Flexural response prediction of C-shaped concrete-filled composite plate shear walls (C-PSW/CF) using response surface methodology

Concrete-filled composite plate shear walls (C-PSW/CF) are an emerging prefabricated structural system that combines high strength, stiffness, and constructability for use in high-rise and seismic applications. Conventional plastic-theory-based flexural models originally developed for planar walls are intended only to estimate peak flexural strength; however, they cannot adequately capture several mechanisms governing the behavior of C-shaped sections, including concrete confinement, plate local buckling, von Mises stress interaction, and shear-lag effects. Moreover, no analytical formulations are currently available for predicting the full monotonic flexural response of such walls. This study develops a surrogate-based modeling framework that integrates high-fidelity finite element (FE) simulations with Response Surface Methodology (RSM) to predict the monotonic flexural response and yield moment capacity of C-shaped C-PSW/CF walls. A validated three-dimensional FE model (FEM) was used to simulate 77 wall configurations generated through a Central Composite Design (CCD) by varying six geometric and material parameters. Second-order RSM equations were derived to estimate moment capacity across drift ratios up to ±4% in both loading directions and to predict yield moments corresponding to the onset of web and flange plate yielding. The developed models show high predictive accuracy (R² > 0.95) and successfully capture nonlinear parameter interactions among section geometry, reinforcement ratio, and steel yield strength. Compared with nonlinear FE simulations, the RSM equations enable rapid prediction of wall capacity using explicit closed-form expressions, providing a computationally efficient tool for performance-based design and parametric evaluation of prefabricated composite wall systems.