Glass Curtain Walls From China - Limited life

Window washers on the 60-story, glass-walled JW Marriott Hotel Shanghai.

Glass-covered towers nearing critical age: China's first buildings to feature glass curtain walls will reach the end of their design life in the next few years, prompting experts to call for better maintenance of the structures to prevent accidents. Glass curtain walls, in which a building's facade is made of sheet glass held in place by framework, began to appear in Chinese blueprints in 1984, and have an average design life of 25 years.

The durability of supporting parts, such as bolts and sealant, is generally 10 to 15 years. In Shanghai, about 900 of at least 4,000 such buildings are more than 15 years old. "But that doesn't mean they should be replaced by new ones or demolished immediately," said Lu Jinlong, deputy director of the Shanghai Research Institute of Building Science. "They can be used for some time if regular maintenance is done well."

China builds 70 million square meters of glass curtain walls each year, according to the China Architectural and Industrial Glass Association. The cost of replacing these could be enormous. "Who should be responsible for the large sum? The developers or the maintenance companies?" said Li Dexiang, a professor at Tsinghua University's School of Architecture. "The problem is there, but there's no efficient solution yet."

Some buildings with glass facades overseas are still in good condition after 50 or 60 years, thanks to timely maintenance. But there have been many cases in China of glass curtain walls in high-rises bursting without warning. In Hangzhou, Zhejiang province, a 20-year-old woman was hit by shards of glass from a window that burst in a glass facade as she walked down the street on July 8. Part of her left leg had to be amputated.

A month later in Yiwu, Zhejiang province, a 20-meter-high glass ceiling in a garment market came crashing down, injuring several children, one seriously. Shanghai enacted a management regulation for glass curtain wall construction on Feb 1, establishing a fund collected from developers and owners of such properties for maintaining and repairing glass curtain walls.

"However, there's a long way to go between setting up the fund and using it to have the glass curtains in good condition in Shanghai," said Lu, of the building research institute. "Let alone in other cities, which don't have such a regulation or plans."

China released a building code for glass curtain walls in 2003, but no guidelines have been issued on who is responsible for the maintenance. According to Motian City magazine, there were 350 buildings higher than 152 meters, and another 287 under construction on the Chinese mainland in March. "The number of completed super high-rises may increase by 10 percent this year," said Wu Chengtao, the magazine's editor-in-chief.

"But the construction of many glass curtain wall buildings takes only the charming exterior into account," he said. "First, they invest more than hundreds of millions in the construction. The cost for later repair and maintenance comes to no small sum," Wu said.

On July 8, when a 19-year-old girl named Zhu Yiyi was walking past a 23-storied building in Hangzhou, a glass curtain wall fell from the 21st floor and hit her, leaving a 20-cm laceration on her left lower limb, severing the arteries in her left thigh, and fracturing her thighbone. Her vessels, muscles and tissues in the left lower leg were also severely damaged, which means amputation at the knee would have been the only viable treatment.

19 year old Zhu Yiyi faces amputation after her leg was virtually severed by a shard of falling glass from a commercial building in Hangzhou, the capital of eastern China's Zhejiang Province on July 8. Zhu is now in a Shanghai hospital for surgery in hopes of preserving most of her leg. Though in stable condition, Zhu must sleep in a corridor because the hospital has no beds available. A sheet of glass, measuring 1 meter in length, dropped from the 21st floor and hit Zhu from behind on her knee as she walked near the 23 story Qingchun Development Building on her way to work. "At that time, I felt extremely painful and I was bleeding seriously. I was very weak and just wanted to be alive," said Zhu Yiyi.
Witnesses said her left leg was almost cut off beneath her knee. Doctors in the Hangzhou hospital said that due to the severe damage to the blood vessels and nerves, Zhu might lose her leg. In order to keep her leg, Zhu's parents, farmers from a village in Jiangxi Province, took her to Shanghai right away to receive better treatment. The father said they hoped the hospital could save her knee so that she could walk with an artificial limb after surgery. A doctor said the hospital would try to move Zhu into a ward from the corridor soon, and promised to let the best doctor perform the amputation. "Amputation is necessary for her and we are concerned where to conduct the amputation. We are trying to conduct it on a lower place of her leg. If we conduct the amputation under her knee, the artificial limb will be functioning in a better way," said Zhang Tao, Executive Director of Orthopaedic Department of Shanghai No. 8 People's Hospital.
Zhu's family is not wealthy and she gave up her education after high school to work in an architectural design company in Hangzhou. Though the sudden disaster has challenged her in an arduous way, she remains positive about her future. "I believe that I will be like a normal person once I have my artificial limbs on. I can do nothing but to face and accept the situation now," said Zhu. "I blame no one, but hope similar tragedies will never happen to others. I still feel optimistic about my future. For example, I can be a senior architectural designer. I can earn more money. I can also find my Mr. Right to love for the entire life," Zhu also said.
The building's property management company issued a written guarantee to Zhu to cover all her medical expenses. Zhu Meilong, the father of Zhu Yiyi, explained that the company initially refused to take full responsibility and gave Zhu only 30,000 yuan in compensation, which was less than the 40,000 yuan needed for medical expenses. He also said the company agreed to pay more after a Hangzhou law firm helped Zhu negotiate with the company voluntarily. Hangzhou police were still investigating who was liable, but Dai Heping, the head lawyer of the law firm who is helping Zhu Yiyi free of charge, said both the property management company and the tenant of the floor, a paper-making company, should be held responsible. 

Tempered glass breakage: A frequent misconception about tempered glass regards its resistance to breakages. Many consider it "unbreakable" or "nearly unbreakable". Such is not the case. As with every other type of glass, also tempered glass can break. Glass breaks when it is exposed to stresses that it cannot withstand. To increase its strength and heat resistance annealed glass can be subjected to a thermal treatment or chemical process. Tempered glass is obtained using this process, and its final form is four to five times as strong as annealed glass of the same type and thickness. When broken, it shatters into many small fragments, which prevent major injuries. Due to these characteristics tempered glass is used traditionally in applications requiring increased strength and reduced likelihood of injury in the event of breakage.
Tempered glass should receive the same care as annealed glass. Unfortunately, the perception of "unbreakable" characteristics of tempered glass may mislead people to provide less care while handling it. Careless handling and improper installation sometimes produce damage, which leads to "spontaneous breakage" or "delayed breakage." This means that occasionally a sheet will not shatter immediately at the time of damage, but perhaps weeks later. Inclusions in glass such as NiS can also trigger a delayed breakage effect. Nickel sulphide inclusion, also known as NiS, occurs during the manufacturing process for float glass. In a glass batch, nickel-rich contaminants such as stainless steel might be present, and then combine with sulphur to form nickel sulphide inclusions. To minimize the risk of NiS breakages, a heat soak test is performed. Although some spontaneous breakages occur due to the above-mentioned factors, much breakage is called "spontaneous" just because there is no easily visible cause.