Structural design and analysis of concrete sandwich panels and their practical applications

The concept of a concrete sandwich panel originated in the United States in 1906 where a building was constructed with sandwich tilt-up wall panels. Since then sandwich panels have developed gradually and have continued to improve. -- There are two types of concrete sandwich wall panels: (1) Architectural wall panels (non-composite type), and (2) Load bearing wall panels (composite and non-composite type). -- In general, the non-composite type of load bearing panel is used more commonly because there are less limitations compared with the composite types. This thesis deals with the structural design and analysis of the non-composite type of load bearing wall panel. -- In the past, certain problems besetted architects, engineers, and contractors working with concrete sandwich panels. These problems are associated with: -- (1) Bonding between concrete and insulation -- (2) Joints in panel -- (3) Panel connections -- (4) Control of cracking. -- This study has been undertaken with the aim of solving some of these problems. Three experiments were conducted accordingly to determine the behavior of concrete sandwich panels. The first experiment was to investigate the effects of heating and cooling on sandwich panels and to compare the experimental results with theoretical calculations. The principal results of this experiment demonstrated the effects on concrete sandwich panels under varying thermal conditions. These results should serve as a guideline for the design of joints in sandwich panels. The second and third experiments were initiated to investigate and compare the bending stresses, deflections and shear strength in concrete sandwich panels either with or without shear connectors. The panels were subjected to a simulated uniformly distributed load under simply supported conditions. It can be concluded from the experimental results that a well designed anchor system joining the concrete sandwich panel faces through the core insulation is a fundamental requirement in the future production of sandwich wall panels in order to obtain full shear transfer between the faces. Without these shear connectors, a concrete structural sandwich panel will usually fail by shear of the bond between the core and faces or by shear failure of the core itself. -- The deflection on a sandwich panel is the sum of ordinary bending deflection and an additional deflection associated with shear deformation of the core. Experimental results showed that deflections were mainly associated with shear deformation of the core for panels without shear connectors. -- Deflections measured were less for panels containing shear connectors. For both panels, from theoretical calculations, it was found that the deflections were mainly associated with shear deformation, with less than 1% due to bending. -- A proper shear connector system transfers all lateral loads including wind forces from the exterior face to the interior structural face of the panel. Hence the sleeve anchor, torsion anchors and connector pins play a very important part in the performance of concrete sandwich panels. Prestressing techniques can also improve the design of such panels and have been widely used in recent developments of sandwich panels. -- For this study, a typical non-composite type of concrete sandwich panel was selected as a design example. For the design of such concrete sandwich panels, the following factors were carefully considered: -- (1) The thickness of both faces of the panel -- (2) The loading conditions -- (3) The fire resistance of the sandwich panel -- (4) The temperature gradient between the faces, and -- (5) The panel anchor system.