Seismic response analysis of turnout girder bridges and vibration mitigation application design with MTC devices

Abstract

Due to their geometric and structural irregularities, turnout girder bridges are particularly vulnerable to various forms of seismic damage. Therefore, it is essential to investigate their seismic response characteristics and develop appropriate mitigation strategies. This study focuses on a double-track-to-single-track turnout girder bridge on a high-speed railway and examines the influence of seismic environmental parameters on its dynamic response. A seismic mitigation approach is proposed based on a Multi-Stage Timely Control (MTC) connection device, and its effectiveness is evaluated through a combined assessment involving seismic reduction ratios and energy-based analyses. The results indicate that: 1) The direction of seismic incidence strongly influences the seismic response of turnout girder bridges. Relying solely on longitudinal and transverse analyses is insufficient for a comprehensive evaluation of seismic safety and stability. 2) The proposed MTC-based mitigation method effectively addresses both longitudinal and transverse seismic demands, overcoming the limitations of traditional longitudinal-only control strategies under oblique seismic excitations. It also optimally utilizes the seismic energy absorption potential of movable piers, reduces the vulnerability of fixed piers, and significantly suppresses girder displacements. 3) The MTC device efficiently reduces both cumulative and peak energy responses under seismic loading, with its hierarchical damping and energy dissipation mechanisms demonstrating adaptability to varying seismic intensity levels.