Mode‐based Beam and Connection Analysis of Frames

Abstract

Major steel structures are commonly constructed as frames or trusses. The connections between its beams and columns have a crucial influence on the global behaviour. However, a detailed assessment of the joints is often neglected with rough simplifications, which may lead to poor results. On the other hand, if performing a detailed assessment it is a time-consuming task requiring special expertise. Consequently, the idea stressed in this paper is a novel approach on how to analyse thin-walled steel frames including a detailed assessment of both the joint and beam mechanics. The approach is based on a transformation from standard degrees of freedom into a displacementbased mode formulation. Furthermore, this transformation reduces the total number of degrees of freedom to be computed for advanced joints and beam elements. All this is achieved by adopting an advanced beam element formulation as well as introducing the idea of a 'joint element' formulated by finite shell elements. One of the main advantages of this idea is a general formulation of the joint, which makes it valid for many beam-to-column configurations. Furthermore, beam members can either be closed or open sections due to the adopted advanced generalised beam theory. Furthermore, a detailed analysis of the joint element itself is also achieved by this approach. Finally, an increased efficiency is achieved due to reduction of the total amount of degrees of freedom of the advanced model, and a new in-depth knowledge of the joint behaviour is gained from this approach as well, due to the displacement-based mode formulation.