Industry Minister Akanat Promphan expressed shock after inspecting the steel used in the collapsed building in Chatuchak. He noted irregularities but did not provide further details.
The ministry has collected six different types of steel for further inspection, mostly from one producer. The focus will be on determining whether the steel meets the required standards and if the labels and sizes match specifications.
The building, part of the new State Audit Office project, is being developed by a joint venture between Italian-Thai Development and China Railway Number 10 (Thailand).
The ministry said that for such projects, standard rebars (steel bars with ridges) are required in sizes DB16, DB20, and DB25 to reinforce concrete. Using substandard rebar can weaken the structure, making it brittle and more likely to break during strong impacts or earthquakes, potentially leading to collapse.
Photos show the building used DB32 SD50 steel, which meets certain tensile strength criteria but may have issues with yield strength. Experts noted the steel is two-layered, hard on the outside and soft on the inside, making it prone to cracking and reducing strength when twisted. This type is unsuitable for tall buildings with movement.
The steel bars are marked with a “T” symbol, indicating they underwent rapid cooling. This process can cause inconsistent strength across the material, making it unsuitable for machining for testing, unlike non-“T” steel. Such steel may not be ideal for tall buildings, especially in earthquakes.
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