DYNAMIC ANALYSIS OF RAILWAY STEEL ARCH BRIDGE

Abstract

An arch bridge is a bridge with abutments at each end shaped as a curved arch. These bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust against abutments at either side. In this dissertation, two arch bridges, one with two ribs and another with three ribs have been modeled as three-dimensional structures with overall span length 225m and rise 50m.The Bridge, is trussed arch with ribs as steel boxes. Both of them are analyzed for dynamic loading. Due to seismic zone V and high wind speed and rocky type soil with 69m deep gorge, arch bridge has been taken for analysis. The end conditions are taken as one side fixed and one having universal ball joint. As the railway bridge is being analyzed, proper train loading for broad gauge has been considered. Wind load distribution for open structure has been done for trussed arch bridge. The bridge is open structure and accordingly proper distribution of wind load has been taken into account. The analysis has been done using STAAD Pro 2004. As there is truss arch system no moment and shear forces will act on the structure. The results have been interpreted by analyzing time period, participation factor, deflections and mode shapes. Arch bridge with two ribs shows more deflection in transverse direction, which is on higher side where as the arch bridge with three ribs is more safe to lateral and vertical deflections.