Seismic collapse performance of reinforced concrete moment frame structures with plan irregularity

Abstract

SummaryTo study the effect of plan irregularity on the collapse performance of reinforced concrete (RC) moment frame structures, three groups of seven‐story RC frame structures with different plan layout, one rectangular and two L‐shaped with different dimensions, were designed and numerically studied. The length‐to‐width ratio, protrusion ratio (length of protruding part divided by the total length), and the length‐to‐width ratio of the protruding part were selected as the study parameters. The fragility curves for the collapse limit state of each structure were generated through incremental dynamic analysis, and the collapse margin ratios of the structures were derived. It is found that the seismic collapse performance of the structure with the rectangular plan is significantly affected by the length‐to‐width ratio, and setting a threshold value of 6 is reasonable. For the L‐shaped structure, the influence of the protrusion ratio and the length‐to‐width ratio of the protruding part on the average collapse resistance capacity is not significant. A larger value increases the collapse resistance under rare earthquake. Effect of setting seismic joint in the L‐shaped structure is also studied, and the results indicate that setting the seismic joint or not hardly influences its seismic collapse performance.