Former senator Anna Dominique Coseteng called for a national audit of all buildings which were constructed in the last 10 years to check their structural integrity amid the use of reinforcing bars which were questioned by an expert.
Coseteng, who now serves as the chairperson of the Philippine Induction Smelting Industry Association, asked the Department of Interior and Local Government to take the lead in checking the structural integrity of high-rise buildings as well as the developers, contractors and structural engineers.
“So when the Big One hits, we can identify and anticipate the consequences, responsibilities and compensation,” Coseteng said in a recent Senate hearing of the committee on trade, commerce and entrepreneurship which looked into the alleged proliferation of substandard and uncertified steel bars in the country.
Coseteng cited the results of a study made by Emilio Morales, a former chairman of the Association of Structural Engineers of the Philippines, who warned about the “clear and present danger” as a result of the use of quench-tempered and thermo mechanically treated steel rebars in high-rise buildings.
Coseteng said she was worried about quenching, a process of subjecting hot steel bars of lower grade, such as grade 40, to rapid water spray cooling. This then creates an outer layer which is stronger, and improves the grade of the steel to grade 60, while the inner layer remains the same.
However, welding or bending “may have detrimental effects on the strength and ductility of the bars,” according to New Zealand's steel standards which Morales quoted in his study “The Clear and Present Danger—the Use of QT or TMT Rebars in Seismic Zone 4.”
Coseteng warned that high-rise buildings using QT-TMT bars could be compromised in the event of a major earthquake.