Postfire Performance of Prestressed Concrete Hollow-Core Floor Systems with Edge Beams

Abstract

This paper presents experimental results and numerical simulation of postfire structural performance of prestressed concrete hollow-core floor slabs with edge beam supports. In total, four tests were carried out, including one test at room temperature and three postfire tests. The three postfire tests all had a load ratio of 0.3 and were exposed to 30, 60, and 90 min of the a standard fire before being cooled down and tested at ambient temperature to determine their residual postfire load-carrying capacities. All specimens exhibited flexural failure with rupture of the bottom pretensioned steel rebars. All three heated specimens suffered degradation in initial stiffness and load-carrying capacity compared with the ambient-temperature specimen. However, the residual deflections of the postfire test specimens were within serviceability deflection limits, and the specimens achieved load-carrying capacities greater than the design load-carrying capacity of the undamaged slab. This indicates that the fire-damaged slabs can be reused after superficial repair. This good postfire performance of the slabs can be attributed to restraint effects of the supporting beams. Numerical simulations were performed to further investigate the load-carrying mechanism of prestressed concrete hollow-core floor slabs.