Explosive Testing of Window Systems – the Underlying Double-Standard

By Kenneth W. Herrle, P.E., and Larry M. Bryant, Ph.D.


As terrorist bombings have become more frequent worldwide, mitigation techniques for such hazards have become commonplace in the design and construction of occupied facilities. Window design, in particular, has seen major changes in recent years largely due to the significant hazards posed by flying glass fragments. Historically, many building occupants who are seriously injured or killed in blast events received their injuries due to flying glass fragments from the building’s exterior window systems. This potential hazard has prompted many federal agencies to mandate explosive testing to pre-qualify window systems prior to being installed in their facilities.

Explosive testing can reveal deficiencies in both new technologies and improperly designed window systems, in addition to providing valuable data for improved analytical methods and software validation.  Such tests can also provide:

  • Proof of novel concepts 
  • General product validation
  • Project-specific validation for a particular design loading and performance level
  • Data for the development, improvement, and refinement of products, and analytical tools and methods

Because these tests provide real-world results, the explosive test bed has become a ‘proving ground’ for both newly-developed hazard mitigation technologies and project-specific designs.  An explosive testing project typically begins by determining the test objectives, selecting the test method to be used, and determining the applicable test standard required for the project.  Unfortunately, either through misinterpretation or ill-intent, compliance with selected test standards has been slowly falling by the wayside. Such practices can unknowingly compromise the validity of a test series. A basic level of knowledge regarding explosive testing and test standard provisions can help test sponsors ensure the efficiency and validity of their test series and keep them from falling victim to unscrupulous or unknowledgeable test providers. Manufacturers of blast mitigation window systems and products, who are typically the sponsor of many of these types of explosive tests, would achieve great benefit from knowledge of test procedures and test standard provisions. However, such knowledge can also prove useful for project managers, facility managers, designers, architects, and engineers who must make decisions regarding the use of tested systems in facilities with blast mitigation requirements.



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