INFLUENCE OF SOIL STRUCTURE INTERACTION ON FATIGUE CHARACTERISTICS OF RAILWAY STEEL GIRDER BRIDGES

Abstract

The use of steel as a structural material is fairly widespread irrespective of the span, the obstacle and the geographical location of the bridge. However steel bridges are susceptible to fatigue damage under the action of moving load. The objective of this dissertation is to study the effect of soil structure interaction on the fatigue life of the steel girder bridges. The fatigue characteristics of two types of steel girder bridges subjected to two categories of train loadings namely MBG and HM for three types of speeds namely operating, rated and future speeds and for four different support conditions namely simply supported, pier supported, pier — abutment supported, abutment supported were studied. Moving load and dynamic analysis were performed for all the conditions, and the fatigue life was computed using Palmgrem-Miner linear damage hypothesis after decomposing the stress history using rainflow counting algorithm. From the results obtained it was concluded that the effect of soil structure interaction is insignificant for larger spans and for shorter spans in pier — abutment supported bridge it has a significant effect based on the speed of the train