Evaluating progressive collapse in multi-story buildings: Influence of slabs and building height

The loss of a load-bearing element, in a building can occur due to various factors and may trigger progressive collapse. The partial collapse of the Ronan Point Apartment in 1968 greatly increased awareness of progressive collapse, which is reflected in the growing number of related publications. This study investigates the progressive collapse behavior of multi-story buildings with and without slabs. In the models without slabs, the load that is expected to be transferred from the slabs to the beams was externally applied to the beams. Additionally, the study considers five different building heights, and evaluates the results based on UFC guidelines. More than 240 removal scenarios, covering six different locations on the building plan and varying story heights, were simulated using the ELS software. The results show that as the number of stories increases, displacements due to column removal generally decrease. Buildings designed to withstand seismic forces demonstrated efficient resistance to progressive collapse, with no significant plastic rotations observed, provided the slab contribution was included in the model. In contrast, models without slabs experienced collapse in all scenarios. This study highlights the importance of including slab contributions in simulations, as neglecting them can lead to inaccurate results. Furthermore, after the loss of a column, initial failure was often observed at the end of the top reinforcement in the beams connected to the removed column. By extending the length of the top reinforcement in the beams, the location of the initial failure shifts to the face of the adjacent column.