基于OpenSees的铁路高墩桥梁弹塑性地震响应研究

Research on Elastic-Plastic Seismic Response of High Pier of Railway Bridge Based on OpenSees

为跨越山谷、河流、公路或其他铁路线路等障碍,铁路桥梁在设计和修建时常采用高墩形式。高墩桥梁在地震作用下具有空间变形特性导致其易受震害,而现有国内外规范对于此类桥梁的抗震设计仍存在盲区。以新建铁路宝鸡至兰州客运专线新店子特大桥为研究对象,基于OpenSees程序对高墩桥梁的弹塑性动力响应及单向激励下的双弯曲现象进行了分析。研究表明,高墩在地震作用下易在墩高中间位置产生塑性区;由于混凝土不对称开裂造成形心在垂直于振动方向产生偏移,则在地震作用下产生垂直于激励方向的弯矩,即在单向地震作用下产生双向弯曲;产生双向弯曲的桥墩,其附加弯矩随着地震激励的增强而增大。

High piers are often used in the design and construction of railway bridges to cross obstacles such as valleys,rivers,highways or other railway lines.High pier bridges have spatial deformation characteristics under earthquake,which makes them vulnerable to earthquake.However,there is still a blind area in the seismic design of such bridges in the existing codes at home and abroad.Taking Xindianzi Bridge of Baoji-Lanzhou Passenger Dedicated Line as the research object,the elastic-plastic dynamic response and double bending under unidirectional excitation of high pier bridge are analyzed based on OpenSees program.The results show that the high pier is easy to produce plastic zone in the middle of the pier height under earthquake;when the centroid deviates in the direction perpendicular to the vibration due to the asymmetric cracking of concrete,the bending moment perpendicular to the excitation direction will be generated under the action of earthquake,that is,the two-way bending will be generated under the action of one-way earthquake;the additional bending moment of the pier with bi-directional bending increases with the enhancement of seismic excitation.