主余震作用下近海钢筋混凝桥梁的地震响应OA

To investigate the seismic response evolution of offshore bridges under the coupled effects of main-aftershock sequences and chloride-induced erosion,a time-dependent damage finite element model of a three-span,three-column simply supported bridge was established based on energy dissipation theory and static pushover analysis.Seismic time-history analysis was conducted to obtain key response indica-tors,including the maximum displacement and residual displacement at the pier top,as well as the pro-portion of cumulative hysteretic energy generated at the pier bottom during aftershocks.The results show that structural durability degradation significantly affected the seismic responses:under the same seismic excitation,the maximum pier-top displacement of long-term service bridges increased by at least 10%,with a maximum increase of up to 43%,compared with newly built bridges.When subjected to high-intensity earthquakes,the residual displacement at the pier top continuously increased with service time,rising by 66%,121%,and 163%after 50,75,and 100 a of service,respectively,compared with new bridges.Aftershocks induced noticeable cumulative damage at critical locations such as the pier bottom,with the cumulative hysteretic energy accounting for an average of 14.08%of the total energy dissipation during the main-aftershock sequence,reaching a maximum of 25.3%.Therefore,it is recommended that both the energy contribution of aftershocks and the effect of durability degradation be considered in the seismic design of offshore bridges.