Fire Safety Science Digital Archive

This paper describes an experimental study at ambient and elevated temperatures on the behaviour of full scale composite floor cellular steel beams. A total of five specimens with different steel geometries and loading conditions were tested under monotonic loading and at elevated temperatures. All beams were designed for a full shear connection between the steel beam and the concrete flange using shear studs. Two failure temperatures were observed in the fire tests indicated that beam with circular opening failed by web post buckling and beams with elongated openings failed by vierendeel bending associated with the buckling of the web posts of the steel section. It can be concluded that cellular beams in fire cannot simply be estimated by applying temperature dependent reduction factors on stiffness, as given in codes. A finite element model is then established with both material and geometrical non-linearity using shell elements to compare the experimental results. The comparison between the finite element prediction and actual tests results are quite good in terms of failure modes, load deflection behaviour and ultimate loads.