No abstract

Bridge collapse events are common in major earthquakes around the world, among which continuous girder bridges are the most involved. In order to explore the collapse mechanism of a continuous girder bridge in an earthquake, the collapse mode of a two-span continuous girder bridge specimen which had been studied by the shaking table test was analyzed. Then, on the basis of the conventional plate rubber bearing system, the collapse control strategies which were high damping rubber bearing, fluid viscous damper, lock-up clutch control methods were discussed. It is found that high damping rubber bearing can delay the collapse time but the collapse mode remains the same; lock-up clutch has the best displacement control effect for the superstructure, but its energy consumption performance is not as good as that of a fluid viscous damper; high damping rubber bearing is quite suitable for protecting the substructure under short-period ground motion to avoid the bridge collapse caused by the failure of piers; fluid viscous damper and lock-up clutch are suitable for protecting the superstructure under long ground seismic motion to avoid the bridge non-use resulted from girder lowering; three collapse control methods can improve the anti-collapse ability of the bridge specimen, although no matter which control method is used, the bridge specimen may still collapse under strong earthquakes, but the target of postponing collapse time can be realized by means of various effective control methods.

The continuous girder bridge is the main type of small- and medium-sized bridges; however, it has poor collapse resistance and suffers frequent earthquake damage. In order to grasp its collapse mechanism and clarify the internal and external factors affecting its collapse resistance, a 1:3-scaled, two-span bridge model subjected to shaking table test research was taken as the research object. The factors such as seismic characteristics, multi-directional seismic coupling, span, pier height, and structural system type were analyzed to determine the influences on the collapse mode of the bridge. The numerical results showed that different ground motion characteristics led to different collapse modes. Vertical ground motion had little effect on the structural response of the bridge. The change of span and pier height significantly changed the collapse resistance. A seismic isolation design could improve the anti-collapse performance, but the collapse mode varied with the system. The final anti-collapse design suggestions could provide reference for the seismic reinforcement of existing continuous girder bridges and the seismic design of continuous girder bridges that will be constructed.