考虑非线性影响的下承式钢拱桥地震响应

Seismic Response Analysis of Steel Through Arch Bridge Considering Effects of Nonlinearity

为研究下承式钢拱桥的非线性地震响应和损伤机理,结合徐州京杭运河大桥工程,采用考虑非线性的计算方法,分析了下承式钢拱桥在强震作用下的地震响应和损伤情况。结果表明,下承式钢拱桥具有良好的抗震性能,在强震作用下损伤程度不明显;在考虑几何非线性与材料非线性条件下,拱顶面外弯矩显著增大;考虑非线性对结构横向振动与竖向振动位移响应的影响基本一致;下承式钢拱桥在拱脚、风撑端部及拱肋容易发生损伤;风撑作为连接构件是横向地震作用下的薄弱环节,在地震高烈度地区设计该类桥梁时,对上述薄弱环节应予以重视。

Nonlinear seismic response analysis was carried out to study the seismic response and damage mechanism of long span steel through arch bridges which were subjected to strong earthquake. Taking the Beijing-Hangzhou canal bridge in Xuzhou as an example, the seismic response and damage of the bridge under strong earthquake were calculated. The results showed that steel through arch bridges had preferable seismic resistant ability and yielded only limited damage under strong earthquake action. The moment for out of plane significantly increased when considering the geometric and material nonlinear state, while the effect of the geometric and material nonlinear state on the transversal and the vertical displacement response was consistent. Steel through arch bridge was prone to be damaged at arch base, lateral bracing and arch rib. Lateral bracings were the weakness of the structure under the lateral earthquake action. We should pay more attention to these weak parts in case this type of bridge is built in a high earthquake intensity area.