In the midst of allegations surrounding the safety of quenched-tempered (QT) steel, the Department of Trade and Industry (DTI) remains firm in its stance that QT steel bar is safe for use in high-rise construction.
On the issue raised about cyclic loading test not being specified in Philippine National Standard (PNS) 49:2002 on steel bars for concrete reinforcement, the DTI clarifies that said test is not a method for steel bars but for Steel Reinforced Recycled Concrete. During a cyclic loading test, steel is embedded in concrete in such a manner that the two materials act together in resisting forces thereby testing its strength, endurance, and safety.
Although cyclic loading is not specified in the steel standards, the Technical Committee on Long Steel (TC11) of the DTI-Bureau of Philippine National Standards (BPS) clarifies that attention is still given to it. In point of fact, the Department of Science and Technology – Metal Industry Research and Development Center (DOST-MIRDC) is conducting further research for future tests. The Philippine Iron and Steel Institute (PISI) will likewise be collecting samples from all manufacturers of QT steel for further testing at the MIRDC.
As to the claim that no information was made available on rebars made through quenching and tempering, PNS 49:2002 clearly states in its scope and application that the standard specifies the requirements for deformed steel bars for concrete reinforcement, and applies to steel bars manufactured from prime billets or ingots, supplied as-rolled and hot-rolled with subsequent quenching and self-tempering.
The DTI strongly emphasizes that the soundness and resiliency of a structure is not dependent on steel alone but also on several other materials such as concrete, a composite material composed of coarse and fine aggregates bonded by cement and water. It possesses high compressive strength but is in need of reinforcement to increase its yield strength, and this is where steel bars come in. These are used to reinforce concrete enabling structures to serve their purpose, with safety as the main design consideration.
In terms of resiliency to earthquakes and other natural phenomenon, whether horizontal or vertical, the DTI explains that this is again not dependent solely on steel but also on multiple variables such as location, soil quality, land use practices, foundation, distance from the fault line, materials, application of earthquake resistant building codes and practices, size of structure, and design execution, among others. Collectively, these are considered to mitigate the effects of earthquakes. The nature of the earthquake also has an effect as its behavior can vary.
The DTI stresses that it finds no factual or technical basis to support the allegation that QT steel is unsafe for high-rise construction after a series of talks with the PISI, Philippine Constructors Association (PCA), Association of Structural Engineers of the Philippines (ASEP), and other relevant stakeholders. Studies and tests conducted by the DOST-MIRDC, DTI-BPS, and the world-renowned American Society of Testing Materials, also affirm this.
The DTI upholds its commitment to ensure quality and safety of products, particularly construction materials used in the Golden Age of Infrastructure with the national government’s Build, Build, Build program.♦