Ultimate lateral load capacity of FRP tube-confined concrete-encased cross-shaped steel column: Experimental and numerical investigation

This study aims to investigate the lateral behavior of fiber-reinforced polymer (FRP) tube-confined concrete-encased cross-shaped steel columns (FCCSCs) to establish a theoretical foundation for their evaluation and design under lateral impact loads. Lateral displacement loading tests were conducted on five foundation-equipped columns, including fixed-simply FCCSCs with varying flange widths, cantilever FCCSCs with different loading positions, and a concrete-encased cross-shaped steel column (CCSC) without glass FRP (GFRP) tube. The experimental results reveal failure modes, lateral load-deflection responses, and strain distribution characteristics. The numerical simulation was also developed using ABAQUS to elucidate the internal force distribution and failure mechanisms for different cross-sectional configurations, while defining three key characteristic points on the lateral force-displacement curve. Parametric analysis was carried out on FCCSCs with fixed-simply supported, focusing on the effects of material properties, loading position, column height, and sectional configurations on the lateral static performance. In addition, predictive formulas for the peak force and ultimate displacement of FCCSCs under lateral loads were proposed, along with a simplified force-displacement trilinear model. This not only accurately predicts the lateral response of FCCSCs but also provides a reliable design basis for engineering applications.