Plastic rotation limits of cold-formed steel hollow sections with moderate heat treatment under combined compression and cyclic lateral loads

This study examines the behaviour of heat-treated cold-formed steel hollow sections under combined axial compression and cyclic lateral loading, focusing on their plastic rotation limits. Material tests are conducted to determine the mechanical properties, cyclic hardening parameters, and failure mechanisms cold-formed sections subjected to subsequent heat treatment, followed by calibration of a Chaboche-based cyclic plasticity model using the experimental data. A dedicated finite element modelling method was developed to accurately simulate the structural performance. The combined influence of geometry and axial load on flexural ductility is highlighted through a parametric study. Supported by a dataset of experimental and numerical results, a new cross-section classificationis proposed, along with their corresponding plastic rotation limits. This classification is developed by modifying both Eurocode 8 and the ASCE approach, incorporating adjusted plastic rotation limits. • Cyclic behaviour of cold-formed hollow section with subsequent heat-treatment is investigated numerically. • Heat treatment of cold-formed steel sections significantly improves ductility and reduced cyclic softening. • A cyclic plasticity model based on the Chaboche framework is implemented and calibrated using experimental data. • A new classification for cold-formed steel sections with subsequent heat treatment is proposed.