Inputs:
Grade of concrete fck = 40 N/mm2
Grade of steel fy = 500 N/mm2
As per soil
report SBC of Soil = 130 kN/m2
Unit weight of water gw = 9.81 kN/m3
As per soil
report Unit weight of soil g= 18 kN/m3
As per soil
report Angle of internal friction f= 30 Degrees
Coefficient of active earth pressure Ka = (1 - Sinf)/(1 + Sinf) = 0.334
IS:3370 Part-II
Clause 7.2 Clear cover to all reinforcement = 50 mm
IS: 3370 Part
II Table 1 Permissible stress in bending tension in concrete = 2.0 N/mm2
IS 456:2000
Table 21 Permissible stress in bending compression in concrete scbc = 10.0 N/mm2
IS 456:2000 Modular ratio m = 280/3scbc = 9.33
IS: 3370 Part
II Table 2 Permissible stress in steel (on water face) sst = 150 N/mm2
Coefficient of neutral axis N =1/(1+sst/mscbc) = 0.38
Coefficient of lever arm j =1-N/3 = 0.87
IS: 3370 Part
II Table 2 Permissible stress in steel (away from water face) sst = 190 N/mm2
IS: 3370
Coefficient of neutral axis depth N =1/(1+sst/mscbc) = 0.33
Coefficient of lever arm j =1-N/3 = 0.89
Min % of steel for 200 thick wall = 0.320 %
Clause 7.1
Min area of steel on each face for 200 thick wall = 240 mm2
Part II
Note: If the length to height ratio of wall is more than two; it is designed as a long wall, else as a short
wall. The long walls are designed as a propped vertical cantilevers from the base and only minimum
reinforcement will be provided in the longer direction. The short walls are designed for both horizontal
and vertical bending. Vertically it will be propped at top and fixed at base, while horizontally it will be
supported on perpendicular walls. Moody's chart is used for the design of short walls.
Loading & Bending Moment (Typical):
Empty Condition Case: (Earth pressure due to soil & surcharge)
The walls shall be designed for 1.2 m earth fill (surcharge) q = 21.60 kN/m2
The effect of surcharge will give a uniform pressure = 0.334 x 21.6 = 7.21 kN/m2
Active earth pressure at the base of wall = 0.334x18x1.3 = 7.82 kN/m2
1.2 m
7.21 kN/m2
1.3 m
15.03 kN/m2
Water Inside Case: (Water pressure)
Intensity of water pressure at the base of 2.5 m high wall = 9.81 x 1.7 = 16.68 kN/m2
0.8 m
1.7 m
16.68 kN/m2
Outer Cantilever Walls: W1
Height of wall = 2.50 m
Height of soil = 2.28 m
Breadth (Considering 1 m) = 1.00 m
Depth of wall = 200 mm
Diameter of bar (Assumed) = 10 mm
Effective cover = 50+10/2 = 55 mm
Effective depth of wall = 200-55 = 145 mm
Case: Empty Sump
Max hogging moment (Tension on earth face) = 11.80 kN-m
Design:
Vertical Reinforcement on Earth Face
Design moment = 11.80 kN-m
Area of steel required = 476 mm2
Provide Y10 @ 150 C/C
Area of steel provided = 524 mm2
Vertical Reinforcement on Inner face & Horizontal Reinforcement
Minimum area of steel required on each face = 240 mm2
Provide Y8 @ 200 C/C
Area of steel provided = 251 mm2
Inputs:
Grade of concrete fck = 40 N/mm2
Grade of steel fy = 500 N/mm2
Unit weight of concrete = 25 kN/m2
IS:3370 Part-II
Clause 7.2 Clear cover to all the reinforcement = 25 mm
IS: 3370 Part II
Table 1 Permissible stress in bending tension in concrete = 2.0 N/mm2
IS 456:2000
Table 21 Permissible stress in bending compression in concrete scbc = 10.0 N/mm2
IS 456:2000 Modular ratio m = 280/3scbc = 9.33
IS: 3370 Part II
Table 2 Permissible stress in steel (on water face) sst = 200 N/mm2
Coefficient of neutral axis N =1/(1+sst/mscbc) = 0.32
Coefficient of lever arm j =1-N/3 = 0.89
IS: 3370 Part II
Table 2 Permissible stress in steel (away from water face) sst = 200 N/mm2
Coefficient of neutral axis N =1/(1+sst/mscbc) = 0.32
Coefficient of lever arm j =1-N/3 = 0.89
Base Slab BS1
Length of short span, Lx = 10.00 m
Length of long span, Ly = 20.00 m
Height of the wall = 2.50 m
Dia. of bar = 20 mm
Slab thickness = 500 mm
Effective depth = 500 - (25+20/2) = 465 mm
Load on Slab
Self weight of wall (200mm thick) = 0x25x2.5/10 = 1.25 kN/m2
Self weight of wall (200mm thick) = 0.2x25x2.5/(10x2) = 0.63 kN/m2
Load due to self weight of cover slab = 0.15 x 25 = 3.75 kN/m2
Roof load = 1.00 kN/m2
Wall load - (10x3x0.2x20x3.5)+(20x2x0.2x20x3.5) = 4.90 kN/m2
Imposed load = 4.00 kN/m2
Toal load 15.53 kN/m2
Design of Bottom slab as Two way slab
om IS:456-2000 Mx = 0.088 My = 0.045
Bending moment at left support = 11.88 kN-m
Bending moment at right support = 0.00 kN-m
Bending moment
=-(11.876056704+0)/2+(0.088*I29*BASE!I16^2)="
at span 148.50 kN-m
Area of steel required = 1786 mm2
Provide Y 20 @ 175mm C/C at top
Area of steel provided = 1795 mm2
Bending moment in long span 70 kN-m
Area of steel required = 840 mm2
Provide Y 16 @ 225mm C/C at top
Area of steel provided = 894 mm2
Design of Cover slab
Center ot center of beam = 3.3 m
Clear span = 3 m
Slab Thickness assumed = 150 mm
Design loads
Self weight of slab (0.15*25) = 3.75 kN/m2
Live load = 4 kN/m2
Finish load = 1 kN/m2
Total load = 8.75 kN/m2
Moment = 9.84 kN-m
Mu/bd2 = 1.025
Ast = 456 mm2
Provide 10 mm dia @ 175 mm c/c at span bottom
The above reinforcement is provided in support top for the flange width
Provide 0.12 % as distribution steel
Ast 180 mm2
Provide 8mm dia @ 200 mm c/c
Design of Tee beam
Grade of concrete fck = 40 N/mm2
Grade of steel fy = 500 N/mm2
Unit weight of concrete = 25 kN/m2
Clear cover to all the reinforcement = 25 mm
Permissible stress in bending tension in concrete = 2.0 N/mm2
Permissible stress in bending compression in concrete scbc = 10.0 N/mm2
Modular ratio m = 280/3scbc = 9.33
Permissible stress in steel (on water face) sst = 200 N/mm2
Coefficient of neutral axis N =1/(1+sst/mscbc) = 0.32
Coefficient of lever arm j =1-N/3 = 0.89
Permissible stress in steel (away from water face) sst = 200 N/mm2
Coefficient of neutral axis N =1/(1+sst/mscbc) = 0.32
Coefficient of lever arm j =1-N/3 = 0.89
Clear span = 10 m
Centre to centre of supports = 10.3 m
Spacing of Tee beam ribs = 3.3 m c/c
Depth of beam required = 0.686667 mm
Assumed depth including slab = 650 mm
Depth of Rib = 500 mm
Width of rib = 300 mm
Loads
Dead load of slab = 11.25 kN/m
Live load = 12 kN/m
Self weight of Rib = 3.75 kN/m
Total load = 27 kN/m
Bending moment, M = 358.0538 KN-m
Shear Force, V = 139.05 kN
Main Steel Reinforcement
Ast = 3269.671 mm2 6.659208
With 25 mm dia bars = 6.659208 Nos
Hence provide 7 Nos of 25 dia bars at bottom
Also provide 3 Nos of 16 mm dia as hanger bars
Effective Flange width is least of
a) bf = 1201.717 mm
b) centre to centre of ribs = 3.3 m
Therefore bf requried = 1201.71 mm
Provided bf = 1650 mm
Hence ok
Check for stresses
bf * n2/2 = m*As*(d-n)
n = 174.63 mm
Lever arm, a = 554.29 mm
Tensile Stress in steel = 187.9454 N/mm2 < 230 N/mm2
Comp. stress in concr = 8.03098 N/mm2 < 10 N/mm2
The stresses are within the safe limits
Shear stresses
V = 139.05 kN
v/bd = 0.756735 N/mm2
100 As/bwd = 1.75619
Design shear strength of concrete = 0.84 N/mm > 0.756 N/mm2
Hence shear reinforcements are not required.
Provide nominal 2 legged stirrups of 8mm dia @ 125mm c/c
