UG sump design

Inputs:

Grade of concrete 40

Grade of steel 500

SBC of Soil = 130

Unit weight of water 9.81

Unit weight of soil g = 18

Angle of internal friction 30 Degrees

Coefficient of active earth pressure 0.334

Clear cover to all reinforcement = 50 mm

Permissible stress in bending tension in concrete = 2.0

10.0

IS 456:2000 Modular ratio 9.33

Permissible stress in steel (on water face) 150

fck = N/mm2

fy = N/mm2

As per soil report kN/m2

gw = kN/m3

As per soil report kN/m3

As per soil report f =

Ka = (1 - Sinf)/(1 + Sinf) =

IS:3370 Part-II Clause 7.2

IS: 3370 Part II Table 1 N/mm2

IS 456:2000 Table 21 Permissible stress in bending compression in concrete scbc = N/mm2

m = 280/3scbc =

IS: 3370 Part II Table 2 sst = N/mm2

Coefficient of neutral axis 0.38

Coefficient of lever arm j =1-N/3 = 0.87

Permissible stress in steel (away from water face) 190

Coefficient of neutral axis depth 0.33


Min % of steel for 200 thick wall = 0.320 %

Min area of steel on each face for 200 thick wall = 240

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):

The walls shall be designed for 1.2 m earth fill (surcharge) q = 21.60

The effect of surcharge will give a uniform pressure = 0.334 x 21.6 = 7.21

Active earth pressure at the base of wall = 0.334x18x1.3 = 7.82

7.21 kN/m21.2 m

1.3 m

15.03 kN/m2

N =1/(1+sst/mscbc) =


Cla

use

7.1

I

S:

33

70

P

art

II


mm2

Note: If the length to height ratio of wall is more than two; it is designed as a long wall, else as a short

Empty Condition Case: (Earth pressure due to soil & surcharge)

kN/m2

kN/m2

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

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

Provide Y10 @ 150 C/C

Area of steel provided = 524

Vertical Reinforcement on Inner face & Horizontal Reinforcement

Minimum area of steel required on each face = 240

Provide Y8 @ 200 C/C


kN/m2

mm2

mm2

mm2

mm2

Inputs:


Grade of steel 500

Unit weight of concrete = 25

Clear cover to all the reinforcement = 25 mm


10.0

IS 456:2000 Modular ratio 9.33







Base Slab BS1

= 10.00 m

= 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

Self weight of wall (200mm thick) = 0.2x25x2.5/(10x2) = 0.63

Load due to self weight of cover slab = 0.15 x 25 = 3.75

Roof load = 1.00

Wall load - (10x3x0.2x20x3.5)+(20x2x0.2x20x3.5) = 4.90

Imposed load = 4.00

Toal load 15.53

Design of Bottom slab as Two way slab

fck = N/mm2

fy = N/mm2

kN/m2

IS:3370 Part-II Clause 7.2

IS: 3370 Part II Table 1 N/mm2

IS 456:2000 Table 21 Permissible stress in bending compression in concrete scbc = N/mm2

m = 280/3scbc =





Length of short span, Lx

Length of long span, Ly

kN/m2

kN/m2

kN/m2

kN/m2

kN/m2

kN/m2

kN/m2

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 at span=-(11.876056704+0)/2+(0.088*I29*BASE!I16^2)=" 148.50 kN-m


Provide Y 20 @ 175mm C/C at top


Bending moment in long span 70 kN-m


Provide Y 16 @ 225mm C/C at top


mm2

mm2

mm2

mm2

Design of Cover slab Center ot center of beam = 3.3 mClear span = 3 mSlab Thickness assumed = 150 mm

Design loads

Self weight of slab (0.15*25) = 3.75

Live load = 4

Finish load = 1

Total load = 8.75

Moment = 9.84375 kN-m

= 1.025391

Ast = 456Provide 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 180Provide 8mm dia @ 200 mm c/c

Design of Tee beam


Grade of steel 500

Unit weight of concrete = 25Clear cover to all the reinforcement = 25 mm


10.0

Modular ratio 9.33


Coefficient of neutral axis 0.32Coefficient of lever arm j =1-N/3 = 0.89


Coefficient of neutral axis 0.32Coefficient of lever arm j =1-N/3 = 0.89

Clear span = 10 mCentre to centre of supports = 10.3 mSpacing of Tee beam ribs = 3.3 m c/c

Depth of beam required = 0.686667 mmAssumed depth including slab = 650 mmDepth of Rib = 500 mmWidth of rib = 300 mm

LoadsDead load of slab = 11.25 kN/mLive load = 12 kN/mSelf weight of Rib = 3.75 kN/mTotal load = 27 kN/m

Bending moment, M = 358.0538 KN-mShear Force, V = 139.05 kN

kN/m2

kN/m2

kN/m2

kN/m2

Mu/bd2

mm2

mm2

fck = N/mm2

fy = N/mm2

kN/m2

N/mm2

Permissible stress in bending compression in concrete scbc = N/mm2

m = 280/3scbc =

sst = N/mm2


sst = N/mm2


Main Steel Reinforcement

Ast = 3269.671 6.659208With 25 mm dia bars = 6.659208 NosHence 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 mmb) centre to centre of ribs = 3.3 mTherefore bf requried = 1201.71 mmProvided bf = 1650 mmHence ok

Check for stresses

= m*As*(d-n)n = 174.63 mmLever arm, a = 554.29 mm

Tensile Stress in steel = 187.9454

Comp. stress in concr = 8.03098The stresses are within the safe limits

Shear stressesV = 139.05 kN

v/bd = 0.756735

= 1.75619

Design shear strength of concrete = > 0.756Hence shear reinforcements are not required. Provide nominal 2 legged stirrups of 8mm dia @ 125mm c/c

mm2

bf * n2/2

N/mm2 < 230 N/mm2

N/mm2 < 10 N/mm2

N/mm2

100 As/bwd

0.84 N/mm N/mm2

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UG sump design