A Study on Moment–Curvature Relationships for REINFORCED CONCRETE BEAMS with Varying Fire Loading Conditions

In this paper, a numerical study by three-dimensional modeling is done for reinforced concrete beam exposed to fire conditions with various boundary conditions. Both geometric and material properties are taken into account in this formulation because of the changes in material properties and the large variations experienced in fire. The three stages associated with the numerical procedure for evaluating fire resistance of RC beams, namely fire temperature calculation, thermal analysis, and strength analysis are modeled using a finite element (FE) model. The FE model is prepared in ABAQUS software to study the response of an RCC beam under fire during loading conditions. The RCC beams are analyzed for different end conditions and fire loading surfaces. Initially, it is kept at 25 °C. Then the uniform loading of one-third of the compressive strength of concrete is applied as a pressure loading in the beam (3D solid element). The other faces of RCC beam have temperature boundary conditions. The temperature boundary condition is governed by temperature–time curve as per ASTM E119. The moment–curvature (M–k) relationships are developed for the beam at few critical positions of the RCC beam for various end conditions as well as temperature boundary conditions. These M–k relationships may be used to carry out the strength analysis of the beam member and draw significant conclusions.