Source: The Manila Times
Concerns over the use of quench-tempered or thermomechanically (QT/TMT) treated rebar should be focused on substandard manufacturing and not the product itself, industry representatives said.
But structural engineer Emilio Morales, chairman of the Association of Structural Engineers of the Philippines (ASEP), wants builders to use microalloyed (MA) rebar instead, claiming that this is superior in terms of earthquake resistance and thus particularly suitable for the Philippines.
Asked to comment, a representative of SteelAsia Manufacturing Corp. said the use of QT/TMT rebar should not be an issue given the country’s stringent standards.
“Quenched bars have been in the Philippines for decades and has never been an issue with structural engineers because they comply with the very strict Philippine National Standard 49,” SteelAsia Assistant Vice President Rafael Hidalgo told The Manila Times.
“Almost all quenched bars sold in the Philippines are produced by ISO 9001 companies,” Hidalgo added.
“The real issue is that there are still producers who fail PNS:49 and thereby endanger public safety. Market monitoring will show that these are repeat offenders.”
PNS 49:2002, which is the national standard for all steel bars used in concrete reinforcement, was developed by the Bureau of Product Standards’ (BPS) Technical Committee on Steel.
“[T]his has nothing to do with quenching systems which are made by the most modern metal technology companies in Italy and Germany,” Hidalgo said.
“Many ASEP members including past presidents are completely okay with quenched [rebar]. This has been going on for decades and they know too well the properties of quenched [rebar], that is why they buy it and install,” he
“If it is not safe, will they use it?”
The Philippine Iron and Steel Institute (PISI) likewise noted that QT rebar’s qualities have already been tested in a real-life situation.
“Quenched and tempered rebars have been used in the Philippines since the 1970s. Structural engineers have been using it for high-rise buildings since then. In 1991, there was a strong earthquake in Metro Manila and the buildings that used these quenched and tempered bars were not affected,” PISI President Roberto Cola told The Manila Times in an email.
Cola was apparently referring to the 7.7-magnitude temblor that hit Luzon in 1990 that heavily damaged the cities of Baguio, Dagupan and Cabanatuan. Over 1,600 people were killed, at least 80 due to the collapse of the Hyatt Terraces Hotel in Baguio.
The quake was also strongly felt in Metro Manila.
Building collapses, however, were relatively few and Philippine Institute of Volcanology and Seismology director Renato Solidum Jr., in a 2014 interview with Rappler, noted that Philippine building codes were actually good and that the problem lay with implementation.
“Good design, quality materials and good workmanship are needed for a disaster-resilient building,” the report stated.
PISI’s Cola said the real issue was not the quenched and tempered rebar but the “substandard rebars that are being openly sold in the market.”
“These substandard rebars were found in the damaged buildings and infrastructure in Cebu and Bohol earthquake in 2015,” he said.
PISI has alerted the Trade department that substandard rebar was being sold in the provinces of Tarlac, Bulacan, Pampanga and Nueva Ecija.
Tests conducted by the group showed that rebar being sold in some hardware shops were underweight and had failed elongation.
“This is a burden not only for the legitimate rebar producers and manufacturers but mostly the great effect would be on those consumers using substandard rebars without their due knowledge,” PISI Vice President Joel Ronquillo said.
“The fraudulent selling of substandard rebars compromise [the]safety of the general public,” he added.
PISI said the Department of Trade and Industry’s (DTI) Consumer Protection Group should conduct regular monitoring to ensure that only rebar that pass quality tests and standards are sold and used.
Market monitoring teams, Ronquillo said, should conduct actual weighing and measuring to determine conformance and to immediately file cases against hardware store owners and local manufacturers found in violation of product standards.
“The PISI would like to offer its services and create a partnership with DTI in order to stop proliferation of substandard reinforcing steel bars in the market,” he added.
Trade Secretary Ramon Lopez said the government was doing its best to ensure that all steel products used in the country pass the DTI’s tests.
“DTI issues product standard mark or Import Commodity Clearance for standard compliant steel products. DTI makes sure that steel products pass the tests. To date, steel manufacturers pass the standard tests,” Lopez said in a text message.
“What’s important is that these products must pass the tests and must have the PS or ICC marks when sold in the market,” he added.
Trade Undersecretary Ruth Castelo noted the debate on the use of QT rebar and said the DTI was conducting further tests in a bid to settle the issue.
“Some are saying these are not advisable for high-rise projects; some [are]saying it can be used as long as they pass the standard tests,” Castelo said.
“At any rate, DTI is conducting tests now to see if the findings on strength of quenched tempered steel rebars are conclusive,” she added.
The Trade department’s BPS is also reviewing PNS:49 to align this with the National Structural Code of the Philippines.
“The BPS periodically reviews a PNS to ensure that the standard remains relevant and useful to its consumers.
The urgent review of PNS 49 is necessary to consider global developments and subsequently assist the Philippine government, industry, and, consumers,” bureau director James E. Empeño said.
The ASEP’s Morales welcomed the review and said he hoped that the QT/TMT issue would finally be settled.
“In fairness to them, we are moving, although slowly. What we are saying is that for critical structures, these QT rebars cannot be used. So we want that same verbatim qualifications inserted into the PNS:49 because the PNS and the ASEP needs to be mutual in agreement,” he said.
Morales added that the National Structural Code sets prohibitions on the use of QT rebar when these have to be heated, welded or threaded.
“ASEP wants that the qualifications contained in the national structural code will also be inserted into PNS:49 so that … developers can also reference this and really understand that there is something wrong with these rebars if they are going to use it in critical structures,” he said.