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INPUTTank capacity = 400Depth of water, H = 4 mFree board = 0.2 mDenity of Concrete, Wconc = 25Denity of Concrete, Wwater = 9.8Grade of Concrete, fck = 20 Mpa
= 7 MpaGrade of Steel, fy = 415 Mpa
= 230 Mpa
= 115 MpaModular ratio, m = 13.3Effective cover = 30 mm
Solution1 Design constants
k = m σcbc
= 0.288146
j = 1 - k/3= 0.903951
R = 1/2 . σcbc . j . k= 0.911645
2 Dimension of tankEffictive depth of the tank, h = 4 - 0.2h = 3.80 mIf "D" is the diameter of the tank
Volume of the tank, 400 =4
D = 11.60 m
3 Design of sectionMaximum hoop tension = w H D
2= 227360 N/m height from base
Area of hoop steel
= 227360
115= 1977.043
Bar dia = 20 # barsSpacing = 159 mmProvide 20 # bars @ 150 C/C
= 2093.333
If T is thicness of wall, we have, = w H D/2
Kltr or m3
kN/m3
kN/m3
Compressive stress, σcbc
Tensile stress, σst
σs
m σcbc + sst
π D2 h
at base is, Ash
mm2/m height from base
Astact mm2
σct
1000 T+(m-1) Ash
Permissible Direct tensile
= 2.8
T = 72.00429 mmThickness of wall from empirical formula, T = 3 H + 5
= 17 cmT = 170 mm
Spacing of hoop reinforcement near the top can be increased to minimum Ast
= 0.30%= 510
Bar dia = 20 # barsSpacing = 616 mmMaximum spacing = 3 T
= 510 mmProvide 20 # bars @ 510 C/C
If the thickness of wall is less than 225 mm reinforcement provided at the center of thickness. If, however, the thickness is more than 225 mm , half the hoops would have been placed near the inner face and other half at the outer face (i.e. the spacig of the hoops would have been doubled)
Spacing of reinforcement 2 m below the wall top
Maximum hoop tension = w h D2
= 113680 N/m
Area of hoop steel
= 113680
115= 988.5217
Bar dia = 20 # barsSpacing = 318 mmProvide 20 # bars @ 310 C/C
4 Vertical reinforcementDistribution and temprecture reinforcement is provided in vertical direction, Pt = 0.3 - 0.10 ((T-100)/(450-100))
= 0.28 %
= 476
Bar dia = 10 # barsSpacing = 165 mmProvide 10 # bars @ 160 C/C
5 Design of floor tankSince the tank floor is resting on ground throughout, provide a minimum thickness of = 150 mm
minimum Pt = 0.3 %minimum Asv = 450 in each directionHalf reinforcent on each face i.e. 225
Bar dia = 8 # barsSpacing = 223 mmProvide 8 # bars @ 220 C/C in both direction , at top and bottom of floor slab. The floor slab will rest on = 75 mm thick layer of lean concrete covered with a layer of tar felt.
# @mmc/c20# @310c/c
10# @160c/c
20# @150c/c
8# @220c/c both ways-top & bot
stress in concrete σct
Ashmin
mm2
at base is, Ash
mm2/m
Asv mm2
mm2
mm2
INPUTTank capacity = 400Depth of water, H = 4 mFree board = 0.2 mDenity of Concrete, Wconc = 25Denity of Concrete, Wwater = 9.8Grade of Concrete, fck = 20 Mpa
M 20= 7 Mpa
Grade of Steel, fy = 415 Mpa= 230 Mpa
= 115 MpaModular ratio, m = 13.3Effective cover = 30 mm
Solution1 Design constants
k = m σcbc
= 0.447381
j = 1 - k/3= 0.850873
R = 1/2 . σcbc . j . k= 1.332326
2 Dimension of tankEffictive depth of the tank, h = 4 - 0.2h = 3.80 mIf "D" is the diameter of the tank
Volume of the tank, 400 =4
D = 11.60 m
3 Determination of bending moment and hoop tensionThickness of wall from empirical formula, T = 3 H + 5
= 17 cmT = 170 mm
The height above base, upto which cantilever action will be there is given by H/3 or 1 m which ever is heigherH/3 = h = 1.333 m
Maximum hoop tension at1.333m level = w (H-h) D
2
= 151592.3 N
Maximum prerssure at bot = wH
= 39200 N
Maximum cantilever B.M. = 1/2 x Pbot x h x h/3Mf = 11609.01 N-m/m
= 151592.3115
= 1318.194
4 Design of setion for cantilever actionIf d is the effective thickness of tank wall,
d == 93.34528 mm
T = 123.3453 mm= 130 mm
Minimum, T = 150 mmor 3 H + 5= 170
Hence provide T = 170 mmd = 140 mm
= Mf
= 847.4313
Bar dia = 12 # barsSpacing = 133 mmProvide vertical 12 # bars @ 130 C/C upto height 1.4 m at inner faceAbove this height, Curtail half bars & cotinue remaining half bars upto topDevelopment length, Ld
=
=13803.2
= 431.25 mmHence Ok
Kltr or m3
kN/m3
kN/m3
Compressive stress, σcbc
Tensile stress, σst
σs
m σcbc + sst
π D2 h
PH/3
Pbot
at base is, Ash
mm2/m height from base
Sqrt(Mf/Ru b)
Ast for cantilever bending
σst . j .d
Ast mm2
φ . σst
4 . τbd
5 Design of section for hoops action
Maximum hoops tension = 151592.28 N at 1.333 m height from bottomArea of hoop steel
= 151592.3115
= 1318.194Provide Rings on both faceArea of rings in each face = 659.0969
Bar dia = 12 # barsSpacing = 172 mmProvide 12 # bars @ 170 C/C upto height 1.4 m from bottomand above this, the spacing may be increased
= 1329.882
=
= 0.813449 should be less than 2.8Hence Safe
4 Vertical reinforcementDistribution and temprecture reinforcement is provided in vertical direction, Pt = 0.3 - 0.10 ((T-100)/(450-100))
= 0.28 %
= 476
Bar dia = 10 # barsSpacing = 165 mmProvide 10 # bars @ 160 C/C at
5 Design of floor tankSince the tank floor is resting on ground throughout, provide a minimum thickness of = 150 mm
minimum Pt = 0.3 %minimum Asv = 450 in each directionHalf reinforcent on each face i.e. 225
Bar dia = 8 # barsSpacing = 223 mmProvide 8 # bars @ 220 C/C in both direction , at top and bottom of floor slab. The floor slab will rest on = 75 mm thick layer of lean concrete covered with a layer of tar felt.
# @mmc/c12# @170c/c
10# @160c/c
#REF!
8# @220c/c both ways-top & bot
at base is, Ash
Ash mm2
mm2
Astact mm2
σct PH/3
1000 x T + (m-1) x Astact
N/mm2 N/mm2
Asv mm2
mm2
mm2
VALUES OF DESIGN CONSTANTSGrade of concrete M-15 M-20 M-25 M-30 M-35 M-40 Grade of concret
Modular Ratio 18.67 13.33 10.98 9.33 8.11 7.185 7 8.5 10 11.5 13
93.33 93.33 93.33 93.33 93.33 93.330.4 0.4 0.4 0.4 0.4 0.4
Development Length in tension0.867 0.867 0.867 0.867 0.867 0.8670.867 1.214 1.474 1.734 1.994 2.2540.714 1 1.214 1.429 1.643 1.857
0.329 0.329 0.329 0.329 0.329 0.329 M 15
0.89 0.89 0.89 0.89 0.89 0.89 M 200.732 1.025 1.244 1.464 1.684 1.903 M 250.433 0.606 0.736 0.866 0.997 1.127 M 300.289 0.289 0.289 0.289 0.289 0.289 M 350.904 0.904 0.904 0.904 0.904 0.904 M 400.653 0.914 1.11 1.306 1.502 1.698 M 450.314 0.44 0.534 0.628 0.722 0.816 M 500.253 0.253 0.253 0.253 0.253 0.2530.916 0.916 0.916 0.914 0.916 0.9160.579 0.811 0.985 1.159 1.332 1.5060.23 0.322 0.391 0.46 0.53 0.599
bd M-15 M-20 M-25 M-30 M-35 M-400.18 0.18 0.19 0.2 0.2 0.2
0.25 0.22 0.22 0.23 0.23 0.23 0.230.50 0.29 0.30 0.31 0.31 0.31 0.32 M 100.75 0.34 0.35 0.36 0.37 0.37 0.38 M 151.00 0.37 0.39 0.40 0.41 0.42 0.42 M 201.25 0.40 0.42 0.44 0.45 0.45 0.46 M 251.50 0.42 0.45 0.46 0.48 0.49 0.49 M 301.75 0.44 0.47 0.49 0.50 0.52 0.52 M 352.00 0.44 0.49 0.51 0.53 0.54 0.55 M 402.25 0.44 0.51 0.53 0.55 0.56 0.57 M 452.50 0.44 0.51 0.55 0.57 0.58 0.60 M 502.75 0.44 0.51 0.56 0.58 0.60 0.62
3.00 and above 0.44 0.51 0.57 0.6 0.62 0.63
Grade of concrete M-15 M-20 M-25 M-30 M-35 M-40 Grade of concrete M
1.6 1.8 1.9 2.2 2.3 2.5
Reiforcement %
Permissible Bond stress Table tbd in concrete (IS : 456-2000)
tbd (N / mm2)
scbc N/mm2
m scbc
(a) sst = 140
N/mm2 (Fe 250)
kc
jc
Rc Grade of concretePc (%)
(b) sst = 190
N/mm2
kc
jc
Rc
Pc (%)
(c ) sst = 230
N/mm2 (Fe 415)
kc
jc
Rc
Pc (%)
(d) sst = 275
N/mm2 (Fe 500)
kc
jc
Rc
Pc (%)
Permissible shear stress Table tv in concrete (IS : 456-2000)
100A s Permissible shear stress in concrete tv N/mm2 Permissible stress in concrete (IS : 456-2000)
Grade of concrete
< 0.15
Maximum shear stress tc.max in concrete (IS : 456-2000)Permissible direct tensile stress in concrete (IS : 456-2000)
tc.max sct.max
Shear stress tc
M-20 M-20bd bd
0.15 0.18 0.18 0.15
0.16 0.18 0.19 0.18
0.17 0.18 0.2 0.21
0.18 0.19 0.21 0.24
0.19 0.19 0.22 0.270.2 0.19 0.23 0.3
0.21 0.2 0.24 0.32
0.22 0.2 0.25 0.350.23 0.2 0.26 0.38
0.24 0.21 0.27 0.410.25 0.21 0.28 0.44
0.26 0.21 0.29 0.470.27 0.22 0.30 0.5
0.28 0.22 0.31 0.550.29 0.22 0.32 0.6
0.3 0.23 0.33 0.650.31 0.23 0.34 0.7
0.32 0.24 0.35 0.750.33 0.24 0.36 0.82
0.34 0.24 0.37 0.88
0.35 0.25 0.38 0.94
0.36 0.25 0.39 1.000.37 0.25 0.4 1.080.38 0.26 0.41 1.160.39 0.26 0.42 1.250.4 0.26 0.43 1.33
0.41 0.27 0.44 1.410.42 0.27 0.45 1.500.43 0.27 0.46 1.630.44 0.28 0.46 1.640.45 0.28 0.47 1.750.46 0.28 0.48 1.880.47 0.29 0.49 2.000.48 0.29 0.50 2.130.49 0.29 0.51 2.250.5 0.30
0.51 0.300.52 0.300.53 0.300.54 0.300.55 0.310.56 0.310.57 0.310.58 0.310.59 0.310.6 0.32
100A s 100A s
0.61 0.320.62 0.320.63 0.320.64 0.320.65 0.330.66 0.330.67 0.330.68 0.330.69 0.330.7 0.34
0.71 0.340.72 0.340.73 0.340.74 0.340.75 0.350.76 0.350.77 0.350.78 0.350.79 0.350.8 0.35
0.81 0.350.82 0.360.83 0.360.84 0.360.85 0.360.86 0.360.87 0.360.88 0.370.89 0.370.9 0.37
0.91 0.370.92 0.370.93 0.370.94 0.380.95 0.380.96 0.380.97 0.380.98 0.380.99 0.381.00 0.391.01 0.391.02 0.391.03 0.391.04 0.391.05 0.391.06 0.391.07 0.391.08 0.4
1.09 0.41.10 0.41.11 0.41.12 0.41.13 0.41.14 0.41.15 0.41.16 0.411.17 0.411.18 0.411.19 0.411.20 0.411.21 0.411.22 0.411.23 0.411.24 0.411.25 0.421.26 0.421.27 0.421.28 0.421.29 0.421.30 0.421.31 0.421.32 0.421.33 0.431.34 0.431.35 0.431.36 0.431.37 0.431.38 0.431.39 0.431.40 0.431.41 0.441.42 0.441.43 0.441.44 0.441.45 0.441.46 0.441.47 0.441.48 0.441.49 0.441.50 0.451.51 0.451.52 0.451.53 0.451.54 0.451.55 0.451.56 0.45
1.57 0.451.58 0.451.59 0.451.60 0.451.61 0.451.62 0.451.63 0.461.64 0.461.65 0.461.66 0.461.67 0.461.68 0.461.69 0.461.70 0.461.71 0.461.72 0.461.73 0.461.74 0.461.75 0.471.76 0.471.77 0.471.78 0.471.79 0.471.80 0.471.81 0.471.82 0.471.83 0.471.84 0.471.85 0.471.86 0.471.87 0.471.88 0.481.89 0.481.90 0.481.91 0.481.92 0.481.93 0.481.94 0.481.95 0.481.96 0.481.97 0.481.98 0.481.99 0.482.00 0.492.01 0.492.02 0.492.03 0.492.04 0.49
2.05 0.492.06 0.492.07 0.492.08 0.492.09 0.492.10 0.492.11 0.492.12 0.492.13 0.502.14 0.502.15 0.502.16 0.502.17 0.502.18 0.502.19 0.502.20 0.502.21 0.502.22 0.502.23 0.502.24 0.502.25 0.512.26 0.512.27 0.512.28 0.512.29 0.512.30 0.512.31 0.512.32 0.512.33 0.512.34 0.512.35 0.512.36 0.512.37 0.512.38 0.512.39 0.512.40 0.512.41 0.512.42 0.512.43 0.512.44 0.512.45 0.512.46 0.512.47 0.512.48 0.512.49 0.512.50 0.512.51 0.512.52 0.51
2.53 0.512.54 0.512.55 0.512.56 0.512.57 0.512.58 0.512.59 0.512.60 0.512.61 0.512.62 0.512.63 0.512.64 0.512.65 0.512.66 0.512.67 0.512.68 0.512.69 0.512.70 0.512.71 0.512.72 0.512.73 0.512.74 0.512.75 0.512.76 0.512.77 0.512.78 0.512.79 0.512.80 0.512.81 0.512.82 0.512.83 0.512.84 0.512.85 0.512.86 0.512.87 0.512.88 0.512.89 0.512.90 0.512.91 0.512.92 0.512.93 0.512.94 0.512.95 0.512.96 0.512.97 0.512.98 0.512.99 0.513.00 0.51
3.01 0.513.02 0.513.03 0.513.04 0.513.05 0.513.06 0.513.07 0.513.08 0.513.09 0.513.10 0.513.11 0.513.12 0.513.13 0.513.14 0.513.15 0.51
M-10 M-15 M-20 M-25 M-30 M-35 M-40 M-45 M-50-- 0.6 0.8 0.9 1 1.1 1.2 1.3 1.4
Development Length in tension
Plain M.S. Bars H.Y.S.D. Bars
0.6 58 0.96 600.8 44 1.28 450.9 39 1.44 401 35 1.6 36
1.1 32 1.76 331.2 29 1.92 301.3 27 2.08 281.4 25 2.24 26
(N/mm2) (N/mm2) (N/mm2)3.0 300 2.5 250 -- --5.0 500 4.0 400 0.6 607.0 700 5.0 500 0.8 808.5 850 6.0 600 0.9 90
10.0 1000 8.0 800 1.0 10011.5 1150 9.0 900 1.1 11013.0 1300 10.0 1000 1.2 12014.5 1450 11.0 1100 1.3 13016.0 1600 12.0 1200 1.4 140
Grade of concrete M 10 15 20 25 30 35 401.2 2.0 2.8 3.2 3.6 4.0 4.4
Permissible Bond stress Table tbd in concrete (IS : 456-2000)
tbd (N / mm2) kd = Ld F tbd (N / mm2) kd = Ld F
Permissible stress in concrete (IS : 456-2000)Permission stress in compression (N/mm2) Permissible stress in bond (Average) for
plain bars in tention (N/mm2)Bending acbc Direct (acc)Kg/m2 Kg/m2 in kg/m2
Permissible direct tensile stress in concrete (IS : 456-2000)
sct.max
Axles Bearings Bolts4 4 95 7 106 8 11
4
