Effect of Slab Type on Progressive Collapse of Reinforced Concrete Buildings: A Case Study

This study examines the influence of slab type on the progressive collapse resistance of reinforced concrete (RC) buildings, with particular attention to one-way ribbed slabs, solid slabs, and structures without slabs. A six-story RC building in a war-affected area, designed according to ACI 318 provisions and damaged by an explosion that resulted in the loss of three fifth-floor columns, was selected as a case study. A detailed three-dimensional nonlinear dynamic analysis was conducted using the applied element method in Extreme Loading for Structures software. The numerical model was qualitatively validated against limited field data, confirming its reliability in capturing collapse behavior. A total of 18 scenarios were analyzed, considering different slab systems and multiple-column removal at various story levels. The results showed that one-way ribbed slabs significantly reduced vertical displacements and plastic rotations, with maximum values not exceeding 77.8 mm and 0.01 rad, respectively, compared to 107.71 mm and 0.0126 rad for solid slabs. In roof-level failure scenarios, ribbed slabs maintained stability within safety limits, whereas solid slabs exceeded the rotation threshold defined by UFC guidelines, and slabless structures experienced total collapse. The findings highlight the superior performance of ribbed slabs, attributed to the activation of both membrane and flexural mechanisms, and emphasize the importance of further investigation into their role in enhancing RC buildings’ resistance to progressive collapse.