Shear Capacity Analysis of Small Span‐Depth Ratio Steel Plate‐Fiber Concrete Composite Coupling Beams

As a key connecting component in the combined shear wall system, the coupling beam needs to have high bearing capacity, good ductility, and strong energy dissipation capability. However, due to the relatively high brittleness of concrete, its synergy with steel plates is limited. To enhance the seismic performance of composite coupling beams with a small span–depth ratio, this paper proposes small span–depth ratio steel plate‐fiber concrete composite coupling beams (SSPCB) that utilize polyvinyl alcohol (PVA) fiber reinforced concrete (FRC) to facilitate a synergistic effect with the steel plate. The seismic performance of SSPCB was investigated through a combination of experimental research and numerical simulation, and a theoretical calculation method for the shear capacity of SSPCB was proposed. The quasistatic tests utilized ordinary concrete and FRC composite coupling beams, allowing for a comparison and analysis of performance indicators, including the failure process of each specimen. Based on the experimental data, finite element software was employed to study the stress development of the concrete, steel plate, and steel reinforcement in the composite coupling beam, considering and not considering the effect of the floor slab. Additionally, the distribution of bending moment, shear force, and axial force in the embedded steel plate under peak load was analyzed. Based on the influence of various parameters on the shear performance of coupling beams, a calculation method for the shear capacity of SSPCB was developed, utilizing the softened strut‐and‐tie model (ST) and the modified steel plate diagonal rod model. The results indicate that SSPCB exhibits higher bearing capacity and energy dissipation capacity compared to the ordinary concrete composite coupling beam, demonstrating relatively better ductility. Through finite element simulation analysis, as the load increases, the stress in each component propagates towards the midspan. Due to the synergistic effect between the floor slab and the wall limb, part of the load is supported by the embedded steel plate in the wall limb. When accounting for the floor slab, the bearing capacity of the composite coupling beam is enhanced; however, the ductility coefficient is significantly reduced, indicating that the presence of the floor slab limits the ductility of the coupling beam. The standard deviation (Std) and coefficient of variation (Cov) of the calculation results are 0.0886 and 0.0879, respectively, when the shear capacity calculation method of the SSPCB does not account for the effect of the floor slab. Considering that the Std and Cov of the floor slab action are 0.0809 and 0.0776, respectively, this indicates that the calculation model can accurately predict the shear capacity of each specimen.