考虑桥墩剪切破坏的不规则桥梁排架抗震分析模型

Seismic Analysis model for Irregular Bridge Bents Considering Shear Failure of the Piers

基于OpenSees数值分析平台的纤维梁柱、剪切弹簧和转动弹簧单元,建立了考虑桥墩剪切破坏的不规则桥梁排架抗震数值分析模型.其中纤维梁柱单元模拟桥墩、盖梁弯曲变形,剪切弹簧单元模拟桥墩剪切变形,转动弹簧单元模拟纵筋拔出变形.基于圆形截面桥墩抗震试验结果,并结合数值分析手段建立了桥墩剪切破坏时塑性铰区转角计算公式.并以此公式为基础,监测数值模型中桥墩剪切破坏,剪切破坏前桥墩以弯曲反应为主,剪切破坏后桥墩侧向强度和刚度发生显著退化.最后以3座实际不规则桥梁排架为工程背景,进行了排架横桥向地震作用下的滞回性能分析.研究表明,所建立的抗震分析模型可有效模拟由于桥墩剪切破坏造成的强度和刚度退化,为不规则桥梁结构抗震性能分析提供了依据.

Seismic analysis model for irregular bridge bents considering shear failure of the piers was built based on Open Sees platform. The seismic analysis model for the bents consisted of fiber beam-column element that connected in series with shear spring and rotational spring elements.Fiber beam-column element was used to model the flexural deformation of the piers and cap beams,while shear and slip deformation of the piers were modeled by shear spring and rotational spring elements,respectively. A shear failure model relates shear failure to circular pier end rotation,was derived based on collected test results and numerical analysis,and the model was used to monitor shear failure initiation of the bridge piers in the seismic analysis model for irregular bridge bents. Before shear failure,the seismic behavior of the pier was dominated by flexural response. Once shear failure was detected,the seismic analysis model initiated lateral-strength and stiffness degradation. At last,the hysteretic behavior of 3 irregular bridge bents under bridge transverse seismic action are simulated by the proposed seismic analysis model,and the strength and stiffness degradation of the bents as a result of the pier shear failure could be predicted. The model would provide references for seismic analysis of irregular bridges.