Keywords: grillage analysis, finite element analysis, rail bridge, skew effect, skew angle, bending moment, support reaction, IRS 25t-2008 loading standard..

The effect of skew angle on the bridge components is studied using grillage analysis for the IRS 25t-2008 loading standard. The two girder bridge system considered for analysis is meant for a single railway broad gauge track. Fifty superstructures are analyzed for five mostly adopted girder spans on the Indian Railways i.e. 12.2 m, 18.3 m, 24.4 m, 30 m and 40 m with skew angles ranging from 1 degree to 55 degrees; results are presented. The reduction in bending moment is more for shorter spans when compared with longer spans. The reduction in bending moment with an increase in span is a result of a decrease in loaded length. The variation in bending moment between two girders is on account of one side footpath for a load combination under consideration. In the absence of a footpath the live load will be shared approximately equally by both the girders. The acute corners are lifted up by the same amount as obtuse corners are subjected to more reactive forces with an increase in skew angle. With increases in the skew span and skew angle, the support reaction becomes too low at the two corners and too high at the other two opposite corners. On nearly square spans the reactions are evenly distributed.

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