带水平分布钢支撑RC框架结构的抗连续倒塌机理分析

Progressive Collapse Mechanism Analysis of Horizontal Steel Braced RC Frames

基于备用荷载路径法,分析带钢支撑的钢筋混凝土框架结构抗连续倒塌机理.以一幢8层钢筋混凝土框架结构为原型,根据支撑在平面上沿结构横向和纵向布置方式不同以及在结构立面上布置于第二层或中间层柱间建立了5种有限元模型,采用备用荷载路径法并考虑构件失效持时的影响,根据底层柱失效位置的不同分为4种工况,对每种工况下的5种模型进行了动力非线性分析.分析结果表明:底层柱失效后,沿结构平面横向和纵向布置钢支撑均可有效提高整体拉结力,从而显著减小破坏部位竖向位移,避免造成破坏范围的扩散;钢支撑改变了框架梁的抗连续倒塌机制,使框架以桁架机制提供抗连续倒塌能力;由于水平分布钢支撑形成了加强层,为兼顾抗连续倒塌性能和抗震概念可将加强层设于结构中间楼层.

In this study, alternate path （AP） approach was conducted to investigate the mechanism of the horizontal steel braced reinforced concrete （RC） frame structures against progressive collapse. Five finite el- ement models of 8-story RC frame structure, differing in both horizontal and vertical arrangement of bracing were developed. The situation of different columns on the first floor removed was classified into four operat- ing modes. Using AP method together with considering duration of column removing, five models of four operating modes were analyzed with nonlinear dynamic analyses. The result of nonlinear dynamic analyses indicate that horizontal steel braces can improve the integrity of structures to noticeably reduce the vertical displacement above the removed columns, and cease the spreading of collapse. Steel braces can modify the progressive collapse resistance mechanism of RC frame beams to truss action. The strengthen storey which is formed by braces can be arranged in the mid floor for considering not just progressive collapse resistance but also seismic concept.