Preliminary study on the impact of initial imperfections on the post‐buckling rotation of square hollow sections in uniform bending

Abstract

ABSTRACTWith increasing use of high‐strength steel grades, the need for more accurate design specifications arises, with the aim of fully exploiting the material benefits and create economic advantages. According to Eurocode 3, the maximum rotational capacity is limited and linked to the definition of cross‐sectional classes. For class 1, the rotation θ is assumed to be “infinite”, while it drops significantly for class 2 and 3 to a maximum rotation of θpl and θel, respectively. In reality, in spite of their lower hardening capacity and ultimate strains, high‐strength steel sections display a non‐negligible rotational capacity that exceeds these code predictions, which were developed for mild steel and with a level of analysis in mind that is suitable for hand calculations. For an increased use of high‐strength steel sections, it is thus very important to understand and to be able to predict a more realistic deformation and rotation capacity, with the aim of implementing the findings in tools for advanced, FEM‐based Design by Analysis (DbA) approaches. As an initial step in this direction, the proposed paper shows the results from numerical calculations on the rotational capacity of HSS rectangular hollow sections. The numerical results are calibrated against laboratory tests. Consequently, different rectangular cross section dimensions but also variations of the steel grade and the thickness are chosen and calculated in the finite element program ABAQUS.