Sheffield University engineers have developed a simple, cheap, yet innovative technology to ensure stability of buildings damaged in earthquakes.
The technology uses special metal straps that are wrapped around each floor of the building and tensioned by hand or special tools. Recent testing has revealed that damaged buildings, reinforced using this method, are capable of withstanding a major earthquake as powerful as the one that struck Haiti in 2010 with catastrophic consequences.
According to the Sheffield University researchers, the method is considerably cheap compared with other existing techniques, and doesn’t require specialist knowledge to be performed, making it especially suitable for the developing world.
“The strapping works very much like a weight-lifter’s belt, by keeping everything tightly compressed to reduce tension on the concrete columns of the structure,” said the lead researcher Professor Kypros Pilakoutas. “Our method not only makes the building stable again very quickly, but it increases the building’s ability to deform without breaking, making it more able to withstand further earthquake movement.”
The team tested the technique on a full-scale, two-storey building, built according to an old European standard with inadequate reinforcing to withstand earthquakes. During a first test, the building, placed on a specially designed shaking table simulating the earthquake movements, was tested without the reinforcing straps and nearly collapsed as soon as the simulated earthquake reached the magnitude 4 on the Richter scale.
Afterwards, the building was repaired using the new strap-based method and tested again. This time, the shaking table reached the magnitude 7, similar in strength to the devastating Haiti earthquake, at which point the test was stopped.
According to Professor Pilakoutas, the technology does allow prompt repairs of earthquake-damaged buildings, as well as preventing the damage from happening at all, if older buildings in disaster-prone areas are reinforced beforehand.
Reinforcing a typical small building would require negligible investment of £20 and two people working for two hours. Even if bigger multi-storey buildings are considered, the investment should not amount to more than a couple of hundreds of pounds.
“Ideally, governments shouldn’t wait until a disaster happens, but should be identifying buildings at risk and taking steps to make them strong enough to withstand any future earthquakes,” Pilakoutas said. “Because this method causes minimal disruption and is cheap to apply, it’s ideal for bringing existing buildings up to standard – both in the developing world and in earthquake risk areas in Europe as well.”
The research, funded by the European Union, was run jointly by research institutions from the UK, France, Cyprus, Turkey, Romania, Spain and the USA. The results have recently been published in the Journal of Earthquake Engineering.