FINITE ELEMENT ANALYSES ON CORRODED PONY TRUSS BRIDGE FOR REASONABLE MAINTENANCE

Abstract

The load bearing capacity of an existing corroded pony truss bridge, which is used for 100 years was estimated from FEM results for whole bridge model. The beam element model is to clarify that the influence of the residual out-of-plane deformation in main truss structures on the load bearing capacity from the viewpoint of whole bridge. Also, shell element model is to clarify that the influence of severe corrosion damages occurred in many structural members on the load bearing capacity as whole bridge. On the other hand, the influence of assumed support conditions in analytical models were discussed from the analytical results of both type of models, because it will be thought that the performance of shoes deteriorates gradually by long in-service period. The ultimate load bearing capacity was estimated by the critical live load magnification. From the analytical results, the residual out-of-plane deformation of main truss structures in this bridge had little influence on the ultimate load bearing capacity. Also, the ultimate load bearing capacity may decrease up to 20% due to aging deterioration of shoes including corrosion damages. In bridge maintenance, it should be paid attention on local severe corrosion damages on the structural member, which may occur higher secondary stress.