Performance Evaluation of a Stone Masonry–Arch Railway Bridge under Increased Axle Loads

Abstract

Many of the masonry arch bridges in the network of railway bridge stock belong to the civil engineering heritage of the railways. Therefore, their maintenance and management require careful consideration. An effective procedure for performance evaluation should promote solutions that are directed toward preservation and restoration of arch bridges by evaluating their existing structural capacity. In this paper, experimental methodologies adopted for the performance evaluation of a stone masonry–arch railway bridge are presented. One of the primary objectives of the current study was to evaluate the longitudinal force exerted on the bridge due to increased axle loads of freight wagons. An innovative technique using a flat jack was implemented for the evaluation of longitudinal stress due to increased axle load. Three-dimensional numerical modeling and analysis was carried out to identify the critical locations for fixing the flat jacks for evaluation of live-load stresses. A special instrumentation scheme with which very low strain can be measured was adopted for the evaluation of pier strains. From the field study, the maximum deflection under dynamic test conditions was found to be 0.465 mm and this is within the permissible limit. From the dynamic response measured using the flat jack, the maximum longitudinal stress in the arch due to tractive effort was approximately 0.3 MPa. It has been evaluated that the maximum longitudinal force (per rail) at rail level is 12.31T in the instrumented span. The responses measured from the bridge are within permissible limits. The methodology developed and implemented for the performance evaluation of arch bridges would pave the way for undertaking better and timely maintenance strategies.