A Study on the Capacity of Steel Portal Frames using Shell Finite Elements

Abstract

AbstractSteel portal frames are common structures used in practice. Owing to their optimization, members with tapered geometry and slender sections are prevalent. Since local buckling is a possible mode of failure, an additional complexity arises that requires the use of shell finite elements to assess the ultimate capacity of these structures. On the other hand, imperfections, either of geometric or material nature, must be considered because they are unavoidable and reduce the overall capacity of the frames to carry load. The main focus of this study is therefore to characterize the influence of imperfections. Plate imperfections (or local), global (or member) and frame imperfections, are considered as well as material imperfections such as residual stresses that may contribute to degrade the frame's behaviour.An extensive parametric study comprising a total of 24 frames and 15 different imperfection sets was carried out and based on this large pool of results, recommendations for the definition of imperfections are given and conclusions are drawn on their influence. This work aims to be a step further in establishing a numerical framework to generate results that can be later used to validate existing design methods.