LAUSR

Abstract In this study, discontinuity layout optimization (DLO) was used to investigate the effect of openings on ultimate load and collapse patterns. DLO is an automated systematic procedure used in limit analysis for engineering problems to identify critical plastic collapse patterns for plates and slabs. Studies on reinforced concrete slabs with openings are scarce. The present study examined the effect of openings on slabs having different supports and loading conditions. In this approach, after the accuracy of the opening model is verified, an opening is placed in the model. A sensitivity study is conducted on the effect of an increase in opening size and position on the load factor and slab collapse pattern when subjected to out-of-plane loading. The results indicate that the slab collapse load factor decreased under out-of-plane loading up to a specific opening-to-slab dimension ratio, followed by a significant increase in the collapse load factor above this ratio. The collapse mechanism changed significantly when compared to slabs without openings relative to its location and size on the slab. It appears that yielding of the bars at the opening corners and the formation of collapse hinges significantly affected the behavior of the slab.