Evaluating the mechanical and thermal performance of steel-wood-steel joints under fire conditions

Abstract

This study aims to conduct a comprehensive analysis of the mechanical and thermal properties of steel-wood-steel (SWS) connections used in timber structures. The joints were evaluated under both normal conditions and fire exposure. Investigations were undertaken to assess the initial stiffness and load-bearing capability of SWS joints composed of laminated wood and softwood (Radiata Pine and Glulam) including steel dowels of varying diameters. The joints were evaluated at different wood densities and thicknesses of passive protective materials, including gypsum and laminated wood panels. The results demonstrate that wood density, dowel diameter, and protective material composition significantly influence the wood's char rate and load-bearing capacity. Although Eurocode 5 recommends a standardised char rate, the results obtained indicate significant variations depending on the structural configuration and the kind of protection used. Proposals for adjustments to traditional formulas are presented via comparison tables and critical examination. These improvements aim to more accurately represent the structural behaviour of SWS joints under real load conditions and the presence of fire.