A study on longitudinal displacements and damage control of expansion joints of long-span steel bridges under stochastic traffic loads

An expansion joint is one of the vulnerable bridge parts, and for long-span steel bridges, which are vibration sensitive due to high flexibility, their expansion joints encounter more significant damage. To control the damage of expansion joints of long-span steel bridges, an approach for analyzing the displacements of expansion joints under stochastic traffic flow was established, based on the stochastic vehicle model and finite element analysis. The influence of speed, vehicle-induced vibration frequency, traffic volume and heavy traffic on longitudinal displacements was investigated, and it is found that with higher vehicle speed and vibration frequency, larger traffic volume and more heavy vehicles, the cumulative displacements of expansion joints significantly increase. Two kinds of traffic limit measures and installing viscous dampers at beam ends are suggested, so as to control the damage of expansion joints. Analysis results show that the vehicle-type based measure is more effective than the time-based measure. After the use of viscous dampers at beam ends, there is a significant reduce in displacement amplitude, cumulative displacement and high-frequency displacements. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.