Bearing capacities and yield stiffness predictions of CFT frame-BRSPSW linked by different partial bolted connections using RSM

To address the time-consuming and complex nature of traditional methods, such as numerical simulations, Response Surface Methodology (RSM) was employed to evaluate the behaviors and design optimizations of CFT-frame buckling unrestrained/restrained steel plate shear walls (SPSWs/BRSPSWs) connected by bolted four-corner or double-side (FC/DS) connections. A numerical simulation was performed and verified to generate data for RSM, which developed quadratic response (QR) models to predict shear capacities and yield stiffness for four cases, considering bolted connection types and buckling restraints. Linear response (LR) was also used to simplify calculations. These equations were validated against experimental and numerical results, showing high accuracy within ±10 %. The study examines the impact of geometric and loading parameters, including aspect ratio (α), slenderness ratio (λ), axial load ratio (n_d), concrete panel thickness (t_ALC) and bolt characteristics number and diameter (N and D) on shear wall performance. Geometric and loading parameters, particularly λ, α, and n_d, significantly influence shear capacity. Specifically, α increases capacity for both FC and DS connections, while λ increases capacity in DS connections, and n_d reduces capacity due to damage at the base of CFT columns. Additionally, the N and D also notably affect shear wall behavior, particularly FC connections, while t_ALC has an approximately negligible impact on shear walls with both FC and DS connections. Ultimately, the design optimization identified effective variable combinations that improve SPSW and BRSPSW behavior in terms of shear capacities and yield stiffness. Validated by a desirability function, the optimization demonstrated RSM/CCD's effectiveness in enhancing shear wall performance, offering valuable insights for early-stage design.