Structural Evaluation of Semi-Rigid Steel Portal Frames

Over the last few years various investigations related to the development of finite element formulations for semi-rigid steel portal frame design including the geometric non-linear response have been produced. On the other hand, it is suggested that, for a more precise semirigid connection modelling, the axial and shear force effects should be incorporated to the usual bending deformations. These facts motivated the conception and development of a joint finite element that could accurately represent these effects as well as contemplated a possible interaction amongst these stiffness components. This element also enables joint elasto-plastic analysis to be performed based on their associated moment versus rotation curves. Consequently, the main aim of this paper is to describe in detail the proposed joint finite element and also its linear and non-linear formulations that incorporated the transversal deformations due to shear stresses. In order to validate and calibrate this element, and its associate formulation, a three storey semi-rigid steel portal frame proposed by Keulen et al. [4] was analysed and investigated.