Water tank design using IS 3370 stress check shear check reinforcement

1. DESIGN AND DETAILING OF WATERTANK
Data and dimension calculations:
Capacity of Water Tank = 135lpcd ×[4 members × (7+(8×8))] = 38340 litre/day
Length = 4.5m , Width = 2.15m
Height =
𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦
𝐿×𝐵
=
(
38340
2
)
4.5×2.15×1000
= 1.98𝑚
Free board=0.27m
Total Height with free board = 1.98+.27 = 2.25m

2. Joint condition
All vertical joints are rigid and Horizontal Joints of walls and slabs are hinged

3. Moment Calculations:
FROM IS 3370 (PART 4); TABLE 3

4. MH max = Mywa3 , MV max = Mxwa3
W = 9800N/mm2
Long Wall:
Length (b) = 4.5m , Height (a) = 2.25m
𝑏
𝑎
= 2

5. From IS3370 (Part 4) 1967, TABLE 3
@ mid of the wall
MH max = 0.027×9800×2.253 (sagging) , 0.017×9800 × 2.253 (Hogging)
MH max = 3013.95 N-m (sagging), 1897 N-m (Hogging)
MV max = 0.015×9800×2.2×53 (sagging) , 0.086×9800 ×2.253 (Hogging)
MV max = 1674.4 N-m (sagging) , 9600 N-m (Hogging)
@ edge of the wall
MH max = 0.059 ×9800 ×2.253 = 6697.68 N-m (Hogging)
Mv max = 0.01×9800×2.253 = 1116.3 N-m (Hogging)

6. Shear Force
From IS3370 (PART 4) , TABLE-7
@ mid point of edge of wall
SF = 0.3604wa2 = 17880.34 N
Short Wall:
Length (b) =2.15m , Height(a)=2.25m
𝑏
𝑎
= 1

7. From IS3370 (Part 4) 1967 TABLE 3
@ mid of the wall
MH max = 0.011×9800×2.253 (sagging) , 0.008×9800 ×2.253 (Hogging)
MH max = 1451 N-m (sagging) , 893 N-m (Hogging)
MV max = 0.009×9800×2.253 (sagging) , 0.035×9800 ×2.253 (Hogging)
MV max = 1004 N-m (sagging) , 3906.98 N-m (Hogging)

8. @ edge of the wall
MH max = 0.029 ×9800 ×2.253 = 3237.2 N-m (Hogging)
Mv max = 0.006×9800×2.253 = 669.76 N-m (Hogging)
Shear Force
From IS3370 (PART 4) , TABLE-7
@ mid point of edge of wall
SF = 0.258wa2 = 12809.9N

9. Reinforcement @ edge of Long Wall:
MH max =6697.68 N-m (Hogging) On Water face
M = σstAstJd assuming Thickness (t) =200mm , d=200-
30=170mm
σst = 115 N/mm2 IS3370 Part 2 (Table 4)
σcbc = 8.5 N/mm2 IS3370 Part 2 (Table 2)
k =
𝑚σcbc
𝑚σcbc
+
σst
=
11×8.5
11×8.5+115
= 0.448
J = 1-(K/3) = 0.8506
Ast1 =
6697.7×1000
115×0.8506×170
= 402.7 mm2

10. T = 12809.9N
Ast2 =
12809.9
115
= 111.39 mm2
Total Ast = 402.7+111.39=514.09 mm2
IS3370 Part 2 cl. 8.1.1
Ast min = 0.4% of c/s= 0.004×1000×200 = 800 mm2
So provide Ast min = 800 mm2
Assume diameter of bar Ø = 10 mm
S =
1000×3.14×100
800×4
= 98.17 = 95mm
Provide 10mm bar @ 95mm c/c Distance on Water face

11. Stress check
From IS3370 (P-2) , cl-6.3(b)
σcbt’ =
9600×1000×10×200
1000×200×200×200×2
= 1.2 N/mm2
σcbt = 1.8 N/mm2 IS3370 Part 2 (Table 1)
σct’ =
17880.34
1000×200
= 0.1192 N/mm2
σct = 1.3 N/mm2 IS3370 Part 2 (Table 1)
𝛔 𝐜𝐛𝐭′
𝛔 𝐜𝐛𝐭
+
𝛔 𝐜𝐭′
𝛔 𝐜𝐭
=
1.2
1.8
+
0.1192
1.3
= 0.758 < 1

12. Shear check:
τv max =
𝑇
𝑑
=
17880.34
170
= 0.1052 N/mm2
Pt =
100Ast
𝑏𝑑
=
100×800
1000×170
= 0.471
IS 456 TABLE 19
M25 τc = 0.47 > 0.1051 So safe
In top and bottom slab providing minimum reinforcement

14. REINFORCEMENT DETAILING