Experimental Investigation of Damage and Failure Modes in Stirrupless Reinforced Concrete Beams under Varied Thermal-Mechanical Loadings

Abstract

In light of the potential deviation in damage and failure modes of reinforced concrete components during a fire compared to their design expectations at room temperature, this study aims to comprehensively investigate the failure modes of RC beams under various thermal-mechanical loadings. The experimental program encompasses a range of scenarios such as constant load followed by heating, heating followed by load, single-sided and three-sided fire with a constant load, among others. Large-scale fire tests were conducted on stirrupless RC beams subjected to four-point bending, and the progression of damage was meticulously monitored to evaluate the influence of high temperature on the failure modes of the beams. The findings of the study indicate that beams initially designed for bending failure at room temperature may exhibit either bending failure or shear failure under high-temperature conditions. Additionally, beams originally designed with sufficient shear strength but weaker bending capacity at room temperature may demonstrate inadequate behavior when exposed to elevated temperatures. Consequently, it is highly recommended to employ refined modeling and analysis techniques in order to comprehensively assess the response of RC members, rather than relying solely on predictions based on room temperature behavior. This experimental investigation significantly contributes to our understanding of the bending-shear damage mechanism and failure modes of RC beams in fire, providing a crucial foundation for advancing behavior simulations and performance predictions of RC members or structures under fire conditions.