As terrorism becomes more pervasive, building owners beyond those for government facilities and secure locations are looking to improve their blast resistance in particular.
Precast concrete provides a durable material that can withstand the explosive force of an external blast better than any other material. It also can be used to design aesthetically pleasing blockades that keep potential explosive devices at a distance, providing the best solution for meeting blast resistance.
Internal blast resistance requires more consideration. The objective of blast-resistant design is to provide an acceptable level of safety to building occupants in the event of an explosion. Considerable damage is usually acceptable as long as components remain attached to the building, and the building does not experience a progressive collapse.
Load-bearing precast panels must be designed to span failed areas through arching action, strengthened gravity connections, secondary support systems or other ways of providing an alternative load path.
Architectural precast concrete can be designed to mitigate the effects of an explosion and thereby satisfy requirements of the General Services Administration (GSA) and the Department of Defense (DOD). Protecting the entire façade, however, will impose a great cost regardless of the material used.
To provide the best protection for occupants, designers should plan for the building and its cladding to remain standing or attached long enough to protect occupants from injury or death resulting from flying debris and to evacuate everyone safely.
A minimum panel thickness of 5 inches, exclusive of reveals, should be designed. The panels also should include two-way, reinforcing bars spaced not greater than the panel’s thickness to increase ductility and reduce the chance of flying concrete fragments.
The thinnest panel thickness acceptable for conventional loads should be used. The objective is to reduce the loads transmitted into the connection, which must resist the panel’s ultimate flexural resistance.
All building components requiring blast resistance should meet the criteria required for GSA or DOD facilities. They should be designed using established methods and approaches for determining dynamic loads and dynamic structural response.
For more information, contact a PCI Certified Manufacturer.