Chord failure resistance of 3D cut welded connections with CHS columns and through I‐beams

Abstract

This paper investigates the mechanical behaviour of a novel typology of steel beam‐to‐column connection made by welding circular hollow section (CHS) columns with through‐all double‐tee beams. Such connection represents an alternative to the classical configuration with the I‐beam simply welded to the external surface of the hollow profile for which Eurocode 3 part 1.8 provides specific design rules resulting from the “ring model” theory. The main features of connections with through‐all beams derive from a change of the resisting mechanism which leads to a significant increase of stiffness and resistance. Nevertheless, such a change of the mechanical behaviour, strictly affected by the different plasticity pattern, has not been embedded in the ring model theory, yet. Instead, experiments and finite element (FE) simulations have been carried out proving that the resistance exhibited by CHS to through‐all axially loaded plates is about 2‐3 times higher than resistance referred to CHS to branch plates. The last‐mentioned connections represent the basic components in order to assess the flexural strength of connections made by CHS and I‐beams. This means that doubling the resistance of connections with beam welded to the external surface of the column, as some studies have proposed, leads to a significant underestimation of the resistance. Within this framework, in this paper the flexural resistance of connections with CHS columns and through‐all I‐beams is assessed by developing experimental tests and analytical models aiming to propose a new design equation. Specifically, two cyclic ad two monotonic tests on real scale beam‐to‐column connections have been executed at the laboratory of the University of Salerno. Subsequently, finite element (FE) models have been calibrated and verified against the experimental results. Then, the developed FE models have been extended to perform parametric analyses to be used to verify the accuracy of a new theoretical approach able to predict the resistance of such a kind of connections. The theoretical approach has been developed basing on the upper‐bound theorem and exploiting the previous knowledge based on the so‐called ring model. The proposed formulation, when compared to the available experimental data and FE simulations, have proved to exhibit a high accuracy.