Field Testing and Numerical Investigation of Mechanical Properties in Reinforced Steel–Wood Composite Formwork Systems

Traditional steel–wood composite formwork systems often exhibit mechanical imbalances, such as high strength with insufficient stiffness or high stiffness with low toughness, under both ultimate and serviceability limit states. To address the deficiency, this paper proposes a novel reinforced steel–wood composite formwork system (RSWC-FS). The system features a multi-layer plywood panel, ribbed cold-formed thin-walled Q235 steel secondary wales, and double-channel steel primary wales, interconnected by high-strength bolts to create a surface-to-surface bonded interface. This design enhances load transfer efficiency and mitigates stress concentration. Field testing was conducted on cast-in-place shear walls and frame columns, and corresponding finite element models were established in ANSYS for numerical analysis. The results demonstrate that the RSWC-FS delivers stable mechanical performance. The maximum stress of shear walls reaches 42.57 MPa and that of columns 49.98 MPa, while the corresponding displacements are 4.719 mm and 1.541 mm, all of which remain well within the allowable limits. Through an inverse analysis calibration process, optimal load partial factors of 1.26 for shear walls and 1.31 for columns are recommended, significantly reducing the deviation between calculated and measured values. The proposed RSWC-FS effectively resolves the mechanical imbalance inherent in traditional steel–wood composite formwork systems and demonstrates considerable potential for practical engineering application.