Effects of Bridge Accessories in Steel-Concrete Composite Railway Bridges in Service Condition

Bridge accessories, such as parapets, service ducts, and track slabs, are commonly used in railway bridges, but their real effects on the structural behavior of the bridges are still unknown because very few studies have been reported on this significant aspect. In engineering practice, lack of information on the contribution of bridge accessories may cause problems for bridge design, bridge health evaluation and monitoring, bridge management and operation, and bridge maintenance. Given this background, field tests were performed on a railway bridge with typical bridge accessories to confirm their contribution to bridge rigidity (or stiffness), as well as their effects on the sectional normal strain distribution. Both displacements in the midspan and strain results on key sections were measured in the field test and reported in this paper. Based on the field test observations, a numerical model capable of simulating the present railway bridge was built and was used to investigate the effects of the bridge accessories and their expansion joints. Longitudinal normal stress distributions on concrete slabs, steel main girders, and single-parapet panels were given, and parametric analysis considering different arrangement methods of expansion joints in the bridge accessories was also performed. Based on the numerical results, a stress concentration on the concrete slab near the expansion joints was confirmed. The results obtained in this study can be used for improving the design method used in new railway bridges and the maintenance of old railway bridge structures.