Deformations of steel end‐plate beam‐to‐column joint when subject to simulated steady‐state and transient‐state fire heating regimes

Abstract

AbstractThe bearing capacity and rigidity of selected steel end‐plate beam‐to‐column joint are analysed in the paper. Those properties are determined numerically, based on the fire conditions simulated for this node. For comparison, two alternative heating regimes, typical for steady‐state and transient‐state scenarios, are considered. In the first case, an initially statically preloaded joint is evenly heated up to a predetermined temperature and subsequently, in this temperature, subjected to monotonously increasing static load until reaching the ultimate bearing capacity. In the second scenario, the same joint, subjected to the same preliminary static load, is subsequently statically loaded to reach a predetermined ratio of its ultimate bearing capacity and then, during the time of simulated fire, monotonously heated until failure. During the analysis it is assumed, that the steel is heated at a low rate, not affecting its material properties at given temperature. A cluster of curves depicted in the bending moment vs. effective rotation angle system of coordinates is a result of the first analysis. Each of these curves corresponds to a selected steel temperature. In the second case, the deformability of the joint, increasing with temperature, is expressed by a set of relationships between joint rotation and the corresponding temperature of steel. Thus a single relationship of this type corresponds to a selected level of external load applied at the node.