Lateral load tests were performed on four full-scale precast concrete sandwich wall panels. The first panel was a typical precast, prestressed concrete sandwich panel that had shear transfer provided by regions of solid concrete in the insulation wythe, metal wythe connectors (M-ties), and bond between the concrete wythes and the insulation wythe. The degree of composite action developed by each shear transfer mechanism (regions of solid concrete, wythe connectors, and bond) was then evaluated by testing three additional panels that included only one mechanism each. The panels were tested in a horizontal position with simple supports under the action of a uniform lateral pressure. It was found that, for the panel geometries and materials treated in this study, the solid concrete regions provide most of the strength and stiffness that contribute to composite behavior. Steel M-tie connectors and bond between the insulation and concrete contribute relatively little to composite behavior. For design purposes, it is recommended that solid concrete regions be proportioned to provide all of the required composite action in a precast sandwich wall panel.
