(Former Senator Nikki Coseteng discusses with Porac Mayor Condralito dela Cruz photo documentation on the collapsed Chuzon Supermarket. Contributed Photo)
PORAC Pampanga— Former senator Nikki Coseteng, now known as steel advocate, cited yesterday “telling signs” that Chuzon Supermarket, which collapsed during the 6.1 magnitude earthquake last April 22 here, had poor quality quench-tempered reinforcement steel bars (QT rebars) which might also have been used in high rise buildings in Metro Manila.
In an interview here with Punto!, Coseteng said photo documentation of the collapsed structure indicated that the posts remained solid and that the collapse was triggered at corners where steel bars were bent during construction.
This, she stressed, was characteristic of QT rebars which are weakened by bending.
Coseteng cited a study by structural engineer Emilio Morales who noted that in the past decade, contractors of high-rise buildings in the country have been inadvertently using QT rebars instead of the stronger micro-alloyed or MA rebars.
Morales, in a press forum in Clark freeport, had said “advanced countries have warned against these dangers and we believe it is our duty to inform the public and the profession of their use in Seismic Zone 4 (Metro Manila).”
Coseteng said the owner of Chuzon Supermarket or his contractor might not have known that QT rebars were used for the four-story supermarket, since poor quality Grade 40 steel bars are being passed off in the construction market as high quality Grade 60 steel bars.
She noted that tests have shown that QT rebars become vulnerable to earthquakes when bent, usually at corners of posts of buildings.
Asked why none of the high-rise structures in Metro Manila collapsed during the recent quake, Coseteng said some of them were reported to have sustained damages but that “they are keeping silent about it.”
She said that in the past 10 to 12 years, many building contractors are being deceived into thinking that the steel bars they used for buildings are of Grade 60 quality as she blamed members of the Philippine Iron and Steel Institute for lack of transparency on their products.
Coseteng also hit the policy of color coding at the end of steel bars to classify their quality, instead of embossing the quality data on the bars. “At the Chuzon Supermarket, it would be hard to determine the quality of steel since the colors are surely gone now,” she added.
Coseteng has been vocal about her concern over the safety of Metro Manila folk residing or working in high rise buildings amid warnings from the Philippine Institute of Volcanology and Seismology (Phivolcs) that an 8 magnitude earthquake in the metropolis could be triggered anytime from the Westerm Marikina Fault.
One cycle of significant earthquake, which refers to merely one movement of earth from one side to another, is enough to damage a QT rebar’s outer layer. Eventually, the impact would be passed on to the concrete, Coseteng cited engineering studies as saying.
