考虑楼板效应的钢框架结构连续倒塌分析

Progressive Collapse Analysis of Steel Frame Structures under Floor Slab Influence

基于抽柱法对GSA2003建议的角柱失效、边柱失效及内柱失效三种工况对一钢框架结构进行了连续倒塌模拟。通过对比不同失效时间这三种工况下剩余结构竖向位移时程曲线、静力及动力荷载作用下抗力提高系数曲线来探究楼板对结构抗连续倒塌能力的影响。以1/10剩余结构竖向自振周期T2/10为失效时间,探究在抽柱后,楼板对剩余结构传力路径的影响作用。结果表明:失效时间越短,纯框架结构振动响应越明显,含楼板结构仅在角柱失效工况下失效时间对结构振动响应影响明显;以T2/10可较好的反映构件失效后剩余结构动力响应,忽略楼板作用可能低估结构抗连续倒塌能力,边柱失效及内柱失效工况下楼板对结构抗连续倒塌能力改善较明显;通过抗力提高系数R可知,失效时间较长时,动力分析与静力分析结构比较接近,可采用静力分析代替动力分析;楼板加速结构新传力路径的形成,提高了结构整体稳定性,提高了结构的抗连续倒塌能力。

Based on the column extraction method recommended by GSA2003,the progressive collapse of a steel frame structure under three column failure conditions,corner column failure,side column failure and inner column failure,were simulated.By comparing vertical displacement time-history curves and resistance improvement coefficient curves of the remaining structure at different failure times under static and dynamic loads and those three failure conditions,the influence of floor slab on progressive collapse resistance was discussed.Taking 1/10 of the remaining structure’s vertical natural vibration period of,T2/10,as the failure time,the influence of floor slab on force transmission path of the remaining structure was explored after column extraction.The results show that:the shorter the failure time,the more significant the vibration response of the pure frame structure;when influence of floor slab was taking into consideration,the failure time only has a significant effect on the structural vibration response under corner column failure condition;T2/10 can well reflect the remaining structure’s dynamic response after the failure of the structure;ignoring the influence of floor slab may underestimation the structure’s ability to resist progressive collapse;under the conditions of side column failure and inner column failure,the floor slab’s resistance is more significant.According to the study of resistance improvement coefficient R,it is known that the structure’s dynamic and static analysis results are close when the failure time is lo ng.Thus,static analysis can be used instead of dynamic analysis.The existence of floor slab can accelerates the formation of new force transfer path,improve the overall structure stability,and improve the structure’s ability to resist progressive collapse.