Strengthening the Performance of Laminated Glass
Facing the terror threat
Hurricane resistance was not the only benefit to using laminated glass with enhanced polymer interlayers, at the Miami courthouse and indeed at federal facilities across the country. The other major consideration was protection against the blasts of a terrorist's bomb.
In 1998, terrorists bombed the U.S. embassies in Nairobi, Kenya, and Dar es Salaam, Tanzania. One hundred ninety-seven people were killed and over 5,000 people were injured, many from flying glass shards. To combat a growing wave of terrorist attacks and to protect U.S. embassies abroad, the U.S. State Department began an estimated $21 billion embassy construction program the following year.
The State Department recognized the advantages of the advanced polymer interlayer over PVB interlayer to provide retention and resist tearing under high pressures, impulse loading typically associated with truck bombs. The interlayer was incorporated into structural muntin windows intended for use in embassies. These new blast windows utilize steel elements behind the glazing to give the appearance of true divided lites. A characteristic of this window system is that it exhibits substantial deformation at allowable design loads and effectively absorbs the blast energy.
While PVB interlayers are effective in laminates requiring lower levels of blast resistance, the stiff, advanced polymer interlayer has the ability to increase blast mitigation capacity of laminated glass facades. This benefit is derived from its increased polymer tear energy. In addition, attachments can be integrated into the laminate during or after laminating that adhere well to the interlayer and can allow secure attachment of the laminate to the frame, maximizing the full membrane strength of the glazing element.
From security to design
The focus of the use of laminated glass with advanced polymer interlayers at courthouses and in new embassy construction is on safety and security in the context of natural and man-made disasters. But laminated glass with an advanced polymer interlayer is becoming a key solution in expanding design innovation with glass. Some of these solutions incorporate energy efficiency goals and "green" design strategies such as the greater use of daylighting.
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The Shanghai Oriental Arts Center in China, completed in 2004, and designed by Paul Andreu, chief architect of Aeroports de Paris, is Shanghai's new cultural center [Figure 2]. The complex includes three halls: a 2,000-seat symphony hall, a 1,100-seat opera hall, and a 300-seat auditorium. It also features assorted public facilities, including music shops, a restaurant, and an arts library.
For the design concept, the architect wanted the building to glow at night. The design consists of large panels of perforated, galvanized steel metal encapsulated in laminated glass for the façade to create a shimmering effect. The metal featured varying sizes of holes and spacings to reduce solar heat gain and for aesthetics. Laminated safety glass was used for the façade, and the structural interlayer was chosen because it was compatible with the metal and provided all of the desired strength and security features.