Structural behaviour of a novel modular cellular steel beam system at elevated temperatures based on large-scale experimental testing and numerical modelling

Abstract

This paper presents experimental and numerical results of a modular structural steel system, encompassing non-composite cellular beams, that was tested using a 1-h standard fire scenario while loaded. The modular system consists of a 5.66 m × 3.8 m rectangular steel frame, with a sandwich decking (SD) system attached, which comprises of a) profiled steel decking, b) fibre cement, and c) calcium silicate boards. The SD system is hung from the underside of the horizontal structural members to provide inherent fire protection to the steel beams from the bottom and is the load-bearing component of the flooring. The aim of the experiment was to determine the structural systems fire resistance because its unusual geometry renders existing full-scale fire test data inapplicable. Novel temperature and deflection data for the system are obtained from the large-scale experiment conducted, which are used to validate numerical finite element analysis models on a single element and global model basis. The numerical and experimental data are compared and show suitable correlation, and highlight some unusual behaviour regarding vertical deformations. From the numerical models and experimental data, it is shown that (a) the structural steel system typically behaves well due to the limited temperature rise as a consequence of the attached SD system, (b) limited plasticity occurred in the system, (c) small axial forces are induced due to the flexibility of the structure, and (d) the system is heavily reliant upon the integrity of the sandwich decking system it supports. Failure of the SD would lead to loss of compartmentation, and potentially structural failure.