Steel modules of composite plate shear walls: Behavior, stability, and design

Concrete-filled composite plate shear walls (CPSW) consist of a concrete (infill) wall sandwiched between two steel plates that are connected to each other using ties and anchored to the concrete infill using these embedded ties or shear connectors. Steel modules consisting of plates, ties and shear connectors are prefabricated in the shop, transported to the field, and assembled first. The erected modules serve as falsework for construction activities and stay-in-place formwork for concrete casting. This is a primary advantage and appeal of this system. However, there is a lack of knowledge regarding the structural behavior of empty steel modules (before and during concrete casting). This paper presents the results of analytical, numerical, and experimental investigations conducted to evaluate: (i) the structural behavior of empty steel modules under their own self-weight, (ii) the stability and axial load capacity of steel modules for construction loads and activities, and (iii) the effects of concrete casting (hydrostatic pressure) in terms of the deflections and stresses induced in the steel plates. The results indicate that the effective shear stiffness of the empty modules governs their structural behavior as well as their stability. The effective shear stiffness can be estimated using the finite element method (verified using test results), or conservatively using mechanics-based equations presented in this paper. The effective shear stiffness is governed by plate slenderness, defined by the tie spacing and plate thickness, and the relative flexural rigidity of the steel plates and the connecting ties. These parameters can be designed to limit the flexibility and the critical buckling stress of the empty modules. The paper also provides equations for calculating the out-of-plane displacement and stresses induced in the steel plates by the concrete casting hydostatic pressure. •Steel modules of CPSW have to be designed for construction activities and concrete casting hydrostatic pressure.•Structural behavior and stability (buckling) of steel modules is governed by their effective shear stiffness GAeff.•Mechanics-based equations are developed and verified for conservatively predicting the structural behavior and stability of steel modules.•Mechanics-based equations are also developed for calculating the locked-in deflections and stresses in steel plates due to concrete hydrostatic pressure.•Equations are verified using detailed 3D finite element analy