Collapse Analysis and Strengthening of Stone Arch Bridges Against Earthquake

Abstract

The distinct element method (DEM) is used for nonlinear dynamic analysis of a number of stone masonry railway bridges. Since the main concern of this research is estimation of seismic capacity of stone bridges, the DEM is selected to simulate collapse of these structures. In this respect, three stone bridges of the Iran railway are studied under some important earthquakes. A finite element model (FEM) of each bridge is also defined in SAP2000 and is analyzed to derive the dynamic characteristics of the bridges. The earthquake records are applied in the transverse direction and the incremental nonlinear dynamic behavior of bridges each time with multiplying each record by a larger numerical coefficient is studied. This research shows that in the linear region, both FEM and DEM models predict almost an identical behavior for the bridges studied. In the nonlinear region and specifically at the onset of collapse, results gained using the DEM model have a good resemblance with experimental findings. The nonlinear dynamic analysis singles out arches as the most vulnerable parts of the bridge structure. Among the possibilities, it is shown that strengthening only the arches, results in a considerable increase in lateral capacity of stone arch bridges.