OPTIMIZATION ON BEARING CAPACITY AND DUCTILITY OF COLD-FORMED THIN-WALLED STEEL FLEXURAL MEMBER

It aims to improve the bearing capacity and ductility of CFS members by changing the cross-sectional dimensions. An experimentally validated model generated in finite element code ABAQUS is utilized to study the flexural capacity and ductility of channel with web and flange stiffeners and configuration with web stiffener and folded flanges in different section dimensions. Then, the relationships between the section dimensions and optimization criterions (flexural capacity and ductility) are analyzed respectively, and geometrical dimensions of these sections are optimized using ANNs (artificial neural networks) and GA (genetic algorithm). The optimal section dimensions are obtained by TOPSIS (technique for ordering preferences by similarity to ideal solution) and the formulas for designing optimally section dimensions are presented. For the cold-formed thin-walled steel member with the thickness of 1.5 mm, it is demonstrated that: bearing capacity can be improved by increasing the web height in a certain range, and ductility can be improved by using smaller flat flange width, the measure of adding stiffeners can slightly increase the flexural capacity and significantly increase the ductility. Configuration with web stiffener and folded flanges has better mechanical properties among the studied cross sections.