大跨度上承式钢桁架拱桥的地震损伤演化模拟

为评估大跨度钢拱桥在多维地震作用下的损伤状态，以一座铁路上承式钢桁架拱桥为研究对象，首先借助OpenSEES平台建立桥梁弹塑性纤维单元模型；接着选取“双参数”损伤指标和应变指标进行损伤评价；最后通过增量动力分析，从构件和全桥两个层面进行损伤评估，并对比两种指标对桥梁主要构件（钢管、钢管混凝土、钢筋混凝土）的适用性. 研究结果表明:基于变形和能量的双参数损伤指标比应变指标的评价结果会严重1～2个等级；相比于地震波纵向作用，大跨度钢桁架拱桥在横向地震作用时损伤更小，在峰值加速度（PGA）为1.5g时全桥仍处于轻微损伤状态；3种类型构件中，钢管构件损伤数量较多但是损伤程度轻，钢管混凝土构件（拱脚）损伤较早但是损伤程度轻，钢筋混凝土构件（交界墩）损伤最为严重，在抗震设计时，应对相应位置予以重视. 

Seismic Damage Evolution Simulation of Long-Span Deck Steel Truss Arch Bridge

To evaluate the damage state of a long-span steel arch bridge under multi-dimensional earthquake loadings, a deck steel truss arch bridge was studied. A bridge elastoplastic fiber element model was established by OpenSEES code. Two damage index, i.e., strain and two-parameter damage index were selected for damage evaluation. The damage assessment of both members and the whole bridge were obtained by incremental dynamic analysis (IDA). Moreover, the applicability of two damage index on the main members of the bridge (steel pipe, concrete-filled steel tube, and reinforced concrete member) was compared. The results show that the assessment result by the two-parameter damage index based on deformation and energy may lead to 1?2 damage assessment levels worse than by strain damage index. Less damage is caused when the identical earthquake loading is input in transverse direction than longitudinal direction. The full bridge is still in a slightly damaged state when the peak ground acceleration (PGA) is 1.5g. Among three types of members, the damage quantity of steel tube members is large but damage state is slight. The damage of concrete-filled steel tubular members (arch feet) comes early but damage state is slight. The damage state of reinforced concrete members (joint balance pier) is the most serious. Attention should be paid to the corresponding structural locations in seismic design.