Building 'belt' offers cheap, quick repair of earthquake damage

Jan 13, 2014
This is a damaged second floor building joint prior to testing with post tensioned metal straps. Credit: University of Sheffield

Four years after the January 2010 earthquake, 145,000 people still remain homeless in Haiti. A cheap and simple technology to repair earthquake damaged buildings – developed at the University of Sheffield – could help to reduce these delays by quickly making buildings safe and habitable.

Recent tests showed that a damaged building repaired using the technique could withstand a – similar in scale and proximity to the buildings that collapsed during the Haiti earthquake.

The technology involves wrapping metal straps around each floor of the building, which are then tensioned either by hand or using compressed air tools. It is designed for use on reinforced concrete frame buildings – a common construction technique around the world, including countries like Haiti. Unlike other repair methods, it does not require expensive materials or a high level of technical knowledge, making it ideal for use in the .

Lead researcher, Professor Kypros Pilakoutas, explains: "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.

Concrete works well under compression, but not when pulled under tension and this is why it has to be reinforced for use in construction. When the reinforcement is faulty or damaged, it can be very expensive to repair.

"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."

This is the same building joint, following application of post tensioned metal straps and tested on shaking table to equivalent of magnitude 7 earthquake. Credit: University of Sheffield

The team tested the technique on a full scale, two-storey building, built according to an old European standard which has inadequate reinforcing to withstand earthquakes. This construction is typical of many buildings in the developing world, as well as many Mediterranean buildings built before the 1980s.

The building was constructed on a specially designed 'shaking table' which can simulate ground movement caused by earthquakes. During the first test, the building was very near collapse following a small earthquake similar in scale to a magnitude 4 on the Richter scale having about 10000 times less energy than the Haiti earthquake.

This video is not supported by your browser at this time.

The building was then repaired using the post-tensioned metal straps and retested. The researchers were unable to make the building fail during a major earthquake similar in scale to the magnitude 7 Haiti earthquake at the epicentre and stopped the test at that point.

Professor Pilakoutas hopes the new technology will not only speed up the response to major earthquakes, but could also prevent the damage happening in the first place. The cost of the materials for a typical small building column is about £20 and it would take a crew of two people around 2 hours to complete the strengthening. For a typical small dwelling having 6 columns, the seismic rehabilitation would cost around £200 and could be completed in a few days, rather than cost several thousand pounds and take months with other traditional rehabilitation techniques such as jacketing with steel plates or concrete.

"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," he says. "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 risk areas in Europe as well."

Explore further: Retrofitting earthquake protection could save lives

More information: 'Full-scale shaking table tests on a substandard RC building repaired and strengthened with Post-Tensioned Metal Straps' is published in the Journal of Earthquake Engineering, DOI: 10.1080/13632469.2013.847874

Related Stories

Retrofitting earthquake protection could save lives

Jun 05, 2013

Whether or not a building collapses and claims many lives during an earthquake is a matter of structure and statistics, according to researchers in Turkey. Writing in the International Journal of Emergency Management, civil ...

Quicker, quake-proof skyscrapers

Dec 04, 2013

Peel back the outer layers of a skyscraper built in an area vulnerable to earthquakes and you'll find a tangle of steel-reinforced concrete beams that span doors, windows and other openings in the structure's ...

Should we better prepare for earthquakes?

Dec 15, 2011

University of Adelaide researchers are leading an international project to help identify buildings most vulnerable to earthquakes and the best ways to strengthen them.

Studying how skyscraper foundations stand up to earthquakes

Dec 06, 2011

UC Davis engineers are preparing to conduct the first rigorous tests of how the steel columns that secure skyscrapers to their foundations stand up during earthquakes, research that could make the towering structures safer ...

Recommended for you

Lifting the brakes on fuel efficiency

Apr 18, 2014

The work of a research leader at Michigan Technological University is attracting attention from Michigan's Governor as well as automotive companies around the world. Xiaodi "Scott" Huang of Michigan Tech's ...

Large streams of data warn cars, banks and oil drillers

Apr 16, 2014

Better warning systems that alert motorists to a collision, make banks aware of the risk of losses on bad customers, and tell oil companies about potential problems with new drilling. This is the aim of AMIDST, the EU project ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

VENDItardE
1 / 5 (1) Jan 13, 2014
well done
StanFlouride
not rated yet Jan 13, 2014
A similar, though considerably less elegant, solution was used to reinforce the pilings and cross members of San Francisco freeways after the Loma Prieta earthquake.
The pillars were wrapped in rebar and the joints in cages made of them. It was only a temporary solution, intended to hold them up until they were demolished a few years later.

More news stories

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.

Health care site flagged in Heartbleed review

People with accounts on the enrollment website for President Barack Obama's signature health care law are being told to change their passwords following an administration-wide review of the government's vulnerability to the ...

A homemade solar lamp for developing countries

(Phys.org) —The solar lamp developed by the start-up LEDsafari is a more effective, safer, and less expensive form of illumination than the traditional oil lamp currently used by more than one billion people ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...