Maximum Shear Force Calculation for Live Load IRC Class 70R Tracked || Deck Slab Bridge Design ||Part 3

Deck Slab Bridge Design: (Maximum Shear Force Calculation for Live Load IRC Class 70R-Tracked Vehicle)

 

Now I am going to calculate Maximum Shear Force for IRC Class70R Tracked Vehicle.

 Place IRC Class70R Tracked vehicle as shown in the figure. The dispersed area edge will be at support to get maximum shear force. We will get the maximum shear force while the load will be placed near the support.

Here some term has been applied i.e. “c”

c: distance between the inner face of kerb rise or crash barrier to outer edge of the wheel or track. It will be minimum 1.20m for IRC Class 70R Loading Vehicle as per IRC 6 2017, clause 204.1.1,

 

Impact factor: 10% (10 percent upto a span of 40.00m as per IRC 6 2017, clause 208.3.b, page-30).

 

Effective Breadth Of Dispersion:

 

So, Effective breadth of dispersion along span=4.57+2(0.1+0.75) =6.27m

Effective Width:

Effective width for single load=

b_eff= α.a (1-a/l_eff) + b1

Where, α: Constant value depending on B/l_eff ratio.

a: the distance of the centre of gravity of the concentrated

load from the nearer support,

l_eff : Effective length of the bridge.

b1: the breadth of concentration area of the load, i.e., the dimension of the tyre or track contact area over the road surface of the slab in a direction at right angles to the span plus twice the thickness of the wearing coat or surface finish above the structural slab.

 

B/l_eff=8.4/9.6=0.875

α=2.45 (interpretation values from IRC: 21 2000, clause 305.16.2, page-53)

l_eff =9.60m

a=6.27/2=3.135m

b1=0.84+2(0.1)=1.04m

beff= 2.45*3.135*(1-3.135/9.6)+1.04

      =6.2125m

Total effective width for both tracks (beff net) =0.45+1.2+2.9-0.84/2+6.2125/2 = 7.2363m

 

Loading intensity:

=70T/(effective breadth along span)  X (total effective width for both tracks)

=1.1x700/(6.27x7.2363)  (Multiplied by Impact Factor to get dynamic load)

=16.971 kN/m2

 

Now find out the maximum shear force due to loading intensity 16.971 kN/m2

 

This udl load is distributed over 6.27m along span.

Taking bending moment at point B,

Ra X 9.36=16.971x6.27(9.6-6.27/2)

Ra=71.66 kN

Rb=(16.971x6.27-71.66) kN

   =34.748 kN

So, the maximum shear force is 71.66kN.

You may visit my youtube channel: 

1.  Slab-Bridge-Design-In-Midas-Civil-as Per Indian Code IRC 112

More Posts: 

1. RCC Slab Bridge Analysis And Design Step-By-Step Manually || Part-1

2. Live Load Bending Moment IRC Class 70R Tracked Vehicle for Slab Bridge Design Manually || Part 2

3. Maximum Shaer Force Calculation for IRC Class 70R Tracked Vehicle || Slab Bridge Design Manually || Part 3

4. Bridge Deck Slab Design Example as per IRC || Slab Bridge Design example || LSM Method || Part 4

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