Effects of design parameters on the fire resistance of reinforced concrete slabs exposed to fire

Abstract

This paper presents research results on the effects of design parameters on the fire resistance of reinforced concrete (RC) slabs exposed to fire. The results of this study were based on simultaneous thermal-mechanical analyses of RC slabs exposed to ISO 834 fire. SAFIR software was used to analyse the deflection with respect to fire time. The results of thermal analysis were used for mechanical analysis to determine the deflection of RC slabs. The research results showed that the deflection-fire time relationship of RC slabs can be divided into three phases: phase one was almost linear, phase two was a transitional phase, and phase three was the collapse phase. Furthermore, the results indicated that the fire resistance of RC slabs increased by 35.7% when the thickness of the concrete cover increased from 12.5 mm to 20 mm. The fire resistance of RC slabs increased by 31.8% when the thickness of the slabs increased from 7 cm to 9 cm. Especially, the fire resistance of RC slabs increased by 93.3% when the steel area increased from 141 mm2 to 452 mm2. These results indicated that, among the considered parameters, the steel area plays the most important role in the fire resistance of RC slabs.

Keywords: Reinforced concrete slabs; behaviour; deflection; fire; fire resistance.