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Laminated glass interlayers provide significant protection and energy dissipating capacity when windows are subjected to blast loads. Current protection criteria (DoD, GSA) prescribe protective glass assemblies and analytical approaches for validating protection using HazL (DoD) and WinGARD (GSA) glass response and hazard models. The laminated glass membrane models in these “standard” codes (HazL and WinGARD) used to predict glass laminate membrane response have been shown to yield both overly conservative as well as non-conservative results. Protection Engineering Consultants (PEC) has developed an improved and simple laminate membrane model that greatly increases the accuracy of hazard predictions. Static and dynamic laminated glass test data is available from tests in the last two to three years that will improve and validate the new variable modulus-based membrane model. The more accurate membrane model will provide cost savings through more efficient designs that meet protective glazing specifications and higher levels of confidence in protective system response.

PEC has applied its direct experience with laminate glass static and dynamic tests, and has leveraged our relationships with US and UK agencies and laboratories to gather and use static and dynamic test data to improve and validate the glass laminate membrane model. PEC engineers have collected and evaluated recent test data on laminated glass specimens. PEC’s variable modulus membrane model is being updated using this data; both for stiffness adjustments as a function of in-plane strain and for strain rate effects (dynamic increase factors) on membrane response. Following incorporation of all static and dynamic test data into the membrane model, a version of the improved model is being implemented into analysis tools such as Single Degree of Freedom Blast Effects Design Spreadsheet (SBEDS). The SBEDS platform is well-utilized by designers to perform SDOF dynamic analysis for other engineering materials (steel, reinforced concrete, masonry, etc…) and is well suited for incorporation of an additional material.

Read more in the full PEC TechNote by Kirk Marchand…

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