Stress distribution and failures in partially overloaded support-removed flat slab floors

Although concrete slabs have an extensive use in structures due to their architectural and executive benefits, the suitability of their behavior against the progressive collapse phenomenon has always been questioned. This study numerically investigates the step-by-step behavior of a support-removed flat slab floor with square panels under the effect of partial overloading. After validation of the modeling method, parts of the designed floor are exposed to increasing downward and uniformly distributed loading during three separate analyses that correspond to the removal of supporting corner, penultimate and interior columns. The pattern of stress in the slab reinforcement and propagation of cracks in the concrete are presented. The findings showed high concentration of slab damage around the corner columns located in the perimeter of overloaded panels and highlighted the role of slab add bars embedded in the vicinity of exterior columns against failure. It was also shown that, unlike the frame-type structural systems, stress redistribution occurs considerably along the diagonals of the slab panels directly connected to the failed support.