横桥向地震作用对钢拱桥地震损伤发展的影响

为了研究横桥向地震作用对钢拱桥结构地震损伤发展的影响，以一座实际中承式钢拱桥为对象，建立考虑损伤区局部变形影响的全桥混合有限元（FE）模型. 通过对结构进行不同峰值加速度地震作用下的弹塑性地震反应计算，对比分析在空间三维地震作用和仅在桥梁面内地震作用下钢拱桥的损伤发展情况. 结果表明，横桥向地震动输入虽然不改变钢拱桥面内的位移时程响应及地震塑性损伤区域的分布位置，但会增大钢板发生局部变形的程度并加速焊接节点超低周疲劳损伤的发展，从而增大结构发生局部失稳破坏和超低周疲劳破坏的可能性. 在钢拱桥的抗震设计中宜同时考虑3个方向的地震作用，以确保结构的抗震安全.

Effect of transverse earthquake action on development of seismic damage of steel arch bridges

A real half-through steel arch bridge was considered as an example in order to analyze the influence of transverse earthquake action on the seismic damage development of steel arch bridges. A full-bridge hybrid finite element (FE) model considering local deformation effect in the damaged zone was constructed. Damage development of the steel arch bridge under three-dimensional and in-plane earthquake actions were compared according to elastoplastic seismic response calculation results under seismic loads with different peak accelerations. Results show that input of transverse ground motion will not change the in-plane displacement response and the location of plastic damaged zone of the steel arch bridge, but will increase the degree of local deformation of steel plates and accelerate the development of ultra-low-cycle fatigue damage at welded joints, thus increase the risk of localized instability and ultra-low-cycle fatigue failure of the structure. Three-dimensional earthquake actions should be considered to ensure the seismic safety of structures in the seismic design for steel arch bridges.