Seismic Resilience Enhancement of Railway Beam Bridges Based on Viscoelastic Dampers

As the seismic design philosophy of bridges gradually shifts from performance-based to resilience-oriented, the current research focus lies not only in ensuring structural safety under the action of earthquakes, but also in paying more attention to the preservation and recovery capacities of post-earthquake traffic function. Railway bridges serve as critical nodes in transportation networks, and their post-earthquake traffic capacity directly influences the operational efficiency of the lines and the recovery process of earthquake-stricken areas. Based on this, a shear-type viscoelastic damper was proposed to decrease track damage risk by controlling the relative transverse displacement of main beams, thereby enhancing the bridge’s post-earthquake traffic function. By taking a typical five-span railway simply-supported bridge as a case study, a comparative analysis was conducted on the traffic function vulnerability, post-earthquake function recovery capacity, and seismic resilience in the three constraint conditions of no constraint (NC), steel restrainer (SR) only, and SR combined with the shear-type viscoelastic damper (DP). The analytical results demonstrate that proposing the concept of a “component recovery weight coefficient” provides a quantitative index for determining the sequence of component repairs. Additionally, the proposed shear-type viscoelastic damper can significantly control the relative transverse displacement of main beams at beam ends, effectively reducing track alignment irregularity under the strong action of earthquakes and consequently enhancing the bridge’s post-earthquake traffic function. The addition of the viscoelastic damper to SR can notably shorten the post-earthquake repair time. In particular, under higher ground motion intensities, such as peak ground acceleration (PGA) of 0.8g, the repair time can be reduced by up to 9.1 days compared to the NC system. Furthermore, the DP configuration demonstrates significantly better post-earthquake residual traffic function and seismic resilience indices than the SR and NC configurations at various PGA levels. For instance, under PGA=0.4g, the post-earthquake residual traffic function improves by 20.0% and 56.9%, and seismic resilience increases by 13.1% and 34.4% respectively, confirming the remarkable effectiveness of this device in enhancing both post-earthquake traffic function and seismic resilience of bridges.