Hybrid bio-inspired metaheuristic approach for design compressive strength of high-strength concrete-filled high-strength steel tube columns

The specifications of AISC 360 and Eurocode 4 for the design of composite columns limit the maximum steel tube yield stress and concrete compressive strength. In this study, the limitations mentioned in the design codes are evaluated, and a new simplified relation for the nominal compressive capacity of square high-strength concrete-filled high-strength steel tube (HsCHsST) stub columns is proposed. The present study was carried out in three parts. The first part involves compiling a test database of square-filled composite columns with high-strength materials to achieve the aptest relation. The second part consists of developing a simplified relation for determining the effects of material strength on the nominal compressive strength of columns (Pn\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${P}_{{\text{n}}}$$\end{document}) based on the compiled database using a hybrid gene expression programming-invasive weed optimization algorithm. Finally, a new resistance factor (phi c\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\phi }_{{\text{c}}}$$\end{document}) for axially loaded HsCHsST columns is determined in the third part. The predicted results for nominal compressive strength were compared with specifications of AISC 360 and Eurocode 4 in terms of various performance parameters based on measured results to validate the proposed relation. This study's findings can be used as a suitable tool in the design compressive strength of square HsCHsST members.