Lee Coates, Technical Manager of Wrightstyle tells Glass and Glazing Products that safety first must be the rule .

Explosives test glass

In many respects, the history of architecture has also been the history of the window. Each advance in glazing technology has had immense influences over architects. Our skylines, once drab in bricks and mortar, now sparkle with glass towers.

Until recently, the primary consideration facing architects was to balance form and function; to design buildings that worked on the inside and which looked good from the outside. One such building was the Alfred P Murrah Federal Building, Oklahoma City, bombed to oblivion and international notoriety nearly eight years ago.

According to the Glass Research and Testing Laboratory at Texas Tech University, the primary cause of injury was flying glass. Of the hundreds injured, 80% were injured by flying glass. Glass fragments were found six miles from the seat of the blast.

The images from that terrible disaster are also etched in pictures from Omagh to London’s Dockyards, and from Kenya to Bali. Removing explosives from terrorists’ hands is top priority. Removing glass from their arsenal is also vital.

The good news is that the glass and glazing industry has been fighting back. The Texas researchers found that, while most glazing systems used in the downtown area of Oklahoma City were completely destroyed, windows and doors made with laminated glass performed better than any other glass type.

Upon shock wave impact, the glass itself may crack, but the fragments tend to cling to the interlayer and remain within the frame.

In their report, the Texas researchers concluded that damage to people and property in the bombing outrage could have been reduced if laminated glass had been used in the buildings that surrounded the Federal building.

It is a lesson being slowly learned, often painfully. After 9/11, it was found that nearly 15,500 windows had been damaged within a mile of Ground Zero – nearly 9,000 within half a mile.

An obvious solution to the problem might be to encourage architects to reduce the number of windows and make windows smaller, a policy adopted by the US State Department for several embassy projects – and recently dropped as being aesthetically wanting.

A report written for the US National Academy of Engineering, says that: “A more proactive approach is to develop glazing materials that meet aesthetic and functional design objectives but do not contribute to the explosion-induced projectile hazard, either by controlling the nature of the projectile patterns or limiting their range and dispersion patterns.”

The authors go on to say that glazing materials for security applications are available in many forms, including tempered, annealed or laminated – not to mention window films and glass substitutes such as polycarbonates. One crucial question for the owners and occupiers of high-value or high-risk buildings is why so few of them have adequate protective glass.

Whilst glass can be considered as suitable for providing primary protection, it has to be supported and retained by a frame of equal performance. Should the framing system being used with the specialist glass, be unable to provide adequate edge cover or clamping of the glass edge, then the risk of millions of fragments of glass becoming one large deadly pane of flying glass, becomes all too real.

In light of recent events and customer concerns, Wrightstyle Ltd, successfully completed project related high pressure blast-resistant testing on the SR curtain walling and roof glazing systems, successfully demonstrating that modern glass and glazing systems can act as primary protection system against explosive risks.

Independent test analysis conclusively showed that our system, utilising either steel or stainless steel rolled hollow profiles, provides life-saving protection from large explosive detonations within close proximity of the façade.

The framing is designed to withstand the blast pressure whilst still retaining the glass within the system profiles. This, coupled with the performance of the safety-laminated glass can prevent the type of injuries associated with flying glass. In Oklahoma alone, those horrific injuries afflicted some 200 people.

We have pushed the boundaries of what glazed elements can achieve safely and cost-effectively – and therefore the kind of building facades that architects are now able to design. In today’s uncertain world, designing for safety is a much higher priority.

The history of architecture is the history of the window. The new difference is that the window just got safer.

Picture:
Aftermath of Canary Wharf, London (photograph © Press Association)