Laminated glass can minimize blast debris
“A blast pressure of more than 15 psi can rupture ear drums and collapse the lungs or crush the skull. The blast at the Oklahoma City federal building reached 4,000 psi,” Raj Goyal told the audience Feb. 18 during the second day of the Building Envelope Contractors Conference at the Rio All Suites Hotel and Casino in Las Vegas.
Goyal is vice president and general manager of blast mitigation and marketing for Graham Architectural Products Corp., York, Pa. His topic was Designing for Blast.
Architects designing facades in the 1960s, ’70s and ’80s probably didn’t know they’d have to consider terrorists in the 20th century, Goyal said. It’s important now to design without taking short cuts. “If it’s not right, someone is going to get hurt,” he said.
Buildings near potential blast threats also must be protected for collateral damage, Goyal said. The primary fragments of flying glass and building debris travel about 200 feet per second or 136 miles per hour, he said.
When designing structures, the charge weight and standoff distance must be considered, Goyal said, accounting for pressure, impulse and duration.
“Laminated glass is the key to protection in minimizing hazardous flying debris,” Goyal said. “Eighty percent to 90 percent of injuries can be prevented.”
The Department of Defense has Unified Facilities Criteria that prescribes the minimum design requirements for all DoD buildings. It allows architects to specify windows and entrances designed to help protect occupants from serious injury during an attack, even if these systems have not been tested. The UFC requires laminated glass and mandates that the majority of the glass remain in the framing system.
Other BEC presentations
Joseph Solinski, president of Stone & Glazing Consulting, Lewisville, Texas, spoke about Structural Glazing Survey and Repair. He discussed Fountain Place in Dallas that has 500,000 square feet of curtain wall. It was completed in 1986, and his company was called in 1993 after 160 leaks during rain, structural sealant concerns and a history of loose glass under high wind. Inspection, testing and repairs took five years to complete. A suction-cup pull test, administered six times on 26,000 windows, removed 16 windows. Solinski’s pointers for success include applications that suit conditions, proper design, peer review, installer education, quality control both internal and external, industry and trade organizations, and ASTM articles and papers.
Ted Derby, Midwest area sales manager for Pohl Inc. of America, West Valley City, Utah, presented The Application of the Rainscreen Principle with Current Construction Practices. Some of the advantages to rainscreen compared to other wall systems include: water-resistant quality of the total façade that does not rely on sealants; heat stagnation and humidity damage avoidance through venting; and the greatest possible heat conservation through the exterior insulation material.