Experimental and numerical investigation on ductility of composite beams in the Hogging moment regions under fire conditions

This paper presents both the results of an experimental program and numerical simulations, which have been conducted to investigate the ductility of composite beams in the hogging moment regions under fire conditions. The main objective is to study the ductility issue related to the inelastic behavior of composite beams at an elevated temperature. A second objective is to investigate the feasibility of using a finite-element model for parametric studies. To fullfil the first objective, a total of four composite beams with decking slabs were tested to failure. They were designed to represent the internal joint of a continuous beam. The segment between the plastic hinge over support and adjacent point of inflection was represented by one-half of a simply supported beam subjected to a midspan point load. The specimens were heated to a certain temperature before they were subjected to a static point load up to failure. These four test results were then used to validate finite-element models constructed from MSC. Marc Mentat. It is demonstrated that the finite-element analysis gives reasonable accuracy compared to test results. Hence, it provides an efficient, economical, and yet accurate tool to study the inelastic behavior of composite beams in fire. Finally, a parametric study was conducted to investigate the influence of several parameters on the moment-rotation response and the rotational capacity at elevated temperatures.