The 鈥楤ig One鈥� and substandard rebars: A killer mix
SUBSTANDARD STEEL composite image from Inquirer files
MANILA, Philippines—When a magnitude 7.7 earthquake struck Myanmar on March 28, tremors rolled through Southeast Asia. In central Bangkok, the shaking brought down scaffolding and shook high-rises — then, more disastrously, caused a 30-story government building still under construction to collapse.
Twenty-two people were confirmed dead, with over 70 still missing or trapped beneath the rubble. Thai officials launched an immediate investigation, pointing early on to questionable materials and possible lapses in oversight.
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“We will definitely find the true reasons as to why this building has collapsed, because it’s all scientific,” said Thailand’s Interior Minister Anutin Charnvirakul, as quoted by the Associated Press. He added the fault may lie with “the designer, the inspectors, or the builders.”
The building, part of a complex meant for the State Audit Office, crumbled while workers were pouring concrete on the upper floors. Investigators suspect the use of substandard steel reinforcement may have weakened the structure.
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The disaster has renewed scrutiny across the region — especially in the Philippines, where structural engineers and disaster officials warn that a similar threat may already be hiding in plain sight.
Thailand’s broader safety concerns
The tower collapse wasn’t the first fatal construction failure in Thailand this year. Earlier, parts of a highway under construction on the city’s outskirts also gave way, killing several workers.
Investigators in that case flagged the possible use of inferior steel rods embedded in the concrete slabs and columns — raising deeper questions about material quality checks and enforcement of construction standards.
In both tragedies, the common thread was inadequate oversight and concerns about steel — a red flag that hits close to home for Philippine engineers.
Metro Manila: A ticking time bomb
The Philippines sits directly on the Pacific Ring of Fire, where powerful earthquakes are both expected and inevitable. One of the country’s most dangerous fault lines — the West Valley Fault — cuts across Metro Manila and nearby provinces.
The Philippine Institute of Volcanology and Seismology (Phivolcs) warns that a magnitude 7.2 quake along this fault could kill more than 33,000 people and cause 168,000 buildings to collapse.
Office of Civil Defense (OCD) Undersecretary Ariel Nepomuceno said this scenario becomes even more alarming when one considers the estimated number of structurally weak buildings across the capital.
“Based on the scientific study done by JICA (Japan International Cooperation Agency) and PHIVOLCS in 2004, around 500,000 structures are vulnerable,” Nepomuceno told 黑料社.
“This is primarily due to weak structures especially those near the West Valley Fault System,” he continued.
With high-rise buildings tightly packed across cities like Quezon City, Marikina, Taguig, and Pasig, experts say the real threat may not be visible on the surface. It lies inside the concrete itself — in the steel bars that give buildings their strength.
Scientific red flags
Structural engineer Emilio Morales, former chair of the Association of Structural Engineers of the Philippines (ASEP), has long warned against the use of quenched and tempered (QT) rebars — a type of steel reinforcement made by rapidly cooling hot-rolled bars.
In a technical paper titled “A Clear and Present Danger 2 – The Use of QT or TMT Rebars in Seismic Zone 4,” Morales outlined how QT rebars, though they can pass basic bending and pull tests, tend to fail during earthquakes.
Unlike micro-alloyed (MA) rebars that have uniform strength, QT rebars have a hard but brittle outer shell and a softer core. This design, he said, makes them vulnerable during cyclic loading — the kind of repeated stress that occurs when buildings sway violently during a quake.
The outer shell of QT steel is only 1 to 2 millimeters thick. Morales warned that even routine construction processes — such as welding, threading, or bending — can damage this thin outer layer. If the hardened surface is compromised, what remains is the soft core, which may not hold up during intense shaking.
Tests conducted on QT rebars from local manufacturers also showed inconsistencies in strength and poor ductility — the ability to bend without breaking. Morales noted that QT and MA rebars look the same on the outside, which means contractors and even engineers may not realize what they’re working with.
“Substandard construction materials, particularly rebars, would not withstand a magnitude 7.2 earthquake,” Morales previously warned. “This kind of multilayered steel can kill, as the thin outer layer, which is brittle, can be easily damaged during an earthquake.”
The paper strongly recommended against using QT rebars in buildings located in seismic zones unless they are thoroughly tested after modification.
A bridge collapse and broader questions
As experts call for stricter controls and better material traceability, a bridge collapse in northern Luzon has underscored just how much is at stake.
Less than a month after it opened, the third span of the P1.2-billion Cabagan-Sta. Maria Bridge in Isabela province suddenly gave way, injuring six people and paralyzing traffic across the region. A Senate Blue Ribbon Subcommittee launched an inquiry in late March, revealing red flags that had gone unaddressed for years.
READ: ‘Underdesign’ eyed in Isabela bridge collapse
During the March 26 hearing, Department of Public Works and Highways (DPWH) Secretary Manuel Bonoan confirmed that structural concerns had been raised as early as 2018. Project engineer Felipe Lingan testified that cracks had appeared in the bridge deck, piers had tilted, and steel bolts had sheared off. The bridge deck had reportedly shifted horizontally by about 100 millimeters before the collapse.
Photos of the damaged reinforcement showed clean breaks in the steel — not jagged ones — prompting Senator Alan Peter Cayetano to question whether the rebars met proper tensile strength requirements.
“May bumagsak sa tulay sa Pilipinas, a billion-peso tulay, and we do not seem outraged,” Cayetano said.
(A bridge collapsed in the Philippines — a billion-peso bridge — and we don’t seem outraged.)
READ: Cayetano: Collapsed bridge in Isabela reveals numerous ‘fail’ marks
Despite the warnings, no suspensions were issued within the agency, and the contractor involved has reportedly remained active in other government projects.
The incident, which occurred far from the West Valley Fault, highlights a larger issue: the dangers of ignoring signs of weakness — both in infrastructure and in the systems meant to ensure public safety.
‘Lives will be at risk’
In light of these events, Nepomuceno reiterated the importance of preventive action — not just among regulators, but also among developers and local governments.
“Using sub-standard steel can compromise the strength of buildings, houses, and other structures such as bridges, warehouses, etc. Lives will be at risk if such buildings or structures collapse,” he said.
He added that the OCD is pushing local governments to take a more proactive stance in evaluating building plans and issuing permits: “We are encouraging and requesting the LGUs to be more diligent and strict in issuing construction and occupancy permits within their jurisdictions. And inspections must be systematically conducted to ensure safety.”
READ: OCD warns: Substandard steel puts lives at risk if ‘The Big One’ hits Metro Manila
As a message to industry stakeholders, Nepomuceno said the responsibility is shared by both public and private actors.
“Ensuring the safety of our citizens is an integral duty of developers, architects, engineers, and concerned government officials,” he said. “One way of fulfilling this is preventing, if not totally ending, the usage of sub-standard materials especially steel.”
No national inventory, no full accountability
In 2019, the Department of Trade and Industry (DTI) confiscated and destroyed P737,000 worth of substandard re-rolled steel bars in Cavite. The rebars failed to meet the minimum requirements of Philippine National Standards (PNS 211:2002).
“Substandard steel products pose significant risks to public safety, especially in a country like the Philippines that is prone to earthquakes,” said then-DTI Secretary Cristina A. Roque. “We will not tolerate those who compromise the safety and well-being of our citizens for profit.”
The DTI’s Bureau of Philippine Standards oversaw the disposal of over 13,000 rebars and urged consumers to check for safety certifications like the Import Commodity Clearance (ICC) sticker or Philippine Standard (PS) mark.
But despite these efforts, gaps remain.
As of writing, there is no known national inventory or audit of buildings that use QT rebars. To the best of experts’ knowledge, developers are also not legally required to publicly disclose the exact type of steel used in their projects. And while Philippine material standards do exist — particularly at the manufacturing and point-of-sale level — there is currently no consistent, government-led program that inspects or tests steel once it has already been embedded in buildings.
In Thailand, the collapse of a government tower has prompted renewed scrutiny of building permits and material compliance. In the Philippines, however, enforcement has often been reactive rather than preventive.
Graphics by Ed Lustan/Inquirer.net. Sources: PHIVOLCS-JICA Metro Manila Earthquake Impact Reduction Study (MMEIRS), Office of Civil Defense (OCD), Engr. Emilio Morales, “A CLEAR AND PRESENT DANGER 2 – THE USE OF QT OR TMT REBARS IN SEISMIC ZONE 4”
