Most of the current building codes are inappropriate for tall buildings and their use will lead to inefficient and potentially unsafe construction, said an internationally acclaimed seismic design expert.

Michael Willford, the co-chair of the Council on Tall Buildings & Urban Habitat (CTBUH) working group on the 'Seismic Design of Tall Buildings,' was speaking at the 'Meed Building Tall Conference 2008' at the Park Hyatt Hotel in Dubai on Wednesday.

Willford also addressed the issue of seismic design and innovative solutions to wind engineering in tall buildings during the conference.

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

According to Willford, who is also a principal at ARUP, the seismic design of tall buildings, or buildings exceeding 160 feet in height, are introducing new challenges that need to be met through consideration of scientific, engineering, regulatory issues and criteria.

“The current codes around the world, many of which are based on US 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,” explained Willford.

“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.”

During its 8th World Congress in Dubai last March, the CTBUH announced the release of the very first set of recommendations to address the issue of the seismic design of high-rise buildings, developed by Willford, Professor Andrew Whittaker of the New York State University at Buffalo, and Ron Klemencic of MKA, Seattle, Washington, USA.

The CTBUH is recommending a more appropriate ‘performance based’ approach to seismic design along the lines of that practiced in Japan and China. This would require that the design of a proposed new building be evaluated rigorously by being exposed to a series of computer simulated earthquake events consistent with any potential seismic hazard at the site.

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

'The issue from a historical perspective is that the design codes only change after each big earthquake. However, we are now in an era where modern sophisticated computer analysis can predict how a building will behave under extreme earthquakes with reasonable confidence,'  he pointed out.

'We need to use this knowledge to develop new codes and not wait for a disaster to happen before we take action,' he added.-TradeArabia News Service