Hi-tech building bandage promises to hold homes together in quakes
Researchers say buildings in poor, quake-prone areas can be 'bandaged' with a space-age membrane to stop collapse, saving lives and structures
A hi-tech architectural "bandage" could prevent millions of fragile rural homes from collapsing and save many lives during earthquakes, according to mainland scientists developing the technology.
Fibre-reinforced polymer, or FRP, an extremely strong, stretch-resistant plastic material, has already been used on spaceships, cars, ships and skyscrapers to fortify the structures against external shocks.
The researchers said advances in the technology and falling costs mean it could be used more widely to strengthen buildings in poor, quake-prone areas.
The membrane, woven with glass or carbon fibre, is thin and light and when wrapped around structures such as beams, pillars or load-bearing walls, can withstand three times the tensile forces that would snap steel, according to the researchers. Existing techniques to strengthen buildings against earthquakes include adding internal steel or concrete, but the scientists said that using the polymer "bandage" was quicker and easier.
Wang Zhenyu , a structural engineering professor at the Harbin Institute of Technology, said: "Applying it is as simple as putting up wallpaper. You don't need to wrap it all over the building. Only structurally critical areas such as beams and joints need the treatment."
Wang is leading three government-funded projects looking at ways the technology can help buildings withstand quakes.
High costs have limited the technology's use on the mainland to big infrastructure projects such as high-speed-rail bridges. But Wang said the price had more or less halved, making its use more feasible.
"Bandaging" a typical, three-storey rural building of about 600 square metres would cost between 50,000 yuan (HK$62,800) and 100,000 yuan, including design, materials and labour.
"This is still quite a large sum for many farmers in China, especially in less-developed areas," Wang said.
"The central and local governments would need to set aside an enormous fund to subsidise the farmers. The technology is ready, but it can only be introduced to rural areas with financial support."
Chen Guangming , a civil engineering professor at Guangdong University of Technology, said he was optimistic about the use of the technology in the countryside.
Numerous research teams are studying the polymer's effect on buildings in poor areas and some encouraging results have been reported, according to Chen.
Scientists found that using the polymer on a load-bearing wall in an X-like pattern could stop the wall falling during an earthquake.
"The potential is enormous," Chen said. "If FRP seismic retrofits are pushed countrywide in all high-earthquake-risk areas, a huge market would be created."
But Professor Wang Yuanfeng , a civil engineering expert at Beijing Jiaotong University, questioned how effective the polymer technology would be on rural buildings.
He agreed that the death toll in the earthquake in Yunnan province this month could have been much lower if rural homes had been reinforced to take the impact of major tremors. But photographs from the quake zone showed many collapsed buildings did not have basic internal support such as concrete beams or pillars. "These buildings won't stand up to an earthquake even if you wrap them all up," he said.
The cost of reinforcing houses with the polymer could also exceed the price of building new, safer ones, he said.
"More scientific research and experiments are needed to test the technology on rural buildings. At present, traditional methods such as concrete reinforcement may be more suitable to meet the urgent need of rural seismic retrofit projects."
A priority, Wang Yuanfeng said, was to stop local governments turning a blind eye to farmers building structurally fragile homes to save on construction costs.
