Seismic shift needed in earthquake testing

Despite the UAE being at low risk from earthquakes

A seismic design expert has called on developers of tall buildings to put their building models through a seismic hazard assessment before they begin construction.

Michael Willford, the co-chair of the Council on Tall Buildings and Urban Habitat (CTBUH) and a principal at consultancy firm Arup, said building codes that are currently being used are inadequate for tall buildings.

He said that architects, engineers and government officials should be concerned about the ability of tall buildings designed to current code standards to survive major earthquakes.

Willford told Construction Week that, "The building codes here are outdated and don't work for the kind of tall buildings they are constructing here now. Their 'tall' is not the kind of 'tall' that the world is used to so the codes have to be re-examined."

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He said that building designs must be rigorously evaluated and put through a simulated earthquake to test their resilience.

Despite the UAE being at low-risk for earthquake activity, the country has two tectonic belts running close to it with the closest one being the Zagros fault zone 200kms from the northern Emirates.

"Even though the UAE is a low-risk region, one can't take a chance with such things.

"The current codes were developed to address the seismic design of low- to moderate-rise buildings. As such, they fell short in conveying specific modeling, analysis, and acceptance criteria for tall buildings," he said.

"This is mainly due to the fact that the structural characteristics which control seismic behavior of tall buildings are different to those of shorter buildings, in particular the limited degree of ductility inherent in the structure of a tall building.

The CTBUH is recommending a more appropriate performance based approach to seismic design along the lines of that practised in Japan and China.

"The CTBUH is committed to increasing awareness of the inadequacy of tall building codes," said David Scott, CTBUH chairman.

"We are now in an era where modern sophisticated computer analysis can predict how a building will behave under extreme earthquakes with reasonable confidence. We need to use this knowledge to develop new codes and not wait for a disaster to happen before we take action."