-5.)Computations for the centroidal axis and moment of

inertia of the vertical section through the leaf (see Fig-ure 3-7) are not given. Computations of distancesx andy are given in Tables 3-2 and 3-3, respectively.

y = 310 in. I = 42.6 x 106 in.4

Horizontal shear center axis:

(3-29)

YΣ(In y)

ΣIn

1.61 x 106

162,000

10.0 in.

Vertical shear center axis:

The value ofb for all girders is -36.1 in.

(3-30)

XbI

Σ(ayyn)

36.1

42.6 × 106x 13.54 × 106

11.4 in.

d. Load torque areas. (See paragraph 3-4i(3).) Theforces which produce twisting of the leaf are shown inFigure 3-8. Computation of the torque area is given inTable 3-4. Computations for the location of the center ofgravity and deadweight of the leaf are not given.Because this lock handles deep-draft vessels, a waterresistance of 45 psf is used.

e. Evaluation of Ro, R, and Q.

Ro ± 2wt

v(w 2 h 2)½

± 2 × 483 × 37.8

529 (4832 6842)½

±0.0822

Required size of diagonals:

For diagonalUoL1,

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EM 1110-2-270330 Jun 94

Figure 3-7. Lower gate leaf, MacArthur Lock, Sault Ste. Marie

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EM 1110-2-270330 Jun 94

Table 3-1Computation of Modified Polar Moment of Inertia J

n (No. of nlc3

Elements Elements) 1 (in.) c (in.) Horizontal Members Vertical Members

Horizontal GirdersUS flange, 3 12.0 2.44 520.0 -Web, 3 34.0 0.63 30.0 -DS flange, (G1, 2, 3 12.0 0.94 30.0 -and 12)

US flange, 9 16.5 2.78 3190.0 -Web, 9 33.5 0.77 140.0 -DS flange, (G3 9 16.5 1.26 300.0 -through G11)

Skin (betweenflanges)1/2" plate 1 203.0 0.50 30.0 -5/8" plate 1 308.0 0.63 80.0 -

Vertical GirdersUS flange 4 12.0 1.57 - 190.0Web 4 34.0 0.62 - 30.0DS flange 4 12.0 0.94 - 40.0

Quoin & Miter PostsWeb 2 30.0 0.63 - 20.0Flange 2 12.0 1.00 - 20.0Block 2 8.0 2.63 - 290.0

Total = 4320.0 590.0

Table 3-2Computation of Distance Y

Girder In(in.4) y (in.) In.y(in.5 x 106)

G-1 9,000 +374.0 +3.37G-2 9,000 +272.0 +2.44G-3 15,000 +200.0 +3.00G-4 15,000 +128.0 +1.92G-5 15,000 + 73.3 +1.10G-6 15,000 + 18.5 +0.28G-7 15,000 + 36.3 - 0.55G-8 15,000 - 91.0 - 1.36G-9 15,000 - 145.8 - 2.18G-10 15,000 - 200.5 - 3.00G-11 15,000 - 255.3 - 3.84G-12 9,000 - 310.0 - 2.79

Σ 162,000 - 1.61

(3-25)

A ΣTz

sRohv

11,570 × 106

18,000 × 0.0822 × 684 × 529

21.5 in.2

For diagonalLoU1,

A

9,200 × 106

18,000 × 0.0822 × 684 × 529

17.1 in.2

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EM 1110-2-270330 Jun 94

Table 3-3Computation of Distance X

Girder a(in.2) Y(in.) Yn(in.) ayyn(in.4 x 106)

G-1 22.1 +374.0 +384.0 3.17G-2 22.1 +272.0 +282.0 1.69G-3 33.9 +200.0 +210.0 1.42G-4 33.9 +128.0 +138.0 0.60G-5 33.9 + 73.3 + 83.3 0.21G-6 33.9 + 18.5 + 28.5 0.02G-7 33.9 - 36.3 - 26.3 0.03G-8 33.9 - 91.0 - 81.0 0.25G-9 33.9 - 145.8 - 135.8 0.67G-10 33.9 - 200.5 - 190.5 1.29G-11 33.9 - 255.3 - 245.3 2.13G-12 22.1 - 310.0 - 300.0 2.06

Σ 13.54

Figure 3-8. Forces acting on leaf being opened

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EM 1110-2-270330 Jun 94

Table 3-4Computation of Torque Area

Load Force (lb) Moment arm (in.) z (in.) Tz(in.2lb x 106)

Dead load 290,000 27.5a 253 - 2,020

Ice & mud 50,000 27.5 253 -350

Water 74,500 465.0 265 ±9,200b

a From determinations of shear center and center of gravity for various horizontally framed gates, this arm is approximately 3/4t.b Plus value for gate opening.

For diagonal LoU1, the dead load torque is not nowincluded since diagonalUoL1 will be prestressed to sup-port this load. The following diagonal sizes will be usedthroughout the remainder of the design and revised later,if necessary.

UoL1 - 24.0 in.2 (2 @ 12 in.2)

LoU1 - 18.0 in.2 (2 @ 9 in.2)

(3-13)RA

A ARo ± 22

A 22× 0.822)

QRRoEAhv

L

R × 0.0822 × 29 × 106 × A × 684 × 529771

112 × 107 × RA

Computation of the constantQ is given in Table 3-5.

Table 3-5Computation of Constant Q

Diagonal A (in.2) R Q (in.-lb × 106)

UoL1 24.0 +0.0393 1,050.

LoU1 18.0 -0.0452 910.

ΣQ = 1,960.

f. Deflection of leaf.

(3-23)

Gate opening ∆ΣTz

Qo ΣQ

9,200 × 106

(120 1,960) × 106

4.4

Gate closing ∆ ( 9,200 350) × 106

(120 1,960) × 106

4.6

g. Prestressed deflections and stresses in diagonals.Prestress deflections are determined in Table 3-6. Theminimum numerical values ofD (line 3) are the maxi-mum deflections of the leaf. Maximum numerical valuesof (D - ∆) are found by solving Equation 3-24.

(D ∆) sLRE

18,000 × 771

R × 29 × 106

0.478R

Having the maximum numerical values of (D - ∆), themaximum values ofD are determined and placed inline 5. Values ofD (line 6) are then selected betweenthe above limits such that Equation 3-22 is satisfied; thatis, ∑(QD) must equal +2,020 × 106in.2lb. Further, toensure that the diagonals will always be in tension,Dshould be such that the minimum stress is more than

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Table 3-6Stresses in Diagonals During Normal Operation

Positive NegativeDiagonal Diagonal

Line Parameter UoL1 LoU1

1 R +0.0393 -0.04522 Q (in.-lb. × 106) 1,050 9103 Minimum numerical

value of D (in.) +4.4 -4.64 Maximum numerical

value of D-∆) (in.) +12.1 -10.65 Maxumum numerical

value of D (in.) +7.5 -6.26 D (selected value) (in.) +6.7 -5.57 QD (in.2-lb. x 106) +7,030 -5,000

Σ(QD) = 2,030 × 106 in.2-lb

Operation Stress, ksi

8 Gates stationary∆ = 0 9.9 9.4

9 Gates being opened∆ = +4.4 3.4 16.8

10 Gates being closed∆ = +4.6 16.7 1.5

1 kip per in.2 Stresses which occur during normal opera-tion of the gate are computed from

(3-24)sREL

(D ∆)

and are placed in lines 8, 9, and 10.

From Table 3-6, it is seen that the diagonal sizes chosenare quite satisfactory.

h. Method of prestressing. The turn-of-the-nutmethod will be used. After the diagonals are made slack,the deflection of the leaf is measured in the field. Sincethis actual initial deflection is unknown at this time, thetheoretical value will be used (with diagonals slackQ -zero).

(3-21)

∆ΣTz ΣQD

Qo ΣQ

ΣTz

Qo

2,020 × 106

120 × 10616.8 in.

(1) DiagonalUoL1. The slack is removed from thisdiagonal only and the diagonal is clamped. The requiredprestress is then obtained by tightening the sleeve nut thefollowing number of turns:

(3-27)

NnRo(D ∆)

2

2.5 × 0.08222

[ 6.7 ( 16.8)]

2.41 turns

The torque required to accomplish this is found fromEquation 3-28 after determining the resulting leaf deflec-tion from

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EM 1110-2-270330 Jun 94

(3-21)

∆ΣTz ΣQD

Qo ΣQ

( 2,020 1,050 × 6.7) × 106

(120 1,050) × 106

4.4 in.

(3-28)

M0.18 REAd (D ∆)

L

0.18 × 0.0393 × 29 × 106 × 12 × 4.75 (6.7 4.4)771

35,000 in. lb

or 490 lb required at the end of a 6-ft wrench. In thisoption it is assumed that both members of diagonalUoLare prestressed simultaneously.

(2) DiagonalLoU1. The theoretical initial deflectionof the leaf for this diagonal is the final leaf deflection of4.4 in. after prestressing the previous diagonal. To pre-stress this diagonal the required amount, it is necessary totighten the nut through the following turns, after firstremoving the slack.

(3-27)N

2.75 ( 0.0822) ( 5.5 4.4)2

1.12 turns

This tightening will make the leaf plumb (∆ = 0) andwill require a maximum torque of:

(3-28)

M0.18 ( 0.0452) × 29 × 106 × 9 × 4.25 ( 5.5 0)

771

64,000 in. lb

or 900 lb required at the end of a 6-ft wrench.

(3) Plumb/out of plumb. With the completion of thisoperation, the leaf will nearly always hang plumb. If it

does not, the corrected prestress deflection for this diago-nal can be found from Equation 3-21 with∆ equal andopposite to the out-of-plumb deflection. This prestressdeflection can then be substituted in Equation 3-27 toobtain the corrected number of turns required to makethe leaf hang plumb. For instance, for a final out-of-plumb deflection of +1/2 in., the corrected prestressdeflections would be found from∑QD = (∆Qo + ∑Q) -(Tz)D.L. to be +980 in.2lb × 106. With D for diagonalLoU1 maintained at -5.5 in., theD then required for diag-onal UoL1 would be +5.7 in. andN for this diagonalwould become 2.30 turns. The remainder of the compu-tations would be repeated.

3-6. Example 2, Vertically Framed Gate

See Figures 3-9 and 3-10.

a. Evaluation of A′. The cross-sectional area of thebottom girder (see Figure 3-10) is 36.7 in2, the cross-sectional area of any vertical girder is 37.0 in.2, (seeFigure 3-9), and the cross-sectional area of the top girderis 112.5 in.2. Therefore, the value ofA′ (see definition)for all diagonals is

A′ = (1/20) (36.7 + 74.0 + 112.5) = 11.0 in.2

b. Evaluation of Ro, R, and Q. Since this is anexisting lock, the diagonal sizes are fixed.

(3-11)

Ro ± 2wt

v(w 2 h 2)½

± 2 × 232t

723 (2322 5352)½

± 0.00110t

(3-13)

RA

A ARo

± 0.0121 t(A 11)

11(A 11)

Ro

3-21

EM 1110-2-270330 Jun 94

Figure 3-9. Schematic drawing of a vertically framed leaf

3-22

EM 1110-2-270330 Jun 94

Figure 3-10. Average vertical section through leaf

3-23

EM 1110-2-270330 Jun 94

(3-18)

QRRoEAhv

L

RRo × 29 × 106 × A × 535 × 723

471

238 × 108 × RRoA

Computation of the elasticity constantQ is shown inTable 3-7.

(1) Because all the skin in the end panels is not inthe same plane,t (in the end panels) is measured fromthe mean skin shown in Figure 3-9. (See paragraph 3-4hfor the determination oft for skin not in a plane.)

(2) This example provides a good illustration of theinefficiency of past designs. The upstream diagonals arequite ineffective because they are so close to the skinplate. If all the upstream diagonals were omitted (inother words, the number of diagonals cut in half) and the

skin plate placed in their location instead, the leaf wouldbe stiffer and the stresses in the remaining diagonalswould be lower. Further, with a flat skin plate, all posi-tive diagonals could have been made the same size andall negative diagonals, another size (for simplification ofdetails and reduction in cost).

c. Evaluation of Qo. (See paragraph 3-4i(2) andTable 3-8.)

(3-26)

Qo K × Es × Σ(J/h J/v)

4 × 12 × 106

3103 × 535

7003 × 723

25 × 106in. lb

d. Location of shear center. (See paragraph 3-5c.)Computations for the centroidal axis and the moment ofinertia of the vertical section through the leaf (see Fig-ure 3-9) are not shown.

Table 3-7Computation of Elasticity Constant Q

Diagonal A (in.2) t (in.) Ro R Q (in.lb × 106)

a D’stream UoL1 10.00 31.5 +0.0347 +0.0182 150.0a D’stream U1L2 8.00 35.2 +0.0388 +0.0224 165.0a D’stream U2L3 4.50 31.3 +0.0345 +0.0244 90.0

a Upstream LoU1 4.50 18.3 +0.0202 +0.0143 31.0a Upstream L1U2 4.50 14.4 +0.0159 +0.0112 19.0a Upstream L2U3 4.50 17.9 +0.0197 +0.0140 30.0

b Upstream UoL1 10.00 17.2 -0.0189 - 0.0099 45.0b Upstream U1L2 8.00 13.3 -0.0146 - 0.0085 24.0b Upstream U2L3 4.50 17.0 -0.0187 - 0.0133 27.0

b D’stream LoU1 4.50 32.6 -0.0359 - 0.0255 98.0b D’stream L1U2 4.50 36.2 -0.0399 - 0.0282 120.0b D’stream L2U3 4.50 32.2 -0.0355 - 0.0252 96.0

ΣQ = 895

a Positive diagonalsb Negative diagonals

3-24

EM 1110-2-270330 Jun 94

Table 3-8Computation of Modified Polar Moment of Inertia J

nNo. of

Elements Elements 1 (in.) c (in.) Horizontal Members Vertical Members

Horiz. GirdersU/S flange, 1 18.0 2.38 240Web, (Top) 1 72.0 0.50 10

D/S Flange, 2 14.0 0.88 20

U/S flange, 1 12.0 0.50 0Web, (Bottom) 1 48.0 0.38 0D/S flange 1 8.0 1.13 10

Skin plate 1 535.0 0.38 30

Vertical GirdersU/S flange 8 10.0 0.50 10Intermed. flange 6 7.0 0.38 0Web 4 48.0 0.38 10U/S flange 8 10.0 0.50 10

Vertical Beams 9 11.5 1.73 540US flange 9 31.4 0.58 60Web 9 11.5 0.86 70

D/S flange

Total = 310 700

y = 325 in.I = 14.3 × 106in.4

Horizontal shear center axis:

Moment of inertia of:Top girder = 84,100 in.4

(3-29)

YΣ(In y)

ΣIn

84,100 × 210 12,100 × 32596,200

142

Vertical shear center axis:

Computation of the distanceX is shown in Table 3-9.

(3-30)X

Σ(aybyn)

I

69.9 × 106

14.3 × 1064.9 in.

e. Load torque areas. (See discussion in para-graph 3-4i(3).) The forces which produce twisting of theleaf are shown in Figure 3-11. Again, computations forlocating the center of gravity and deadweight of the leafare not shown. Since this is a 9-ft channel handling onlyshallow-draft vessels, a water resistance of 30 psf isused.

For dead load:Tz = -235,000 (10.7 + 4.9) × 355= -1,300 × 106in.2-lb

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Table 3-9Computation of Distance X for Vertically Framed Gate

Girder a (in.2) b (in.) y (in.) yn (in.) aybyn (in.5 × 106)

Top girder - U/S 62.8 +37.4 +210 + 68 + 33.5Top girder - D/S 31.8 - 35.1 +210 + 68 - 15.9

Bottom girder - U/S 8.2 +13.1 -325 -467 + 16.3Bottom girder - D/S 19.5 - 35.1 -325 -467 -103.8

Σ = - 69.9

Figure 3-11. Torsional forces on leaf

3-26

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For live load: Tz = ±27,000 × 464 × 362= ±4,350 × 106 in.2-lb

(positive value for gate opening)

f. Deflection of leaf.

(3-23)

∆ΣTz

Qo ΣQ

± 4,530 × 106

(25 895) × 106±4.9 in.

Where positive value is for gate opening.

g. Prestress deflections and stresses in diagonals.The prestress deflections are determined in Table 3-10.The minimum numerical values ofD (column 4) are themaximum deflections of the leaf. Maximum numericalvalues of (D - ∆) are found by solving Equation 3-24

(D ∆) max sLRE

18,000 × 471

R × 29 × 106

0.292R

Having the maximum numerical values of (D - ∆), themaximum numerical values ofD are determined andplaced in column 6. Values ofD (column 7) are thenselected such that Equation 3-22 is satisfied; that is,∑QD must equal +1,300 × 106 in.2-lb. Because all butthe top 10 ft of the skin consists of buckle plates (seeparagraph 3-4i(4)), an attempt is made to have the diago-nals carry as much of the vertical dead load shear aspossible. Therefore, values ofD are made as large aspossible for the diagonals extending downward towardthe miter end, and as small as possible for the other diag-onals. Further, to ensure that the diagonals are always intension,D should also be such that the minimum stress ismore than 1,000 psi. The unit stresses in the diagonalsare found from

(3-24)sREL

(D ∆)

Before computing normal stresses (columns 10, 11,and 12), the stresses which occur during the prestressingoperation are computed (column 9) as a check on thevalue ofD. The twist-of-the-leaf method for prestressing

is used. Because of the large value ofD for some of thenegative diagonals, it is best to prestress all negativediagonals first.

h. Dead load shear in skin: (buckle plates). Pre-stressing of many gates in the Rock Island District hasproved that buckle plates can support the shear imposedon them during and after the prestressing operation with-out any apparent distress. However, it is still considereddesirable to have the diagonals carry as much of thevertical dead load shear as possible. If the skin had beenflat plate, this consideration would have been omitted. InTable 3-11 the dead load shear remaining in the skin(buckle plates) is determined.

i. Method of prestressing. The twist-of-the-leafmethod will be used as outlined in paragraph 3-4j(1).The maximum force will be required when the leaf isdeflected +10.0 in. against the action of the negativediagonals (which are prestressed, in this case, first).

P∆ (Qo ΣQ) ΣQD (Σ Tz)DL

hv

[ 10.0 (25 410) (2,620) ( 1,300)] × 106

535 × 723

21,000 lb

Upon completion of this prestressing operation, the leafis very rarely out of plumb. Should it be, however, thecorrected prestress deflections can be found from Equa-tion 3-21 with ∆ equal and opposite to the out-of-plumbdeflection, as follows.

∑QD = ∆ (Qo + ∑Q) - (∑Tz)DL

In this example, for a final out-of-plumb deflection of+½ in., revised values ofD would be selected to make∑QD equal to +840. × 106 in.2-lb. The leaf would thenhang plumb. Repeat computations, if necessary.

3-7. Vertical Paneling of Leaf

The previous design applies to miter gate leaves that aredivided into panels (not necessarily equal) longitudinally.With a slight modification of the termRo the design isextended to apply to leaves that are divided into panelsvertically as well as longitudinally. Figure 3-12 showsthe most general arrangement of paneling. In practice,an effort would be made to make the panel heights andwidths the same. To design the diagonals use

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Table 3-10Computation of Diagonal Stresses

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Table 3-11Computation of Dead Load Shear in Buckle Plates

Panel Diagonal A (in.2) s (lb/in.2) As (lb) Σ(As h) (lb) Panel SkinL

DSUoL1 10.0 11,200 +112,0000-1 USUoL1 10.0 7,300 + 73,000

USLoU1 4.5 6,600 - 29,000 +119,000 lb - 196,000 lb +77,000 lbDSLoU1 4.5 8,300 - 37,000

DSU1L2 8.0 10,300 + 82,0001-2 USU1L2 8.0 6,300 + 50,000

USL1U2 4.5 5,200 - 23,000 + 68,000 +117,000 lb +49,000 lbDSL1U2 4.5 9,100 - 41,000

DSU2L3 4.5 9,800 + 44,0002-3 USU2L3 4.5 4,300 + 19,000 +41,000 lb

USL2U3 4.5 6,500 - 29,000 - 2,000 - 39,000 lbDSL2U3 4.5 8,100 - 36,000

Figure 3-12. Vertical and longitudinal arrangement of leaf panels

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(3-11)′Ro ±

2w h t

H v (w 2 h 2)1/2

This value of Ro replaces that given in Equation 3-11,being a more general expression. It is seen that for avalue of h = H (no vertical paneling) Equation 3-11′reverts to Equation 3-11. With the above value ofRo, allthe other expressions and the method of analysis remainidentical to that previously outlined.

3-8. Derivation of Equation 3-11 ′

The general value ofRo can be found as follows. (Referto paragraph 3-4d). Let d = deflection of panel; othersymbols are as defined previously. Figure 3-13illustrates the displacements of points of a verticaldivided panel.

Let δo = change in length of any diagonal

(See Figure 3-13)

δo

dw

t cos α

dh

t sin α

d tw

w

(w 2 h 2)1/2

d tw

h

(w 2 h 2)1/2

δo

2dt

(w 2 h 2)1/2

Whereh andd are the height and deflection ofonepanel

then

ro

δo

d±

2t

(w 2 h 2)1/2

The relation between the deflection of the panel and theleaf becomes

(3-11)′

d

wv

hH

∆ or ∆

vw

Hh

d

Ro

δo

∆

2dt

(w 2 h 2)1/2

1

vw

Hh

d

Ro ±

2w h t

H v (w 2 h 2 )1/2

The remainder of the expressions are the same as before,for distance

Ro

δ∆

r d

vw

Hh

d

wv

hH

r

wv

hH

A

A A

Ro

wv

hH

A

A A±

2t

(w 2 h 2)1/2

Therefore

Ro ±

2w h t

H v (w 2 h 2)1/2

A

A A

Ro

A

A A

In similar manner it can be shown that the expressionsfor Q andQ0 (Equations 3-18 and 3-26, respectively) stillapply with H substituted forh.

3-9. Temporal Hydraulic Loads

The effect of temporal hydraulic loads on the miter gatediagonal design will be evaluated at each lock withappropriate conditions selected for the design. A mini-mum temporal hydraulic load of 1.25 ft (with a periodexceeding 30 sec) will be used for gate diagonal designif it governs, with a leaf submergence corresponding to

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Figure 3-13. Displacement of points of a vertical divided panel

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normal navigation pool conditions. For this load condi-tion, a 33-1/3 percent overstress is allowed for diagonaldesign. Temporal hydraulic loads in the lock chamberand/or lock approaches may be caused singly or in com-bination by the following:

a. Wind waves and setup.

b. Ship waves.

c. Propeller wash.

d. Lock overfill and/or overempty.

e. Lock upstream intake and downstream exitdischarges.

f. Landslide waves.

g. Tributary and/or distributary flow near lock.

h. Surges and reflected waves in canals.

i. Seiches.

j. Changes in spillway or powerhouse discharges.

k. Tides.

3-10. Procedure for Prestressing Diagonals

a. The following steps establish a procedure forprestressing diagonals. There are different procedures forstressing diagonals, this being just one. Use Figure 3-14with this procedure.

(1) With all diagonals slack, adjust anchorage bars soquoin end is plumb and bottom girder is horizontal.Pintle shoe shall be fully seated against the back of thepintle base.

(2) Lubricate the nuts on the diagonals so they canturn easily.

(3) Place rosettes for strain gages on all diagonals aminimum of 20 hours before prestressing unless anapproved quick-setting cement is used.

(4) Without the restraint of any guys or jacks, theleaf will deflect in a negative direction under its owndead load weight. Measure this deflection.

(5) Guy the leaf at its miter end to the tiebackanchor and place jacks at the miter end.

(6) Jack the miter end away from the wall until theleaf has a deflection equal toD1.

(7) Hold the deflection and tighten diagonals 1and 3. Tighten these diagonals so that there is no hori-zontal bow. Do not attempt to remove all vertical sag.

(8) Tighten diagonals 2 and 4.

(9) Proceed with the jacking until a deflectionD2 isobtained. During this operation do not change the adjust-ment of diagonals 1 and 3. However, continue tighteningdiagonals 2 and 4 until there is a slight tension in themembers when the leaf is in its final deflection position.

(10) During the prestressing operation use a straingage to determine the stress in the diagonals. The maxi-mum allowable stress shall be 0.75Fy.

(11) After the final adjustments of the diagonalsremove the guys and jacks. The leaf should return to theplumb position. A deflection +1/4 in. will be permittedin the lower leaf and +1/8 in. on the upper leaf. A largertolerance is allowed for the lower leaf because it is muchtaller than the upper leaf.

(12) Final minimum and maximum stresses, unlessotherwise approved by the Contracting Officer, shall be0.45Fy minimum and 0.55Fy maximum for all diagonals.

3-11. New Information on Diagonal Design

a. New preliminary information has been gainedthrough the finite element study made by Drs. L. Z.Emkin, K. M. Will, and B. J. Goodno of the GeorgiaInstitute of Technology regarding torque tubes and leafstiffness (USAEWES 1987). For all current gatesdesigned with the 2.5-ft differential head, it appears thatthe values arrived at through the finite element analysisof Bankhead Lock lower gate in Tuscaloosa, AL, arerealistic. This includes the values of leaf stiffness with-out diagonals, with diagonals, and with horizontal topand bottom torque tubes. These values are only a recom-mendation and consideration should be given to anyvariation in leaf configuration and modifications made toadjust the design factors accordingly.

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Figure 3-14. Methods for prestressing diagonal

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b. The use of top and bottom torque tubes is sug-gested as a suitable means of increasing leaf stiffness,although it appears that the conventional method of pre-stressing by twisting the leaves with a jack may need tobe altered. On the Oliver Lock in Tuscaloosa, AL,where the torque tubes were used and diagonals sized forsurge loading, it appeared that the twist-of-the-leafmethod of prestressing the diagonals had about reachedits maximum. Due to the increased leaf stiffness andcorresponding jack capacity (+150 tons), it appeared thatdamage to the leaf, such as localized buckling of plates,excessive deflection of the quoin post, damage to thegrease seals, pintle, pintle socket, etc., could beimminent.

c. The values representing leaf stiffness for thisparticular study were determined to be:

Qo = stiffness factor of leaves without diagonals

Qd = stiffness factor of diagonals

Qt = stiffness factor of top and bottom torque tubes(One 6-ft girder space at top and one 4-ftgirder space at bottom)

Qd = 2.4Qo

Qt = Qo

d. It is recommended that consideration be given toprestressing new gate leaves with torque tubes by turningthe nuts on the ends of the diagonals and using suitablemeans to prevent twisting of the diagonals. This wouldsimplify the prestressing and reduce the risk of damageto the gate leaves as well as reduce the risk to personnel.There may be commercial sources that have equipmentavailable that could be readily adapted to this means ofprestressing, as has been the case in prestressing theanchor bolts of the embedded anchorage.

e. Additional studies are needed to advance theunderstanding of miter gate leaf stiffness. Significantfactors are dead load deflection, jack loads, if used, straingage readings, problems encountered, alignment of gudg-eon pin over pintle, and any other information thought topossibly be pertinent. For additional information seeUSAEWES (1987).

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Chapter 4Sector Gates

4-1. Sector Gates

a. Skin plate and vertical ribs.

(1) Skin plate. The skin plate is designed as a con-tinuous member supported by vertical angles of tees, withthe calculated thickness being increased by one-sixteenthfor corrosion loss. Normally, 3/8-in. total thickness or adesign thickness of 5/16 in. is sufficient for the entireheight of the gate. The allowable stress is 0.50F for basicloading conditions with a permissible increase of one-thirdfor abnormal loading conditions. The edge of the skinplate should not be turned back on a radius to the hori-zontal beam. (See Plates B-34 through B-36 for addi-tional information.)

(2) Vertical ribs. The skin plate is attached to verti-cal ribs, usually angles or tees, by continuous welds.These ribs are designed as continuous members supportedby the horizontal beams. The skin plate is considered asan effective part of the vertical ribs, with the effectivewidth of skin plate determined according to the AISCspecifications. The minimum depth of ribs should be8 in. to facilitate painting and maintenance, with designloads consisting of water load only.

b. Horizontal beams. The normal gate leaf has threehorizontal beams supporting the vertical ribs and skinplate. Each beam is designed for water load and a com-bined water and boat load. The minimum depth of hori-zontal beams is 2 ft-0 in. out-to-out of flanges. The beamis designed as a continuous member supported by thehorizontal struts and braces at midpoint between thestruts. The curve of the beam can be neglected, with thelength used for design equal to the arc length along thecenter line of the beam.

(1) In order to reduce the effect of dead-load eccen-tricity on the horizontal beams, the vertical members ofthe center and recess-side vertical trusses may be framedinto the webs of these beams as shown in Section A-A,Plate B-34. The vertical member of the channel-sidevertical truss should be attached to the downstreamflanges of the horizontal beams as shown in Plan,Plate B-34, to reduce operating forces required duringopening of the sector gate under reversed head conditions.Based on model test results published in Technical ReportH-70-2 and Appendix A to this report (see USAEWES

1970, 1971) the framing method described above is rec-ommended for new sector gates.

(2) Numerous existing sector gates are framed asshown in Plate B-35 where horizontal ribs are used tosupport the skin plate. The horizontal beams consist ofstraight members, with a length equal to the chord lengthdetermined by one-half the interior angle of the gate leaf.The beam is assumed to be a continuous beam of twoequal spans, with the center support being braces from thehorizontal struts. This type of framing is not recom-mended for new construction. The boat load applied tomembers of the leaf normally consists of 125,000 lbapplied as a single concentrated force.

c. Frames. The basic sector gate leaf frame consistsof three horizontal trusses and three vertical trusses, withhorizontal and vertical trusses having some commonmembers. The top and center horizontal frame, consistingof three horizontal struts and related bracing, forms atruss that is designed for water and boat load, with theconcentrated boat load of 125,000 lb being applied at anypoint on the horizontal beam and at any panel point onthe canal side of the truss. The bottom frame, or hori-zontal truss, is designed for water load only, assuming noboat impact at this level.

(1) The vertical trusses are designed for dead loadand boat load, with the concentrated boat load of125,000 lb being applied at the top corner and the centerpanel points. The vertical trusses are also designed for acombination of dead load and concentrated boat loadapplied at the panel points on the canal side of the leaf,with the boat load applied at the elevation of the topframe or the center panel point. The top horizontalmembers of the channel and recess side vertical trussesare also designed to support the walkway loads.

(2) The interior angle of the horizontal frames canvary from 60 to 70 deg, with the 70-deg angle preferredfor 84-ft locks and larger.

(3) Rather than segmenting the gate leaf into hori-zontal and vertical trusses necessary for a manual solu-tion, it is now practical to design and analyze sector gatesas three-dimensional space frames utilizing availablecomputer programs.

d. Hinge assembly. The hinge bracket and the hingebracket support are made of cast steel or a weldment.The hinge bracket support is connected to the lock wallwith bolts, prestressed to slightly more than the maximum

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tension load obtained from dead load and the maximumreverse head.

(1) The adjustment of the hinge assembly is providedbetween the embedded hinge bracket support and thehinge bracket section containing the pin barrel. Shims areused to adjust the gate leaf both horizontally and trans-verse to the axis of the lock. The bolts should extend intothe concrete a sufficient depth to transfer the gate leafload to the concrete, keeping the stress in the concretewithin the range of 600 psi. The bolts should have ananchor frame or other positive means of transferring theforces to the concrete, assuming all of the transfer ismade through bearing on the frame and none throughbond on the bolts. The pin barrel segment of the hingebracket should be designed as a curved beam similar inanalysis to the gudgeon pin barrel described in para-graph 3-5 on horizontally framed gates. The pin barrelshould be provided with a bronze bushing, with the bear-ing stress kept below 1,500 psi.

(2) The hinge pin may be made of forged steel orcorrosion-resisting steel, depending on the location of thelock in relation to corrosive elements. Suitable means oflubricating the pin shall be provided either through the pinor with a grease fitting through the pin barrel and bush-ing. (See Plates B-37 and B-38 for suggested details.)

e. Pintle assembly.

(1) Pintle. The spherical pintle has proved to be themost satisfactory type for sector gates. This type of pintlehas the advantage of allowing the gate leaf to tilt slightlywithout binding and also facilitates the replacement of thegate leaf after it has been removed for maintenance orrepair. The pintle is designed for the maximum reaction,consisting of the combined water, boat, and gate deadloads.

(a) Corrosion-resisting steel is indicated by pastdesign to be the most suitable material for the pintlewhere salt or brackish water is encountered.

(b) The pintle shaft, the cylindrical shaped lower seg-ment of the pintle, extending 1 ft 3 in. to 2 ft 1 in. belowthe curved surface of the pintle, fits into a recess in thepintle base. This section of the pintle is designed forshear and moment as well as bearing on the pintle basedbetween the pintle shaft and pintle base. The end of thepintle shaft is a flat surface that bears directly on thebottom of the recess in the pintle base.

(c) A seal should be provided at the lower edge ofthe pintle bushing to seal between the bushing and thepintle shaft.

(2) Pintle bushing. The pintle bushing, made ofbronze, Alloy 913, Federal Specification QQ-C-390B, ismade in two parts, with the plane of the vertical jointplaced at 90 deg to the horizontal reaction of the gate.Grease grooves are provided in the bushing along with asuitable means of lubrication. The bushing is so con-nected to the pintle socket so that rotation between thesocket and bushing is eliminated.

(3) Pintle socket. The pintle socket is made of caststeel and is the common point of intersection of thevertical pipe column between the pintle and hinge pin, thelower horizontal struts, and the diagonal chord membersof the vertical trusses. The connections of members tothe pintle housing are normally made by welding.

(4) Pintle base and anchorage.

(a) The pintle base and anchorage have the samefunction as the pintle base of miter gates, that is to trans-fer the horizontal and vertical forces of the gate leaf tothe mass concrete. The pintle shaft fits into a recess inthe pintle base, and through a combination of direct stress,bending, and shear, the force is transferred from the pintleto the pintle base. The base, in turn, transfers the forceinto the concrete. A grillage of small beams, normally inthe range of an 8-in.-wide flange, is used to transfer theshear and distribute the bearing into the concrete. Anchorbolts are placed in first-pour concrete with the base placedin second pour. The base may be made of cast steel or abuilt-up weldment. In some cases, anchor bolts, pre-stressed to compensate for slightly more than the designforces, may be used to hold the pintle base in contact withthe concrete. These bolts will be so located and pre-stressed that a compressive force will exist between allparts of the pintle base and the concrete under all loadingconditions. Where prestressed bolts are used the grillageof beams may be eliminated. See Plate B-37 for typicaldetails of pintle and pintle base.

(b) An alternate pintle anchorage design and detailsmay be used as shown in Plate B-38. This design elimi-nates the grillage beams and assumes that the concrete incontact with the pintle pedestal base is not stressed. Thepintle forces (direct stress, bending, and shear) are trans-mitted into the concrete through the anchor bolts.

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f. Seals. The vertical seals on sector gates usuallyconsist of a pair of 3-seals for the gate closure at thecenter of the lock and a single 3-seal attached to thecorner of the gate recess. The seals at the gate closure,with one seal on each leaf, are presently 1/8 in. each seal,for a total of 1/4 in. to assure a minimum amount of leak-age when the gate is closed. The recess seal is also set soas to have 1/4-in. compression when the gate is closed.On the recess seal the vertical plate, or angle, at 90 deg tothe skin plate, should not extend over 6 in. from the skinplate and a lesser extension is preferable. The bottomseal utilizes an offset “J” seal, with the bulb offsetupstream, or away from the convex side of the skin plate.Normal procedure is for the corner, where the bottom sealmeets the vertical seal at the miter point, to be fabricatedintegrally with the bottom seal. (See Plate B-36 for typi-cal details of all seals.)

g. Walkway. Access around the perimeter of the gateleaf and across the lock is provided by walkways mountedon top of the gates. On the recess and skin plate sidesthe overall width of walkway should be 3 ft 0 in., with2 ft 8 in. center-to-center of rails. On the channel side,where a greater width is necessary for the transfer ofmaintenance equipment, the overall width should be 4 ft0 in., with 3 ft 8 in. center-to-center rails. The dimen-sions given are for normal conditions and may be variedfor unusual circumstances. Design loads should be100 psf for the recess and skin plate walkway and 150 psffor the channel-side walkway. Grating is preferred overthe raised pattern floor plates unless special circumstanceswarrant the use of plate. When grating is selected,type II, hot-dip galvanized after fabrication, should beused for most applications, with a minimum depth of 1-1/4 in. for bearing bars. Grating panels should be madein convenient size panels for installation and removal.Where raised pattern floor plate is used instead of grating,consideration should be given to hot-dip galvanizing forcorrosion resistance and minimum maintenance. Handrailshould be provided for all walkways, using 2-in. diameterextra-strong post with 2-in. standard pipe rail inconformance with paragraph 2-1n. Where special loadingconditions are present the size of rail and post may bevaried accordingly. Generally, the railing should beremovable and made in convenient size panels to facilitateremoval without equipment.

h. Fenders, lifting supports, and gate stops.

(1) Fenders. Timber fenders should be utilized on thecanal side of all gate leaves to facilitate the distributionand absorption of barge or boat impact. The usual fendersystem is of 8-in. by 12-in. white oak timbers bolted to

vertical beams, which in turn are connected to horizontalbeams or girders. The horizontal beams are connected tothe vertical members of the canal-side vertical truss. Thetimber should be surfaced all four sides, with boltsrecessed into the timber a minimum of 1 in. The mini-mum size bolts used to support the timbers should be3/4 in. in diameter. Under normal circumstances thehorizontal timbers should be spaced 2 ft 0 in. on center,with the top timber placed on the center line of the tophorizontal strut. The timber protection system shouldextend to or slightly below the minimum water level to beencountered during operation.

(2) Lifting supports.

(a) Jacking pads should be provided on the bottomof the gate leaf, located at panel points of the verticaltrusses. The pads should be so located that the fullweight of the gate can be supported by the pads whilemaintaining the gate in a stable position. A minimum ofthree pads should be used on each leaf.

(b) Lifting lugs on top of the gate should be consid-ered for complete removal of the gate from the lock.These lugs should be so located that a standard three-legbridle sling can be used to lift the gate leaf in the normalposition. Lugs should be located on the vertical trusspanel points if possible.

(3) Gate stops. Timber bumpers should be providedto prevent damage to the gate leaf caused by the leafbeing forced against the wall of the recess. Under normalconditions three bumpers are used for each leaf, with thetop bumper placed below the operating rack or cables andthe middle and lower bumpers placed on the center line ofthe respective horizontal trusses or frames. The bumpersshould be made of 6- by 10-in.-white oak timbersapproximately 2 ft 0 in. long, with each bumper attachedto the vertical beam adjacent to the skin plate with fourcorrosion-resisting bolts. Each timber on the leaf has acompanion bumper attached to the wall of the recess, witheach pair of bumpers having matching alignment. Therecess bumper is also attached with a minimum of fourcorrosion-resisting bolts, extending approximately 1 ft4 in. into the concrete with an additional 3-in. standardhook. The bolts should be so spaced that the bolts in thetimber on the leaf are not in line with the bolts in thetimber recess. All bolts should be recessed to provide aminimum of 1 in. between the head of the bolt and theface of the timber. (See Plate B-36 for a typical detail.)

i. Embedded metals. The items normally included inthis category are hinge anchorage, pintle base and

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anchorage, seal beam for the bottom seal, and the embed-ded plate which supports the side seal beam. The hingeanchorage and pintle base and anchorage have been dis-cussed in previous paragraphs.

(1) The seal beam for the bottom seal normally ismade up of a rolled beam with a corrosion-resisting plateattached to the top flange. The top of the corrosion-resisting plate is flush with the floor of the lock. Thebeam should be placed in second-pour concrete withanchor bolts, also used for adjustment, extending intofirst-pour concrete.

(2) The embedded plate which supports the side sealbeam is located at the corner of the gate recess. Thisplate should be made of structural steel and should beanchored with bolts set in the first-pour concrete. Theside seal beam should be bolted to the embedded platewith corrosion-resisting bolts. The seal contact of thebeam should be clad with corrosion-resisting material.See Plate B-36 for typical details of side seal and bottomseal embedded metal.

j. Cathodic protection. Primarily two basic types ofcathodic protection systems are used on sector gates. Onesystem, using sacrificial anodes, is the least efficient ofthe two systems but has a lower initial installation cost.Another disadvantage of the sacrificial anode system isthat the gate leaf has to be removed or dewatered formaintenance or replacement of anodes. Impressed currentcathodic protection should be used on sector gates. SeeChapter 7 for additional information on cathodicprotection.

(1) The other system, commonly known as theimpressed current system, has a higher initial installationcost but is more efficient than sacrificial anodes. Button-type anodes used with this system have the same disad-vantages as the sacrificial anodes for maintenance andreplacement.

(2) The thickness of the skin plate should beincreased 1/16 in. and cathodic protection omitted fromthe convex face of the skin plate. This allows a betterside seal as the seal can be placed closer to the skin plateof the leaf.

(3) Where possible to schedule the gates for removalor dewatering for maintenance and painting (at intervalsnot to exceed six years), sacrificial anodes should nor-mally be used in lieu of the impressed current systemunless more severe corrosive elements indicate the needfor a more efficient system. When time intervals between

dewatering exceed six years impressed current should beused.

(4) Where the corrosive elements of the waterrequire a more efficient system of cathodic protection theimpressed current system may be used, utilizing string-type anodes that can be removed or replaced withoutdewatering or removing the gate.

(5) See Chapter 7 for additional information on cath-odic protection.

k. Erection and testing. The same general proce-dures that were discussed for horizontally and verticallyframed gates should apply to sector gates. Each gate leafshould have the same shop assembly and matchmarkingas well as the same general allowable tolerances.

(1) The gate leaves should be erected in position onthe pintle and temporary supports the same as horizontallyand vertically framed gates. The clearances of the gateleaves above the lock floor may preclude the use of tem-porary concrete pedestals for erection.

(2) All items covered under miter gates hereinshould apply to sector gates with the exception of diago-nals and zinc or epoxy filler. The remaining commentson erection, trial operation, and workmanship should beapplicable to sector gates as well as miter gates.


a. General description. The sector gate is generallyoperated by machinery similar to the electric-motor-drivenmiter gate machinery. The machinery used normally con-sists of a hydraulic motor or an electric motor, a herring-bone gear speed reducer, a specially designed angle drivegear unit, an electrically operated brake, limit switches,and other accessories connected so as to drive a largeradius rake which is bolted to the top upstream edge ofthe gate. A general arrangement is shown in Plate B-54.An alternate machine utilizing a cable and drum arrange-ment can be used to pull the gate in and out of the recess.This arrangement is shown in Plate B-55. The machinerycomponents would be similar to the gear machine exceptthat a drum and cable would be utilized in lieu of thepinion and rack.

b. Design considerations and criteria.

(1) General. Difficulty was experienced in thedesign of the first sector gates when operating underreverse heads. Prototype tests showed that the

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hydrodynamic and friction forces were much greater thananticipated in the design. The normal operating forces onsector gates are primarily caused by friction on trunnionand hinge pin, forces on seal bracket, bottom friction, andhydraulic loads. Extensive tests have been made to obtainoperating forces on sector gates. These tests, made by theWaterways Experiment Station (WES), have been pub-lished in Technical Report H-70-2 and Appendix A to thereport (USAEWES 1970, 1971). Subsequent tests madeby WES resulted in the design of a new improved gatewith operating forces approximately 20 percent of thoseexperienced in the original designs.

(2) Machinery components. Under normal heads,sector gate tests have shown that the loads created byflowing water tended to close the gate but were consider-ably less than those observed under reverse heads. Underall reverse head conditions, loads imposed on the gate bythe flowing water tended to close the gate. Loadsincreased with gate openings up to 5 to 7 ft then showeda tendency for a slow decrease at greater openings.Model data for gate openings of about 6 ft can be used topredict peak torque for various lower pools and reverseheads. Model and prototype tests demonstrated that themajor loads on the gate are caused by structural membersin the immediate vicinity of the skin plate at the miternoses of the gate leaves and by the side seal bracket thatblocks side flow at the recess edge of the skin plate.Timber fenders, which are offset from the skin plate, havea very negligible effect on forces. General criteria appli-cable to machine components are presented inparagraph 1-11.

c. Determination of machinery loads. When deter-mining operating loads for a sector gate, Technical ReportH-70-2 and Appendix A to the report (USAEWES 1970,1971) should be used as a guide. However, if a gatedesign varying considerably from the type shown in thereport is used, model studies to determine the loadsshould be performed.

(1) After maximum operating conditions on the sectorgates have been determined, the gate operating loads

should be computed both for normal flow and for reverseflow conditions. Due to the construction of the bottomseal no bottom seal friction is created during reverseheads. Loads due to reverse head conditions will usuallyestablish the size of machine to be used; however, loadsdue to normal heads should be checked.

(2) Water load on the gate will be created by theprojected width of miter beam, skin plate rib, and sealbracket. Figure a, Plate 44 of Technical Report H-70-2,Appendix A, gives the peak closing pintle torque for theimproved type gate. These torque curves are reproducedfor this manual and are shown in Plate B-81. This torqueis based on a gate having a total projected width of miterbeam, skin plate rib, and seal bracket of 30.375 in.(17.875 in. + 8 in. + 4.5 in. = 30.375 in.). The torquetaken from Plate B-82, Sheet 2, should be corrected inaccordance with Froude’s law of similarity to the lengthsused on the proposed gate based on the scalar ratio.Hinge friction and pintle friction torque should be addedto the above water load to determine the total machineryload. Reference should be made to Miscellaneous PaperH-71-4, paragraph 14 (USAEWES 1971), in conjunctionwith establishing reasonable values of hinge and pintlefriction. Typical calculations for determining loads on theimproved type of sector gate are shown in Plate B-82,Sheets 1-3.

d. Operating machinery controls. Sector gates areusually controlled from a small control house locatedadjacent to each pair of gate leaves. For electric motordrive, the control equipment consists of the combinationof full voltage magnetic controllers, limit switches, controlpushbuttons, and switches arranged to produce the desiredoperating sequence. For fluid motor drive, the speed ofthe gate is varied by controlling the flow of oil to thefluid motor either by throttling or by use of a variablestroke piston pump. With this system, control valves canbe either manually or electrically controlled.

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Chapter 5Vertical-Lift Gates

5-1. Vertical-Lift Gates

a. General description.

(1) Two types of vertical-lift gates may be used.One type, a double-leaf or triple-leaf, vertical-lift gate,referred to in this chapter as emergency gate, is locatedat the upper end of each lock chamber. The upstreamleaf, consisting of horizontal girders and a skin plate, isdesigned for use as a movable sill. The downstream leaf,also consisting of horizontal girders and a skin plate, isdesigned for operation through flowing water. Thedownstream side of both leaves is provided with a grat-ing screen to prevent drift and debris from lodgingbetween the horizontal girders. A screen and bulkheadare provided above the ends of each leaf to prevent driftfrom entering the recess and to prevent damage to therecess from tows entering the locks. The hoist compo-nent at each side of a gate is mounted on a structuralsteel frame which is anchored to a concrete structure onthe lock wall, the unpowered component for each lockbeing on the middle wall and the powered component onthe opposite wall. The structure is of such height thatthe hoist machinery will be above high water. The hoistassembly is enclosed in a concrete housing with remov-able aluminum roof sections. For the normal open orstored position, the leaves are lowered into the sill. Theemergency gate is used for lock closure in the event ofaccident or damage to the lock gates that otherwisewould result in a loss of the navigation pool. The gatewill also be used to skim ice and drift from the lockapproaches, or for upstream lock closure during mainte-nance and repair operations in the lock chamber, and inconnection with opening the lock gates to pass floodflows when necessary after navigation is suspended.(See Plate B-42.)

(2) The other type of vertical-lift gate is a single-leafgate that can be used at either end of a lock and is fre-quently used as a tide or hurricane gate along the seacoast. This type of gate is raised when not in use, per-mitting normal traffic to pass underneath. This type isreferred to as a “Tide” or “Hurricane” gate in this chap-ter (See Plate B-41).

b. Skin plate.

(1) The primary design method for skin plates ofvertical-lift gate leaves supported by girders or trusses

should be as described previously in paragraph 2-1c forhorizontally framed miter gates. The skin plate may bedesigned by the method of Column Analogy, utilizing thethickness of the flange in conjunction with the skin plateto form a beam of variable section spanning from centerto center of girder webs. The stress should be deter-mined at the center line of girder webs, which is the endof the assumed beam, at the edge of the girder flange,and at the center of the beam, midway between girderwebs. See Plate B-43 for additional information on thismethod of analysis.

(2) The skin plate of gate leaves with close girderspacing or without intercostals may be designed ascontinuous members.

c. Framing. Vertical-lift gates may be fabricated ofplate girders or horizontal trusses, with economy nor-mally indicating which system will be used. The basicframing of gates utilizing plate girders consists of theplate girders, downstream bracing, intercostals, dia-phragms, and end girders. When horizontal trusses areused the main framing items are the horizontal trusses,vertical trusses acting as diaphragms, downstream brac-ing, and end girders. When gates are lifted above thelocks for clearance, the lifting towers are included in themajor framing.

(1) Plate girders. Plate girders are essentially thesame as those for horizontally framed miter gates.Girder webs should be determined in accordance withcurrent AISC Specifications, with the web depth-to-thick-ness ratio such that no reduction in the allowable stressfor the compression flange is necessary. In the eventlongitudinal stiffeners are considered to be advantageouson girder webs for special conditions, the stiffenersshould be placed and sized according to the AmericanAssociation of State Highway and Transportation Offi-cials Specifications.

(a) The girders should be designed by the momentof inertia method. The effective design length should bethe full length from bearing. For buckling about theminor axis of the girder due to any applicable axialloads, the effective length may be the lesser of dia-phragm spacing or panel spacing of vertical trussesformed by the downstream bracing.

(b) Girders should be designed to withstand waterload and a combination of water and dead load and boatimpact. Emergency loadings such as boat impact shallhave a permissible increase of one-third in the allowablestresses. The water load should include wave pressure if

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applicable, with consideration given to the effects ofbreaking or nonbreaking waves, whichever is moreappropriate. The downstream flanges of girders that actas the chord member of a vertical truss formed by thedownstream bracing shall be designed for the combinedloading of water and dead load. The force in the flange,from acting as the chord member of the vertical truss,should be determined from one-half the vertical load onthe leaf, assuming the skin plate to carry the remainingone-half. The resulting axial force in the flange shall beconsidered as an eccentric column, with the stress beingthe normal P/A + MC/I. The allowable axial stress Fa

shall be determined by using a value of the radius ofgyration computed as shown in Plate B-43. The allow-able bending Fy shall be the appropriate value as deter-mined from EM 1110-2-2105 or from AISC as indicatedin paragraph 1-6b.

(c) Girder webs should be investigated for shear andthe requirement for transverse stiffeners as well as theeffect of combined shear and tension, which may reducethe allowable tensile stress to less than 0.6Fy. Web crip-pling should also be investigated for all uniform andconcentrated forces applied to the girders.

(d) Deflection should be investigated for all girders,especially those of high strength steel.

(2) Horizontal trusses. Horizontal trusses serve thesame function as plate girders, with the choice of plategirders or trusses being determined by economics andweight. Where trusses are used the diagonal membersshould be designed as tension members. Working linesof truss members should coincide with the centroidal axisof the members in order to minimize secondary stresses.Secondary stresses in truss members caused by stiffness,restrained joints, and excessive deflection due to trussdepth limitation should also be investigated. Wherebeams are used as chord members the webs are normallyplaced horizontally, except the top frame where it may bemore advantageous to place the webs vertically to sup-port walkways and equipment. An operational loadingequivalent to a minimum differential head of 6 ft appliedto either side of the gate should be considered as actingon each truss. The reduction of negative moments forcontinuous members in the truss is not recommended.Deflection should be investigated for all horizontaltrusses.

(3) Diaphragms. Diaphragms on vertical-lift gateswhere plate girders are utilized serve two main purposes,one being to distribute girder loads and the other to sup-port the vertical loads applied to the leaf where the leaf

is being used as a movable sill. The diaphragm shouldbe sized according to AISC Specifications governing thewidth-to-thickness ratio of the vertical web. Verticalstiffeners should be utilized in accordance with theappropriate sections of AISC Specifications, with thestiffeners and effective section of the web being designedas a column, with each pair of stiffeners carrying a pro-portional part of the total vertical load on the diaphragm.

(a) The design shear load applied to the diaphragmwill be the difference between the assumed load to causeequal deflection of the girders and the actual water loadon each girder. The diaphragm should be checked forthis shear and the requirement for transverse stiffeners toprevent buckling of the diaphragm due to this shear load.The vertical flange of the diaphragm should be designedas a column, consisting of the flange plate and the effec-tive section of the diaphragm. The effective or unsup-ported width of flange and the effective section of thediaphragm should be determined according to the AISCSpecifications. The load applied to the flange is theappropriate load from the vertical truss action of thedownstream bracing.

(b) The extension of the diaphragm on the bottom ofthe gate leaf should have a bearing plate designed toresist both bearing and moment, with the forces createdfrom the reaction between the plate and the concrete orsteel pedestal. Stiffeners should also be provided on theextension of the diaphragm, acting as columns to transferthe load from the diaphragm through the bearing plate tothe support pedestal.

(4) Vertical trusses. Vertical trusses, used in gatesutilizing horizontal trusses instead of plate girders, per-form the same function as the plate diaphragms discussedin the preceding paragraph. The vertical chord membersshould be designed as columns with the effective lengthequal to the horizontal truss spacing. The degree offixity at the ends of the vertical chords, connecting themto the horizontal trusses, will determine the appropriateeffective length factor K for design of the members ascolumns, with a minimum value of 0.65 being used formembers considered completely fixed. The effect of thevertical chord acting as a chord of the downstream brac-ing should also be included in the design of the verticaltruss. The deflection of the vertical trusses should beinvestigated, giving consideration to the effects of thedeflection of horizontal trusses on the vertical trusses.

(5) Downstream bracing. The downstream bracingof a gate leaf, in conjunction with the appropriate girdersor trusses, forms a vertical truss that supports the vertical

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forces applied to the leaf, including the weight of theleaf. Normally the bracing carries one-half of the verti-cal load with the skin plate carrying the remaining one-half. The bracing should be placed so that the maximumnumber of members, while acting as truss members, willbe designed for tension rather than compression. Endconnections of the bracing should be such that the forcesin the member will be applied concentrically as far aspractical. Any eccentricity of the connection from thegravity axis of the member should be considered indetermining the stress in the member. The stress createdin the girder or horizontal truss by the downstream brac-ing shall be combined with the bending from horizontalforces as indicated in preceding paragraphs on plategirders.

(6) Intercostals. Intercostals are essentially the sameas discussed in the section on horizontally framed mitergates. The span of the intercostal is from center to cen-ter of horizontal girders or trusses, with the loadingbeginning at the edge of the flange or 6 in. from thecenter line of the girder web, whichever is the smallerdimension. The skin plate is assumed to be an effectivepart of the intercostal, with the effective width deter-mined according to AISC Specifications. The mostdesirable shape for intercostals is an unequal leg angle,with the longer leg of the angle attached to the skinplate. This gives a much stronger member than a flat barused as an intercostal. For additional information, seeparagraph 2-1c(2).

(7) End girders. End girders, on vertical-lift gatesused as upper gates where the gate is lowered into thesill or used as a movable sill, serve to distribute thevertical and horizontal reactions of the gate or gate leaf.These girders are designed as columns with a combinedaxial and bending load. The axial load is a combinationof the dead weight of the gate in the dry plus silt andmud load. This force, normally applied through offsetbrackets attached to the outside of the end girder web,produces a bending moment in the end girder as well asa normal direct axial load. Usually the force on the endgirder is divided between two brackets, with eachbracket, along with its effective web and flanges, consid-ered as an individual member, acting as a continuousbeam fixed at the horizontal girder webs. Each memberis subjected to a combination of bending and axialloading.

(a) The bracket on the outside edge of the end girderweb, shown as bracket A in Plate B-44, makes up avertical member in conjunction with the vertical plate

that acts as a flange of the end girder, and the relatedflanges of the bracket itself.

(b) The bracket shown as bracket B in Plate B-44makes up a vertical member consisting of the bracket andusually two standard rolled tees attached to the end girderweb above the tapered segment of the bracket, forming amember with a haunched section on one end.

(c) The brackets are checked for shear in two direc-tions, one being the vertical shear from direct loadingand the other being horizontal shear caused by themoment resulting from the beam action of the member.See Plate B-44 for information on a typical effectivecolumn (or beam). Welds attaching the bracket to theweb of the end girder are subjected to both direct shearand bending stress and should be sized accordingly.

(d) The end bracket is fitted with a base platedesigned for bearing and bending. Where the loads areof such magnitude that the base plates would be exces-sively thick to prevent bending, stiffeners may be used tosupport the plate and thereby keep the thickness of theplate in a more desirable range. The stiffeners should beattached to the bracket web plate and be of sufficientlength to transfer a proportional share of the force fromthe web to the base plate, acting as a short column.

(e) The lifting pin plates are generally attached tothe end girder web where reaction wheels are not used.The transfer of the vertical force should be made throughthe welds attaching the pin plates to the end girder web.When reaction wheels are used the lifting connection isgenerally outside the end girder or reaction girder web.The vertical plate serving as the downstream flanges ofthe horizontal girders is extended past the reaction girderweb and, with the appropriate stiffeners, serves as thevertical web for the lifting connection. The entire end ofthe gate is usually extended and boxed in by theextended vertical plate, skin plate, and an end plateattached to the ends of the horizontal girder webs.

(f) End girders on vertical lift gates used as lowergates, or where the gate is lifted above the sill for clear-ance, usually serve only to distribute the horizontal forceapplied to the gate, acting similar to the vertical platediaphragm discussed in paragraph 5-1c(3), distributingthe load so that all reaction wheels carry their appropriatepart of the total force applied to the gate. The end girderfor this type of gate consists of a solid end plate with anupstream and a downstream flange. The flanges may beof rolled members or of flat plate. The vertical load of

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the gate is transmitted through the vertical diaphragm ortrusses through the bottom seal assemblies to the con-crete sill.

(8) Towers. Where vertical-lift gates are used forthe lower gate of locks, or where gates must be liftedabove the sill for clearance, towers are usually requiredon top of the lock walls to lift the gate to the requiredvertical clearance. The towers should be designed for thevertical load of the gate, including 50 percent impact,applicable vertical bridge load, loading due to expansionor contraction of bridge, plus the wind load applied tothe gate, bridge, and tower. Wind forces should be asindicated by TM 5-809-1, with a minimum force of25 psf applied for all areas. The allowable stress can beincreased by one-third for all loading conditions thatinclude wind load, provided that the required sectioncomputed on this basis is not less than that required forthe design dead load, live load, and impact, computedwithout the one-third stress increase. Considerationshould be given to the effect of torsion on the tower,created by the wind load, reaction from the gate, andeccentric loading, as well as wind on the tower itself.

(a) Two basic types of towers used are steel framedor reinforced concrete, with economics normally deter-mining the appropriate type. Hybrid towers of compositeconstruction may in some cases be advantageous butnormally are not the most economical. Steel towersshould be designed on the basis of each face acting as aplanar truss, with the diagonal members carrying tensileforces only. Horizontal cross-bracing should be providedat each panel point to resist shearing and torsional forcescaused by the eccentricity of loading along the guidesystem as well as wind on the tower itself. Concretetowers should be designed with a minimum of 3,000-psiconcrete, with the loading essentially the same as that forsteel framed towers. Both types of towers should bedesigned as free-standing cantilevers, with the baseplatesfor steel towers attached to mass concrete with corrosion-resisting anchor bolts. Baseplates should be checked forbearing and bending from downward axial loads and alsofor bending due to uplift, with the connection of thebaseplate to the tower leg being analyzed for maximumstress. For concrete towers the applied torque should beconsidered as resisted by pure flexure in the flanges atthe cantilever fixed end and by pure torsional shearabove the fixed end, with a transitional section betweenthe two. The critical stress may be located in the transi-tion with the shape of the tower influencing the length oftransition and the stress concentrations.

(b) The gate guide system should be connected tosteel framed towers only at panel points, so that gatewheel reactions will cause no lateral bending in towerlegs. In the event it is not practical to avoid bending insome tower members these members shall be designedfor the combined axial and bending loads. The guidesshould be designed as continuous members subject tomoving loads from the gate reaction wheels. Where theguide system is attached to concrete towers, considerationshould be given to the transfer of shear between the steelportion of the guide system and the tower proper, ensur-ing that suitable means of transfer are provided.

(c) If a bridge is used on top of the towers to sup-port the vertical load of the gate, the bridge should bedesigned for the dead load plus impact and wind. Thebridge should be connected to the top of the towers withfixed bearings, pinned to allow for deflection of thebridge and towers. The bearings should be designed inaccordance with AASHTO Specifications, with the bridgeframing meeting the requirements of EM 1110-2-2105 orAISC as indicated in paragraph 1-6b. Bracing shall beprovided between girders to stabilize the bridge againstlateral loads.

(d) When a bridge is not used, cantilevered gatesupports must be used on top of the towers. This systemcauses more tower deflection under load and this shouldbe considered when selecting the support system for thegate.

(e) Whichever support system is selected, cantile-vered supports or a bridge, the tower deflection must bechecked and the effect considered on the guide system ofthe gate. If necessary the towers may be cambered sothat the gate guides and tower faces at channel-side willbe in vertical alignment under the dead load of the gate.

(f) Access across the lock should be provided byway of the towers and the bridge as well as the normalwalkway across the top of the gate.

(g) Consideration may be given to the use of coun-terweights to reduce the cost of electrical and mechanicalequipment but the disadvantages of the counterweights,such as the additional load on the tower, the possibilityof the need for the full weight of the gate to seat thegate, and the special adaptation of the tower wind brac-ing to provide clearance for the counterweights and theirguide systems, must be compared with the advantagesbefore a final decision can be reached.

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d. End bearing. The end bearing of vertical-liftgates is essentially the same as that for a simple beam.There the upper gate is made of two leaves, the upstreamleaf, depending on the intended use of the leaf, may befitted with standard bearing plates designed for momentand bearing. The bearing surface of the plate should bemade on a radius to act as a rocker to allow for deflec-tion of the gate leaf. For the allowable stresses anddimensions related to the radius of the curved bearing thecurrent AASHTO Specifications should be used. Wherereaction wheels are used so that the gate may be operatedunder load, the wheels may be sized so that the require-ments of AASHTO are met or other similar methods ofanalysis may be used. For additional information con-cerning reaction wheels see paragraph 5-2b(3)(f).

e. Seals. Rubber “J” seals are used to seal betweenthe end of a single-leaf gate, or the downstream leaf of adivided gate, and the gate recess. Where the upper leafis used as a temporary sill a rubber “J” seal is bolted tothe upstream face of the leaf to provide a seal betweenthe leaf and the existing concrete sill. A short section ofrubber caisson seal is used to seal between the gate andthe recess on the bearing-bar side of the leaf. Onemethod of sealing between the two leaves at the loweredge of the skin plate of the downstream leaf is to use atube member normally made of aluminum and in inter-changeable lengths, held on top of the upstream leaf byguide brackets and forced into position against the skinplate of the downstream leaf by the force of the water.The seal tube is fabricated so that the water fills the tubeafter installation, with the tube and brackets installed inthe dry and the upstream leaf lowered to a point wherethe tube is filled before lowering the leaf into its finalposition. The effect of the water load on the tube shouldbe investigated.

(1) Where the gate is made of a single leaf, a solidblock-type rubber seal is used on the bottom of the leaf,sealing against embedded metal in the floor of the lock.

(2) All seals should be fastened with corrosion-resist-ing bolts spaced approximately 6 in. on center. For addi-tional information on seals, see Plates B-40 and B-41.

(3) Where corrosive elements are encountered, con-sideration should be given to using corrosion-resistingseal plates or the use of a plate or member with theexposed surface clad with corrosion-resisting metal.

f. Lifting arrangement. Vertical-lift gates are usuallylifted by an arrangement of sheaves and cables. Wheregates are used as upper gates, the hoist motor is normally

fixed on the lock wall and through an assembly ofsheaves attached to the gate, lifts the gate to the requiredheights.

(1) Similar systems are used for lower gates exceptthat the hoist motor may be mounted on the gate or if abridge is used between towers, the hoist motor isgenerally mounted on the bridge.

(2) For any system the supporting members used onthe gate or for supporting the hoist drums or sheavesshall be designed for the actual load plus 100 percentimpact. This should apply to all related pins, bolts, andanchor bolts.

g. Dogging arrangement. Support beams may beused for vertical-lift gates used as upper gates or wherethe gate is not lifted above the lock walls. These beamsshould be designed for shear and moment, using50 percent impact for the applied loading. Stiffenerplates should be used on each side of the support beamweb under the support brackets of the gate and at thereaction points of the support beam.

(1) Where the gate is lifted above the lock wall ontowers, dogging devices should be provided to allow thetension to be removed from the lifting cables under con-tinuous loading. The preferred dogging device consistsof a horizontal pin that moves into pin plates attached tothe top of the gate. The pin should be so arranged that itcan be operated from the control station of the gate, withinstruments provided to show when the pin is fullyengaged or fully released. (See Plate B-43 for suggesteddetails.)

(2) The pin and pin plates on both the gate and sup-port structure should be designed for the full gate loadplus 100 percent impact.

(3) Limit switches should be installed so that whenthe cables become slack the gate drive motor stops andthe brakes set. (See paragraph 5-2d for additionalinformation.)

h. Tracks. Tracks for vertical-lift gates are usuallyincorporated into the guide system, with the track itselfconsisting of a corrosion-resisting plate where contactwith salt or brackish water is a possibility. Where thecorrosive elements of the water are minor, as with nor-mal fresh water, the bearing plate or track may be ofstructural steel with a cladding of corrosion-resistingmaterial on the exposed surface.

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(1) Above the water line, consideration may be givento the use of structural carbon steel for the bearing ortrack plates with the determining factor being theeconomic comparison of maintenance and replacementagainst the higher cost of clad material.

(2) The bearing plate or track should be attached to asuitable support member, normally a standard rolledbeam, with the support member embedded and anchoredin the concrete wall or attached to the tower at towerpanel points.

(3) The track plates are provided in pairs, one eachon the upstream and downstream side of the recess orguide system.

i. Guides. The guide system for a vertical-lift gateconsists of two bearing or track plates and an end guideplate. The bearing plates are so arranged that the wheelsor bearing plates of the gate react against the bearingplates of the guide system. The system is arranged sothat the gate may be loaded from either side and thebearing plates will remain effective.

(1) The end bearing plates are similar to the reactionbearing plates but are placed so that bumpers on the endof the gate will strike the end bearing plate and preventexcessive lateral movement of the gate in relation to thelock.

(2) The normal clearances should allow for not morethan 1 in. total movement between gate and bearing plateand not more than 1/2 in. between gate and end bearingplate. See Plate B-41 for suggested details of a guideshowing the recommended clearances.

(3) The end guide or bearing plate should be of thesame material as the bearing or track plates, using thesame criteria to determine the use of corrosion-resistingsteel, clad steel, or standard structural steel.

(4) To minimize the effects of the guide system onthe support towers the system should be connected tosteel towers only at panel points of the structure.

j. Sill. The concrete sill for a vertical-lift gate maybe of two types. One type, where the gate is loweredinto a recess behind the sill, carries the weight of thegate on the lower segment of the sill on extended con-crete pedestals or on steel pedestals bearing on an exten-sion of the sill. The other type of sill, where the gate islifted above the sill for clearance, carries the full weightof the gate on the top of the sill, with the weight of the

gate being transferred through the seal assembly alongthe entire length of the gate. For this type of sill anembedded beam with corrosion-resisting seal plateattached is used in the top of the sill. The beam shouldbe placed in second-pour concrete with anchor bolts, alsoused for adjustment, placed in first-pour concrete. Thetop of the corrosion-resisting seal plate should be flushwith the concrete of the sill.

k. Walkway. Where gates are lifted above the sillfor clearance and the top of the gate in the lowered posi-tion is at the same elevation as the lock wall, accessacross the lock should be provided by means of a walk-way on top of the gate. The walkway should normallybe the same overall width as the gate, with the walkwaymaintaining its width over the tapered ends of the gate.The minimum width of walkway shall be 4 ft 0 in. back-to-back of support angles. Where the gate width is morethan 4 ft, the walkway may be made the minimum widthif the additional width is not needed for the transfer ofequipment. The support angles will also act as toeboards for the walkway, with a minimum vertical leg of3-1/2 in. by 3/8 in. The vertical supports of the walkwayshould be designed as columns and located on the dia-phragms and vertical members of the gate wherepractical.

(1) The walkway shall be designed for 100 psf withgrating having a minimum depth of 1-1/4 in. The endsof all grating shall be banded with bars the same size asthe bearing bars, with panels made in convenient size forinstallation and removal. Usually four standard clips perpanel will be used to fasten each panel of grating.Grating shall normally be type II and hot-dippedgalvanized after fabrication.

(2) Handrail should be made with 2-in. diameterextra strong pipe post and 2-in. standard pipe rail, orequivalent aluminum rail and post if economy dictatesaluminum railing for the lock walls. Railing should bemade removable and in convenient size panels for instal-lation and removal. When standard and extra strong pipeis used handrail panels should be hot-dipped galvanizedafter fabrication. See paragraph 2-1n(5) for additionalinformation.

l. Erection and testing.

(1) The procedures for vertical-lift gates are essen-tially the same as those for “miter gates.” Items that donot apply to vertical-lift gates are diagonals, pintle,anchorage links, and zinc or epoxy filler. The remainingdiscussion pertaining to trial operation, testing, and

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workmanship should, in general, apply to vertical-liftgates. (See Chapter 2.)

(2) Towers for vertical-lift gates should be checkedfor deflection during the trial operations of the gate todetermine if the guide system is in vertical alignment.The vertical alignment should be such that the guide andbearing plates of the guide system remain fully effectivewithout binding on the gate and without excessive deflec-tion or distortion of any member.


a. General description. Two types of vertical-liftgates may be used. One type is a double-leaf gate thatnormally is lowered into the sill. One leaf is locatedupstream from the other, and may be used as an upperlock gate or as an emergency gate in conjunction with anormal miter gate. This type of gate is referred to hereinas an “Emergency Gate.” The other type of vertical-liftgate, a single-leaf gate, can be used at either end of alock and is frequently used as a tide or hurricane gatealong the sea coast. This type of gate is raised when notin use, permitting normal water traffic to pass under-neath. This type of gate is referred to herein as a “Tide”or “Hurricane” gate. On both types of gates, the leavesare raised by a cable hoist with the machinery mountedon the lock walls.

(1) Emergency gate machinery. The emergency-typegates generally consist of two leaves, one upstream andone just downstream of the other. The downstream gateis equipped with wheels and is designed to be raised inflowing water. The upstream gate is designed to beraised only in a balanced pool or when the swell head is1 ft or less. The gates are used when failure of the lockmiter gate occurs or when it is necessary to pass ice ordebris with the miter gates open and latched in therecess. When operating the gates, the upstream leaf mustbe raised in steps behind the downstream leaf. Operatingprocedures for this type of gate are shown in Plate B-39.

(a) The hoist machinery used to raise the emergencygates consists of a double grooved rope drum driven bytwo stages of open spur gearing, a herringbone or helicalgear reducer, and an electric-drive motor with spring set,magnet release holding brake. The rope drum hasseveral layers of rope. One rope from the double drumattaches to one end of the gate through a multipart reev-ing. The other rope from the drum crosses the lockthrough a tunnel in the gate sill and passes through amultipart reeving which is attached to the other end ofthe gate. (See Plates B-56 and B-57.)

(b) The hoist components are generally mounted ona structural steel frame which is anchored in variousways to the lock wall or a concrete structure. Each leafis raised by its individual hoist mounted side by side onthe lock wall. The hoist structure is of such height thatthe machinery will be above high water. A typical hoistarrangement is shown in Plate B-58.

(2) Tide gate or hurricane gate machinery. Themachine used for raising this type of gate consists of adual drum cable hoist mounted adjacent to one of thelifting towers. The two drums are driven by a piniongear located between the two drums. A triple reductionenclosed gear unit drives the pinion. The gear unit isdriven by a two-speed electric motor with a double endedshaft. A magnet-type electric brake is provided betweenthe motor and reducer. The motor shaft extension per-mits the connection of a hydraulic “emergency” loweringmechanism. The low speed of the motor is used whenstarting and stopping the gate. The gate is normallylowered by means of the electric motor; however, in theevent of a power failure, the gate may be lowered bymeans of the hydraulic mechanism.

(a) The emergency lowering mechanism consists ofa radial piston-type hydraulic pump connected to theelectric motor shaft extension, a flow control valve, oilcooler, check valve, and necessary piping, all connectedand mounted on an oil storage reservoir. When loweringwithout electric power, the weight of the gate, actingthrough cables and reduction gearing, turns the hydraulicpump. Oil from the pump is circulated through a flowcontrol valve creating a transfer of energy to the oil inthe form of heat. Excess heat in the oil is removed by atubular-type oil cooler.

(b) The two drums wind both ends of a continuouscable which lifts the gate through a series of sheaves, thenumber of which are selected to give the mechanicaladvantage desired. Two of the sheaves mounted on thegate serve as equalizing sheaves to equalize the line pullin event one drum winds slightly more cable than theother. Each drum is precision grooved so that eachwinds the same amount of cable on each layer. Wherethe fleet angles of the cable approaching the drum exceed1.5 deg, a fleet angle compensator must be provided.

(c) The hoist machine should be located adjacent tothe gate and in line with the hoisting sheaves. The hoistshould be enclosed in a small protective building. Ahydraulically operated dogging device should be providedto secure the gate in the raised position. A typical hoistarrangement is shown in Plate B-59.

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b. Design considerations and criteria.

(1) Emergency gate machinery. The design ofvertical-lift gate machinery should be determined by thecombination of all loads applicable to the type and designof gate used. For two-leaf emergency gates, theupstream leaf or movable sill should be raised only underbalanced head conditions or when lower pool is no morethan 1 ft below the upper pool (the swell head whencontrol of the river is lost). For design purposes a “swellhead” of 1 ft should be used. Since horizontal force onthis gate is light, gate rollers may not be required and thegate should be designed to slide against friction plates inthe gate recesses.

(a) The downstream leaf will normally be raised inflowing water, thereby creating an additional horizontaland vertical force. The horizontal force usually will begreat enough to require the use of reaction rollers oneach end of the gate. Gate lifting speed for both leavesshould be approximately 1 ft/min to 5 ft/min adjusted tosuit the speed of the nearest standard speed motor.

(b) When this type of gate is used as an operatinglock gate it would normally be operated under balancedhead conditions and not through flowing water. Gatespeed should be approximately 5 ft/min to 10 ft/min.

(2) Tide gate machinery. Criteria for the design oftide gate machinery are the same as those for theemergency gate machinery except that the gate must becapable of being raised or lowered against a differentialhead, plus against a force created by wind on theexposed section of the gate. In order to clear trafficpassing under the gate, the gate must be raised a greaterdistance than either of the emergency-type gate leaves;therefore, the lifting speed should be approximately 5 ft/min to 10 ft/min or a speed sufficient to permit openingthe gate in approximately 10 min. Wind load on theexposed section of the gate should be assumed to be20 psf (for machinery design). (See Plate B-59.)

(3) Machinery components.

(a) General criteria. General criteria applicable to alltypes of operating machinery covered in this manual arepresented in paragraph 1-11.

(b) Hoist motor selection. The required torque ofthe downstream vertical-lift gate hoist motor should bethe root mean square value of torque vs. time curve foroperation of the gate with the motor selected having a1.15 service factor. The peak torque required should not

exceed 125 percent of the rated full load motor torque.The normal hoist load for the downstream leaf will bethe loads resulting from the required torque of the motor.The hoist motor should have torque characteristics con-forming to Guide Specification CW-14615. A desirablefeature to be considered is variable speed (AC or DC)hoist motors with a ramping function adjustable throughthe drive controllers.

(c) Hoist load division. The normal hoist load shallbe considered as equally divided between the two drivesof the hoist. For nonequalizing hoist arrangements, theloads resulting from the maximum torque of the motorwill be divided between the two drives of the hoist byassuming that only one side of the gate is jammed. Theload on the jammed side will be the loading resultingfrom the maximum torque of the motor minus the loadstaken by the free side. Both drives of the hoist will bedesigned to withstand the jammed loads. For equalizinghoist arrangements the stalled torque of the motor will beconsidered as equally divided between the two drives ofthe hoist. For emergency-type gate machinery, forcecontrol switches may be used to limit the rope pull understalled conditions and thus reduce the loads on themachinery components.

(d) Wire rope. Wire rope for these types of hoistsshould be 6 × 37, preformed, lang lay, independent wirerope core, 18-8 chrome-nickel corrosion-resisting steel.Wire rope shall be designed for a factor of safety of5 based on normal load. A factor of safety of 3 shouldbe provided for peak loads occurring during normal oper-ation and a minimum factor of safety of 1.5 based on themaximum stalled rope load. Where multilayer hoistdrum-winding is necessary, 6 × 30 Type G, lang lay,independent wire rope core, flattened strand wire ropeshould be used.

(e) Sheaves. Sheaves should be aluminum bronzebushed or antifriction bearing type as dictated by theconditions involved. Sheaves should be of standarddimensions with grooves clad with stainless steel. Pub-lished ratings of sheaves should be used in determiningthe factor of safety. The diameter of the sheaves may beas small as 24 times the rope diameter when used with6 × 37 strand wire rope for an emergency-type gate.When used with a lock operating gate, sheave diametershould be 30 times the rope diameter.

(f) Gate wheels. Wheels for the underwater gatesare a critical item and should be designed for the individ-ual conditions encountered. A gate being raised with aconsiderable horizontal load caused by flowing water

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would have considerable deflection at ends. To avoidpoint contact of the wheels on the flat plate track causedby gate deflection, the wheels should be constructed witha crowned, hardened tread. A method for designing awheel subject to gate deflection is shown in Plates B-90.This method was developed utilizing formulas fromRoark and Young (1975). (The formulas in the fifthedition may also be used. However, the formulas forcomputing maximum compressive stress are in error.)Formulas give the maximum compressive stresses, whichoccur at the center of the surface of contact, but not themaximum shear stresses, which occur in the interiors ofthe compressed parts, nor the maximum tensile stress,which occurs at the boundary of the contact area and isnormal thereto. Due to the flexure in the gate, it is diffi-cult to determine accurately the distribution of load onthe gate wheels; however, it is considered satisfactory todesign the wheel tread for a maximum compressive stressof from 2.0 to 2.5 times the yield strength of the materialinvolved based on the maximum wheel load from thegate. A slight misalignment of the track surfaces willprevent a wheel of the gate from bearing on the track forshort distances of travel, causing an overload on some ofthe adjacent wheels. This condition should be taken intoconsideration when determining maximum wheel load.An option to the crowned wheel to compensate for gatedeflection at the ends would be to use flat wheels withself-lubricating, self-aligning, spherical bushings. Theseare available in many bearing and lubricant combinationsto suit a variety of applications. Self-lubricating, self-aligning, spherical bushings have been used successfullyin nuclear offshore, industrial, structural, and damapplications.

(g) Hydraulic lowering brake. A vertical tide gate isnormally lowered by an electric-drive motor on the hoist,with a diesel electric generator set standing by in theevent of power failure. In some cases, it may be desir-able to use a second standby means of lowering the gate.This can be done by coupling a hydraulic motor to theshaft extension of the electric-drive motor. This fluidmotor is connected in an oil circuit which permits freeflow of the oil in the raise position but restricts flow inthe lowering position. A typical circuit required for thisoperation is shown in Figure 5-1. The flow control valveused in this circuit should be designed and adjusted inthe field to limit the speed of the electric motor to about140 percent of its synchronous speed in order not todamage its windings or rotor. The flow control valveand fluid motor shall be sized so that the pressure of theoil leaving the motor shall not exceed the normal work-ing pressure rating of the fluid motor. When loweringthe gate, approximately 10 min may be required and

during this time braking energy will be transformed intoheat in the oil as it passes through the flow control valve.A shell-and-tube-type heat exchanger must be provided inthe circuit to prevent the temperature of the oil in thetank from exceeding 120 deg F. Since this system isused so seldom, cool clean potable water or raw watermay be used in the heat exchanger then exhausted todrain. A thermostatically controlled valve may be usedto automatically control the flow of water through theheat exchanger.

c. Determination of machinery loads.

(1) Since this type of gate is required to be closed inflowing water, considerable difficulty was originallyencountered in the design of the crest for the downstreamleaf. The original gate, in laboratory tests, was found tobounce violently during certain tailwater conditions. Inorder to obtain a gate which would perform satisfactorily,WES was requested to perform a series of tests on gatecrests for this type of gate. Eight alternate gate designswere investigated, incorporating the following modifica-tions: triangular-shaped crest with slope on downstreamside; crests with the apex offset from upstream gate faceby a horizontal or sloped surface; vented girders; crestskin plate; various girder locations; truss-type gates; andcombinations of the preceding modifications.

(2) The design recommended for prototype construc-tion is a triangular-crest with a IV on 3H slopingupstream offset and has the flanges of the gate girdersturned downward. This design was found stable for allconditions investigated and required no aeration of thecrest. Maximum downpull on the gate was about220,000 lb and maximum uplift was about 50,000 lb. Acurve showing uplift or downpull plotted against gateposition above sill is shown in Plate B-89, Sheet 10.Loads taken from these curves should be used in thedesign of vertical-lift gate machinery where the gate is ofsimilar proportions. The complete results of the abovetests may be found in Report 2-527 (USAEWES l959).

(3) In designing the downstream leaf of a vertical-lift emergency gate hoist, the following loads should beconsidered and used to determine cable pull.

(a) The weight of the gate leaf, trash screens, andrecess protection in air. There should be no buoyanteffect since the normal tailwater is generally too low tokeep the gate submerged when it is lifted a few feet.

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Figure 5-1. Typical circuit requirements for raising and lowering a vertical tide gate

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(b) Silt at 125 pounds per cubic foot (pcf) whichmay be trapped above the web of the girders to theheight of the downstream flange.

(c) Side seal friction. Load caused by sliding fric-tion using coefficient of rubber on steel of 1.0.

(d) Roller friction. The total friction due to the gatereaction rollers running against steel tracks and the fric-tion of the bearings in the reaction rollers shall be takenas 5 percent of the load normal to the gate leaf.

(e) Downward hydrodynamic force. This force onthe gate nappe when the gate is raised through flowingwater may be obtained from the curve showing results ofstudies by WES. (See curve in Plate B-89, Sheet 10.)

(4) The upstream leaf normally will not be equippedwith reaction rollers or buoyancy tanks. It should belifted only under balanced head conditions or when lowerpool is 1 ft or less below upper pool (the swell headwhen control of the river is lost). The hoist design loadwill be the dead weight of the gate leaf in air, side sealpreset force, weight of trash screens, weight of silt load(when raised to maintenance position), or the summationof the following, whichever is larger:

(a) Weight of gate leaf minus weight of waterdisplaced.

(b) Silt load amount trapped by flanges less weightof water displaced.

(c) Sliding friction due to horizontal force caused by1.0 ft swell head. The coefficient of friction for thiscondition should be assumed as 0.40 for steel on steel.

(d) Downward hydrostatic load due to 1.0-ft swellhead.

(e) Weight of recess protection and trash screenminus weight of water displaced.

(f) Side seal friction based on a differential head of1.0 ft plus preset force for approximately 3/4-in.deflection. The friction coefficient for rubber on steel isassumed to be 1.0.

(5) Typical calculations for determining loads fordesign of emergency gates are shown in Plate B-88 forthe upstream leaf and in Plate B-89 for the downstreamleaf.

(6) Loads used for design of vertical-tide gates aresimilar to the loads used for vertical-emergency gatesexcept that the wind load is a more critical factor. Thegate is hoisted high above the structure permitting bargetraffic to pass underneath. This exposes the gate to aconsiderable wind load which must be included. To findthe hoist capacity, the following two conditions should beconsidered and the condition creating the greater loadshould be used for design of the hoist.

(a) Condition I. Weight of gate leaf in water con-sisting of the skin plate, framing, sheaves and brackets,wheels, etc., and the weight of silt (125 pcf) trapped bythe flanges of the gate girders less the weight of waterdisplaced. Rolling friction of 5 percent of the horizontalload on the gate caused by the largest combination ofdifferential head when the gate is lowered into positionplus the wind load, at 20 psf, for the exposed portion ofthe gate.

(b) Condition II. Weight of the gate leaf in air con-sisting of the skin plate, framing, sheaves and brackets,wheels, etc., and the weight of silt (125 pcf) trapped bythe flanges of the gate girders. Rolling friction of5 percent of the horizontal load on the gate caused by thewind load, at 20 psf, for the exposed surface of the gate.

d. Operating machinery control. Control stations forvertical-lift gates are usually located adjacent to the gatealong with the hoist machinery. The control equipmentconsists of the combination of full voltage magnetic con-trollers, limit switches, and control switches arranged toproduce the desired operating sequence. The limitswitches used in previous designs were usually of thetraveling-nut type in the National Electric ManufacturersAssociation’s four enclosures. Due to the unavailabilityof traveling-nut limit switches, cam-operated switches arebeing used. Slack cable limit switches and skew controland indication should be used on vertical-lift gates toprevent them from becoming stuck. Gate leaf controlcan be performed as indicated on the typical electricalschematic diagram for an emergency gate hoist(Plate B-73) or by using electronic devices such as posi-tion encoders, and position and speed tachometers.

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Chapter 6Submergible Tainter Gates

6-1. Design Analysis

The design of a submergible tainter gate is similar to thatof a spillway tainter gate. Guidance in EM 1110-2-2702should be followed. Navigation locks are wider and havelower forebay heads than spillway gates. Because of thegreater lock widths, the gates main horizontal structuralmembers will be trusses or plate girders. Secondarystresses in truss joints should be considered. Because oflock clearance requirements, trunnion anchorages areplaced in lock wall recesses. Anchor bolts require specialconsiderations in design. Eccentricity of hub alignmentduring construction introduces some additional stressesduring gate operation. A typical navigation lock plategirder, submergible tainter gate is shown in Plates B-45and B-46.

6-2. Seal and Gate Deicing

Devices for preventing the formation of ice, or to thawice adhering to the gates and seals, will be necessary forthe lock to function during subfreezing weather. Lockoperation in winter will be facilitated by the use ofdeicing (and trash clearing in all seasons) systemsdescribed.

a. Heaters. Two types of electric heating systemscan be used for gate seals; one is by direct heating theseal by an electrical resistance element inserted below theseal face and the other by circulating electrically heatedheat-transfer oil.

(1) Direct electrical heating. Replaceable heatingelements can be installed in recesses in back of the sealsurfaces to be kept thawed, the recesses being insulated soas to direct heat toward the surface to be heated. Becauseof the length of the sill seal and its inaccessibility, it isimpractical to use this method across the bottom of thegate.

(2) Heating by circulating fluid. The usual method ofseal heating is done by a design circulating heat-transferoil through pipes built into the seal plates next to thesurface to be thawed. Immersion-type electrical heatingunits, thermostatically controlled, heat the oil which isforced through the pipes by circulating pumps. The heat-ing stations are located in the hoist machinery spaces atopposite ends of the gate.

b. Air deicing and trash clearing systems.Air noz-zles at about 10-ft spacing and 4-ft3 free air per minuteper nozzle terminate both upstream and downstream ofthe gate face. The air discharging from these nozzlescarries the warmer water to the surface (when water tem-perature is below 39 deg F) and melts any ice buildup atthe surface. This air system is most useful in clearingfloating debris from the path of a rising gate at all timesof the year. The air to the upstream nozzle sets is con-trolled by two sets of reducing valves to prevent one setfrom “hogging” to the lower outlet pressure. Theupstream and downstream air control valves are separatelyoperated from the gate control stand to be used at thediscretion of the lock operating personnel.


a. General description. The machinery used tooperate lock-type tainter gates usually consists of twoequal hoist units of contra-facsimile design arranged to lifteach end of the gate. The hoist units are kept in synchro-nism by power selsyn motors. Each hoist unit consists ofa rope drum, open gear set, speed reducer, magneticbrake, hoist motor, and power selsyn. The drum ismounted on a cantilevered shaft of a size to preventexcessive error in the mesh of the final drive pinion andgear due to shaft deflection. A general arrangement of anelectric-motor-driven hoist for the lock-type tainter gate isshown in Plate B-60.

b. Design considerations and criteria. The designcapacity of the hoist should be based on the maximumload at normal speed which is found to be at the nearlyclosed or raised position. The hoisting speed should beselected so as to raise the gate from full open to closed in2 to 3 min, varying so as to allow the selection of amotor of standard horsepower and speed. General criteriaapplicable to the design and selection of various hoistcomponents are presented in paragraph 1-11. Shock,impact, and wear factors are considered negligible andmay be disregarded. Wire rope for these types of hoistsshould be stainless steel, lang lay, style G, flattenedstrand. Drum diameter should not be less than 30 timesthe rope diameter.

c. Determination of machinery loads. The maximumdynamic load on the hoist normally occurs near the end ofthe raising cycle. The maximum holding rope load occurswhen the gate is fully raised and the lock water level isbelow the upper sill. No consideration should be given torope loads created by the flow of water over a partiallyopened gate. The rope loads from these conditions are

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indeterminate and control features are provided to preventtheir occurrence. The total load on the rope drum is thesum of the following:

(1) Deadweight of the gate as applied to a momentarm (W × CG) divided by the perpendicular distance ofthe rope to the gate trunnion center line.

(2) Side seal friction (total seal force × 0.05).

(3) Weight of the ropes can be neglected.

(4) Trunnion friction less than 200 lb can beneglected.

(5) The static load of the water head on the unbal-anced area on the bottom seal when the lock level isdown.

(6) Ice buildup and silt formation should be consid-ered when severe freezing or silt-loaded water are factors.The air deicing and seal heating systems usually minimizethese factors.

d. Operating machinery control.

(1) General. The electrical equipment for the opera-tion of a power selsyn drive for the hoists for a taintergate consists of two squirrel-cage induction-type motors,two wound rotor induction motors (synchronizing drive),two electrically operated brakes, two limit switches, and acontrol system that will provide operating features appli-cable to the particular installation. Equipment meeting therequirements of Guide Specification CW-14615 is consid-ered to be the best suited for the service.

(2) Motors. The squirrel-cage induction motorsshould have high-torque high-slip (between 8 and 10 per-cent) speed torque characteristics with drip-proof framesas this equipment is usually located indoors. The drivemotor should be continuous rated and sized to drive thegate machinery without overload during any portion of theoperating cycle. No arbitrary limit should be placed onmotor speed other than that which is practical and eco-nomical. The wound rotor motor for synchronizing shallbe of the same horsepower rating as the drive motor, as itmay be necessary, under some circumstances to providethe full torque of a drive motor. For the protection of themotor windings, means shall be taken to provide windingheaters or encapsulation. Motors should be specified inaccordance with the applicable provisions of Guide Speci-fication CW-14615.

(3) Brakes. The brakes should be of the shoe orsplit-band type, spring-set with direct current magnet-operated release, suitable for floor mounting and shouldbe provided with NEMA 12 moisture-resisting, enclosingcase. The brake mechanism should be of corrosion-resis-tant construction using nonferrous parts for bearings, pins,etc. The necessary direct current for operating the brakeshould be obtained from a rectifier mounted within thecontroller enclosing case. The torque rating of the brakeshould be of a value corresponding to approximately150 percent of full load motor torque when referred to theshaft on which the brake wheel is mounted. A spaceheater should be provided within the brake enclosure asrequired in Guide Specification CW-14615.

(4) Control. The control equipment consists of acombination of magnetic controllers, limit switches, con-trol stations, and remote gate position indication as shownin Plate B-74. The main control station (remote from theequipment) is located at the upstream control stand alongwith the other controls for the navigation lock. A localcontrol station along with a local-remote transfer switch islocated in one of the machinery rooms, and is providedfor operation of the equipment during maintenance. Thecontrol equipment may be located where convenient butusually in one central location in a control center. Therotors of the two wound rotor motors are connected sothat when the stators are energized from a common tiethrough a controller the rotors will rotate in a commondirection, either raise or lower. When final adjustmentsare being made and the gate leveled, the rotors are syn-chronized with the couplings disconnected. The statorsare energized first single-phase and then three-phase topull the rotors into synchronism. Then the couplings areconnected while the gate is in level condition supportedon the ropes. During normal operation the drive motor,wound rotor motors, and brakes are all energized simulta-neously and run until stopped by a limit switch in eitherthe open or closed position or by the movement of acontrol switch to the stop position. During the stoppingsequence, both the drive motors and brakes arede-energized but the wound rotor motors remain energizedfor a short time (5 sec) while the brakes are setting. Thisprevents skewing of the gate should the brakes setunevenly because of wear or misadjustment. A synchrosystem is used to show gate position at the control stand.A system of interlocks is used in the control circuit toprevent opening the gate at a time which might causedamage to the equipment or create hazardous conditions.Among these is a differential level circuit which willallow opening the gate only when the water surfaces on

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either side of the gate are nearly at the same elevation.Control voltage is obtained from the control transformerwhose primary is connected to the load side of the woundrotor motor supply which prevents gate operation unlesssynchronizing power is available. The controllers are of

the combination air circuit breaker disconnect and revers-ing magnetic contactor type, with thermal overload pro-tection. The limit switch should be of the heavy duty,high-accuracy type in order to ensure reliable operation ofthe control system.

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Chapter 7Corrosion Control

7-1. Corrosive Environment of Lock Gates

Lock gates are located in river water which is a sub-merged corrosive environment. Corrosion causes differ-ent degrees of structural and metallic deterioration of thegates. This affects operation and repair of the gates.Adequate coating (painting) and cathodic protection withprotective potential achieving minus 850 millivolts“instant off” over 90 percent of each gate leaf face willextend the life of a lock gate leaf well over 100 years.(See Plates B-75 through B-78.)

7-2. Corrosion and Corrosion Control

a. Most of the time, the locks initially perform theirfunction in spite of frequent use, floating impact, floods,and corrosion. The lock gates (usually miter type) arevital to the locking function and require periodic mainte-nance in such areas as the quoin and miter blocks, diago-nals, lower areas of the gate, loss of gate plumb, and lossof seals. This is caused by flooding, waterborne impact,frequent use of equipment (under pressure and highvelocity), loss of protective paint, and corrosion. Theseproblems are usually resolved with expenditures or lockreplacement. Since the gates are key operating elements,failure of their function causes disruption of river traffic.Repairs and/or replacement are very expensive. Becauseof this loss of service and high cost of dewatering, gaterepair, and painting, it is becoming more important toensure that cathodic protection is providing protectivepotentials.

b. Corrosion causes the lock gates and valve gates todeteriorate, and consequently preventative maintenance isrequired. Many times when corrosion causes the needfor maintenance it is not attributed to the corrosionprocess.

c. A significant number of the maintenance problemscan be delayed, and even prevented, with effective coat-ing and cathodic protection. It can be established thatlock gates can be protected from the devastating effectsof corrosion with proper coating and cathodic protection.While it is true that this does not place the lock gates ina perpetual state of corrosion prevention, and while itwill not undo earlier deterioration due to corrosion, it is afact that a properly maintained and adjusted cathodicprotection system will decrease the need for many lockrepairs and prevent the expensive lock facility from

becoming obsolete by deterioration. The initial expenseof installing cathodic protection and the expense of regu-lar maintenance of the systems can easily be shown toprovide a very high cost-benefit ratio.

7-3. Painting Structures

a. The primary corrosion control system for lockgates is painting. The paint protects some areas of thelock gate components. This provides some degree ofcorrosion protection. When paint is scratched and cutwith waterborne impact, metal surfaces or holidays areexposed to the corrosive electrolyte. The base surfaceareas become anodes and will corrode in a concentratedarea. This affects the limit states of strength and service-ability of the steel in the gates. The corroded area ismanifest in operation and maintenance of lock gates.

b. The following approaches should be used toimprove the painting system and ensure its durability:

(1) Determine that the surfaces to be painted haverounded edges and corners, and smooth joints.

(2) Avoid waterborne impact.

(3) Install cathodic protection to protect the exposedareas of the steel.

c. Environmental concerns have caused some restric-tions on metal preparation and application of qualitypaints used in the past which are also presently beingused when possible. The environmental concerns haveresulted in poorer quality of paint on the market.

(1) Recently, a study at the Construction EngineeringResearch Laboratory (CERL), Champaign, Illinois, wasmade on a large number of different paints on the mar-ket. The paints studied represented most currentapproaches to painting and some new, highly toutedpaints that met environmental concerns.

(2) Most of these paints failed in the laboratory tests.Only a small number of the best were selected for fieldtests. In field tests (in water environment and sub-merged), these paints did not perform well when com-pared to paints presently being used (vinyl). Futureenvironmental concerns will further restrict or eliminatethe use of presently applied paints. Only in certain areasof several states are those restrictions in effect at thistime. This, of course, emphasizes the importance ofcathodic protection and painting where needed.

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(3) With the advent of poorer quality paint, theproper installation and maintenance of cathodic protectionwill become much more critical. The paint quality forsubmerged metals is becoming a serious problem becauseof environmental controls of cleaning and painting metal.Corroded metal structures could cause unsafe and waste-ful operation of facilities. Periodic inspections help toidentify potential unsafe conditions, deteriorating condi-tions, and equipment not working. Cathodic protectionequipment should be working. Periodic inspectionreports on civil works structures should include the mostrecent dated electrolyte potential survey, condition ofcathodic protection system, and plans for cathodic protec-tion system repair and modification if required.

(4) Future emphasis on limiting dewatering of locksis another factor that increases the importance of opera-tional cathodic protection.

7-4. Type of Cathodic Protection

a. Impressed current. Cathodic protection for lockgates should be provided utilizing Guide Specifica-tion CW-16643. Cathodic protection should beimpressed current and should have good impact protec-tion to protect the anodes from waterborne impact.

b. New techniques. Guide Specification CW-16643provides new techniques for impact protection and forachieving operational cathodic protection systems, andaddresses methods of providing protection against ice anddebris, steps to increase quality construction, and trainingon design, installation, operation, and maintenance ofcathodic protection systems.

c. Cathodic-protection testing, evaluation, and resto-ration. All testing, evaluation, restoration, or new instal-lation should be supervised by a professional engineerregistered in corrosion engineering, or an individual whohas satisfied the requirements for accreditation as a cor-rosion technologist or specialist by the National Associa-tion of Corrosion Engineers (NACE). Installation of thecathodic protection systems should also be witnessed byappropriate Government representatives qualified in cath-odic protection.

d. Restoration of cathodic-protection systems. Exist-ing inoperable cathodic-protection systems at many navi-gation structures can be restored. This approach is lessexpensive than installing complete new cathodic protec-tion systems and, therefore, should be considered first.When graphite anode strings are exhausted, they shouldbe replaced with cast iron anode strings. In many cases

anode strings can be replaced and cathodic-protectionsystems repaired without dewatering.

e. Complete replacement of cathodic-protectionsystems. Guide Specification CW-16643 should be fol-lowed when designing and installing new cathodic-protection systems or when complete replacement ofcathodic-protection systems at navigation structures isfound to be necessary.

7-5. Cathodic-Protection Operation

An impressed current cathodic-protection system shouldbe provided for each gate leaf. Each system consists ofa rectifier supplying protective voltages to anodes whichwill distribute uniform protective voltages through theriver water to the submerged gate structure. Cathodic-protection should be installed on those portions of thegates submerged at normal pool levels. The faces of thegates are protected to upper pool stages, except that thedownstream face of the lower gates shall be protected tothe lower pool. Meters are provided as part of the recti-fier for monitoring of the cathodic-protection systems.Surveillance of the rectifier output (voltage and current)is required to ensure that the rectifier unit operates on acontinuous basis at the desired output levels. Voltageand current indications with the lock chambers filledprovide surveillance of the rectifier and cathodic-protec-tion operation. The cathodic-protection systems willencounter flooding and floating debris and will requireimpact protection to prevent damage to the cables provid-ing voltage to the anodes.

7-6. Anode Concepts

One of two basic concepts for providing cathodic protec-tion should be used. Method one uses cast iron buttonanodes on the skin plate and string type (sausage) anodesin the compartment areas. The sausage anodes andcables are protected from impact by installing them inperforated plastic pipes and in areas subject to ice anddebris by installing channel and angle iron in front ofeach anode string. The button anode cables are protectedfrom impact with conduit. The cast iron button anodesare more durable and can withstand impact. The secondmethod uses cast iron button anodes in all areas.

7-7. Flooding and Emergency Maintenance

The rectifiers are portable (normally with wheels) so thatduring flooding conditions they may be removed andsafeguarded from water or storm damage.

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7-8. Cathodic-Protection Tests, Adjustments andReports

a. Tests, adjustments, and data collection. Testsshould be performed and data tabulated showing structureto reference cell potentials at a number of differentpoints. Test data should include rectifier voltages andcurrents. There is no prescribed time interval for testingnew systems, but as a general rule measurements shouldbe made monthly until steady state conditions areobtained, and at about 6-month intervals thereafter for thefirst year or two; and thereafter at least at yearlyintervals, depending on the judgment of the corrosionengineer responsible for the tests. Based upon the mea-surements taken, the current and voltage of the rectifiershould be adjusted as required to produce a minimum ofminus 850 millivolts “instant off” potential between thestructure being tested and the reference cell. This poten-tial should be obtained over 90 percent of each face ofeach gate leaf. This must be achieved without the“instant off” potential exceeding 1,200 millivolts. Accep-tance criteria of the cathodic-protection systems aredefined in the National Association of Corrosion Engi-neers Publication NACE RP-01-69-92.

b. Reports. Reports in a format similar to that illus-trated in NACE RP-01-69-92 (see Table 7-1) of a mitergate showing the measurements made and data obtained,should be prepared and evaluated.

7-9. Measurement of Existing Cathodic-Protection Systems

The performance of existing systems should be measuredannually and appropriate actions taken.

a. One structure to electrolyte potential survey (usingreference cell) should be performed annually. Any sys-tem found to not be operating in accordance with estab-lished criteria should be optimized (adjusted).

b. Any cathodic protection system found to be inneed of repair should be repaired.

c. A report showing the condition of the cathodicprotection systems, and/or plans to repair the systems,should be submitted each year.

7-10. Cathodic Protection for Miter and QuoinBlocks

One of the most expensive maintenance problems thatoccurs on lock gates is corrosion of the miter and quoinblocks. This can be prevented with impressed currentanode strings in the vicinity of the miter and quoinblocks. Guide Specification CW-16643 provides draw-ings showing anode locations I-1 anode string 2S1 and1S1 that can provide voltage sufficient to protect themiter and quoin blocks. All areas of the miter block andpush-pull rods should be painted. The area where theblocks seal against each other does not have to bepainted.

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Table 7-1Steel to Reference Cell Potentials

Rectifier No. 1UPPER GATE - LAND LEAF - UPSTREAM SIDE(Impressed Current Installation)REPORTS CONTROL SYMBOL ENGW-E-7DATE OF TEST: 1 Oct. 1991

Current OffPre-Protection Current On (Instant Off)

Depth Below Quoin Middle Miter Quoin Middle Miter Quoin Middle MiterWater Surface End End End End END End

0’-6" -0.500 -0.505 -0.495 -1.050 -1.000 -1.055 -0.655 -0.700 -0.650**

2’ -0.500 -0.500 -0.500 -1.040 -1.030 -1.035 -0.700 -0.735 -0.705

4’ -0.500 -0.500 -0.500 -1.050 -1.085 -1.050 -0.825 -0.755 -0.815

6’ -0.500 -0.495 -0.495 -1.050 -1.100 -1.055 -0.855 -0.765 -0.850

8’ -0.495 -0.490 -0.490 -1.050 -1.085 -1.050 -0.865 -0.770 -0.850

10’ -0.490 -0.480 -0.485 -1.080 -1.110 -1.070 -0.880 -0.880 -0.850*

12’ -0.490 -0.480 -0.480 -1.070 -1.080 -1.060 -0.885 -0.880 -0.880

14’ -0.480 -0.479 -0.470 -1.070 -1.070 -1.065 -0.880 -0.885 -0.980

16’ -0.470 -0.464 -0.460 -1.000 -1.020 -1.030 -0.885 -0.890 -0.980

18’ -0.465 -0.455 -0.450 -1.000 -0.979 -1.050 -0.880 -0.885 -0.985

20’ -0.460 -0.445 -0.440 -0.950 -0.930 -1.000 -0.870 -0.875 -0.1075

Rectifier voltage = 2.10 voltsRectifier current = 0.50 ampsCoarse tap position = LFine tap position = 2Meter used 5 meg ohms/volt 2 volt scaleHalf-cell 0’-3" or less from lock steelResistance of circuit: E = IR

2.10 = .5RR = 2.10/.5 = 4 ohms

* Acceptable reading** Unacceptable reading

NOTE: Include as many 2’ increments as necessary to cover submerged depth of gate.

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Appendix AReferences

A-1. Required Publications

Note: References used in this EM are available on inter-library loan from the Research Library, ATTN: CEWES-IM-MI-R, U.S. Army Engineer Waterways ExperimentStation, 3909 Halls Ferry Road, Vicksburg, MS39180-6199.

Federal Specification QQ-C-390BCopper Alloy Castings (Including Cast Bar)

Federal Specification FF-S-325Shield, Expansion; Nail, Expansion; and Nail Drive Screw(Devices, Anchoring, Masonry)

TM 5-809-1Load Assumption for Buildings

EM 1110-2-2105Design of Hydraulic Steel Structures

EM 1110-2-2608Navigation Locks-Fire Protection Provisions

EM 1110-2-2702Design of Spillway Tainter Gates

EM 1110-2-3400Painting: New Construction and Maintenance

CW 05036Metallizing, Hydraulic Structures and Appurtenant Works

CW 05501Metalwork Fabrication, Machine Work and MiscellaneousProvisions

CW 05502Miscellaneous Metal Materials, Standard Articles andShop Fabricated Items

CW 09940Painting: Hydraulic Structures and Appurtenant Works

CW 11290Hydraulic Power Systems for Civil Works Structures

CW 14615Electrical Equipment for Gate Hoists

CW 16643Cathodic Protection Systems (Impressed Current) for LockMiter Gates

American Associat ion of State HighwayTransportation Officers (Current Edition)American Association of State Highway TransportationOfficers. (Current Edition). “Standard Specifications forHighway Bridges.”

American Gear Manufacturers Association (CurrentEdition)American Gear Manufacturers Association. (Current Edi-tion). “Tooth Proportions for Coarse-Pitch Involute SpurGears,” 201.02.

American Institute of Steel Construction (CurrentEdition)American Institute of Steel Construction. (Current Edi-tion). “Manual of Steel Construction, Allowable StressDesign and Load and Resistance Factor Design.”

American Iron and Steel Institute StandardsAmerican Iron and Steel Institute Standards. “Types 303and 304 Wrought Stainless Steel.”

American National Standards InstituteAmerican National Standards Institute. “Hydraulic FluidPower--Contamination Analysis Data,” B93.30M.

American Society for Testing and Materials 1991American Society for Testing and Materials. 1991.“Standard Specifications for Structural Steel,” A-36.

American Society for Testing and Materials 1991American Society for Testing and Materials. 1991.“Standard Specifications for Alloy-Steel and StainlessSteel Bolting Materials for High Temperature Service,”A193.

American Society for Testing and Materials 1991American Society for Testing and Materials. 1991.“Standard Specifications for Carbon and Alloy Steel Nutsfor Bolts for High Pressure and High TemperatureService,” A194.

American Society for Testing and Materials 1992American Society for Testing and Materials. 1992.“Standard Specifications for Carbon Bolts and Studs,60,000 psi Tensile Strength,” A-307.

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EM 1110-2-270330 Jun 94

American Society for Testing and Materials 1992American Society for Testing and Materials. 1992.“Standard Specifications for Carbon Steel Bolts andStuds, 120/105 ksi Minimum Tensile Strength,” A325.

American Society for Testing and Materials 1990American Society for Testing and Materials. 1990.“Standard Specifications for Seamless Steel MechanicalTubing,” A511.

American Society for Testing and Materials 1992American Society for Testing and Materials. 1992.“Standard Specifications for Austenitic Stainless SteelSheet, Plate, and Flat Bar,” A666.

American Society for Testing and Materials 1991American Society for Testing and Materials. 1991.“Standard Specifications for Steel Forgings, Carbon andAlloy for General Industrial Use,” A668.

American Welding Society (Current Edition)American Welding Society. (Current Edition). “Struc-tural Welding Code, Design of New Bridges,” AWS D1.1.

National Association of Corrosion Engineers (CurrentEdition)National Association of Corrosion Engineers. (CurrentEdition). “Control of External Corrosion on Undergroundor Submerged Metallic Piping Systems,” NACE StandardRP0169.

National Association of Corrosion Engineers (CurrentEdition)National Association of Corrosion Engineers. (CurrentEdition). “Standard Recommended Practice Discontinuity(Holiday) Testing of Protective Coatings,” NACE Stan-dard RP0188.

National Electric Manufacturers Association 1980National Electric Manufacturers Association. 1980.“Enclosures for Industrial Controls and Systems,” Publica-tion No. ICS 6-1978, Rev 1.

Occupational Safety and Health Administration (Cur-rent Edition)Occupational Safety and Health Administration. (CurrentEdition). “OSHA Standards.”

U.S. Army Engineer Construction EngineeringResearch Laboratory 1979U.S. Army Engineer Construction Engineering ResearchLaboratory. 1979 (Dec). “Cathodic Protection of Civil

Works Structures,” Technical Report M-276, Champaign,IL.

U.S. Army Engineer District, Chicago 1960U.S. Army Engineer District, Chicago. 1960. “TorsionalDeflection of Miter Type Lock Gates and Design of theDiagonals,” Chicago, IL.

U.S. Army Engineer Waterways Experiment Station1954U.S. Army Engineer Waterways Experiment Station.1954 (Jul). “Greenup Navigation Dam - Analysis ofHydrodynamic Forces Acting on Emergency Gate,”Vicksburg, MS.

U.S. Army Engineer Waterways Experiment Station1959U.S. Army Engineer Waterways Experiment Station.1959 (Oct). “Emergency Gate, Greenup Locks, OhioRiver, Kentucky,” Technical Report 2-527, Vicksburg,MS.

U.S. Army Engineer Waterways Experiment Station1964U.S. Army Engineer Waterways Experiment Station.1964 (Jun). “Operating Forces on Miter-type LockGates,” Technical Report 2-651, Vicksburg, MS.

U.S. Army Engineer Waterways Experiment Station1970U.S. Army Engineer Waterways Experiment Station.1970 (Mar). “Operating Forces on Sector Gates UnderReverse Heads,” Technical Report H-70-2, Vicksburg,MS.

U.S. Army Engineer Waterways Experiment Station1971U.S. Army Engineer Waterways Experiment Station.1971 (Dec). “Operating Forces on Sector Gates UnderReverse Heads,” Appendix A, “Results of SupplementalTests,” Technical Report H-70-2, Vicksburg, MS.

U.S. Army Engineer Waterways Experiment Station1971U.S. Army Engineer Waterways Experiment Station.1971 (Feb). “ Calcasieu Saltwater Barrier, PrototypeSector Gate Tests,” Miscellaneous Paper H-71-4,Vicksburg, MS.

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U.S. Army Engineer Waterways Experiment Station1987U.S. Army Engineer Waterways Experiment Station.1987 (Aug). “Finite Element Studies of a HorizontallyFramed Miter Gate,” Technical Report ITL-87-4,Reports 1-7, Vicksburg, MS.

U.S. Army Engineer Waterways Experiment StationU.S. Army Engineer Waterways Experiment Station.“Miter Gate Barge Impact Testing, Lock and Dam 26,Mississippi River,” Vicksburg, MS.

U.S. Army Engineer Waterways Experiment Station1974U.S. Army Engineer Waterways Experiment Station.1974. “Study of the Forces Occurring During the Move-ment of Miter Gate of Locks,” Translation No. 74-11,Vicksburg, MS.

A-2. Related Publications

American Welding Society 1973, 1976American Welding Society. 1973, 1976. “WeldingHandbook,” 6th and 7th ed., 3 volumes, New York.

Black and Adams 1968Black, P. H., and Adams, E., Jr. 1968. “MachineDesign,” 3rd ed., McGraw-Hill Book Co., New York.

Bleich 1952Bleich, F. 1952. “Buckling Strength of Metal Struc-tures,” 1st ed., McGraw-Hill Book Co., New York.

Carmichael 1950Carmichael, C. 1950. “Kent’s Mechanical EngineersHandbook,” 12th ed., Design and Protection volume, JohnWiley and Sons, Inc., New York.

Craeger 1945Craeger, W. P. 1945. “Engineering for Dams,” vol. II,Concrete for Dams, John Wiley and Sons, Inc., NewYork.

Douma, Davis, and Nelson 1969Douma, J. H., Davis, J. F., and Nelson, M. E. 1969.“United States Practices in Lock Design,” presented inSection 1 of XXII International Navigation Conference,Paris.

The Engineer School 1940The Engineer School. 1940. “Engineering Construction,Canalization,” vol. II, Fort Belvoir, VA.

Faires 1965Faires, V. M. 1965. “Design of Machine Elements,”4th ed., MacMillan Publishing Co.

Hinds, Creager, and Justin 1945Hinds, J., Creager, W. P., and Justin, J. D. 1945.“Sharp-Crested Weirs,” Engineering for Dams, Vol 2.

King and Brater 1963King, H. W., and Brater, E. F. 1963. “Handbook ofHydraulics,” 5th ed., McGraw-Hill Book Co., New York.

Priest 1954Priest, H. M. 1954. “Design Manual for High StrengthSteels,” U.S. Steel Corporation.

Roark 1943Roark, R. J. 1943. “Formulas for Stress and Strain,” 2nded., McGraw-Hill Book Co., Inc., New York.

Roark and Young 1975Roark, R. J., and Young, W. C. 1975. “Formulas forStress and Strain,” 5th ed., McGraw-Hill Book Co., NewYork.

Seely and Smith 1952Seely, F. B., and Smith, J. O. 1952. “AdvancedMechanics of Materials,” 2nd ed., John Wiley and Sons,Inc., New York.

Spotts 1962Spotts, M. F. 1962. “Design of Machine Elements,” 3rded., Prentice Hall, Englewood Cliffs, NJ.

Timoshenko 1936Timoshenko, S. 1936. “Theory of Elastic Stability,” 1sted., McGraw-Hill Book Co., New York.

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Appendix BIllustrative Plates

B-1. Illustrative Plates

a. General information and typical details.

PlateNo. Title

B-1. General Elevation and Sections, HorizontallyFramed Miter Gates

B-2. General Plan and Elevation, Vertically FramedMiter Gates

B-3. Typical Girder Data, Horizontally Framed MiterGates

B-4. Pintle and Recess Geometry, Horizontally FramedMiter Gates

B-5. Quoin Post, Horizontally Framed Miter Gates

B-6. Gudgeon Pin Hood, Horizontally Framed MiterGates

B-7. Gudgeon Pin Hood Design Data, Horizontally andVertically Framed Miter Gates

B-8. Anchorage Links Design Data, Horizontally andVertically Framed Miter Gates

B-9. Anchorage Links Gudgeon Pin Barrel, Horizon-tally and Vertically Framed Miter Gates

B-10. Design Data on Gudgeon Pin Barrel, Horizontallyand Vertically Framed Miter Gates

B-11. Anchorage Links Design Data, Horizontally andVertically Framed Miter Gates

B-12. Embedded Anchorage, Horizontally and VerticallyFramed Miter Gates

B-13. Lower Gate Pintle Assembly, HorizontallyFramed Miter Gates

B-14. Upper Gate Pintle Assembly, Horizontally FramedMiter Gates

B-15. Top Anchorage Assembly, Horizontally FramedMiter Gates

B-16. Fixed Pintle Assembly, Horizontally FramedMiter Gates

B-17. Diagonals, Horizontally and Vertically FramedMiter Gates

B-18. Quoin and Miter Blocks, Horizontally FramedMiter Gates

B-19. Walkway and Miter Guide, Horizontally andVertically Framed Miter Gates

B-20. Miter Guide, Horizontally Framed Miter Gates

B-21. Sill Angle and Seals, Horizontally Framed MiterGates

B-22. Sill Angle and Seal, Horizontally Framed MiterGates

B-23. Quoin and Miter Water Seals, HorizontallyFramed Miter Gates

B-24. Gate Latches, Horizontally and VerticallyFramed Miter Gates

B-25. Upper and Lower Latching Devices, HorizontallyFramed Miter Gates

B-26. Automatic Latching Device, Horizontally FramedMiter Gates

B-27. Geometry and Forces on Arch, HorizontallyFramed Miter Gates

B-28. Typical Arch Girder, Horizontally Framed MiterGates

B-29. Horizontal Arch Diaphragm, HorizontallyFramed Miter Gates

B-30. Quoin Block and Seals, Vertically Framed MiterGates

B-31. Miter Seals, Vertically Framed Miter Gates

B-32. Pintle and Sill Details, Vertically Framed MiterGates

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B-33. Operating Strut Connections, Horizontally andVertically Framed Miter Gates

B-34. General Plan and Sections, Sector Gates

B-35. General Plan and Elevation, Sector Gates

B-36. Seals and Timber Bumpers, Typical Details,Sector Gates

B-37. Hinge and Pintle Assemblies, Sector Gates

B-38. Alternate Hinge and Pintle Assemblies, SectorGates

B-39. Emergency Gate Operating Procedure

B-40. General Plan and Elevation, Double Leaf, Verti-cal-Lift Gates

B-41. General Elevation and Typical Details, SingleLeaf, Vertical-Lift Gates

B-42. General Plan and Elevation, Multileaf Gates,Vertical-Lift Gates

B-43. Typical Design Data, Vertical-Lift Gates

B-44. Design Data for End Girders and Support Brack-ets, Vertical-Lift Gates

B-45. Typical End Frame and Cross Section, Submerg-ible-Type Tainter Gates

B-46. Typical End Frame, Submergible-Type TainterGates

B-47. Panama-Type Machine Assembly, Miter Gates

B-48. Modified Ohio Type Machine Assembly, MiterGates

B-49. Ohio Type Machine Assembly, Miter Gates

B-50. Direct Connected Machine Assembly, Miter Gates

B-51. Gate Strut, Spring Type, Miter Gates

B-52. Strut Assembly, Belleville (Disk) Spring-TypeGate Strut, Miter Gates

B-53. Spring Assembly, Belleville (Disk) Spring-TypeGate Strut, Miter Gates

B-54. Gear-Type Drive Machine, Sector Gate

B-55. Cable-Type Drive Machine, Sector Gate

B-56. Elevation-Hoist Mechanism, Multileaf Vertical-Lift Gate

B-57. General Arrangement, Elevation-Hoist Mecha-nism, Multileaf Vertical-Lift Gates

B-58. Hoisting Mechanism, Sections, Vertical-LiftGates

B-59. Hoisting Mechanism, Elevation, Vertical-LiftGates

B-60. Hoisting Mechanism, Tainter-Type Gates

B-61. Hydraulic System Schematic, Manually Oper-ated, Constant Displacement Pumps

B-62. Hydraulic System Schematic, Solenoid Operated,Variable Displacement Pumps

B-63. Hydraulic System Schematic, Solenoid PilotOperated for Inundated Locks, Variable Dis-placement Pumps

B-64. Electrical System, Single Line Diagram

B-65. Electrical System, Control Schematics

B-66. Electrical System, Valve/Gate Control Sche-matic, (Sheets 1-5)

B-67. Electrical System, Gate Limit Switch Location,(Sheets 1 and 2)

B-68. Electrical System, Miter Gate Latch

B-69. Electrical System, Control Console Layout

B-70. Electrical System, Backup Control Console

B-71. Electrical System Control Schematic, MiterGates, Single-Speed Motor

B-72. Electrical System Control Schematic, MiterGates, Two-Speed Motor

B-73. Electrical System Control Schematic, Vertical-Lift Gate, Emergency Type

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B-74. Control Diagram, Tainter-Type Lock Gates

B-75. Lock Cathodic Protection, Upper Miter Gate,Upstream Elevation

B-76. Lock Cathodic Protection, Upper Miter Gate,Downstream Elevation

B-77. Lock Cathodic Protection Details

B-78. Lock Cathodic Protection Details

b. Mechanical design data and sample computations.

B-79. Miter Gates, Ohio River Linkage (Sheets 1-12)

B-80. Miter Gates, Panama Canal Linkage (Sheets 1-13)

B-81. Sector Gates, Effects of Reverse Head on ClosingPintle Torque

B-82. Sector Gates, Determination of Total PintleTorque (Sheets 1-3)

B-83 throughB-86. Miter Gates, Gate Torque Curves, for Ohio,

Modified Ohio, and Panama Canal Linkage

B-87. Miter Gates, Direct Connected Cylinder(Sheets 1-10)

B-88. Vertical Lift Gates, Determination of Loads forUpstream Leaf (Sheets 1-9)

B-89. Vertical Lift Gates, Determination of Loads forDownstream Leaf (Sheets 1-19)

B-90. Vertical Lift Gates, Design of Wheels(Sheets 1-8)

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Appendix CSample Computations

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C-4

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Appendix DAir Bubbler Gate Recess Flusher

D-1.

High flow air bubblers placed in the gate recess willeffectively clear debris and ice. Standard pipe is used forthe supply and distribution lines. The supply feed is fromthe quoin end. Proper spacing and nozzle size will ensuremaximum nozzle flow for a given air supply. A typical

recess flusher installation is shown in Figure D-1. Airdischarge from the orifices is calculated by:

Qo (L 3T 1)Cdπd 2

4(2∆P / ρa)

1/2

Cd = loss coefficient, sharp-edged circular orifice

d = orifice diameter

Figure D-1. Emsworth Lock & Dam, Ohio River, Air Screen Gate Recess Flusher

D-1

EM 1110-2-270330 Jun 94

∆P = pressure difference between inside and outsideof distribution line at the nozzle

ρa = mass density of air

The pressure losses due to friction in the lines are calcu-lated using the friction loss equation for turbulent flow:

∆Pf (F L 2)fρa L v 2

2Dg

f = friction factor

L = equivalent length of pipe

v = air velocity

D = pipe diameter

g = gravitational constant

D-2.

The numerical analyses for air discharge rates are deter-mined by an iterative procedure starting with a trial dead-end pressure and the end orifice. Working toward thesupply source, the air flow and pressure at each orificeand in the supply line are calculated to obtain a calculatedcompressor pressure. The trial dead-end pressure is thenadjusted and the procedure repeated until the calculatedand the true compressor pressures agree. The sum of thenozzle flows gives the required compressor capacity. Theinitial trial dead-end pressure is taken as:

Pd Pw 0.25 (pc pw)

Pc = true compressor pressure

Pw = ρw g h

ρw = mass density of water

h = submergence depth

Subsequent trial pressures are estimated by:

Pd(new) Pw (Pd(old) Pw) (pc pw) / (p pw)

p = calculated compressor pressure

Pd(new) andPd(old) = new and old trial dead-endpressures

D-3.

Output pressure must be high enough to overcome hydro-static pressure at the submergence depth, frictional lossesin the supply and distribution lines, and still provide apressure differential at the last orifice to drive the air outat the desired rate. Supply and distribution line diametersshould be large enough so that frictional pressure lossesalong the line are small. A small increase in line diam-eters often results in significant reduction in frictionallosses and results in more uniform discharge rates alongthe line. Orifice diameter and spacing should be selectedto maximize rates. Too large an orifice diameter canresult in all the air being discharged at one end. Submer-gence depth will be dictated by operational limitations butshould be lower than the expected depth of trash pile-up.Typical installation depths are 10 to 15 ft.

D-4.

Standard piping techniques can be used for strapping andsupply and distribution line make-up. The distributionline can be assembled from standard pipe fittings, e.g., atee-connection at nozzle locations with a drilled pipe plugused for the nozzle.

D-2

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