CLARK FREEPORT -- Former Senator Anna Dominique “Nikki” Coseteng said that the Quenched-Tempered (QT) or Thermo Mechanically Treated (TMT) steel bars, which are proliferating in the market for the past 10 years are not suited for high-rise buildings.
Coseteng issued the statement during the Pampanga Press Club’s media forum dubbed News at Hues held at Park Inn by Radisson Clark.
The former legislator said that the integrity of high-rise commercial buildings and condominiums in Metro Manila and parts of Central Luzon are now questionable because of the prevalence of the QT steel bars.
Coseteng was accompanied by engineer Emilio Morales, author of a study entitled “A Clear and Present Danger 2 – The Use of QT of TMT Rebars in Seizmic Zone 4” which was prepared in 2010.
Steel manufacturers in the country have replaced the micro alloy rebars with QT TMT without the knowledge of the people especially structural engineers, architects, contractors and other concerned entities, according to her.
“We need to know exactly how many steel companies are manufacturing and selling grade 60 QT TMT rebars,” Coseteng said.
“This has been happening for a very long time now. It has been more than 10 years that steel manufacturers decided to change the steel that they used to manufacture called micro alloy. They did not inform anyone but simply changed it to QT,” she added.
Morales claimed that various studies and research in Italy, New Zealand and other countries indicated the dangers posed by the QT rebars when used in buildings under Seismic Zone 4.
These rebars behave quite differently under cyclic loading. Their strength are also affected by heating, welding, bending, galvanizing, and threading, according to him.
“There is a clear and present danger in the use of QT TMT rebars in Seismic Zone 4 due to the non-ductile behavior of these rebars under conditions that are typical or common in local construction practice,” Morales said.
He also expressed apprehension over the structural integrity of high-rise buildings and critical government projects like airports, and bridges which were built with QT rebars.