Analysis of Composite Steel-concrete Beams Exposed to Fire using OpenSees

Abstract

OpenSees is an open-source object-oriented software framework developed at UC Berekeley. The OpenSees framework has been recently extended to deal with structural behaviour under fire conditions. This paper summaries the key work done for this extension and focuses on the validation and application of the developed OpenSees to study the behaviour of composite steel-concrete beams under fire conditions. The performance of the developed OpenSees are verified by four mechanical tests and two fire tests on simply supported composite beams. A parametric study is carried out using OpenSees to study the influence of boundary condition as well as composite effect of slab on the behavior of composite beams exposed to fire. The stress and strain along the beam section is output and compared with yield stress limit at elevated temperature to explain these influences in detail. The results show that the stress distribution in the web of the steel beam is more complex due to the support effects.