Thermal Cyclic Testing on a Concrete Sandwich Panel System

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Title: Thermal Cyclic Testing on a Concrete Sandwich Panel System

Author(s): R. K. Devalapura, J. M. Seng, M. F. McBride, D. W. Winiarski, and B. D. Johnson

Publication: Special Publication

Volume: 209

Issue:

Appears on pages(s): 905-918

Keywords: insulated sandwich panel; panel movement; thermal deformation; thermal durability; wall service loading; weather cycles

Date: 9/26/2002

Abstract:
When insulated concrete sandwich panels are used in the envelope of a building, the experior and interior are subjected to two different environments. The exterior concrete wythe is subjected to outside weather swings in the temperature and humidity causing thermal expansion and contraction, whereas the interior is exposed to a controlled steady room temperature environment. Dimensional change in the panel depends primarily on the height of the panel and the relative change in temperature. The severity increases when the outside concrete wythe of a tall panel is supported (and hence constrained) on the foundation dlowing vertical movements only at the top. If these weather cyclic movements are restricted, the panels may experience cracking and eventually may experience a premature failure. Therefore, the tie system used in the panels should be flexible enough to accommodate these differential movements. This often is the most critical issue in the service life of the building when sandwich panels are used. There is no standard test method available to evaluate the thermal non-uniform cyclic behavior of insulated panel systems. The authors have followed a sci- entific approach to evaluate these stresses by subjecting the ties to real life cycles occurring over a period of time. The system used in this study includes a low-conductivity polymer connector with extruded polystyrene rigid foam insulation. The testing was continued until the failure of the system or to more than 100 years of equivalent cycling (the expected service life of the building), whichever is less. This paper focuses on the methodology developed and parameters considered in developing the criteria for testing weather cycles. The procedure may be followed to evaluate any given insulated panel system to predict its long-term durability.