Testing of Annealed Glass with Anchored-Film Glass Retention Systems for Fallout Protection After Thermal Stress Cracking

摘要

Recently adopted ASTM Standard Test E 1886-97, "Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors, and Storm Shutters Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials" and its accompanying specification, E 1996-99, "Standard Specification for Performance of Exterior Windows, Glazed Curtain Walls, Doors, and Storm Shutters Impacted by Windborne Debris in Hurricanes" are used to determine the the performance of exterior fenestration elements when subjected to hurricane-like conditions. The intent of these standards is to minimize property or personal loss due to the breaching of fenestration elements in a hurricane. Protective systems for both new and existing buildings have been developed in response to these new standards. One possible application for existing building glass is an anchored-film system. This system relies on a polyester film adhered to the existing glass. The film is anchored around the glass perimeter to the window frame. An existing building with a history of thermal stress glass breakage required a system to safeguard against the possibility of glass fallout. Testing was necessary to determine the effectiveness of an anchored-film system for this application. The aforementioned ASTM standards were consulted; however, the cause of cracking, the nature of anticipated wind loads, and the pass/fail criteria were significantly different from those presented in these standards. Test criteria were developed by the authors to simulate the cracked glass, to apply appropriate loads and to measure the degree of fallout protection. This paper summarizes the development, implementation, and results of the test program, thereby demonstrating the feasibility and effectiveness of anchored-film systems for this unique application.