Shear-flexural coupling effect of steel truss-embedded double steel-concrete composite shear wall

Steel truss–embedded double steel–concrete composite shear walls (STSCWs) exhibit pronounced DSCW–ST coupling effect under lateral loading. Conventional capacity models generally superimpose the individual contributions of the composite wall and embedded truss. This treatment neglects deformation compatibility, stage-dependent yielding, and force redistribution, which can lead to inaccurate estimates of the coupled resistance. This study develops a mechanics-based OpenSees macro-model that explicitly represents the composite wall, embedded truss, DSCW–ST coupling effect, and flexible foundation restraint. The model is validated against six quasi-static tests covering shear- and flexure-dominated responses. It reproduces the global hysteretic behavior, deformation patterns, and strength capacities, with maximum errors of 4.68% and 7.58% for the yield and peak loads, respectively. A height-wise interaction-force index is proposed to quantify wall–truss force transfer and distinguish the two deformation modes. Two stage-dependent coupling coefficients, the yield coordination coefficient λ y and the peak enhancement coefficient λ m , are defined to quantify the effective truss contribution at the yield and peak stages. Parametric analyses examine the effects of axial force ratio, steel-plate thickness, and chord-to-web stiffness index on the coupling behavior. Regression expressions for λ y and λ m are subsequently incorporated into design-oriented capacity equations. Comparisons with the six tests show that the predicted yield and peak capacities differ by less than approximately 4% and 9%, respectively. The proposed coefficients provide stage-specific modification factors for accounting for wall–truss synergy and support practical estimation of the yield and peak strengths of STSCWs.