As defined in Wind Load on Substructure, the wind angle is the angle between the normal to the longitudinal direction of the bridge and wind direction, positive if anti-clockwise, measured from the normal of the bridge to the wind direction. The wind load on live load depends on the wind angle and live load length. It is calculated by multiplying the wind pressures in transverse and longitudinal directions with the live load lengths. Then, it is resolved into pier cap X and Z-directions (global coordinates) if the bridge is on skew.

Program computes pressure based on plain terrain or terrain with obstruction as explained in wind on structure section. It uses the length of live load as 50% of span 1 + 50% span 2 or user defined length. As per clause 212.3.6, IRC 6-2000, exposure area for live load is computed:

Area= Length X 3

Transverse force acting on live load is computed as Pz X A1 X G X Cd, Longitudinal force is computed as 25% of transverse force.

Both transverse and longitudinal force are applied at a distance of 1.5 m above the road surface.