Thermal Behavior of Precast Prestressed Concrete Three-Wythe Sandwich Wall Panels

Precast concrete sandwich wall panels are often used for building exterior cladding and may also serve as bearing or shear walls. These precast concrete sandwich wall panels are commonly constructed of two wythes of concrete separated by a layer of thermal insulation. In these two-wythe panels, solid concrete regions which extend directly through the entire thickness of the panel are often provided for embedded hardware for lifting, handling, and connections, or to provide composite action. These solid concrete regions have a significant adverse impact on the thermal performance of the panels. This research was directed towards the development of precast concrete three-wythe sandwich wall panels with improved thermal and structural performance. A three-wythe panel has three concrete wythes and two insulation layers. All three concrete wythes are connected by solid concrete regions, and the connections between successive concrete wythes are staggered in location so that no concrete path extends directly through the entire thickness of the panel. This paper describes the thermal performance of precast concrete three-wythe sandwich wall panels. Possible panel configurations of the three-wythe panels are proposed, and their thermal performance is studied by estimating R-values using the finite element method (FEM) analysis. It was found that, in general, the thermal performance of three-wythe panels is better than that of two-wythe panels due to the increased thermal path length through the panel.