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Imagine the Big One striking now

June 25, 2019

MAURO GIA SAMONTE

Last of 2 parts

PROFIT is the culprit.

That was the finding of the study made by the engineer Emilio Morales, as cited in the first part of this article, on the predicament the country now faces in regard to the use of rebar. The study revealed that given the imminent occurrence of the giant tremblor, the Big One, there is urgent need to shift back to the use of micro-alloyed rebar. But steel manufacturers are not about ready to do that. Why? Because here we are talking about P400-billion yearly income from the manufacture of quench-tempered rebars. And who is the capitalist that would let go of such huge profit!

DTI committee head a steel maker

In fact, as Morales discloses, his study of the rebars problem was requested by the chairman of the technical committee on rebars (whom he refuses to name) 12 years ago. It turned out that said chairman happened to be a big steel manufacturer himself who would have none of the study findings that quenched tempered steel bars are substandard and must be rejected. The study proposed a return to the manufacture of the original micro-alloyed steel with proven grade quality of 60.

In the interview for Veronica Files of The Manila Times Television, Morales endeavors to enable the audience to understand the problem the way he did in his study.

What is a quench-tempered rebar?

Morales explained: “This is produced by actually producing from a base material which is a lower grade steel. It comes in the steel [furnace] as red hot rebars and then suddenly it is quenched by a cold spray of water. That quenching actually results in tempering because what happens is if this is the redhot steel, immediately the outer skin is tempered. Meaning, it’s cooled down, and because of the cooling process, it changes the metallurgy.”

In other words, a grade 40 steel base material is processed, producing what else than rebars of grade 40. As a Latin expression translates into English: “No product can be greater than the source.” But through quenching — an ingenious method whereby red hot grade 40 steel bars are sprayed with cold water — the outer skin of the steel is made to imbibe the strength of grade 60 steel.

It is this kind of rebar that goes into the market. To conform to requirements by the Department of Trade and Industry, such rebars are marked as grade 60. Random checking of the steel bars will show that they are indeed of the “grade 60” quality which rebars must contain.

But here’s the catch that the Morales study uncovered: those rebars undergo radical modification during actual use in construction. For instance, those bars are bent or welded, and this bending and welding cause the rebars to retrograde to the base quality of the steel used in the manufacture, which is grade 40.

Those were the days

Time was when integrity in the manufacture of steel was an honored value. In the field of reinforcing steel bars, micro-alloyed steel was the one single material used. But as technology has proven to be a boon to certain aspects of human existence, the digital sphere for instance, in certain other aspects, technology has become a bane. This is particularly true in steel manufacture. When I need to buy iron sheets for the roof of a new structure in my compound, I go to scrap yards for materials vintage 1985. Old iron sheets from this era are a lot stronger than brand new ones today; what was gauge 26 in the 1980s was really gauge 26; now it’s half less thick.

In like manner, grade 60 reinforcing steel bars during the period were produced from grade 60 steel material. But technology made it possible to produce grade 60 reinforcing bar from grade 40 steel material. That technology they called quench tempering.

Surely, steel manufacturers know this. But it is a lot cheaper to manufacture quench-tempered rebars than micro-alloyed steel ones, and the profit difference is so big no capitalist will ever want to go back to the latter anymore.

Circumventing DTI standards

Technically speaking, steel manufacturers cannot be deemed violative of government regulations by putting into the market quench-tempered rebars classified as “grade 60,” because indeed they are. It is in the use that those rebars are reduced to “grade 40.”

And it is in the actual use of quench-tempered rebars that the current concern over the protection of people against the devastation by the imminent Big One must be resolved.

We reiterate how engineer Morales has brought the issue forward: “Now, assuming you have two similar buildings. Same everything and same design, and same material except for the rebars. One is quench-tempered and the other one is micro-alloyed rebar. In a severe earthquake, assuming that both of this will fail, the quench-tempered rebar will fail earlier. So, where is the ample adequate evacuation time [in the case of quench-tempered rebars]? Wala (None).”

What is at issue is not whether or not there is a protection against building collapse during earthquakes. In the case of the Big One, the Morales study even assumes that all buildings can crumble. What the study proposes is for structural engineers to assure that building occupants are given the lead time to rush out before buildings collapse.

As shown by the Morales study, quench-tempered rebars have no such assurance; micro-alloyed rebars have.

Legislating the issue

Pending before Congress is House Bill 8871, introduced by Rep. Scott Davies S. Lanete, MD Its title reads: “An act ordaining standardization of steel reinforcing bar quality in high-rise structures to resist against wind and earthquake in the Philippines and for other purposes.”

Section 4 of the proposed bill sums up its intention, thus: “All high structures shall make use of, at the minimum, grade 60 micro-alloyed steel rebars, which are capable of passing the cyclic loading test.”

So, what happens now to the quench-tempered rebars that dominate the Philippine market (Taiwan, for one, has completely banned that kind of steel; more countries are said to follow suit)?

Section 9 of the proposed bill prohibits, among others, “a. Use of quench-tempered or thermo-mechanically treated steel rebars in high rise structures…”

In its totality, the bill assures people just the lead time they need to run out of buildings for their lives at the strike of the Big One.

Credit belongs to : www.manilatimes.net

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