Keywords: steel structural, beam-to-column joints, extended endplate joints, semirigid joints, experimental analysis, component method.

The structural joints play a key role in the global behaviour of steel structures. Based on an attempt to understand the behaviour of a real joint, and its influence on the overall strength of the building steel frames, many investigations have been performed over the last few years. By understanding the real joint behaviour, it becomes possible to develop new design recommendations for evaluating the mechanical properties of joints and, consequently, this hypothesis could be adopted in the building design structures procedures.

Steel beam-to-column joints are often subjected to a combination of bending and axial forces. Current specifications that take in account the steel semi-rigid joint behaviour do not consider the simultaneous presence of axial forces (tension and, or compression) acting in the joints. On the other hand, an empirical limitation of 5% of the beam plastic resistance is the only limitation suggested in Eurocode 3 [1]. In the cases where the axial force magnitude acting in the joint is less than this limit, its effects in the joint design can be disregarded.

The main objective of this paper is to present a numerical study of extended endplate beam-to-column joints. First, the investigated joints were subjected only to bending moment and were followed by cases with combined actions of bending moment and axial forces (tension and compression). The numerical results were calibrated against the Eurocode 3 provisions [1], experimental results [2], and the Cerfontaine Model [3].

The presence of axial force in the extended endplate modified the joint response in terms of bending moment resistance. In the scenarios that consider the presence of axial force on the joint, the numerical results were higher than those obtained experimentally. However, the observed differences do not interfere with the quality of the results.

The numerical and the experimental results indicated that when the joints are subject to bending moment and compressive axial force, an increase of the joint bending moment resistance was noticed allowing the use of more economical joint configurations. However, for higher levels of compression axial forces, the joint bending moment resistance may decrease, fact that was also verified experimentally.

1

Eurocode 3, prEN 1993-1.8, "Design of steel structures - Part 1.8: Design of joints ("final draft")", CEN. European Committee for Standardisation, Brussels, 2003.

2

L.R.O. de Lima, P.C.G. da S. Vellasco, L.A.P.S. da Silva, S.A.L. de Andrade, "Experimental Evaluation of Extended Endplate Beam-to-Column Joints Subjected to Bending and Axial Force", Engineering Structures, 46(7), 1-15, 2004. doi:10.1016/j.engstruct.2004.04.003

3

F. Cerfontaine, "Etude analytique de l'interaction entre moment de flexion et effort normal dans les assemblages boulonnés", Construction Méttalique, 3, 1-25, 2001.

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