Performance of space steel structure under fire

In the fire resistance and design, high temperature has an obvious effect on the physical and mechanical properties of steel. When the temperature of structural members which are under fire increases, their resistance reduces significantly until they reach the critical level. And also, the structural defects affect its capacity. The aim of this study is to provide analysis of models on the behaviours of steel structural members in fire as single elements, in truss and in space steel frame. Specifically, this study also, emphases the effect of initial geometric imperfection on structural compression members under fire conditions. The ABAQUS/Explicit finite element program is used to conduct all computational simulations for all structural analyses. The beam elements are used with considerable material and geometric nonlinearity. The solutions of a number of investigations on individual structural element, on truss members and the space frame subjected to the external loads at both ambient and increased temperatures, with and without initial imperfection are conducted. For single members, ABAQUS solutions is compared to theoretical solutions. According to the analyses throughout this study, the structural member can create very significant forces at high temperatures due to thermal expansion constraint. These thermally generated forces diminish the column's capacity to withstand external load and also the initial imperfections reduce the structure capacity as well. Therefore, the performance of columns exposed to fire might be significantly impacted by thermally generated forces.