Luzon quake tests inferior steel bars

posted May 01, 2019 at 09:55 pm
by  Ray S. Eñano
Luzon quake tests inferior steel barsLuzon quake tests inferior steel barsThe magnitude 6.1 earthquake that rattled Central Luzon and Metro Manila on April 22 has evoked bad memories from the July 16, 1990 killer quake. That magnitude 7.7 temblor nearly three decades ago flattened buildings in Baguio City and Nueva Ecija and Pangasinan provinces and left over a thousand people dead.

Last month’s earthquake was nowhere near the strength of the July 16, 1990 tremor but it was strong enough for people to cower and to cause significant damage on one grocery store in Pampanga.

The  6.1 quake also tested the integrity of high-rise buildings and condominiums. Cracks were found in Clark Airport, a school in Manila, while the Chuzon Supermarket in Pampanga collapsed. There are unconfirmed reports that the steel products used by the supermarket were substandard.

Engineer Roberto Cola, president of the Philippine Iron and Steel Institute, seemed to be playing coy when he declined to categorically answer repeated questions from former senator Nikki Coseteng during the recent ‘Kapihan sa  Aristocrat’ on claims that PISI members were selling just grade 40 steel bars to developers and passing them off as grade 60.

Coseteng said local steelmakers who are members of the PISI had replaced micro-alloyed steel products with substandard steel bars that underwent a questionable testing process to determine their tensile strength.  The engineering community, developers, and building owners have no clue about this industry practice.

The issue has been hounding the steel industry since last year. During a Senate hearing in 2018, Cola conceded that  “steel bars grade 40 are quenched with spray of cold water so that hopefully, they become grade 60.” They are sold as grade 60, but the raw material itself is grade 40.

This can be likened to an adulteration practice illicitly adopted by a dairy company in China, where it added Melamine, a nitro-rich compound, into the milk to increase the protein count in their milk and dairy products. Melamine is harmful if swallowed, inhaled or absorbed through the skin.

When grade 40 steel bars are ‘passed’ or upgraded to grade 60 and used as reinforcement bars for high-rise buildings, meanwhile, they can potentially cause the foundations of buildings to crumble. The impact of a high magnitude earthquake on such building materials could be disastrous.  

Coseteng during the same forum challenged Cola to show her a signed document assuring PISI’s products were grade 60 inside and out.

The Philippines is part of the ‘ring of fire’ or seismic circle where tectonic plates collide. The possibility of a high-magnitude quake such as the dreaded Big One can occur. This is the reason the 1992 National Building Code was revised to include industry regulations preventing developers to weld, galvanize or thread steel bars.

Unfortunately, Coseteng said steel products supplied by PISI members were only tested at the jobsite. “How rigid are steel testing on job sites?” she asked.

The former senator called for a more definitive testing process to ensure all steel products in the country were safe to use.  Coseteng added the current standards of the Department of Trade and Industry, the agency responsible in approving and regulating standards of steel products, should be more stringent than normal, given the seismic condition of the Philippines.  

Many of the steel rebars produced by steelmakers in the country only undergo a static test where their products are not subjected to welding, threading or bending.  

Under the international-standard “cyclic loading test,”  rebars are subjected to repeated, fluctuating intensity stress tests. The minimal steel  grade requirements  for rebars to be used in high rise buildings and other major infrastructure is Grade 60.

Coseteng said the impact of using substandard steel bars during natural disasters would be colossal: “Kapag may earthquake na mangyari, luluhod ang mga building. Gusto ba nating mangyari yan? Pag may isang building lang na lumuhod sa BGC, the economic impact is going to be terrible. Yung mga building diyan sa Pasig River pagka-lumuhod baka maging dam ang Pasig River sa dami ng konkreto.

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Topics: magnitude 6.1 earthquake , Central Luzon , Chuzon Supermarket , Nikki Coseteng , Roberto Cola
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