Current design codes for fire resistance of structures are based on isolated member tests subjected to standard fire conditions. Such tests do not reflect the behaviour of a complete building under either normal temperature or fire conditions. Many aspects of behaviour occur due to the interaction between members and cannot be predicted or observed in tests of isolated elements. Performance of real structures subject to real fires is often much better than that predicted from standard tests due to structural continuity and the provision of alternative load paths. This paper reports on the results of a collaborative research project (Tensile membrane action and robustness of structural steel joints under natural fire, European Community FP5 project HPRI-CV 5535) involving the following institutions: Czech Technical University (Czech Republic), University of Coimbra (Portugal), Slovak Technical University (Slovak Republic) and Building Research Establishment (United Kingdom). It consists of an experimental programme to investigate the global structural behaviour of a compartment on the 8-storey steel-concrete composite frame building at the Cardington laboratory during a BRE large-scale fire test, aimed at the examination of the temperature development within the various structural elements, the corresponding (dynamic) distribution of internal forces and the behaviour of the composite slab, beams, columns and connections. r

The sliding hinge joint (SHJ) is a type of supplemental energy dissipation system for column bases or beam-to-column connections of steel Moment Resisting Frames (MRFs). It is based on the application of symmetric/asymmetric friction dampers in joints to develop a dissipative mechanism alternative to the column/beam yielding. This typology was initially proposed in New Zealand and, more recently, is starting to be tested and applied also in Europe. While on the one hand this technology provides great benefits such as the damage avoidance, on the other hand, due to the high unloading stiffness of the dampers in tension or compression, its cyclic response is typically characterized by a limited self-centering capacity.To address this shortcoming, the objective of the work herein presented is to examine the possibility to add to these connections also a self-centering capacity proposing new layouts based on a combination of friction devices (providing energy dissipation capacity), pre-loaded threaded bars and disk springs (introducing in the joint restoring forces).In this paper, as a part of an ongoing wider experimental activity regarding the behaviour of self-centering connections, the attention is focused on the problem of achieving the selfcentering of the column bases of MRFs by studying a detail consisting in a column-splice equipped with friction dampers and threaded bars with Belleville disk springs, located above a traditional full-strength column base joint. The main benefits obtained with the proposed layout are that: i) the self-centering capability is obtained with elements (threaded bars and Belleville springs) which have a size comparable to the overall size of the column-splice cover plates; ii) all the re-centering elements are moved far from the concrete foundation avoiding any interaction with the footing. The work reports the main results of an experimental investigation and the analysis of a MRF equipped with the proposed column base joints.

A procedure for the evaluation of ductility in steel joints is presented. Using the component method as background, a non-linear analysis for a number of end-plate beam-to-column joints is performed that is capable of identifying the ''yield'' sequence of the various components and the failure of the joint. Each component is characterised using a bilinear approximation for the force-displacement relation. Comparing these results with the corresponding experimental results leads to a proposal of the post-limit stiffness of the various components. A component ductility index is proposed for each component as a means of classification with respect to ductility, using the three ductility classes currently proposed in the literature. A joint ductility index is also proposed, which can be used to verify available rotation against the structure required rotation. Ó

When a beam is bent about its major axis, it may twist and move laterally, before it reaches its elastic/plastic resistance in bending. Although the problem of lateral-torsional buckling of steel beams at room temperature has a well-established solution, the same problem at elevated temperature has not. A numerical investigation of the lateral-torsional buckling of steel I-beams subjected to a temperature variation from room temperature up to 700 v C, with the aim of assessing the effects of the residual stresses in this mechanism of failure, is presented in this paper. To this purpose, a geometrically and materially non-linear finite element program has been used to determine the lateral-torsional resistance of steel I-beams at elevated temperatures, using the material properties of Eurocode 3, Part 1-2. The numerical results have been compared to the results of the simple model presented in Eurocode 3, Part 1-2 (1995) and a new proposal that is being considered for approval.

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Recent experimental evidence has shown that steel joints exhibit a distinct change in their moment-rotation response under increasing temperature. In terms of cold design, the component method is currently the widely accepted procedure for the evaluation of the various design values. It is the purpose of the present paper to extend the component method to the prediction of the response of steel joints under fire loading. Using typical mechanical models consisting of extensional springs and rigid links, whereby the springs exhibit a non-linear force deformation response (here taken as a bi-linear approximation), an analytical procedure is proposed capable of predicting the moment-rotation response under fire conditions that incorporates the variation of yield stress and Young's modulus of the various components as the temperature increases. An application to a cruciform flush end-plate beam-to-column steel joint is presented and compared to the experimental results obtained under various loading conditions.

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Structural glass corresponds to an innovative material with extraordinary aesthetical and architectonic potential that has undergone significant technological advances in recent years, yielding it stronger and safer. For this reason, the use of structural glass has increased considerably in the last decade and is now an unavoidable presence in most of recent reference buildings. The structural capacity of glass elements is brought in from reinforcing techniques of different types. One of the possibilities corresponds to pre stressed cables reinforcement. This technique is very effective in terms of resistance and deformability and corresponds to a light reinforcing element rendering the so called spider web effect. In the framework of the research project “S‐Glass: Structural performance and design rules of glass beams externally reinforced” [1] study the behavior of laminated glass beams reinforced by too twin external steel rods. The work presented in the current paper is within the framework of S‐Glass project aiming at characterizing the behavior of reinforced laminated glass beams in the non‐crack regimen. For this purpose experimental and numerical analysis were prepared. The numerical model was used for a cable layout optimization analysis. Furthermore an analytical solution is put forward, which tackles the beam‐cable load transfer indetermination. Final conclusions are established on the bases of a comparison established between experimental, numerical and analytical results.