x Abu Dhabi, UAEThursday 27 July 2017

Experts map Abu Dhabi quake risk

Scientists are drawing up seismic maps to identify risk areas in preparation for new building codes.

ABU DHABI // Earthquake experts are drawing up seismic maps to identify risk areas in the capital in preparation for new building codes. "There are many studies that have been done to determine the 'seismicity' of the region," said Ali Bukair, a policy consultant with the Department of Municipal Affairs, which is overseeing the hazard analysis project, referring to the frequency of earthquake activity in a given area.

"This study ... will give more precise, more comprehensive data. Ultimately, it's to determine the seismic forces on a building so we can design buildings properly to resist these forces." The bottom line is expected to be safer buildings in what is considered a "moderate-level" earthquake zone. Abu Dhabi's forthcoming building codes, originally scheduled for adoption early this year, will for the first time bring uniformity to design and engineering practices for all new structures. The project is being co-ordinated by the US-based International Code Council and Macedonia's Institute of Earthquake Engineering and Engineering Seismology.

Dr SK Ghosh, a seismic analyst and building codes consultant from Chicago, held workshops last week in Abu Dhabi to educate structural engineers about the new codes. The Ministry of Presidential Affairs has also asked that engineers be trained to ensure building components, such as light fixtures and facades, are properly anchored. Parapets or pumps that are not braced properly could become hazards.

"In an earthquake, a building moves and what happens to those lights hanging?" Dr Ghosh said yesterday, during a workshop. "Many times, those would simply fall. And if people happen to be around, they'd be hurt. These tall ceilings quite often fall in an earthquake because they're not tied back to a structure. So in seismic design, we pay a lot of attention to the architectural, mechanical and electrical components." The Macedonian team will also devise "wind maps" to determine how much wind speed a building should be designed to withstand.

The International Building Codes are based on US data, and the Abu Dhabi codes would have to be modified, said Dr Ghosh, since wind speeds are generally lighter in the capital than in most US territories. "The Macedonian study is more fundamental, but it's not code-related," he said. "Although, it's important that if they come up with seismic maps, they should not conflict with the maps in the code. That would totally baffle the practitioner, so there needs to be co-ordination."

The Macedonian seismic hazard and risk study will include "microzonation", in which researchers will assess the earthquake potential at specific districts within the capital. The structural "health" of buildings will also be monitored using instruments to measure various weaknesses, such as corroded reinforcements. "They will also do liquefaction analysis to see whether the soil in a potential site will liquefy, which happens in earthquakes," Dr Ghosh said. "Certain types of soil become like liquids, and a building becomes like a ship that literally floats."

A date for the introduction of the new building codes has not yet been announced. mkwong@thenational.ae