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DESIGN OF BACKING WALL & BED BLOCK:

0.35

CONCRETE MIX = M20 0.10

RCL 103.125

R.C.L = 103.125

= 36 deg.

1.675

Deck thickness = 1.675 m

Wearing coat thk. = 0.10 m

Ka = 0.246

0.211

= 1.80 t/cum

0.30

Width of backing wall = 0.35 m

Live load surcharge = 1.20

Thickness of Bed = 0.30 mblock

Width of Bed block = 1.20 m

(h) Height of Backing wall h = 0.10 + 1.675 0.211 = 1.986 m

a) Moment due to Earth Pressure:

Pa = 1/2 Ka h2

= 0.873 t/sqm

Lever arm = 0.42 X 1.99 = 0.834 m

Moment = 0.873 X 0.834 = 0.73 t-m

3

B.M due to fluid pressure of 480 kg/sqm = 480 1.986 = 0.627 t-m

1000 6

< 0.728 t-m

b) Moment due to Live load surcharge:

Intensity of Live load surcharge at RCL = 0.246 1.80 1.20 = 0.531 t/sqm

2

Moment = 0.531 X 1.99 2 = 1.048 t-m

c) Moment due to Breaking force:

Max.axle load is 20.00 tonne for class 70r wheeled load.

Breaking force is 20% of axle load I.e = 20.00 X 20 = 4.000 t

100

Breaking force under each wheel = 2.00 t

a) Dispersion width at top of bed block = 0.86 2 1.99 = 4.83 m

(Tyre width = 0.86 m) (For second wheel)

BACKING WALL:

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b) Dispersion width at top of bed block

(For first wheel)

= 0.475 + 1.2 + 0.860 + 1.99 = 4.52 m

Intensity of second Wheel load / RM = 2.00 4.83 = 0.414 t/m

Intensity of first Wheel load for overlapping portion = 2.00 4.52 = 0.44 t/m

Total Wheel Intensity = 0.41 + 0.44 = 0.86 t/m

Lever arm = 1.99 + 1.20 = 3.19 m

Moment due to Breaking force = 0.856 X 3.186 = 2.728 t-m

Total Moment = 0.73 + 1.048 + 2.728 = 4.50 t-m/m

For V.R.C.C M20 mix: Q = 7.702 j = 0.916

d = 4.50 * 105

= 24.18 cm

100 * 7.70

d available = 35.00 2.5 0.6 = 31.90 cm

> 24.18 cm

A st = 4.50 * 105

= 7.71 Cm2

2000 0.916 31.90

Spacing of 12 mm dia tor bars = 1.131 X 1000 = 147 Cm c/c

7.71

Spacing of 12 mm dia tor bars @ 140 mm c/c vertically in the form of Stirrups.

Distribution steel:

A st = 0.12 X 100 X 35.00 = 4.2 Cm2 /m

100

Spacing of 10 mm dia bars = 3.142 1.0 X 100 = 18.702 cm

4 X 4.2

Provide 10 mm dia tor bars @ 200 mm c/c horizontally on both faces.

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Width of bed block = 120 cm

Steel to be provided = 120 X 30 100 = 36.000 Cm2

Longitudinal bars at top & bottom = 36.0 4 = 9.000 Cm

2

Provide 8 nos of 12 mm dia tor bars @ top & bottom equally spaced in a

width of 1.20 m (Steel provided= 8 X 1.131 = 9.046 Cm2)

Steel in Transverse direction = 36.0 2 = 18.000 Cm2

Volume of steel per 1m length = 18.00 X 100 = 1800 Cm3

Length of each Stirrup = 115 + 25 2 = 280 cm

Using 10 mm dia bars volume of each stirrup = 280.0 0.786 = 220.080 Cm3

No of stirrups = 1800 220.1 = 8.179 no

Spacing of Stirrups = 100 8.179 = 12.23 cm

Provide 10 mm dia stirrups @ 120 mm c/c

12 mm dia tor bars @

140 mmc/c

10 mm dia tor bars @

1.99 m 200 mm c/c

8 nos of

12 mm dia each at top &bottom

0.30 m 10 mm dia stirrups @

120 mm c/c

1.20 m

ABUTMENT BED BLOCK DESIGN:

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Width of bed block 180 cm

Steel to be provided 180 X 30 100 54.000 Cm2

Longitudinal bars at top & bottom 54.0 4 13.500 Cm2

Provide 12 nos of 12 mm dia tor bars @ top & bottom equally spaced in a

width of 1.80 m (Steel provided 12 X 1.131 13.569 Cm2)

Steel in Transverse direction 54.0 2 27.000 Cm2

Volume of steel per 1m length 27.00 X 100 2700 Cm3

Length of each Stirrup 175 + 25 2 400 cm

Using 10 mm dia bars volume of each stirrup = 400.0 0.786 314.400 Cm3

No of stirrups 2700 314.4 8.588 no

Spacing of Stirrups 100 8.588 11.64 cm

Provide 10 mm dia stirrups @ 110 mm c/c

12 No 12 MM

10 MM @ 110 MM C/C

PIER BED BLOCK DESIGN: