DESIGN OF CANTILEVER TYPE WATER TANK CLOSE OR OPEN FROM TOP 

DESIGN RESULT 
DESIGN OF CANTILEVER TYPE WATER TANK RESTING ON GROUND  TYPE I Height of Tank above GL in M (h1): 3 Depth of Tank below GL in M (h2): 1 Width of Base in M (b1 = Heel + Toe + t2 ): 2.5 Width of Tank Toe in M (b2): 0.6 Thickness of Stem at Top in M (t1): 0.15 Thickness of Stem at Base in M (t2): 0.6 Thickness of Heel / Toe Slab in M (t3): 0.6 Depth of Key if required in M (hk): 0.55 Thickness of Key if required in M (tk): 0.25 Vertical Load From Roof Slab in T/M (V): 0 Horizontal Load From Roof Slab in T/M (H): 0 SBC at Depth " h2 " in T/M2: 10 Coefficient of Friction between Soil and Base: 0.55 Dia of Main Reinforcement: 12 Concrete Grade: M30 Steel Strength (fy) [N/MM2]: 415 Dia of Secondary Reinforcement: 8 Min Tank Dimension in M: 15  SBC at Depth " h2 " in T/M2: 10 Coefficient of Friction between Soil and Base: 0.55 Dia of Main Reinforcement: 12 Concrete Grade: M30 Steel Strength (fy) [N/MM2]: 415 Dia of Secondary Reinforcement: 8 Horizontal Water Pressure at Base in T/M2 = 3.4 Horizontal Water Force at Base in Tons = 5.78 Overturning Moment due to Lateral Water Force in TM = 6.55 Weight of Stem in Tons = 3.19 Weight of Base in Tons = 3.75 Weight of Water in Tons = 5.18 Restoring Moment in TM = 16.85 Total Vertical Load in Tons = 12.12 Base Eccentricity in M = 0.4 Maximum Pressure in Base in T/M2 = 9.5 Minimum Pressure in Base in T/M2 = 0.19 FOS against Overturning = 2.57 FOS against Sliding = 2.28  BM in Stem at Base Top in TM = 6.55 Equivalent Design BM in Stem at Base Top in TM = 7.54 SF in Stem at Base Top in Tons = 5.78 BM in Stem at 2/3 rd Height from Top in TM = 1.94 Equivalent Design BM in Stem at 2/3 rd from Top in TM = 2.36  BM in Heel at Stem Face in TM = 2.62 SF in Heel at Stem face in Tons = 2.98  BM in Toe at Stem Face in TM = 1.4 SF in Toe at Eff. Depth from Stem face in Tons = 0.39  Capacity of Stem Sec. in BM in TM = 54.4 Depth of Neural Axis for Stem in MM = 97.2 Vertical Stem Reinforcement near Base at Water Face in CM2/M = 11.2 Provide Vertical Stem bars near Base at Water Face as dia 12 MM @ 101 MM c/c Provide Vertical Stem bars at 2/ 3 rd from top at Water Face as dia 12 MM @ 251 MM c/c Provide Vertical Stem bars near Base at Away from Water Face as dia 12 MM @ 251 MM c/c Provide Horizontal Stem bars at Each face as dia 8 MM @ 112 MM c/c Factored Shear Stress in Stem in Kg/CM2 = 1.58 Max. Permissible Shear Stress in Stem in Kg/CM2 = 36.7 Capacity of Stem Section in Shear in Tons = 12.44  Capacity of Heel Sec. in BM in TM = 54.4 Depth of Neural Axis for Heel in MM = 58.9 Main Heel Reinforcement at Top in CM2/M = 6.02 Provide Main Horizontal Transverse Heel bars at Water Face as dia 12 MM @ 188 MM c/c Provide Horizontal Longitudinal Base Slab bars at Each face as dia 8 MM @ 84 MM c/c Factored Shear Stress in Heel in Kg/CM2 = 0.81 Max. Permissible Shear Stress in Heel in Kg/CM2 = 36.7 Capacity of Heel Section in Shear in Tons = 9.37  Capacity of Toe Sec. in BM in TM = 54.4 Depth of Neural Axis for Toe in MM = 43.4 Main Toe Reinforcement at Bottom in CM2/M = 3.77 Provide Main Horizontal Transverse Toe bars at Bottom as dia 12 MM @ 300 MM c/c Factored Shear Stress in Toe in Kg/CM2 = 0.11 Max. Permissible Shear Stress in Toe in Kg/CM2 = 36.7 Capacity of Toe Section in Shear in Tons = 7.53  Capacity of Key Sec. in BM in TM = 7.19 Depth of Neural Axis for Key in MM = 39.1 Main Key Vertical Reinforcement in CM2/M = 5.1 Provide Main Vertical Key bars on Each Face as dia 12 MM @ 222 MM c/c Provide Horizontal Key bars at Each face as dia 8 MM @ 168 MM c/c Factored Shear Stress in Key in Kg/CM2 = 0.9 Max. Permissible Shear Stress in Key in Kg/CM2 = 36.7 Capacity of Key Section in Shear in Tons = 5  Water Table is assumed to be absent or beyond h2. Provide minimum Grade Slab thickness of 150 MM. If Minimum Tank Dimension (Length or Width) is < = 15 M. then provide reinforcements as Tor 8 @ 135 c/c near the top surface of grade Slab. If Minimum Tank Dimension (Length or Width) is > 15 M. then provide reinforcements as Tor 10 @ 135 c/c near the top surface of grade Slab. Provide Expansion Joint between Heel and Base Slab of Tank. If Roof Slab / Platform is present then Provide Suitable Sliding Joint between Roof Slab / Platform & Stem.  Total Concrete Quantity Consumed by Stem + Heel + Toe in M3 / RM = 2.91 Total Steel Quantity Consumed by Stem + Heel + Toe in Kg / RM = 108.58 Clear Cover to Reinforcement is taken as 40 MM : Load Factor = 1.5 For Expansion and Construction Joint details refer Standards. Design Roof Slab (If reqd.) as per IS 456. Use Minimum M30 Grade Conc. Important Note : Design Engineer to rerun Program & Check the design of Heel and Toe Slabs under Central Wall and Provide the revised Heel & Toe Reinforcements / Thickness accordingly. Note that Tank Stem is designed as cantilever & not as Propped Cantilever. The Applied Unbalance Load { H } if any shown on Top is from Roof Slab / Platform. Sliding Joint in Steel Platform can be provided by providing Slotted holes in Beams. ooooooooooooooooooo fini oooooooooooooooooooooooo 