外廊式RC框架破坏机理的振动台试验研究

通过地震现场调查，对汶川地震中大量倒塌的外廊式钢筋混凝土框架结构的破坏特点、倒塌方向及堆积情况进行了总结。设计相似比为1/4的两层外廊式框架结构模型，并进行了振动台框架倒塌试验。试验再现了典型外廊式框架的倒塌过程。根据框架倒塌模式及试验结果分析，研究了各层加速度反应随结构破坏程度加深的关系及层间位移角变化规律。总结出框架结构破坏不同阶段所对应的层间位移角限值，计算了不同输入下各柱的动轴压力大小，分析了外廊式框架的破坏机理及倒塌原因。研究结果表明：在倾覆弯矩引起的动轴压力作用下，外廊式框架单柱侧的总轴压比升高，延性显著降低，柱端塑性铰区出现压剪破坏是引起外廊式框架倒塌的主要原因。

SHAKING TABLE TEST ON FAILURE MECHANISM OF RC FRAME WITH EXTERIOR CORRIDOR

Through site investigation of collapsed RC frames with exterior corridor (RCEC frame) in Wenchuan earthquake, the damage characteristics, collapse directions, and accumulation conditions were summarized. A scale model of a two-story RCEC frame with similarity 1/4 was designed and tested on a shaking table. The collapse process of the typical frame was reproduced in the test. From the analysis of collapse modes and test results, the relationship of the acceleration response of each floor are studied, which is corresponding to the structural damage and variation of story drift angles. The story drift angle limits reflecting different damage stages of the frame are analyzed and the dynamic axial compressions of each column are calculated. Then the failure mechanism and collapse causes of an RCEC frame are discussed. The experimental results show that the gross axial compression ratio of exterior corridor columns rises and ductility severely reduces under the dynamic axial compression caused by toppling moment, and that the crush of core concrete in the plastic hinge area of a column end is the main cause of the collapse of an RCEC frame.