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Connections are the most vulnerable parts of a structure under fire conditions. A novel steel connection with high axial and rotational ductility has been proposed with the objective to improve the performance of steel-framed buildings in fire. Analytical model has been developed to determine the axial displacement of the top and bottom flanges of the beam end at high temperatures. A series of sub-frame models with this ductile connection have been built using Abaqus to study the influence of the characteristics of the connection part between the fin-plate part and face-plate part on the overall connection behaviour. The current critical failure mode of the ductile connection is bolt pull-out from the face-plate zone, and the tensile deformation capacity of the connection is not fully utilized. Therefore, measures to improve the bolt pull-out failure mode of the connection have been tested using the Abaqus sub-frame models, including adding a strengthening plate to the face-plate part of the connection and increasing the connection plate thickness. The simulation results show that the bearing failure of the beam web will become another critical failure mode of the connection, once the bolt pull-out failure is eliminated. To further optimize the high-temperature performance of the connection, the Abaqus steel frame models have also been used to test some measures to delay the occurrence of the beam web bearing failure, including adding strengthening plates to the part of the beam web in contact with the connection, and improving the material properties of the part of the beam web around the bolt holes at high temperatures. [ABSTRACT FROM AUTHOR]

Previous building fires and research has shown that simple (shear) connections develop large axial force and flexural demands during a fire leading to potential failure of the connections and progressive collapse of a building. These findings have motivated decades of international research on the fire behavior of simple (shear) connections. While this research all confirmed that simple connections experience large axial force and flexural demands, it occurred without consistency of testing methodology, testing setup, and reporting of results. Due to this inconsistency, the decades of research have yet to be synthesized into comprehensive code changes for the design of simple connections in fires. This paper will summarize international experimental and numerical research on simple (shear) connections and highlight the inconsistencies between this research in an effort to motivate consistent testing and data reporting for future research developments. [ABSTRACT FROM AUTHOR]

Fire safety has always been a major concern in the design of timber construction. Even though wood is a highly combustible material, timber members can perform adequately under elevated temperatures. The thermal response of timber connections, however, is in most cases poor and determination of their fire resistance is usually the crucial factor in evaluating the overall load-bearing capacity of wood structures exposed to fire. The analysis of timber joints under fire conditions can be challenging due to their complexity and variety. After presenting the variation of the properties of timber with temperature, this paper reviews the fire performance of various connection types, such as bolted or nailed wood-to-wood and steel-to-timber joints. Results from relevant experimental programs and numerical studies are discussed in detail and future research needs are highlighted. The effect of several factors on the fire resistance of timber connections, such as the fastener diameter, timber thickness and joint geometry, is investigated and useful conclusions are drawn. Based on these, preliminary guidelines for the efficient design of timber connections under fire exposure are presented. [ABSTRACT FROM AUTHOR]

The knowledge in the field of structural fire engineering has been greatly advanced through assessment of a number of real fires (WTC, Torre Windsor, Broadgate, etc.) and, especially, by the Cardington series of full scale structural fire tests. This knowledge has been used to validate and verify the use of computational finite element models that have expanded the range of structures that can be investigated under severe fire exposure. This paper presents a selection of key lessons learned by the authors through the assessment of structures in fire for real commercial building projects. The key areas of sensitivity that have been encountered are described and a discussion of each point presented. The paper is aimed at describing potential weaknesses that have been observed in the commercial work of the authors, often driven by the requirements for efficient ambient structural design. The paper concludes with some suggested advice for structural engineers aimed at increasing the general robustness of building structures. This is based on designing out as far as possible in the ambient design of a structure the potential weaknesses identified in past project work. [ABSTRACT FROM AUTHOR]

In order to address the complex loading condition of steel joints in fire, and based on the experimental fire tests on steel frames with different joint typologies, performed at the University of Coimbra (Santiago et al. 2008), a detailed three-dimensional model was developed and calibrated to simulate the behaviour of welded and bolted end plate beam-to-column joints. The structural frame is modeled combining 3D shell, solid and joint elements, thereby taking into account the effect of the local failure modes, and the realistic behaviour of the frame exposed to a natural fire. The numerical model accounts for the initial geometrical imperfections, non-linear temperature gradient, geometrical and material nonlinearity and temperature dependent material properties. The results show the performance of each individual structural joint component under heating and cooling conditions and identify the main dependencies of the geometrical and mechanical variables of the components on the joint behaviour. The global behaviour of the frame and the joint failure modes are compared and discussed with the experimental observations. [ABSTRACT FROM AUTHOR]

One of the most recent studied components in the connections of a steel structure exposed to elevated temperature is the column panel loaded in shear. A set of three tests were performed to confirm the analytical prediction model at the Czech Technical University in Prague. The model takes into account the distribution of the internal forces in the shear panel affected by the transfer of the forces by bolt rows in tension. Two panels were tested at ambient temperature and four panels at elevated temperature. The gas temperature in the furnace followed the temperature measured during the seventh Cardington large compartment test in 2003. This contribution is focused on the presentation of the experimental results and an analytical prediction model with a component method. [ABSTRACT FROM AUTHOR]