Metro may not be ready for ‘big one’ — expert

MANILA, Philippines — Metro Manila may not be ready for a 7.2-magnitude earthquake that the Philippine Institute of Volcanology and Seismology (Phivolcs) has warned could be generated by the West Valley fault.

Emilio Morales, chairman of the Association of Structural Engineers of the Philippines (ASEP), said the use of quench tempered or thermo mechanically treated (TMT) steel reinforced bars (rebars) in the past years constituted a clear and present danger to the country’s state of preparedness when a strong earthquake strikes particularly in Metro Manila, now replete with high-rise and medium-rise buildings.

In a forum held at the Quezon City Sports Club recently organized by a consumers’ group, Morales raised concern about the quake resilience of buildings and establishments in Metro Manila and other urban areas due to the widespread use of quench tempered steel rebars over better quality micro-alloyed steel.

The recent magnitude 6 earthquake that hit Hualien in Taiwan resulted in the collapse of many buildings and the death of a Filipina maid, which Morales said posed questions on the use of TMT steel in high-rise construction.  

Morales said that in preparing for the so-called Big One, attention should be given to the fact that since more than a decade ago, the formula and process for manufacturing steel bars were deliberately modified by local factories without informing the general public and government. 

“The quench tempered rebars crept into the market, and in the process, there were buildings built with both micro-alloyed and QT rebars… As far as I know, right now, about 85 percent supplied in the local market are QT rebars,” Morales said.

The ASEP chairman, an engineering professor and lecturer in top engineering schools, said there has been an apparent misrepresentation among some manufacturers about these low quality steel bars being sufficient for structural application.  

These inferior steel bars are being sold to consumers, contractors and developers, without them knowing of the danger they are exposed to. Worse, Morales said the sale of lower quality steel was done without lowering the price of the bars.

Morales said that quenching is the process of subjecting the hot steel bars to rapid cooling. This creates an outer layer that passes the tests conducted by the Bureau of Product Standards of the Department of Trade and Industry (DTI). However, tests done by the BPS do not expose the danger that could arise from these quenched steel bars, which should not be welded, bended, threaded and galvanized. 

He said studies in Italy, Australia and New Zealand have concluded that quench tempered steel is not for high-rise buildings, and that DTI Undersecretary Ruth Castelo has admitted this in interviews.