Blast off: Despite minor damages, laminated glazing holds up against disasters
Remodeling the Charles E. Bennett Federal Building in Jacksonville, Fla., was no easy feat. In addition to needing updated heating, ventilation, air-conditioning and electrical systems, new tenant office spaces and a rehabilitated façade, 1,300 leaking windows needed replacing. Updating the structure did not end there. Today, federal buildings, possible targets for terrorist activity, come under the U.S. General Services Administration’s strict design and construction standards created to protect people from injury and death in the event of an attack. So the Florida facility was rebuilt to withstand a bomb blast, sustain hurricane-force winds and debris impact. Rodriguez and Quiroga Architects Chartered of Coral Gables, Fla., tackled the Bennett Building challenge. Laminated glass was the solution for safety, security and design.
Since the Alfred P. Murrah Building bombing in Oklahoma City in 1995 and subsequent terrorist bombings around the world, protecting buildings, especially government buildings, from bomb blasts has been thrust to the forefront of architectural planning and design throughout the world. However, contending with man-made disasters does not eliminate the need for buildings to also withstand natural disasters and offer inhabitants protection against extreme natural elements. Architects and their clients want to wrap safety and security in beautiful, modern buildings that push architecture to the next level.
To innovate while simultaneously providing protection against multiple man-made and natural elements, architects turn to laminated glass, says Gérard Savineau, marketing technical applications manager for Europe, Africa and the Middle East at Solutia of St. Louis, producer of polyvinyl butyral interlayers. “We like to tell architects that we have a laminate product to meet every need, and that our laminate products provide additional benefits at no extra cost.”
Bomb blast and hurricanes
The Charles E. Bennett Federal Building demonstrates the many functions of a single laminated glass product in the form of Saflex HP, one of Solutia’s two high-performance interlayers for hurricane resistance in large openings under high pressures. It can be used in architectural applications to span great spaces and resist huge loads. By incorporating laminated glass manufactured with Saflex HP into the renovation, the Bennett Building now can resist substantial bomb blast forces and sustained hurricane-force winds.
Architects planning other high-security buildings in coastal regions also turn to Solutia’s high-performance interlayer Vanceva Storm. A specially formulated blend of PVB and film, the composition blends the rigidity to provide hurricane protection with the flexibility to withstand bomb-blast loads.
Bomb blast and aesthetics
While planning for security has become crucial, aesthetic designs serve as prerequisites. When outlining a campus to replace the destroyed Murrah building in Oklahoma City, lead designer Carol Ross Barney of Ross Barney + Jankowski of Chicago, Illinois, used laminated glass to create a bright, open building that looks nothing like the stronghold it is. Built to replace a building viciously destroyed by man, planners said it was psychologically important to federal employees, visitors, community members and the country that its appearance not suggest U.S. citizens cower to terrorism (see story, Glass Magazine, Sept. 2003, p. 36).
“Security was paramount when designing the campus, but we also wanted to create a sense of openness in a sustainable building,” says Ross Barney. “Generous use of glass allowed us to accomplish these objectives.” Ordinary monolithic glass, however, can be incredibly dangerous during a bomb blast. Experts at Texas Tech Glass Research and Testing Laboratory, Lubbock, Texas, estimate that approximately 75 percent of all damage and injury from bomb blasts can be attributed to flying and falling glass following an explosion. They note that a single square foot of unprotected glass can project as many as 100 sharp shards at speeds of up to 300 feet per second.
Laminated glass can mitigate these problems. During a blast wave, even if laminated glass cracks, fragments tend to adhere to the laminate interlayer, thus reducing or eliminating the dangers associated with flying or falling glass. The unit also provides occupants with protection against exterior flying debris because the glass and interlayer remain in the frame.
“The properties that allow glass to remain in the frame and cling to the interlayer during a bomb blast make laminated glass a safe hurricane protection alternative as well,” says Julie Schimmelpenningh, architectural technical applications manager at Solutia. “In proper configurations, laminated glass can resist hurricane-strength winds and debris impact.” Although the glass might crack, the unit remains in its frame, offering protection against repeated impacts and protecting the building envelope by preventing wind and water penetration that could cause structural collapse or severe mold problems.
High-performance blast and energy efficiency
If there can be small miracles found amid the rubble of the Sept. 11, 2001, attacks on the United States, they are in the performance of blast-resistant glazing in the Pentagon. The Pentagon was in the process of having its exterior windows and the structures that support them retrofitted to provide increased external bomb-blast protection. The blast-resistant work had just been completed in Wedge One when that sector of the building took the brunt of the impact from American Airlines flight 77.
The outer most shell collapsed, and the damage continued inward. However, the blast-resistant windows helped support floors above the impact for more than 30 minutes, allowing hundreds to escape. Most windows in the adjacent Wedge Two, where windows had not yet been updated, failed.
The blast-resistant window systems in Wedge One were manufactured by Viracon of Owatonna, Minn. Officials at Viracon worked with contract glazier Masonry Arts of Bessemer, Ala., and Solutia to fabricate laminated glass with a custom Saflex PVB interlayer to meet intense government security requirements. The laminated glass window systems also gave the Pentagon thermal-performance characteristics. By introducing a low-emissivity coating in combination with the protective glass, planners helped reduce hot-cold transfer from inside to out, creating a more comfortable environment inside.
Bomb blast, ballistics and intrusion
Instances of using laminated glass to solve multiple safety, security, environmental and design challenges have grown popular around the world. “Solutia’s consulting group may be called to find suitable and economical global solutions based on glass made with Saflex or Vanceva interlayers,” Savineau says. We have a great deal of experience with all security aspects and bomb blast in particular.”
In Riyadh, Saudi Arabia, thick layers of laminated glass were used in the Celebration Building façade of the King’s Palace to provide security against bomb blasts, bullets and intruders. Solutia researchers worked with Oger International France to define the best double laminated insulating glass units. The proposed solution, based on a high-performing Saflex PVB interlayer, was approved by engineers from Rashid Engineering of Saudi Arabia and General Contractor Oger International of Paris, France. Glazing was supplied by Saudi American of Saudi Arabia.
In Paris, the Organization for Economic Cooperation and Development Worldwide Headquarters Building went through a full window-replacement program to enhance the protection of their employees and visitors from possible terrorist attack. The project involved retrofitting security windows into OECD’s historic building. Solutia researchers were invited to propose a global bomb-blast and bullet-resistant glazing and window solution that met the perceived risks. The proposed design was chosen by the OECD’s security officers. The laminated glazing based on Saflex PVB interlayer was manufactured by Macocco of Paris.
In appropriate configurations, laminated glass has proven to offer buildings exceptional levels of support against bomb blasts, and can also meet other structural and design goals in a building. It can provide ballistics and intrusion protection and hurricane and earthquake protection. Laminated glass can reduce perceived noise levels to provide sound insulation and offers exceptional filtration of ultraviolet rays. Sustainable building practices also benefit by the use of laminated glass in combination with low-emissivity coatings or tinted glazings to lower heating and cooling costs and create daylit spaces.
U.S. Federal Courthouse, Jacksonville, Fla.
Owner: General Services Administration, Washington, D.C.
Size: 457,416 square feet
Cost: $80 million
Architect: HLM Design, Jacksonville, Miss.
Glass fabricator: Viracon, Owatonna, Minn.
Interlayer manufacturer: Solutia Inc., St. Louis
Unitized curtain wall and window systems: Masonry Arts Inc., Bessemer, Ala.
Curtain-wall engineer: Heitman & Associates, St. Louis
Contract glazier: Masonry Arts Inc.