Modelling partial end-plate connections under fire conditions

Abstract

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 springsuch 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 the 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.

The effects of protected beams and their connections on the fire resistance of composite buildings

“…Recently, two robust simplified connection models have been developed by the authors [15,16] for modelling the end-plate and partial end-plate connections between steel beams and columns in fire. The proposed models are based on the two-node connection element framework developed by Huang [21].…”

“…For modelling the behaviour of connections which connect beam to flange of column (majoraxis) at elevated temperatures, two simplified connection models were developed [15,16] and incorporated into software VULCAN. As described in Reference [15], a simplified model has been proposed to predict the performance of flush and extended end-plate beamto-column flange (major-axis) connections in fire.…”

“…Another simplified 2-node connection element model for simulating the behaviour of partial end-plate beam-to-column flange (major-axis) connections under fire conditions is presented in Reference [16]. The two stage rotational behaviour of partial end-plate connection is taken into consideration, including the performance of the connections after the beam bottom flange comes into contact with the column flange.…”

“…Lima et al [23] proposed a finite element model to simulate the behaviour of a minor-axis connection consisting of double web angles, a seat angle, or a transverse web stiffener welded to the column web. The initial stiffness of the whole connection was assessed using the component-based method, which requires defining the active basic components within the The initial stiffness can be expressed as: The tension resistance of column web component is obtained based on SCI P358 [25], which can be defined as: The two-node major-axis connection element model, presented in Reference [16], were fully validated and will be used, in this study, for modelling the connections between the primary beams and columns. Also this major-axis connection element is modified with the new component described above to produce a new two-node minor-axis connection element for modelling the partial end-plate connections between beam to column web, or secondary beam to the web of primary beam in fire.…”

“…The partial end-plate connections are adopted to connect secondary beams to columns, and primary beams to secondary beams, respectively. These two types of the connections are modelled using the simplified connection models developed by the authors [15,16]. The proposed two connection models have good numerical stability under a static solver condition, and can be used for large scale modelling of composite buildings in fire.…”