Older high-rise buildings 'a quake risk'

national June 09, 2014 00:00


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7.2 magnitude quake could bring down over a dozen towers in Bangkok, experts warn

IF A 7.2 magnitude earthquake strikes nearer to Bangkok than Chiang Rai, which was rattled by a raft of strong tremors last month, up to 17 towers in the capital would topple over, as they were built without appropriate safety measures, a Bangkok seminar heard recently.

Safety regulations should be amended to be enforced on all kinds of buildings, not just those above the minimum height of five storeys, to ensure they can withstand future seismic activity, which will be potentially harsher, said Assoc Prof Pennueng Wanitchai, a leading expert with the Asian Institute of Technology.
The Kanchanaburi fault lines are potentially more dangerous and cover larger areas than those in Chiang Rai that spawned strong shakers and more than a thousand aftershocks. Minor quakes occurring every 50 years may pose no risks to skyscrapers, but those occurring every 500 years could cause up to 12 structures taller than 12 metres to collapse, he said.
More powerful quakes occurring 
 every 2,500 years may flatten buildings with 20-40 storeys in Bangkok. The ministerial regulation of 1997 requires that |buildings with five storeys – or a height of about 15 metres – to be installed with quake safety measures. 
The Chiang Rai quakes damaged or destroyed many buildings with fewer than five storeys and other installations because there were no safety measures available when they were constructed.
City planning, which is non-existent in Thailand, could also help by restricting construction of tall buildings in areas where the soil is unstable, such as mud or clay.
Seismologists and engineering experts have attempted for a decade to seek the amendment of the quake safety regulations. 
The Department of Public Works and Town and Country Planning under the Interior Ministry would need to spearhead the effort to amend the law with a push and cooperation from the Bangkok Metropolitan Administration and local administrative bodies across the country.
Schools being repaired
Assoc Professor Anek Siripanichgorn, a civil engineering lecturer at King Mongkut’s University of Technology Thon Buri, and the chairman of the Engineering Institute of Thailand (EIT) under Royal Patronage, said two quake-damaged schools in Chiang Rai were being repaired with the cost covered by Her Royal Highness Princess Maha Chakri Sirindhorn based on EIT criteria for quake safety measures.
The EIT is planning to construct two-storey quake-safe buildings in Chiang Rai to serve as models.
Assoc Prof Suttisak Soralump, at the EIT’s Coordination Centre for Disaster Mitigation, said a nationwide database on active fault lines should be updated and a new survey be carried out. About 220 engineers had surveyed the damage to 100 houses, with 90 of them in serious condition. Local construction workers have been trained on how to repair those homes, as they fear that they may be at risk if the homes they work on collapse.
Assoc Prof Amorn Pimanmas, a lecturer with the Sirindhorn International Institute of Technology under Thammasat University, said about 10,000 homes, buildings and installations were damaged in the Chiang Rai quakes in May. 
Authorities should design standard quake-safe models for owners to study and use when building new homes, he said.

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