Sunshine Skyway BridgeCloses the Gap

W hen the last segment in the middle ofthe main span was lifted into place

on August 23, 1986, the new SunshineSkyway Bridge fulfilled its promise as thelongest precast prestressed concretesegmental bridge in the world. The 4.14mile (6.7 km) long Skyway links St.Petersburg and Bradenton (on Inter-state 275) across lower Tampa Bay onthe west coast of Florida. The skywaywill carry two lanes of highway traffic withfull width emergency lanes in each direc-tion.

The new bridge, which was designed towithstand hurricane wind forces, has amain span of 1200 ft (366 m) with a clear-ance of 175 ft (53 m) above the TampaBay ship channel (see diagram on page170). These features give the new bridge a

longer main span and higher clearanceover the water than the original twin trussbridge which lies adjacent to the newstructure.

The closure of the superstructure wasmarked by colorful ceremonies which wereattended by dignitaries, highway officials,bridge engineers and the press. Florida'sSecretary of Transportation, Thomas E.Drawdy, spoke eloquently about the bridgeas an engineering triumph — one whichwill have a profound influence on futurebridge construction.

Planning for the new bridge began in1980 after a ship rammed the originalbridge, destroying much of the southboundspan and taking 35 lives. To maintain thealignment of 1275. the 21.878 ft (6673 m)long Skyway is adjacent to the old bridge,

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where the undamaged north roadway hasbeen used for two-way traffic since the ac-cident six years ago. Next year the centerportion of the old bridge will be dis-mantled, leaving the approaches on bothsides to be used as fishing piers.

There were basically five major opera-tions involved in the construction of thebridge.

1. Substructure — The substructureconsists of piles and 606 match cast boxpier segments rising from 28 to 135 ft (8 to41 m) above sea level where the structuretransitions to single piers. The segmentswere manufactured at a casting yard inPort Manatee about 4 miles (6.4 km) fromthe bridge site. They were barged to thesite where they were assembled andpost-tensioned vertically in place.

2. Trestle approaches — Low levelnorth and south twin trestles of 4281 and8736 ft (1306 and 2664 m) spans, respec-tively, consist mostly of 100 ft (30.5 m)spans of Type IV AASHTO precast pre-stressed I girders with 8 in. (203 mm) thickcast-in-place reinforced concrete decks.There are 256 such spans with five girdersper span for each roadway.

3. High level north and south ap-proaches — These 2430 ft (741 m) spanslie on each side of the main span. Theywere erected using the now well estab-lished span by span method of construc-tion. The sections change from I girders totwin trapezoidal box girder segments.There are 584 such precast segmentsmaking up 18 spans of 135 ft (41 m). Thespans rise at a roadway grade of 4 per-cent.

The units are made with epoxy coated,reinforcing steel grade 60 and 5500 psi (38MPa) concrete. Three tendons of four 0.6in. (152 mm) diameter strands are im-mediately tensioned to keep the wings ofthe decks compressed. Each span con-sists of pier segments and seven inter-mediate segments. Generally, the post-tensioning consists of three tendons of 19,24 and 25 1/2 in. (12.7 mm) diameterstrands in 4 in. (102 mm) polyethyleneduct.

PCI JOURNAL'November- December 1986

Initially, the seven intermediate seg-ments are loaded, aligned and temporarilystressed together on the barge mountinglifting frame at the casting yard. The bargeis then floated to the bridge site where theentire unit is lifted into position between thetwo piers with the aid of a steel gantry.Once the unit is set in its final position, aclosure pour of 6 in. (152 mm) is made ateach pier. The unit is sequentially stressedand then the gantry moves to the nextspan. The same procedure is repeatedspan by span.

4. High level balanced cantileverspans — The twin roadway sectionstransition to one structure for 4000 ft (1220m), including two 140 ft (43 m) spans, six240 ft (144 m) spans, then two 540 ft (165m) spans and finally the 1200 ft (366 m)main span that is erected with the cablestays.

There are 333 large roadway segmentsof 95 ft (29 m) width to accommodate bothnorthbound and southbound spans. Due to

The last precast segment of the Skyway wasplaced on August 23, 1986.

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shipNew Skyway ' "'annel

Existing bridge

4281' 430` 4000' 430 9736 --_____ ^J

Plan and elevation of Sunshine Skyway Bridge. Observe that the elevation drawing is exaggeratedin order to show clearance. (Note: 1 fl = 0.305 m.)

the relatively large width of the segments,internal inclined struts are necessary toproperly support the top deck. These strutsare precast separately ahead of time tofacilitate mass production. Diagonalpost-tensioning is also provided to cablestay anchor segments in order to distributestay forces to the webs.

The transverse deck post-tensioningconsists of 0.6 in. (152 mm) diameterstrands in 1 x 3 in. (25 x 76 mm) flat poly-ethylene duct. Also, the base slab is ten-sioned after the concrete has attained astrength of 2500 psi (17 MPa).

The large segments are match cast toeach adjacent segment using the short linemethod. A freshly cast segment is movedto the match cast segment. Using an ad-justable pallet to the bottom slab, thewhole segment is aligned both horizontallyand vertically so proper geometric controlcan be achieved.

The balanced cantilever method re-quires an erection sequence to start at apier and extend equidistant both ways witha maximum imbalance of one segmentthus explaining the first span of 140 ft (43m) transitioning to the span by span piers,then a series of 240 ft (73 m) spans.

To facilitate erection, a two-plate girderassembly is used. Initially, the travellinghoisting crane alternately lifts segments for

the first two positions on either side of thepier; then the remaining eight segments onthe backward side of the pier. Two beamand winch assemblies cantilever off theleading segments and counterbalancethrough the previously erected segmentsto provide lift on the forward side of thepier.

As the cantilever advances, so do thebeam and winches in sequence with thebackside where the lifting crane providesthe lift. The backside cantilever closes tothe tip of the previous forward cantilever tocomplete the span. The whole processthen repeats itself with the lifting of the nextpier segment and the moving of the plategirder assembly.

A special lifting beam assembly is usedwith the segments to ensure proper dis-tribution of stresses. The web shear keyson the segments are used to guide themtogether. Epoxy is spread over the weband bottom slab mating faces. Threadedbars in both the top and bottom slab areconnected and stressed to hold the seg-ment temporarily in place. The top slabclosure pour is formed and completed.When this concrete attains 2500 psi (17MPa), the lifting frames can be released.

The permanent post-tensioning consistsof multistrand tendons, each seven wirestrands in plastic duct, encased in con-

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42.75'

1 ^

9 25.

Low level trestle approaches

^ I j

High level approaches

t

12.5'

' Cable stayanchorage

where required

3283

Main span

Precast segmental box girder sections for various portions of Sunshine Skyway Bridge.(Note: 1 ft = 0.305 m.)

crete for the top slab and exposed. Theonly exceptions are the pier segment sad-dle and deviation blocks for the drapedcantilever tendons which are needed foreach pair of segments. When this post-tensioning is completed, the whole erec-tion cycle is repeated for the next twosegments, and so on until the whole spanis completed.

5. Cable stayed spans — To achievea main span of 1200 ft (366 m), two mainpylons of reinforced concrete, 435 ft (133m) above the water or 240 ft (73 m) abovethe road surface, provide the vertical sup-port.

The cable stayed spans were erectedentirely with winches on self-advancing

beams, with the stays replacing the longi-tudinal post-tensioning required in theshorter spans. After closure, the internalcontinuity strands were stressed to carrytheir final suspended loads.

Each pylon carries 21 stays, anchored inevery other segment [every 24 ft (7.3 rn) ]but passing freely through individual sad-dles in the pylon. Made up of multiwirestrand and ranging from 38 to 82 highstrength steel strands, the cables are en-cased in 65%a and 8 5/a in. (168 and 219 mm)steel pipe, grouted after final stressing.

The pipe was erected first, then the ca-bles were pulled through. The 1700 ton(1542 t) rams and other equipment neededfor the pulling and stressing were set up

PCI JOUf3NALrNovember-December 1986 171

inside the segments. After initial stressing,the next non-stay segment was lifted, clo-sure pours made and the cycle begunagain by advancing the beam andwinches.

Part of the cable stay design is a provi-sion for removing and replacing any onecable. If necessary, the pipe and groutsystem will be decompressed by removinga series of shims to bring the anchorageback down until it rests against its bearingplate.

Concluding RemarksIn retrospect, the various precast pre-

stressed segmental phases and especiallythe cable stayed portion of the project pro-ceeded very efficiently. In particular, thegeometry control proved to be excellent.Only a very few joints had to be shimmed.

The two massive twin piers providedgood rigidity during construction of the bal-anced cantilevers, but have sufficient flexi-

bility to accommodate thermal expansionunder highway traffic. As a result, thebridge structure has exceptionally goodstability.

The construction of the bridge causedlittle or no interference with the ship traffic.Closely spaced cable stays allowed thebridge to be built by the cantilever methodwithout any falsework. The close spacingof the stays also gives the advantage ofallowing stays to be replaced easily, ifnecessary, without causing major trafficdisruption. The cables are located on thecenterline of the structure which will allowmotorists an unobstructed view of TampaBay. It will be opened to traffic in early1987.

The cost of the Sunshine Skyway Bridgeis estimated to be $220 million, This figureincludes design, construction and inspec-tion of the bridge, pier protection islandsand dolphins and a motorist warning sys-tem, plus refurbishing the old bridge for re-creational fishing.

Placement of final deck segment closed the world's longest precast prestressed concrete segmentalbridge. The main span is 1200 ft (366 m) long.

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•.aaynp }rasnid.a-. -. .., v,rr

To celebrate the placement of the final precast Aerial view of 4.14 mile (6.7 km) long bridge withsegment on the superstructure, an official last precast segment in place. The bridge will beceremony was held on August 23, 1986. opened to traffic in early 1987.

Credits

The bridge is owned by the Florida DOTwhich also was involved in the planningand design aspects of the bridge. In addi-tion, the FDOT Bureau of Structures De-sign played a key role in checking manyelements of the design.

Figg & Muller Engineers, Inc., Talla-hassee, designed the 8800 ft (2684 m)high level approach and main span. Thelow level approaches were designed byParsons, Brinckerhoff, Quade & Douglas,New York City, and the FDOT Bureau ofStructures Design.

Construction inspection is being handledby SKYCEI, a consortium called SkywayConstruction Engineering & InspectionConsultants. Participants include Parsons,Brinckerhoff, Quade & Douglas. New YorkCity; DRC Consultants, New York City;Kissinger, Campo & Associates, Tampa;and H. W. Lochner. Inc., St. Peters-burg.

Contractors are Hardaway Constructorsof Georgia and Michael Construction Co.,Tennessee, main pier foundations: Pas-chen Contractors, Inc.. Chicago, AmericanBridge, Chicago, and Morrison-Knudsen,Boise, high level approach and main span;Ballenger Corp., South Carolina, low leveltrestle spans; Meisner Marine Construc-tion, Tampa, main pier dolphins.

Construction Technologies Laboratory,Skokie, Illinois, instrumented the bridge;VSL, Los Gatos, California, engineered theprestressing. LoBuono Armstrong & As-sociates, Tallahassee. were structuralconsultants to Paschen Contractors forerection of the segmental and cable stayedsections.

The pier elements and the box girdersegments were manufactured by POMCO(as a subcontractor to Paschen Contrac-tors) at its plant in Port Manatee.

The photographs for this article werefurnished through the courtesy of Figg &Muller Engineers, Inc.

PCI JOURNALNovember-December 1986 173

served as the company's executive vicepresident and chief operating officer.

Mr. Danciger, president since the com-pany's formantion in 1958, will remain aschairman and chief executive officer.

Mark W. Huggins(1911-1986)

Mark W. Huggins, professor of civil en-gineering at the University of Toronto,Ontario. Canada during the past 35 years.has died at the age of 75. During the past10 years he was emeritus professor. Pro-

fessor Huggins obtained both his under-graduate and graduate degrees from theUniversity of Toronto, where he developedan early interest in the work of EugeneFreyssinet. Upon graduation he joined thefirm of E. P. Muntz. engineering contrac-tors, an association which greatly influ-enced his future interest in prestressedconcrete.

In 1946, he became a partner in Mor-rison, Hershfield, Millman & Huggins, Con-sulting Engineers. In this capacity, in 1952,he participated in the design of pre-stressed concrete roof joists for the Hydro

Podolny, Jr. Wins 1986 T. Y. Lin Award

Walter Podolny, Jr. has won thisyear's T. Y. Lin Award from the Ameri-can Society of Civil Engineers. Theaward, a handsome plaque and a$500.00 check, was given to Dr.Podolny in Boston, Massachusettsduring the Society's annual convention.

Dr. Podolny received this prestigiousaward for his paper "The Cause ofCracking in Post-Tensioned ConcreteBox Girder Bridges and Retrofit Proce-dures," which was published in theMarch-April 1985 PCI JOURNAL.

This marks the eleventh time in thir-teen years that a paper published in thePCI JOURNAL has been selected bythe American Society of Civil Engineersto receive the T. Y. Lin Award.

For each 12 month period ending inJune, the American Concrete Institute,Prestressed Concrete Institute, andAmerican Society of Civil Engineers areinvited to nominate a single paper fromtheir respective publications. The threepapers are then reviewed by a com-mittee and a grand winner is named.

Dr. Podolny is a structural engineer inthe Bridge Division, Office of Engineer-ing, Federal Highway Administration,

Dr. Walter Podolny, Jr.

Washington, D.C. He is the author ofmore than fifty publications and coau-thor (with Jean Muller) of the book"Construction and Design of Pre-stressed Concrete Segmental Bridges."Dr. Podolny has served on severaltechnical committees of the PCI andother professional organizations andhas also served as a juror on the PCIAwards Program. He received PCI'sState of the Art Award in 1985 for thesame paper that won the T. Y. LinAward.

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Electric Power Commission of Ontario. Atthe same time he, jointly with E. P. Muntz,produced a prestressed concrete runwaydesign. Since then, he designed manyprestressed concrete bridges and was re-sponsible for numerous prestressed con-crete structures.

Professor Huggins was chairman of thecommittee charged with developing thefirst Canadian Standard for the Design ofPrestressed Concrete. He was alsocoauthor with L. G. Cazaly, in 1962, of theCanadian Prestressed Concrete InstituteHandbook, the first in North America. Hewas a founding director of the CanadianPrecast Concrete Bureau which has sincebecome a CSA Plant Certification Com-mittee.

A lasting legacy of his lite's work was theeloquent article he wrote for the PCIJOURNAL on "The Beginnings of Pre-stressed Concrete in Canada," which waspublished in the November-December1979 PCI JOURNAL and later republishedin the volume "Reflections of the Begin-nings of Prestressed Concrete inAmerica-" For this article Professor Hug-gins received a Special Award of Recogni-tion from the Prestressed Concrete Insti-tute.

Material Service Corp.Announces Promotions

Material Service Corporation ofChicago, Illinois recently announced thepromotions of Morris Lauwereins andRichard E. Levy, two long-time companyemployees.

Mr. Lauwereins has been named seniorvice president-operations and will be re-sponsible for the company's aggregate op-erations, ready-mix and precast concreteproducts, engineering and real estate.Formerly vice president of operations, hehas been with Material Service for 33years in various capacities, includingserving on the company's board of direc-tors.

Mr. Levy will step into the position of vicepresident of operations and will be respon-

sible for all production facilities in the com-pany's pits and quarries, ready-mix plants,marine department and Lockport, Illinoisrepair shop. Formerly president of a Mate-rial Service subsidiary, El Paso SandProducts Corporation, Mr. Levy will alsoserve as the Texas company's chairman ofthe board.

Harris RetiresTexas Industries, Inc., Dallas, Texas has

announced the retirement of Phillip H.Harris, vice president of cement planning,

Mr. Harris began his career with thecompany in 1965 as president of CreoleCorporation, a wholly-owned subsidiary. In1967, he became president and generalmanager of the south Texas region and forseveral years prior to his retirement wasvice president-cement marketing andplanning.

Mr. Harris is expected to keep a con-tinuing, consulting relationship with thecompany.

Moore Relocates to TexasWiss, Janney, Elstner Associates, Inc.,

Northbrook, Illinois has announced thatMark Moore has recently relocated to thefirm's Dallas area office. He had been as-sociated with WJE's Princeton area officesince 1982.

PCI JOURNAL'November-December 1986 175

Mr. Moore has been involved with theanalysis of prestressed concrete bridgegirders and seismic monitoring of struc-tures subjected to blast-induced vibrations.Recently, he has been involved in testingprecast bridge deck panels in conjunctionwith a FHWA study.

Swiss Joins CONACConcrete Accessories Inc. (CONAC),

Port Jefferson, New York has announcedthe appointment of Steve Swiss to the po-sition of regional manager for the North-east. Mid-Atlantic, and MidwesternStates.

A graduate civil engineer from the Uni-versity of Massachusetts, Mr. Swiss hasworked in the engineering and sales de-partments for a major United States pre-caster. He also has several years experi-ence in the sales of accessory products tothe precast prestressed concrete industry.

Tindall ConcreteElects New Officers

Tindall Concrete Products. Greenville,South Carolina recently elected RichardBlumberg as president of the companyand William Lowndes IV as vice chairmanof the board.

Mr. Blumberg joined the company threeyears ago as general manager of the pre-stress division and will retain responsibilityfor the management of that division. A 35-year veteran in the construction industry,he was most recently president and chiefexecutive officer of Paterson-Leitch SteelCompany of Cleveland. Ohio, a position heheld since 1979.

Mr. Lowndes joined Tindall ConcreteProducts in 1977 and was named generalmanager of the utilities division in 1983. Hewill continue to manage that division, aswell as serve on the company's board ofdirectors.

The 15 1/ mile (25 km) Saudi Arabia-Bahrain Causeway is being built using innovative products fromPreco Industries Ltd., Plainview, New York. (A more detailed look at the project appeared in theSeptember-October PCI JOURNAL on pages 179-180.)

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