Week 8 Challenge

To calculate the centrifugal load as per IRC-6 and IRC-21 for the given load data, consider the formula C = WV^2 / (127 * R) as per the Indian Road Congress (IRC) codes.

Step 1: Calculate the centrifugal load as per IRC-6: IRC-6 provides guidelines for calculating the centrifugal load due to the dynamic effect of moving vehicles on bridges.

Given data: Span of the bridge (L) = 12 m Width of carriage way (B) = 7 m Design speed (V) = 75 km/hr Radius of curvature (R) = 3 m

First, let's convert the design speed of the vehicle from km/hr to m/s: Design speed (V) = 75 km/hr = (75 * 1000) / 3600 m/s ≈ 20.83 m/s

Now, we can calculate the centrifugal load (C) as per IRC-6: C = (W * V^2) / (127 * R)

To determine the vehicle weight per unit length of the bridge (W), we need to refer to IRC-6 Table 3.4. In this case, for a Class 70R tracked vehicle, the weight per unit length is given as 7.5 kN/m.

W = 7.5 kN/m = 7.5 * 1000 N/m = 7500 N/m

C = (7500 * 20.83^2) / (127 * 3) ≈ 316117.61 / 381 ≈ 829.39 N/m

Step 2: Calculate the centrifugal load as per IRC-21: IRC-21 provides additional guidelines for calculating the centrifugal load, taking into account the bridge type and radius of curvature.

Given data: Span of the bridge (L) = 12 m Width of carriage way (B) = 7 m Design speed (V) = 75 km/hr Radius of curvature (R) = 3 m

IRC-21 recommends using the formula C = WV^2 / (127 * R) for calculating the centrifugal load.

C = (W * V^2) / (127 * R)

Using the same vehicle weight per unit length (W) as obtained from IRC-6 (7500 N/m), we can calculate the centrifugal load (C) as per IRC-21:

C = (7500 * 20.83^2) / (127 * 3) ≈ 316117.61 / 381 ≈ 829.39 N/m

Both IRC-6 and IRC-21 yield the same value for the centrifugal load, approximately 829.39 N/m, based on the given load data.