Finite Element Analysis of a Semi-Rigid Endplate Beam-to-Column Joint with Stiffeners

Abstract

This article examines the mechanical behavior of steel endplate beam-to-column joints with different stiffeners under bending moment. This type of connection is commonly used in steel frameworks to transmit loads from beams to columns. In frame design procedures, engineers tend to consider beam-to-column joints either ideally pinned or fully rigid. The present study aims to show their semi-rigid behavior by analyzing the characteristics of the relation between the bending moment and the rotation of the studied connection. The analysis is based on the development of a finite element model considering the material, geometrical and contact nonlinearities between the components. Three types of stiffeners are introduced in different positions to investigate their effect on the global behavior of the joints. The moment rotation curve is defined together with the procedure of determination of the initial rotational stiffness, the elastic and plastic moments of the connection. The numerical model is validated by comparing the moment rotation curves with those of similar studies available in the literature and also with the design approach proposed by Eurocode 3. The obtained results have showed that the use of stiffeners in the column web or on the endplate increases significantly the rigidity of the studied connection. The failure modes have been discussed in detail for each configuration with respect to the rotation capacity and the initial stiffness. Finally, the model has been used to show the influence of three bolts classes on the ultimate load of the joints and the deformation of the endplate and bolts at failure.