Modeling the performance of reinforced concrete slabs cast with high-performance concrete under fire

As a result of the rapid population increase and the limited construction land area, there was a need to construct high-rise buildings. This led to development of a new type of concrete with enhanced properties named high-performance concrete (HPC). Civil engineering is facing the tremendous challenges of fire damage building construction and service. This paper presents a finite element (FE) modeling to predict the thermal and structural behavior of reinforced concrete (RC) slab made-up of different concrete types subjected to fire. Five concrete types including normal strength concrete (NSC), high-strength concrete, fly ash-concrete, HPC with polypropylene fiber (HPC-PP) and HPC with steel fiber (HPC-SF) were modeled under ISO834 standard fire curve. Two stages of analysis are carried out using FE ABAQUS to find the thermal and structural behavior of the RC slab. The first to be used in transient thermal analysis, to evaluate the thermal behavior of the RC slab, and the second to be used in a transient structural analysis, where mechanical and thermal loads are used to obtain the structural behavior of the RC slab. Moreover, parametric study has been conducted to demonstrate the effect of load intensity, aggregate types, concrete cover thickness, slab thickness, concrete tensile strength, and steel yield strength on the behavior and fire resistance of slabs cast with NSC and HPC-SF. The results of the proposed model showed that the behaviors of RC slab under fire depend on the concrete types. NSC recorded the higher deflection, where HPC-PP recoded the smallest deflection. HPC-PP fiber proved better fire resistant than other concrete types in lower deflection and lower reinforcement temperature. Concrete cover and concrete slab thickness significantly delayed the failure of slabs exposed to fire. In contrary, increases load intensity lead to decrease the fire resistance for both concrete types. Concrete tensile strength has minor effect on RC slab deflection.