Numerical assessment of the dynamic load allowance on long-span modular steel bridges considering vehicle-bridge interaction

Abstract

Dynamic effects caused by vehicles on bridges is a key aspect to consider on the designing, monitoring and maintenance of the roadway infrastructure. This is particularly important in the case of modular truss bridges as they face operational restrictions when spans lengths are larger than 60 m. In the recent years, new efforts are being directed to develop fully-functional modular steel bridges of substantially larger spans. For this purpose, it is essential to fully understand the dynamic effect of vehicles on such structures. This paper provides a detailed study on two modular steel bridges considering span lengths from 120 to 140 m. A 3D coupled vehicle-bridge model is used to simulate the vehicle-bridge interaction and evaluate the dynamic load allowance of the structures. Different profiles of road irregularities are generated and their influence is investigated. The results reveal the importance of defects that excite vertical bouncing modes of the vehicle. The effects of considering different span lengths and vehicle speeds are also discussed. Finally, the dynamic load allowance obtained for the bridges under study is compared to that calculated with the expressions given in several design codes.