Hélder D. Craveiro

Influence of web stiffeners on cold-formed steel beams subjected to fire

Purpose This paper aims to present the results of a study on the behaviour of cold-formed galvanized steel beams subjected to fire, using the results of a large programme of experimental tests. Design/methodology/approach The research investigated the influence of web stiffeners in the sections and the stiffness of the surrounding structure, including the axial and rotational restraining to the thermal elongation, on the flexural behaviour of the beams in case of fire. In other words, the structural response of different open cold-formed steel beams, with and without web stiffeners, was compared in case of fire. Findings The results showed that a good choice between using cold-formed steel beams, with and without web stiffeners, may depend on the section shape and the internal forces generated in these members during a fire. Originality/value Temperatures in the furnace and at several points of the beams, as well as deformations and restraining forces and moments, were measured to achieve those goals and consequently to assess the critical time and temperature of these beams.

STRUCTURAL ANALYSIS OF A STEEL COLUMN EXPOSED TO A LOCALIZED FIRE

(Received: 13 October 2017; accepted: 14 November 2017) Tonko Faldić University of Split, Faculty of Civil Engineering, Architecture and Geodesy, Master Student Corresponding author: tonko.faldic@gmail.com Helder David Craveiro ISISE University of Coimbra, Faculty of Science and Technology, Department of Civil Engineering, Invited Assistant Professor Aldina Santiago ISISE University of Coimbra, Faculty of Science and Technology, Department of Civil Engineering, Assistant Professor Neno Torić University of Split, Faculty of Civil Engineering, Architecture and Geodesy, Assistant Professor

Cold-formed steel columns at both ambient and fire conditions

Purpose The use of cold-formed steel members has increased significantly in the past few years; however, its design is only briefly addressed in the current design codes, such as the EN 1993-1-3. To evaluate the compressive behavior of single and built-up cold-formed steel members, at ambient and simulated fire conditions with restrained thermal elongation, experimental and numerical tests were undertaken. Design/methodology/approach Four cross-section shapes were tested, namely, one single (lipped channel), one open built-up (I) and two closed built-up (R and 2R), considering two end support conditions, pinned and fixed. Two test set-ups were specifically developed for these tests. Based on the experimental results finite element models were developed and calibrated to allow future parametric studies. Findings This paper showed that increasing the level of restraint to thermal elongation and the initially applied load led to lower critical temperatures. Increasing the level of restraint to thermal elongation, the failure is governed by the generated axial restraining forces, whereas for lower levels of restraint to thermal elongation, the failure is controlled by the temperature increasing. Originality/value This paper is a contribution to the knowledge on the behavior of cold-formed steel columns subjected to fire, especially on the ones with a built-up cross-section, where results on thermal restrained ones are still scarce. It presented a set of experimental and numerical results useful for the development of numerical and analytical analysis concerning the development of new simplified calculation methods.