隔震斜交连续梁桥地震反应及环境温度影响研究

Seismic response of isolated continuous skew bridge and the effect of ambient temperature on seismic behavior of bridge

针对斜交桥震害特点及低温环境改变隔震支座力学特性现象,以用铅芯橡胶隔震支座的斜交连续梁桥为例,采用Hertz-damp模型考虑梁体与桥台的碰撞作用。基于OpenSees地震分析平台建立动力分析模型,分析桥墩位移、墩底反力、碰撞力、梁体旋转度与斜交桥斜度关系及梁端碰撞力分布规律。在对比不同隔震支座温度特性修正方法差异基础上,讨论隔震斜交桥梁地震反应与环境温度及斜度关系。结果表明,梁体双向水平与平面内转动耦合使梁体与桥台在其钝角处先发生碰撞,而碰撞作用会加剧梁体转动;低温引起的支座特性改变将会放大桥墩地震反应,若不计其影响,在0℃、-10℃、-30℃条件下,与常温(23℃)相比墩底剪力及弯矩会被低估10%、20%、40%。

According to the damage characteristics of skew bridges during earthquakes and the stiffness and strength of rubber bearings changing with low temperature environment,the seismic behavior of a skew bridge isolated with lead rubber bearings （LRBs）was studied.3-D nonlinear dynamic models of the bridge with various skew angles,considering the pounding between girder and abutment with the Hertz-damp impact model,were developed using the computational platform OpenSees.The distribution of pounding force on abutments with various skew angles was discussed.The seismic responses of two isolated bridges with bearing of different mechanical properties were compared with each other.By investigating the relationships between seismic responses of piers,skew angles,and various ambient temperatures,it is shown that the seismic pounding happens firstly at the obtuse corners of bridge deck due to the coupling of bidirectional translation and in-plane torsion motion of superstructure;and the in-plane rotation of skewed bridge deck is further increased by pounding response.The seismic response of isolated skew bridge is increased due to the change of mechanical properties of the LRBs by low temperature.If the effect of low temperatures is not considered,the shear and bending moment on piers will be underestimated by about 10%,20% and 40% than in the case at nomal temperature while the isolated bridge stays at low temperatures of 0℃、-10℃ and -30℃.