EFFECT ON SUPPORT REACTIONS OF T-BEAM SKEW BRIDGE DECKS

T-beam Bridge is a common choice among the designers for small and medium span bridges. In order to cater to greater speed and more safety of present day traffic, the modern highways are to be straight as far as possible. This requirement, along with other requirements for fixing alignment of the bridges, is mainly responsible for provision of increasing number of skew bridges. The presence of skew in a bridge makes the analysis and design of bridge decks intricate. For the T-beam bridges with small skew angle, it is frequently considered safe to ignore the angle of skew and analyze the bridge as a right bridge with a span equal to the skew span. However, T-beam bridges with large angle of skew can have a considerable effect on the behavior of the bridge especially in the short to medium range of spans. In this paper a study on the behavior of T-beam skew bridges with respect to support reactions under standard IRC-70R wheeled loading is presented and the study was based on the analytical modeling of T-beam bridges by Grillage Analogy method. Effects of support reactions for different spans have been studied. The analysis provides the useful information about the variation of support reactions with respect to change in skew. The negative reactions were observed with increase in the span and skew angles. It was found that in skew T-beams bridges, the high positive and negative reactions develop close to each other. Negative reactions were very less in the 8m right span and introduced at an angle of 500 and onwards, while for 16m right span it was introduced an angle of 300. In 24m and 32m right spans the negative reactions develops at smaller skew angles (i.e. 200 and onwards)