Simplified model for partially-composite precast concrete insulated wall panels subjected to lateral loading

A simplified model to predict the partially composite response of precast concrete insulated wall panels to lateral loading is proposed. A conventional insulated wall panel design consists of two concrete wythes which sandwich a foam insulation layer. Shear ties are used to connect the two concrete wythes through the insulation layer - these ties can be designed to resist flexural demands via composite, partially composite or non-composite action of the section. Numerous types and configurations of shear ties (many of them proprietary) are available with a large range of constitutive properties, and thus the response of a wall panel can vary based on the type of tie used in its construction. Standard design practices do not consider the constitutive properties of the tie, compatibility of the wythes, or locations of the ties within the panel. A simplified model is proposed which incorporates the relative shear tie deformation as well as the tie's constitutive properties. The approach superimposes the sum of the force couple developed in each shear tie and the capacity of each concrete wythe via an iterative process by which the strength, deformation and level of composite action is calculated at each load increment. This model provides an accurate estimate of the load-deformation responses of these panels when subjected to lateral loads (perpendicular to the panel). The method is used to illustrate the sensitivity of flexural response in a precast insulated wall panel to tie properties and placement. The proposed model is demonstrated to be an effective tool for efficient flexural performance-based design and selective detailing of precast concrete insulated wall panels.