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

Abstract

According to full-scale fire tests, it is noticed that tensile membrane action within the concrete floor slabs plays an important role in affecting the fire resistance of composite buildings. It is well known that the development of tensile membrane actions relies on the vertical support along the edges of the slab panel. However, there is at present a lack of research into the influence of vertical supports on the tensile membrane actions of the floor slabs. In this paper, the performances of a generic three dimensional 45m x 45m composite floor subjected to ISO834 Fire and Natural Fire are investigated. Different vertical support conditions and three steel meshes are applied in order to assess the impact of vertical supports on tensile membrane action of floor slabs. Unlike other existing large scale modelling which assumes the connections behave as pinned or rigid for simplicity, two robust 2-node connection element models developed by the authors are used to model the behaviour of endplate and partial end-plate connections of composite structures under fire conditions. The impact of connections on the 3D behaviour of composite floor is taken into consideration.The load-transfer mechanisms of composite floor when connections fail due to axial tension, vertical shear and bending are investigated. Based on the results obtained, some design recommendations are proposed to enhance the fire resistance of composite buildings.

Model Parameter Sensitivity for Structural Analysis of Composite Slab Structures in Fire

“…Many theoretical models have been adopted to represent the material behavior of steel and concrete at elevated temperature. In this study, the Eurocode was selected because it is widely used and has been validated by many researchers (Memari et al, 2014;Lin et al, 2015;Selamet and Bolukbas, 2016;Jiang and Li, 2018).…”

Improving the performance of composite floors subjected to post-earthquake fire

“…The analyses also demonstrated that the surrounding cool structure can improve the fire resistance of the fire compartment. Lin et al [18] investigated the effect of protected beams on the fire resistance of composite buildings. They compared the behaviour of the composite floor with fixed and non-fixed vertical support on the protected steel beams at the perimeter of the slab panel.…”

Three-dimensional modelling of composite frames with ductile connections in fire

“…They also proposed a simplified method to calculate the non-linear characteristics of composite connections in the analysis of beam catenary action at high temperatures, which was validated against their experimental results. Lin et al [14] used 2-noded connection elements representing end-plate and partial-depth endplate connections in their high-temperature 3-D composite floor model to take into account of the impact of connections on the 3-D behaviour of composite floors in fire. Selamet et al [15] modelled a composite steel-framed floor system with beam-to-beam shear connections at elevated temperatures and found that the connection reaches its axial and rotational capacities during the fire cooling phase, leading to the failure of bolts caused by combined shear and tension.…”