Impact and Blast Protection
Aluminum is a widely-used material for protection from forced entry, hurricanes/impact, blast and ballistics. Though an important portion of the overall fenestration package is the proper glass selection, aluminum frames designed to incorporate these infills can achieve very high levels of protection. And continuous improvements increase the level of security desired by owners, architects and occupants.
- Impact - (from hurricanes/tornadoes)
- Forced Entry
Impact (from hurricanes/tornadoes)
Due to ever increasing impact requirements in Florida and along the coast line, products and projects are under more and more scrutiny for their ability to withstand hurricane events. Testing consists of ball bearing and/or 2” x 4” board being shot at representative samples. After every major event, extensive research and investigation occurs to determine what else could be causing further damage. The results are considered for further code enhancements. Because of its structural properties and the flexibility of extrusions, aluminum is poised to meet the needs in such environments.
Hurricane events, often associated only with Florida, occur from Mexico to Canada. Also, tornadoes occur much more frequently than hurricanes and, cumulatively, can be more destructive and deadly. Individual states, code groups and organizations are establishing new standards and rating systems that will mean more protection for the public. The AAMA Certification Policy Committee authorized accreditation of AAMA-accredited labs for tornado hazard mitigation testing and authorized an appropriate tornado mitigating tab to the AAMA gold label for products tested and certified to AAMA 512, Voluntary Specifications for Tornado Hazard Mitigating Fenestration Products, which provides a system for testing and rating the ability of windows and their anchorage to withstand extreme wind loading, debris impact and water penetration typical of tornadoes. (Click here to read more about AAMA 512.)
Aluminum is well situated to handle all of these concerns due to the accumulation of years of testing and design. Aluminum has a record of keeping you safe and will continue to do so regardless of weather conditions.
Blast resistant design is a challenge due to the complexity of not knowing the source or its resulting power. Blast design entails not only building and window design but also the surrounding environment and landscaping, as well as the distance away from the building that a vehicle is allowed (i.e., standoff distance).
Agencies of the government establish minimum blast size requirements, which are the basis of all design considerations.
Aluminum framing systems (windows, storefronts and curtain walls) are designed based on these charge sizes and tested to prove their resilience. Even though the glass selection plays a major part in resisting damage from a blast, the framing is just as important. Aluminum systems are designed to stay within the surrounding conditions, hold the glass in place (even when the glass fractures) and withstand the impact itself.
The term “forced entry” can range from someone attempting to break the glass in a frame, to someone using a crowbar to break a door lock to someone using more extreme measures, such as ramming the entrance with an automobile. For the purpose of this example, we limit it to the scope of 1304-02, Voluntary Specification for Forced Entry Resistance of Side-Hinged Door Systems. An oversimplification of this standard is that it consists of applying a 300-pound point load on the door frame to try to create a 6-inch gap between the door and the frame.
Aluminum framing systems are sturdy by the very nature of the material. With the proper selection of glass and glazing technique (sealing the glass in place), aluminum doors could withstand all but the worst assault.
Aluminum framing systems can, and have been, designed and tested to ballistic standards. Though not as common as forced entry, impact and blast resistance, some projects require ballistic protection. In those situations, there are options available to the architect and owner.
As with other configurations, it is important to select the proper frame and glass combination that will provide the protection required and desired.