按照现行我国规范的要求，设计了平面形状分别为矩形和 L 形的2组钢筋混凝土框架结构，变化的主要参数分别为矩形平面的长宽比、L 形平面的外凸长度与相应投影方向总尺寸的比值。采用 OpenSees 建立了各组结构的三维有限元计算模型，参考 FEMA P695提供的方法对结构进行增量动力分析，得出了各个结构的最大层间位移角-与第一自振周期谱加速度值关系曲线，进而计算了罕遇地震时的抗倒塌储备系数 CMR 和倒塌概率，研究了上述各设计变化参数对结构抗倒塌能力的影响规律，并对比 L 形平面结构设置抗震缝与不设置抗震缝抗倒塌储备系数的变化情况。结果表明：矩形平面结构随着平面长宽比的增加，结构的抗倒塌能力逐渐降低；随着 L 形平面凸出长度与相应投影方向总尺寸比值的增加，结构的抗倒塌能力先增加、后减小，但总体变化不显著；对于平面形状为 L 形的结构，不设抗震缝的平面不规则结构与设置抗震缝的平面规则结构相比，结构的抗倒塌能力变化不显著，因此，从抗倒塌能力的角度看，对于 L 形平面建议不需要设置抗震缝。%There were many buildings with irregular planar shape.Chinese codes set specific limits on the regularity of buildings' planar shape.Two groups of reinforced concrete frame structures were designed in this study according to the Chinese codes, whose planar shapes were rectangular and L-shaped.The parameters of planar shape for the frame structures were length-width ratio of rectangular planar shapes,projection ratio (the protruding length to the total length in the projection direction)of L-shaped planar shapes.3D finite element models were developed by OpenSees in this study.The incremental dynamic analysis method was adopted to calculate those frames'IDA curves and CMR,which was the collapse margin ratio of the buildings. Effects of planar parameters on the structure probability of collapse were analyzed according to the FMMA P965 and the CMR of L-shaped structures having seismic joint was compared with that without seismic joint.The results showed that with the increase of length-width ratio of rectangular planar structures,the collapse resistance decreased.When projection ratio of L-shaped struc-tures increased,its collapse resistance slightly increased to some extent but began to decrease.By comparing the collapse resist-ance of structure with seismic joints with that without seismic joints,it was suggested that L-shaped structures do not need seis-mic joints.
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