Safetydrape® GSA Compliance
The US General Services Administration (GSA) oversees the design and construction of new facilities and manages the existing real property inventory for a large portion of the US Government. After the bombing of the A.P. Murrah Building (Oklahoma City) in 1995, a Presidential directive was issued ordering government agencies to take actions to protect government facilities. In response, the GSA published its Security Criteria which specifically addresses blast protection issues for both new and existing GSA facilities.
Among other issues, GSA criteria addresses window glazing and the associated hazards generated by a blast. The criteria were generated in part by a series of GSA-performed blast tests on windows. The tests grade the glass fragment hazard for windows based on the location of glass fragments after a blast. The GSA requires that manufacturers of glass fragment mitigating products test their products using these criteria in order to be considered for use in GSA facilities.
Testing Safetydrape® for compliance
To demonstrate Safetydrape®’s efficacy, a computer-based terrorist event in a typical GSA office building was modeled. This model predicted glazing damage in a typical scenario and showed how Safetydrape would mitigate glass hazards.
The software used for the computer generated model is the Anti-Terrorism (AT) Assessor, developed by ARA Applied Research Associates predicts damage to building components from exterior blast threats. Geometric depictions of building facilities are modeled in a 3D environment.
Air blast prediction models based on formulations given in the TM5-855 military design manual are used and these are compared against pressure-impulse failure relationships for the given component models. From this, a damage prediction estimate is generated.
As shown in Figures 1 and 2, the building used for the comparison is approximately 140 ft by 160 ft in plan and is 8 stories high. In the damage prediction figures, damage is displayed and color coded for windows on floors 2-8 only. All other windows and structural elements are displayed as a light gray color.
The window used for the comparison is the same 48” x 66” x 1/4-inch thick monolithic annealed glass window that was tested. The charge weight used is a 100-lb TNT charge located at the curbside 20 ft from the front edge of the building. The comparison is made between an unprotected window with no blast curtain and a window with Safetydrape®.
In Figure 1, a model for the capacity of a plain monolithic window is used to predict window breakage. Hazardous breakage of the windows is indicated in red and it can be seen that in this scenario, hazardous uncontrolled breakage of all windows in the building is predicted.
Figure 2 shows the potential benefit of using blast curtains. In this scenario, all glass is predicted to be broken, but controlled by the blast curtain to varying extents. In areas of the building color coded green, glazing failure is predicted to be significantly controlled (at GSA Condition 3). In regions colored orange, blast loads may be high enough to cause Condition 4 or worse within the blast curtain. It is important to note that the analysis assumes the exterior walls and the connection of the curtain into the wall are adequate to survive the blast. Competitive Analysis Chart (PDF).