An experimental appraisal of composite joint components

Abstract

The component method incorporated in Eurocodes 3 and 4 is one of the most accepted models for composite semi-rigid beam-to-column joint design. This method explicitly considers the contribution of the components with the most relevant composite action, such as reinforcing bars, concrete and shear connectors. This was the main motivation to further improve the assumptions employed in the structural response of composite joints to surpass the current limits of its adoption in hogging moment regions. However, in hogging moment regions the concrete slab is not under compression forces, leading to extensive concrete cracking, which can influence the actual structural joint response. An alternative set-up, namely, pull-out tests, was developed to better represent composite joints where tension forces act in the concrete slab. The overall results served as the main basis for a better understanding of some of the components present in composite joints, enabling a better formulation for their design capacities. The present paper focuses on a series of pull-out tests that presented failure modes associated with a tensile reinforcing bar rupture or anchorage capacity. The test results enabled a better understanding of the reinforcing bar failure modes and their relevance over the global beam-to-column joints' structural response.