Modelling partial end-plate connections under fire conditions

This paper presents a simplified robust 2-noded connection element for modelling the behaviour of partial end-plate connections under fire conditions. In this new model the partial end-plate connection is modelled as a 2-noded nonlinear spring element. The characteristics of the spring - such as stiffness, tension, compression, shear strengths and bending moment resistance - are determined based on each component of the connection. It is well known that the rotational response of a partial end-plate connection comprises of two stages, due to the shift of the compression centre of the connection from the end of the endplate to the centre of the beam bottom flange at large rotation. This two stage behaviour is considered in the model proposed. Compared to normal component-based models the most significant of the current model is that this simplified model has very good numerical stability under static solver condition. The model also retains the advantages of both simple and component-based models. Fourteen tests of partial end-plate connection previously conducted by other researchers were used to validate the proposed model. It is evident that the model is capable to predict the behaviour of flexible end-plate connections under fire conditions. In order to investigate the influences of the connections on the behaviour of steel structures, a series of numerical studies has been conducted on a 2D steel frame, subjected to ISO834 Fire and Natural Fire. It is clear that the model can be used to represent the partial end-plate connections in performance-based fire resistance design of steel-framed composite buildings.