Behaviour of composite joints under combined bending moments and axial loads - Deliverable D.9 - Robustimpact

The present work is dedicated to the behaviour of composite joints under combined bending moments and axial loads. The results presented in this part have been mainly developed in [1]. The component method is a nowadays widely recognized procedure for the evaluation of the design properties of structural joints. It is used as a reference method in the Eurocodes and the proposed rules in these codes are mainly devoted to the characterization of joints subjected to bending moments and shear forces. However, in some situations, these joints can be subjected to combined axial loads and bending moments, for instance in frames subjected to an exceptional event leading to the loss of a column, situation where significant tying forces can developed in the structural beams above the lost column. The purpose of this work is to present and validate a design model, founded on the component method, aiming at predicting the behaviour of composite joints subjected to combined axial loads and bending moments. In particular, in the following the validation of this model through comparisons to recent experimental tests performed on steel composite beam-to-column joints at University of Stuttgart will be presented. The proposed method is mainly adapted from the former research work of Demonceau [2]. Some changes are made in order to improve the former method and also to extend it to the type of joints used in the framework of the current European project (Deliverable 5). Beam to column composite joints with flush-end-plate connection are mainly investigated hereinafter. The work will manly focus on the behaviour of joints under sagging moments, as it has not been widely researched yet in comparison to joints under hogging moment. An excel-based routine of the proposed method has been developed; it has been designed to be adaptable to different types of composite joints, with the objective to facilitate the verification and/or the application of the above-mentioned design model.