Performance and Characterization of Shear Ties for Use in Insulated Precast Concrete Sandwich Wall Panels

Insulated precast concrete sandwich wall panels are commonly used for exterior cladding on building structures. The insulation is sandwiched between exterior and interior concrete layers to reduce the heating and cooling costs for the structure. The panels can be designed as composite, partially composite, or noncomposite. Shear ties are used to achieve these varying degrees of composite action between the interior and exterior concrete layers. A variety of shear ties are available for domestic construction. An experimental study was conducted to assess the relative strength and response of these commercially available ties. Fourteen different shear tie types were examined, the failure modes and responses were quantified, and simplified engineer level multilinear strength curves were developed for each connection. The test results indicate that shear ties used in sandwich wall construction have considerable variation in strength, stiffness, and deformability. The maximum shear strength of the discrete ties averaged 9.3 kN (2,100 lbf) with a minimum of 3.2 kN (730 lbf) and maximum of 18.4 kN (4,138 lbf). The ties exhibited elastic-brittle, elastic-plastic, and plastic-hardening responses. The results were used to develop trilinear constitutive relationships, which were used to approximate the flexural response of sandwich wall panels.