Building expert warns vs use of substandard steel in high rises

MANILA, Philippines — A building expert has warned against the use of substandard construction materials, particularly reinforced steel bars (rebars), that are still being used in high-rise commercial buildings and residential condominiums in key business districts.

Emilio Morales, former chairman of the Association of Structural Engineers of the Philippines (ASEP), said the stability of locally manufactured steel bars for high-rise buildings is a cause for concern, especially in the face of recent strong earthquakes in the region:

“Being near the Pacific Ring is the main reason why certain types of steel materials are not recommended for use in high-rise buildings in the country,” he explained.

“Substandard construction materials, particularly rebars, would not withstand a magnitude 7.2 earthquake.”

Morales  revealed that big local steel manufacturers changed the steel bar manufacturing process some 12 years  ago, without notifying the government or the public.

These manufacturers reportedly replaced micro-alloyed (MA) steel bars with quenched-tempered (QT) bars without the knowledge of the contractors, developers and end-users.

QT steel is made by spraying cold water on a red-hot steel bar. “This process alters the steel’s metallurgy: the outer core becomes very strong and brittle, but it is relatively very thin – about one or two millimeter in thickness,” Morales said.

“This kind of multilayered steel can kill, as the thin outer layer, which is brittle, can be easily damaged during an earthquake.”