Portal Frame Rafter Design

1 Deltec Engineering LimitedRev 1, July, 2011

Structural Design Calculations for 40,000-Gallon Overhead Water Tank Support Tower & Foundations


Consulting Engineers

Deltec Engineering Limited(Consulting Engineers & Project Managers)

Lagos Office 11, Shasha Road (Opp. Union Bank)

Akowonjo Lagos Tel: 01-7730278

July, 2011

Email: [email protected]

Job No: DEL/2011-134 Date: 09/08/2011 Job Title: DESIGN OF 40,000-GALLON OVERHEAD WATER TANK SUPPORT

TOWER AND FOUNDATIONS S T R U C T U R A L D E S I G N I N F O R M A T I O N INTENDED USE & BRIEF DESCRIPTION OF STRUCTURE The proposed steel tower is to provide support for a 40,000-gallon (181,840 litre-capacity) Braithwaite pressed steel water tank at a height of 12.0m above ground level. The tank measures 6.1mx6.1m on plan and is 4.88m deep. The structural solution consists of a 4-legged lattice tower, 12m high, carrying a platform, which measures 7.9mx7.9m on plan. The platform is made of 356x171x45UB secondary girders `POS 16, placed at 1.22m intervals over 533x210x82UB Main girders `POS 18 which are in turn, supported by the tower legs made of 203x203x46UC `POS 01 at 3.66m centres in the longitudinal and transverse directions. Both the secondary and main girders are extended with 80x80x6RSA sections to carry the walkway and the handrails. For stability the tower is braced horizontally at 3.0m intervals with 100x100x8RSA `POS 02. Cross bracing is made of 80x80x6RSA `POS 03, designed as ties. The Holding Down system consists of 350mmx350mmx25 base plates which are anchored to the concrete base with M20 grade 8.8 galvanized bolts. The foundation is made of 450mm thick reinforced concrete slab at 450mm above ground level, with downturn perimeter containment beams. Further details of the design are given in the accompanying drawings. GENERAL LOADING CONDITION Imposed loading

Self weight of tank = 116.84kN (Braithwaite tank Ref 554).Contents (water) = 1818.4kNOpen flooring system = 0.5kN/m2 (35x5 steel grating)Maintenance load=5.0kN/m2Railing & Posts = 0.35kN/m Wind loading

Basic wind speed, v=35m/s (3-sec gust speed) DURABILITY & FIRE RESISTANCE

Fire resistance-: 1 hour for all elementsMinimum cover to all reinforcement - 50mm substructure CODES OF PRACTICE & REFERENCES

EUROCODE 1: EN199111: 2002: Actions on Structures, EUROCODE 2: EN19921 - 12004: Design of Conceret Structures,EUROCODE 3: EN1993 - 1 - 1: 2005: Design of Steel Structures, EUROCODE 3: EN1993 - 1 - 8: Design of JointsANSI/EIA/TIA-222-G-2003: Structural Standards for Steel Antenna Towers and Antenna Supporting StructuresSubsoil Investigation Report by Otoko Soils, 13 Timbo Close, Off 66 Abuloma Road, Amadi-Ama, Port-Harcourt.

MATERIALS & STRENGTHS Normal Weight Concrete grade 35Characteristic cube strength, fcu = 35N/mm2Characteristic cylinder strength at 28 days, fck = 0.8 xcharacteristic cube strength = 28N/mm2 ReinforcementHigh yield deformed bars type 2 to BS 4449Characteristic strength, fyk = 410N/mm2

Structural Steel Grade S275 (43A)Youngs Modulus, Es =205kN/mm2

BoltsMild steel bolts grade 8.8 Prepared by: Emmanuel Ofovwe Bobor, B.Eng

Date: 11/08/2011 Agreed: Engr. Samson Ivovi, B.Eng, MSc, MNSE, FNIStructE,

Date: 11/08/2011












Date: 11/08/2011


DELTEC

DELTEC ENGINEERING LTD Job No.

Calculation Sheet DEL /2011 - 134

Member/LocationJob Title: Design of 40,000-Gallon Overhead Water Tank Support Drg Ref.

Tower Made by

REFERENCE CALCULATIONSBASIC ASSESSMENT OF OVERHEAD WATER TANK

STRUCTURAL DESIGN INFORMATIONTankType:Reference Code:Length of Tank, L:Breadth of Tank, B:Depth of Tank, D:Volume of Tank:Gravity LoadsMaintenance load on walkway:Self weight of Tank:Weight of water in Tank:Open Flooring system:Railings and posts:PLATFORM LOADING


INTERNAL TANK BEARER 'SG 1'From tank own weight = 65.53/(4.88 x 4)Water = 872.83/(4.88 x 4)Open Flooring System: = 0.5x1.22Maintenance Load: = 5x1.22Railings + Posts = 0.35x1.22EXTERNAL TANK BEARER 'SG 2'From tank own weight: = 65.53/(2x4.88x4)Water: = 872.83/(2x4.88x4)

At cantilever: = 0.5x0.5x1.22At Span: = 0.5x0.5x0.9At cantilever: = 5.0x0.5x1.22At Span: = 5.0x0.5x0.9

Railings + Posts = 0.35x1.22PERIMETER BEAM 'SG 3'Open Flooring At cantilever: = 0.5x0.5x1.22

At Span: = 0.5x0.9Maintenance LAt cantilever: = 5.0x0.5x1.22

At Span: = 5.0x0.9At cantilever: = 0.35x1.22At Span:

Open Flooring System:Maintenance Load:

Railings + Posts


DELTEC




Tower Made by

REFERENCE CALCULATIONSINTERNAL TANK BEARER 'SG 1'

1.35

22.459 98.50649.128 118.762

123.7539.1585.49109.105

EXTERNAL TANK BEARER 'SG 2'

72.7435.25912.93354.551

PERIMETER BEAM 'SG 3'

6.0221.4164.606

Calculations in accordance with BS EN 1993- 1- 1: 2005All loads and moments are factored

Factors of Safety: G = Q =

TYPICAL TANK BEARER 'SG': I - SectionBS EN 1993- 1- 1: 2005

Z

Gk1 = 0.427 KN

610 3660

MVRSRDRL

900

gk2 = 0.61 KN/mqk2 = 6.1 KN/m

gk1 = 3.357KN/mqwk1 = 44.715KN/m

RW

Gk2 = 0.427KN

610 3660

RSRDRL

900

gk4 = 0.305KN/mqk4 = 3.05 KN/m gk3 = 1.679KN/mqwk3 = 22.357 KN/m

RW

gk5 = 0.305KN/m, qk5 = 3.05KN/m

Gk2 = 0.427KN

1510 3660

RSRDRL

gk6 = 0.35KN/m

gk7 = 0.305KN/m, qk7 = 3.05KN/m


Design Info:Design bending moment about major axis, Design shear force,Force through flange

Preliminary Sizing:Deflection: For the beam above, the maximum deflection occurs at the mid-span of SG1, thus:

where 48.0726.71610

L = 3660Thus: 91,176,217Check Moment:

From Table 3.1

Try 356 x 171 x 45kg/m UB

Steel Designer's Manual - 6th Edition (1996)

Actual deflection, = L2/384EI [w1(5L2 - 24N12) - 48w2L2N2(0.5N2 + N1)2 - 48P(N1 + N2)]Limiting deflection, lim = span/720 = L/720

Equating both to ensure deflection is within the limit gives; Ireq = 720L/384E [w1(5L2 - 24N12) - 48w2N2(0.5N2 + N1) - 48P(N1 + N2)]

w1 = 1.0gk1 + 1.0qwk1 = w2 = 1.0gk2 + 1.0qk2 =

N1 =

Ireq =

Applied moment, Msd = Assume t > 40mm; fy =

Plastic Modulus Required, Wpl,y reqd = Msd/fy =

h

b

tw

tf

Y Y

Z


DELTEC




Tower Made by

REFERENCE CALCULATIONS

Section Properties: 356 x 171 x 45kg/m UBDepth of Section h = 356mmWidth of Section b = 171mmWeb Thickness 6.9mmFlange Thickness 9.7mmDepth Between d= 312.3mmRoot Radius r = 10.2mm

8.8145.8

121,000,000mm48,120,000mm4

Classify Section:9.7mm

0.9248.81< 10 'Flange is at least compact'45.8< 83 'Web is at least compact'

Shear Buckling:51.6 Column flange thickness Ok

mm < 40mm 275 Plate thickness Ok259.270mm259.270mm

4c2 + 1204.6c + 5793.16fyp = N/mm2fck = N/mm2

fcd = ccfck/c = N/mm2fjd = 0.67fcd = N/mm2Ap' = NEd/fjd = mm2

mm2

ts req = 16.616mmts prov = 25mm

fyp = N/mm2Dpmin = 2c + hc = Bpmin = 2c + bc = Baseplate 350 x 350 x

25mm


Job No. Sheet No Rev.

DEL /2011 - 134 20 OF 23

EOB Date: 09/08/2011 Chd. SAI

CALCULATIONS OUTPUTCalculations in accordance with BS EN 1993- 1- 8: 2005

69.428KN19.521KN

KN

mmmm

KN

KN

Bolt Tension Capacity OkKN Tensile Capacity Ok

KNKNKN

Bolt Shear Capacity OkKN Shear Capacity Ok

< 1.0

Column to baseplate welds:mmmm

Ft,Ed = Fv,Ed =

N/mm2Ft,Ed = 17.07 KN

Ft,Ed = 147 KN

Fv,Ed = 4.88 KNFv,Ed = 98 KN

Bolt size and number chosen are suitable

Holding down bolts should be anchored into the foundation by washer plate or other load distributing member embedded in the


mm

N/mmN/mmmmN/mmN/mm

N/mmN/mmN/mm

N/mm

N/mm

Weld Capacity OkN/mm Weld chosen is suitableSUMMARY OF BASEPLATE REQUIREMENTS

Size 350mm x 350mm x 25mmGradeS275 steel

Edge distance50mmBolts4 Nos. 20mm, Grade 8.8

Welds6mm fillet weld all round

fw,Ed = 881.38 KN

N/mm2Table 10.12; Fillet Weld Resistances,

IStructE Manual, Page 116

fw,Rd = 903 KN



DEL /2011 - 134 21 OF 23


CALCULATIONS OUTPUT

Wind at 450

DL = 273.347 KNLL = 31.356 KNWk = +118.488 KN

DL = 273.347 KNLL = 31.356 KNWk = 0

B

3660

DL = 273.347 KN LL = 31.356 KN+Wk = +52.51 KN

B


Wind normal to face

DL = 273.347 KN LL = 31.356 KN+Wk = +52.51 KN

3660



DEL /2011 - 134 22 OF 23


CALCULATIONS OUTPUTSTABILITY ANALYSIS

15.52KN19.88KN

17.27KN34.79KN

OVERTURNING MOMENT AT TOWER BASE (AT SERVICE)Service Moment,

(17.27 x 6) + (34.82 x (16.462 - 3.66/2) 609.335KNm

A Z

h = 350mmw = 25 x h = 8.75

Maximum Service Load,1218.811KN

m

Minimum Service Load,

to Tower) (At Service)Mo = 613.297 KNm

KN/m2

Total axial load (At service), = 4 x (21.611 + 31.356 + 218.209) Pmax = 1218.811 KN

- 1218.811L - 5203.99 = 0KN/m2KN/m2

Total axial load (At service), = 4 x (21.611 + 31.356) + 134.107


KN

m

47.61

At ultimate,1645.39KN N = 1645.39 KN573.130KNm

Ultimate stresses,

166.235KN/m

345.975 + 8.75L2 P min = 345.975 + 8.75L2

- 345.975L + 5203.99 = 0KN/m2 (To ensure that the base remains in contact

with the soil)m2

Provide 6.9 x 6.9 x 350mm Base Area prov,

Aprov = m2 Base Area = 47.61 m2

Total axial load, N =[ 4(1.35*50.669) +

Mo = 576.526 KNm

net = 2891.45 6 x 855.464 6.9 6.92 fmax = 311.119KN/m

fmin = fmin = 165.807KN/m

1620

311.119 KN/m



DEL /2011 - 134 23 OF 23


CALCULATIONS OUTPUT Total

999.281KN = 1645.394

1.62

276.775 310.691

475.848

523.433

-466.021Bending Moment Diagram

410

999.281KN

fyk = N/mm2

NEd = NEd = 1000.429 KN


h = 350mmc = 40mm = 16mm

294mmu = 4 x 350 = 1400mm

1852.200kN

KN Shear Resistance Ok

6600mm = 588mm

Soil pressure per unit width at 2.0d from column face, 289.09KN/m309.48kN0.15951.4628

582.268

M = 466.021kNmd = h - c - /2 = 302mm

0.9719 0.95 la = 0.954170.303 33 T16 @ 200 BB & BT

deff. = 0.5(dy + dz) = h - c - =

VRd,max = 0.5ud[0.6 (1 - fck/250)]fck/1.5 = VRd,max = 1852.20 KN

bv =

f2.0d = f2.0d = 524.06 KN/mVEd = 0.5(1.5-2d)(f2.0d + 549.87)=

Ed = VEd/bd = N/mm2k = (1+(200/d)0.5) = mm-1

Asv = (vEd/(0.12k))3(bd/(100fck)) = mm2 Asv = 949.777 mm2/m

Use la = As = M/(0.95fyklad) = mm2

6633 mm2/m












Date: 11/08/2011


OUTPUT


Msd = 98.506 KNmVsd = 118.76KNFsd= 167.89KN

Ireq = 91,176,217mm4

Wpl,y req = 386,298mm3


OUTPUT

Section Ok

Iprov = 121,000,000mm4

Wpl,y prov = 774,000mm3

Section is ok, Class 2

Full lateral restraint assumed

Msd = 98.506 KNVsd = 118.76KN

Vpl,Rd = 386.29 KN


Shear Capacity Ok

Moment Capacity OkMpl,Rd = 202.71 KN


OUTPUT

Web bearing capacity Ok

Fsd = 270.81 KN

Ry, Rd = 270.55 KN

Ra, Rd = 278.68 KN

Web crippling capacity is Ok


Web buckling capacity Ok

356 x 171 x 45kg/m UB

KNKNKNmKNmKNKNKN

Nb, Rd = 290.99 KN


OUTPUT

Msd = 215.6 KNmVsd = 251.84 KN

Fsd= 370.79 KN


Ireq = 132,508,207mm4

Wpl,y req = 845,490mm3

Iprov = 337,400,000mm4

Wpl,y prov = 1,702,000mm3


OUTPUT

Section is ok


Section is Ok for lateral torsional buckling


Shear Capacity Ok

Moment Capacity Ok

Msd = 215.60 KNVsd = 251.84 KN

Vpl,Rd = 665.21 KN

Mpl,Rd = 445.76 KN


OUTPUT

Fsd = 370.79 KN

Ry, Rd = 431.14 KN

Web bearing capacity is Ok

Ra, Rd = 501.54 KN

Web crippling capacity is Ok


356x171x45 UB

KNKNKNmKNmKNKNKN

Nb, Rd = 581.75 KN

Web buckling capacity is Ok


OUTPUT


OUTPUT

Try HE 160 B

Try 100 x 100 x 8 RSA

Try 80 x 80 x 6 RSA


OUTPUT

= 19.90 KN = 34.82 KN

= 15.52 KN = 17.27 KN

= 384.35 KNm


= 613.30 KNm


OUTPUT

WL = +/- 118.488 KNDL = 273.347KNLL = 31.356 KN


OUTPUT

Slenderness Ok

NEd = 589.081 KN



Slenderness OkSlenderness Ok

HE 160 B

KNKN

NEd = 589.081 KN

Nb, Rd = 982.71 KN

Compressive Capacity Adequate


OUTPUT

NEd = 41.289 KN

Class 3, Do a strength reduction or use an effective area


NEd = 641.289 KN

Nb, Rd = 84.20 KN

Compressive Capacity Adequate


OUTPUT

Deflection ok

Tensile Capacity Adequate

100 x 100 x 8 RSA

KNKNKNmKN

Use two bolts M20 at each end

NEd = 41.289 KN

Nu, Rd = 455.467 KN


OUTPUT


NEd = 51.007 KN


Slenderness Ok

Tensile Capacity Adequate

80 x 80 x 6 RSA

KNmKN

Use two bolts M20 at each end

NEd = 51.007 KN

Nu,Rd = 261.8 KN


OUTPUT


Plate thickness Ok

ts req = 16.616mmts prov = 25mm

Baseplate 350 x 350 x 25mm


OUTPUT

Bolt Tension Capacity Ok

Bolt Shear Capacity Ok

Ft,Ed = 17.07 KN

Ft,Ed = 147 KN

Fv,Ed = 4.88 KNFv,Ed = 98 KN


Weld Capacity Ok

350mm x 350mm x 25mmS275 steel50mm4 Nos. 20mm, Grade 8.86mm fillet weld all round

fw,Ed = 881.38 KN

fw,Rd = 903 KN


OUTPUT


OUTPUT

Service Moment,

Maximum Service Load,

Minimum Service Load,

Mo = 613.297 KNm

Pmax = 1218.811 KN


At ultimate,N = 1645.39 KN

Ultimate stresses,

P min = 345.975 + 8.75L2

Provide 6.9 x 6.9 x 350mm

Base Area = 47.61 m2

Mo = 576.526 KNm

fmax = 311.119KN/mfmin = 165.807KN/m


OUTPUT

KN

NEd = 1000.429 KN


la = 0.95 33 T16 @ 200 BB & BT

VRd,max = 1852.20 KN

f2.0d = 524.06 KN/m

Asv = 949.777 mm2/m

6633 mm2/m

Sheet2

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