Empirical Evaluation of Glazing Systems in Response to Blast Loads

As the requirement for blast-resistant design has become more common over the last few decades, significant advances in the analysis of glazing subject to blast loads have been made, along with the development of analytical tools based on theoretical and empirical data. A recent research test program funded by the US Army Corps of Engineers, Protective Design Center and conducted by Baker Engineering and Risk Consultants (BakerRisk) included a comprehensive literature search (Idriss, et. al 2012) and test program (Idriss, et. al. 2013) to evaluate the response of complete laminated glazing systems subjected to blast loads. The paramount goal of the research test program, literature search, and data evaluation effort was to document the critical response parameters characterizing the behavior of laminated glazing subjected to blast loads. Parameters and behavior for characterization include general glazing post-break performance, deflected shape, and glass edge reactions. Glass edge reactions of interest include both out-of-plane as well as in-plane reactions created due to the tensile membrane response of the laminated interlayer material. The collection of multi-direction glass edge reaction time histories in the test program provides significantly more response parameters than what was available through previous glazing research test efforts. The measured dynamic test data acquired in this program provides the basis for direct comparisons between the new and existing analytical glazing models. Initial comparisons to existing glazing model predictions indicate that although the existing codes generally predict glazing performance well, differences exist between predicted reaction forces and measured forces. The reaction data, along with other response parameter details, will be useful in the development of improved glazing analysis codes with more accurate prediction of reaction loads. Better prediction of glazing reaction forces leads to more confident design of window and curtain wall frame systems and edge capture and retention of the glazing itself. Significant work in the development of analysis code improvements will follow the completed research program. Other necessary related work includes specific research on the response of the glazing system support framing and its allowable dynamic response limits; which are addressed in this paper.