DYNAMIC PIER REACTIONS IN CURVED METRO BRIDGES UNDER MOVING AXLE LOADS

Abstract

Curved metro bridges produce lateral forces due to the centrifugal actions by moving trains. Due to these forces ,pier experiences fluctuating reactions which may influence the behaviour and safety of that structure. The present study focuses on analysis of loading spectra on curved metro bridge piers due to moving centrifugal loads of a metro train of 8 coaches. Different span length (from 4m to 60m) model is developed consisting deck elements and piers in STAAD.Pro. The metro train was represented using moving axle point loads having equally distributed centrifugal force on each axles. The simulation of train movement was done by shifting the axle loads in small increments across the bridge, and for each loading position the horizontal reactions are developed at the pier. The loading spectra were generated for various spans and then compared to study the variations in maximum centrifugal reaction and dynamic component. The different results obtained indicates the changing significant loading behaviour with span length. The spans approximately close to the multiples of coach length exhibit negligible dynamic fluctuations, whereas shorter and certain intermediate spans showed considerable oscillatory behaviour and very high dynamic components. The study illustrates the importance of selection of span in controlling the dynamic effects in curved metro bridges. The generated loading spectra can further be used for the time-history and dynamic analysis of bridge piers under moving train loads for considering different parameters.