Mechanism and Parametric Analysis of Multi-Level Control Mode of Unseating Failure Prevention for Concrete Girder Bridge during Earthquakes

Based on the ideas of passive energy dissipation, multi-failure and damage reduction, a multi-level control mode of seismic unseating failure for concrete girder bridge is presented. The control mode, respectively, provides: (1) displacement restriction by energy dissipation-based pier-girder connection mode; and (2)unseating prevention by girder-girder connection mode. The two-level control modes can be automatically transformed according to the preset threshold value of "structural fuse". Firstly, the analysis model of the multi-level control mode is established and the control mechanism is investigated. Furthermore, the nonlinear seismic responses of a concrete girder bridge equipped with multi-level control mode are analyzed based on a simplified mechanical model to examine the control effectiveness. Finally, parametric influence laws of unseating failure control effectiveness are researched. It is found that the multi-level control mode can achieve unseating failure prevention and structure safety protection effectively for girder bridges during earthquakes.