MANILA – All structures in the country must be able to withstand natural calamities such as strong typhoons and earthquakes.
“Based on one of the priority areas of the National Climate Change Action Plan (NCCAP), an infrastructure has to be climate smart and disaster resilient in order to save lives. For instance, a hotel or school can stand more than 300 kph tropical cyclone," said Glenn Banaguas, organizer of the Climate Smart and Disaster Resilient ASEAN conference.
According to Dr. Francis Aldrine Uy, the Dean of Civil, Environmental and Geological Engineering at the Mapua University, there is a need to install systems such as the Universal Structural Health Evaluation and Recording System (USHER).
The conference, keynoted by US Ambassador Sung Kim at the Bayleaf Hotel, focused its discussion on earthquakes late Monday afternoon, when a huge tremor was felt by the participants.
The magnitude 6.1 earthquake, which had its epicenter in Zambales, caused a major infrastructure - such as the Clark International Airport, to be closed, at least temporarily, due to the damage caused by the quake. There were also buildings that were seen swaying, or some that have been severely damaged after the quake.
This puts into question the safety of all high-rise and mid-rise buildings, not only in Metro Manila, but also in other major cities in the country, if these buildings can withstand an even higher magnitude, or a stronger earthquake.
Last year, hearings were held at the Senate, under the Committee on Trade, Commerce, and Entrepreneurship, under Senator Koko Pimentel, which discussed the safety of Quench Tempered (QT) or Thermomechanically Treated (TMT) rebars, which involves the rapid cooling of plain low carbon steel, by means of using a fine water spray.
QT rebars are said to have a fatal flaw since only the outer skin of the rebar meets the minimum grade, and thus becomes vulnerable, in the event of a major calamity, such as an earthquake.
A number of studies abroad has cited the disadvantages of using quenched steel for high-rise buildings. QT steel are also said to be manufactured and sold by big steel mills.
For example, a study published in the American Journal of Engineering and Applied Sciences in 2015, says, “Numerous studies conducted after the 7.7 magnitude 921 earthquake in Taiwan in 1999, have reported that because heat-treated steel features relatively unstable mechanics properties, using such steel in welding, bar splicing, or as thread-cutting components in structures may result in the lack of resistance to seismic activity.”
A 2016 study in Japan highlights the importance of improving the standards of steel bars. It concludes, “As for buildings, accompanied by the trend in high rise structures, the strength of steel materials was enhanced, and steel materials excellent in seismic resistance were developed, in which the upper limit of yield ratio and the validation limit of yield strength are specified.
Pampanga Governor Lilia Pineda, when interviewed on ANC, questioned the manner of the construction of the four-story Chuzon Supermarket, which collapsed due to the earthquake.
“Titingnan namin yun specifications niya sa materyales niya. Kung ito ba ay pumasa sa standards, sa bakal niya, sa timpla ng semento niya, at ano yun lalim ng poste niya sa paggawa ng (We will look at its specifications and the materials used to see if these passed standards. The metal frames, the mixture of cement and how deep was the post situated for it to be able to have a) 4th floor,” Pineda said.