KARMAVEER BHAURAO PATIL COLLEGE OF ENGINEERING, SATARA

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R.C. C. Design of E.S.R (Cap. 76,000 liters)@Triputi, Tal.Koregaon, Dist. Satara

(Rashtriya Payjal Yojana)

Agency- M/s. Bhoite Constructions and Earth Movers, Wagholi, Tal. Koregaon, Dist. Satara

Data- 1. Height of Staging- 12.00 m 2. Tank height- 03.00 m 3. Foundation level below G.L. - 02.00 m 4. Free board- 00.30 m 5. Safe bearing capacity of soil strata- 250.00 kN/m^2 6. Seismic zone- III/IV

Materials- 1. Concrete- M25 2. Rebar Steel Fe415

Codes used-1. IS:456-20002. IS:13920-19933. IS:3370-1965(Part I / II/ IV)4. IS:1893-2002 ( Part I/ II)

Methods of Design-1. Working stress method for container components i.e. roof slab, tank wall, floor base slab, floor beam and balcony2. Limit state method for staging design i.e. columns braces and footings.

Soft wares used for finite element analysis of all components 1. STAAD.Pro 20062. SAP 2000 Nonlinear( for verification)

Loads and load combinations 1. DL 2. LL3. EL/WL And combinations thereof.

Capacity calculations-

Capacity - 76,000 liters =76 m^3 Assume internal dia. of the tank to be 6.02 m. Effective .Span. ---6.22 m Height total -3.0m Depth of water in the tank 3.0 m 0.3 m (F.B.) = 2.7 mVolume available =76.85 m^3 Ok.

Design of Roof Slab (140 mm thick) M25Loading ---- i) self wt. --------------0.14 x 25 = 3.50 kN/m^2 ii) Finish --------------- = 1.00 kN/m^2 iii) Live load ----------- = 1.50 kN/m^2 ___________ Total intensity (w) = 6.00 kN/m^2

Bending moment in radial (Mr) and circumferential (Mc) directions

BM.kNm/m Simply SupportFully Fixed*Partially FixedSTAAD.Pro

EndSpanEndSpanEndSpanEndSpan

Mr0.0010.88-07.253.625-3.62507.25-6.114.84

Mc07.2510.88 03.625 3.62507.25 0.884.84

*Partial fixity here indicates 50 % relaxation of end moments

The moment Mr and Mc at mid-span and ends depends on actual support end conditions. In Staad.Pro we can model wall (support to the roof slab) and slab together giving realistic values for the moments. Here max. Span moment is taken for partially fixed condition and Staad.Pro results for end moment (being greater) as highlighted in the table above.

Eff. Depth (d) required. = 72.48 mmEff. Depth (d) available =140-25-10-10/2 =100mm Ok.Area of steel at center (Ast)c=555.50 mm^2>304.37 mm^2 (0.28% for tk.140mm) .Bottom steelProvide 10mm@ 140 mm c/c at centre in the form of mesh.Also provide 4-8mm ring bars at end at 200 mm c/c.Top SteelProvide 10mm @175 mm c/c for a length of 1 m in radial direction with 4-8mm ring bars at 250 mm c/c

Design of Tank Wall (200 mm thick)-M25

IS: 3370-1967(Part-IV) gives coefficients for hoop tension and bending moments for individual components with certain end conditions. The actual end conditions

(Due to continuity between components- wall, slabs etc.) for E.S.R. can be much different from those of IS: 3370. The following table shows the comparison between IS: 3370 and actual results. The deflected shape of the tank wall due to continuity with roof and base slab is shown in the figure below ( Staad.Pro result file).H^2/Dt=7.508.0Hoop Tension(T) kNBending moment (Vr.) kNm/m

*IS3370Staad.Pro*IS3370Staad.Pro

0.0h00.09-1.80 -----------

0.1h -09.36 -39.20 00.0005.18

0.2h-19.62-51.20 0.0272.93

0.3h-30.15 -52.00 0.0551.44

0.4h-39.60-48.00 00.220.86

0.5h-48.06 -40.00 00.430.96

0.6h-51.75 -40.00 00.761.34

0.7h-47.70 -26.00 01.031.46

0.8h-34.20 -5.00 00.780.57

0.9h-13.5914.40 -00.59-02.22

1.0h-----14.00 -03.94-7.73

*Results are for fixed base condition

Hoop tension steel In the form of rings in horizontal direction It is designed for max hoop tension of 52.00 KN of the table above. No crack condition is satisfied. ( c act = 0.25 N/mm^2 ) Ah required = 346.67 mm^2 < Ahmin. (0.27%= 540 mm^2)Steel on face 540/2= 270 mm^2Provide on each face of wall 10mm@ 250 mm c/c ring bars staggered. i).Vertical steel (on inner face)Designed for max. -ve B.M of 7.73 kNm/m (tension on inner face at bottom)Ast required=343.43 mm^2 Provide 10mm@ 225 mm c/c throughout ii) Vertical steel (on outer face) Designed for max. + B.M. of 5.18 kN.m/mProvide 10mm@ 250 mm c/c throughout the height of the wall

. Design of Floor Base Slab-(250 mm thick) M25- (square panel)

Loading ---- i) self wt. --------------0.25 x 25 = 06.25 kN/m^2 ii) Finish --------------- = 01.00 kN/m^2 iii) Water load ----------- = 30.00 kN/m^2 ___________ Total intensity (w) = 36.25 kN/m^2

BM.kNm/m at Mid Span(Mx & My)BM.kNm/m at Edge (Mx & My

IS:456 -2000Staad.ProIS:456 -2000Staad.Pro

16.8421.77-22.45-20.01

Above moments also differ (IS: 456 & Staad Pro) as IS: 456 coeff. are for certain condition( fixity) of the slab( i.e. continuous interior panel) but Staad results are based on actual continuity or partial fixity status at the edge.So design moments are taken from Staad.Pro resultsEff.Depth( d) required=125.60 mm Eff. Depth (d) available = 250-25-1.5 x10 =210mm Ok.Bottom Steel Ast at center =627.14 mm^2Provide 10mm@ 125 mm c/c at mid-span in the form of mesh. Top SteelAst at support /edge = 615.10 mm^2Ast available =312 mm^2 from bent up bars of mid span steel. Now provide extra cut bars (L/4) 10mm@ 250 mm c/c. Extend this steel in curved portion of the slab such that it will rest upon 2-16mm provided in the wall at bottom as wall also supports some load of curved portion of the base slab. Max moment (hogg) in the curved portion in the vicinity of edge of tank wall is - 13.48 kNm/m

Design of Balcony (100 mm thick and 0.9 m wide) M25

Loading ---- i) self wt. --------------0.1 x 25 = 02.50 kN/m^2 ii) Finish --------------- = 01.00 kN/m^2 iii) Liver load ----------- = 01.50 kN/m^2 ___________ Total intensity (w) = 05.00 kN/m^2

B.M max= 2.02 kN.m ( Staad.Pro Value-2.15 knm/m)d required = 39.92 mmd available = 100-25-10/2 = 70 mmAst required = 238.345 mm^2Provide 8mm@ 200 mm c/c. Also provide distribution steel in the form of rings -6mm@ 150mm c/c.

Floor Beams (300 mm x 1000 mm overall) M25

B.M.max = 129.46 kN.m at mid span and 7.53 kN m at support. Eff. Depth required = 560 mm Eff. Depth available- 100 -40-20/2 = 950 mm. Ok.Ast at required at mid-span = 1044.24 mm2Provide 4-20mm longitudinal bars throughout. At top provide 2-16mm through- out and extra 1-20 mm for L/4 at end.Also provide 2- 10mm on each side face. Max Shear =106.09 kN. Provide 8mm 200mm c/c throughout.

Seismic Analysis of the tank as per IS:1893-2002 ( Part-II)

Vb = 118.30kN (See Details on page No.7)

Wind load AnalysisWind load (Vb) < Seismic Load (Vb). So only Seismic loads will be considered for staging design Column Design (400mm Dia.)- M25 Load Comb. - 1.5 (DL + EQ)Design forces ( Top right column is critical ).Axial force Pu-749 kNMux- 86.70 kNm, Muy- (Min) 14.98 kNmPrivide column of size 400 mm dia. circular sections with 7-16 barsMuxl= 104 kNm, Muyl= 104 kNmPu/Puz =0.4 = 1.33[Mux/Muxl] ^ + [Muy/Muyl] ^ = 0.86 371.91 mm Ok.Ast required at Ends =937.11mm^2Provide 2-20 mm throughout and 1 -20mm at end (L/4)Max shear 68.10 kNProvide 8mm @ 125 mm c/c FOR length up to 1.0m (9 No.) at ends and 225mmc/c through out

Ground Level Braces (250 mm x 450 mm) - M25External Braces Design moment Mu = 85.46 kNm Provide 2-20mm through out at top and bottom. Also provide 8mm @ 150 mm c/c through outInternal braces Design moment Mu = 50 kNm Provide 2-16mm through out at top and bottom Also provide 8mm @ 150 mm c/c through out

Design of column footings (M25)Axial load Pu = 1102 kN Axial load Pw = 1102 /1.5 = 734.66 kN Moment Mu = 59.75 kN Moment Mw = 59.75/ 1.5 = 39.83 kNm Provide Size of Footing 2.0 m x 2.0 m (Area = 4. 00 m^2)M.I.of footing- 1.33 m^4Upward Pr. = 213.54 kN/m^2 > 1.25 x 250 = 312.5 kN/m^2 Ok.BM max = 136.66 kNm (1.5 x 136.66 = 205 kN.m)Eff. Depth required = 363.38 mm Provide total depth of 550 mm at column face and 200 mm at edge.Ast required = 1128.54.49 mm^2Provide 12mm @ 200 mm c/cCheck for punching shear (at dist. d/2 away from column face)1.5 x 213.54[2.0^2- 0.88^2] = 1031.013 kNShear stress =0.67 N/mm^2 Permissible shear stress = p = ks x c ks =( 0.5 + 1) < 1.0 .Hence ks =1 c = 0.25x sq. root ( fck) = 0.25 x sq. root( 25) = 1.25 N/mm^2p = 1.0 x 1.25 = 1.25 N/mm^2 > 0.67 N/mm^2 Ok.Hence provide footing of size 2000 mm x 2000 mm x 600/200 mm with 12 No. of 12mm bars in both the directions.

Seismic Analysis of the TankDi=6mtwall=0.2MZ=0.24

h=2.7mtroof=0.14mI= 1.5

fb=0.3mtbase=0.25mR=2.5

H=3mtbal=0.1m

Ww=763.506kNWt of floor beam

Wc=756.5106kNb=0.3Beam No.4

Wroof=112.6093kND=1Length4.4

Wwall=292.206kNWfb5.625kN

Wb=201.088kN

Wbal.=51.60735kNWst=373.93kN(Staad Output)

Wbeams99kN1/3Wst=124.6433kN

Total of Ww and Wc

1520.017kNC.G. of the empty tank from top of the floor

Total of Wc and 1/3 of Wsy=0.917936m

Ws881.154kNms89822.01kg or89.82201tonnes

Parameters of spring model-

mass m 77829.36kg or77.82936tonnes

h/D=0.45

mi/m=0.497953mi=38.75532tonnes

mc/m=0.475168mc=36.98202tonnes

Time period (Implusive Mode)

Ti=1.05689Sec.ks=4545.45kN/M(Staad Output)

Time period (Convective Mode)

Tc=2.49578Kc=234.4501kN/M

Design Seismic Coeff.

Sa/g(i)= 1.286794Sa/g0.701184

Ah(i)=0.092649Vb(i)=116.8624kN

Ah=0.050485Vb18.31571kN

Tank full condition

Vb=118.289kNSloshing wave height

Tank empty condition0.278639 Vb( Tank Empty). So tank full condition governs the design.