On March 31, 2025, authorities in Thailand revealed troubling findings regarding the steel used in the construction of the State Audit Office building, which collapsed earlier this year. Steel samples taken from the site during the investigation failed critical tests, showing that the materials used in the building’s foundation and structural elements did not meet the required industry standards. While the investigation is still ongoing, these findings could provide vital clues to understanding the causes of the collapse. This article expands on the nature of the failed steel samples, the ongoing investigation, and the broader implications for construction standards and safety in Thailand.
Investigation Findings:
The investigation into the State Audit Office building collapse led by Thitiphats Chotidechachainan, the head of the working group, has revealed that two steel samples taken from the site did not comply with national construction standards. These samples are pivotal in understanding the potential role of substandard materials in the building’s failure. The two main problematic samples were:
1. 32-millimeter deformed bar: This sample was found to be below the required yield strength standards, a crucial parameter that determines the steel's ability to bear weight without deforming. This kind of steel is often used in building foundations and must be able to support significant pressure. The yield strength of the steel is essential to ensuring that the building’s foundation does not bend or break under the weight it carries. The failure of this steel to meet strength standards could have been a critical factor in the collapse of the building, particularly if it was subjected to loads greater than its capacity.
2. 20-millimeter deformed bar: This sample failed due to its light mass, which means it was underweight compared to the standard. Steel bars of this type are typically used in smaller base structures or columns in a building. The failure in mass could lead to serious structural weaknesses, especially when it comes to the calculation of load-bearing capacities. Structural components that are too light may not offer sufficient support for the entire building, making the structure vulnerable to failure. The light mass of the bar could have affected calculations for the entire building’s design, potentially leading to unforeseen weaknesses in the structural framework.
Both of these steel samples came from the same steel manufacturer, a company that had previously been shut down by the Thai Industrial Standards Institute (TISI) in December 2024 for failing to meet national quality standards. However, despite the closure, it is suspected that steel from this factory was still used in the construction of the building. Authorities are now investigating how this substandard steel ended up being used in the building project, especially given the factory’s prior non-compliance.
The Role of Steel in Construction:
Steel is an integral part of modern building construction, particularly in the foundation and structural supports of a building. The role of steel in ensuring a building's safety cannot be overstated. When steel fails to meet the required yield strength or mass, the integrity of the entire structure is compromised.
• Yield Strength is the amount of stress a material can handle before it begins to permanently deform. In buildings, steel components are often subjected to immense pressure, particularly in foundations. If a steel bar has insufficient yield strength, it could bend or break under pressure, causing a chain reaction of failures across the structure.
• Mass per Meter is crucial for the correct sizing of steel bars used in structural elements. Insufficient mass means the bar cannot carry the intended load, and calculations of the building’s weight-bearing capacity could be flawed. If lighter steel is used in critical structural areas, like columns or beams, the entire building could become unstable.
The findings in this case underscore the vital importance of ensuring that steel suppliers meet the quality standards set by regulatory bodies like the Thai Industrial Standards Institute. If even one part of the steel supply chain fails, the entire project could be at risk.
Steel Supplier’s Role and Investigation:
The investigation has placed significant focus on the steel production company responsible for the faulty steel bars. This company had already faced regulatory scrutiny due to its previous violations of safety standards, leading to its closure by the Thai Industrial Standards Institute in December. Despite this, the steel produced by the company seems to have found its way into the State Audit Office building construction.
Authorities are currently investigating whether illegal production, improper transportation, or forged certification played a role in allowing these substandard steel materials to be used. The TISI has already expressed concerns about the possibility of illicit activities allowing these materials to slip through the cracks despite the factory’s closure. The investigation aims to determine whether there were any breaches in regulations, such as falsifying quality certificates or circumventing inspection procedures.
Given the previous closure of the steel factory, there is also a possibility that the company may have continued producing steel and distributing it illegally to contractors, bypassing inspections and quality checks. The findings from this investigation could lead to stricter enforcement of industrial regulations to prevent future incidents.
Challenges in Testing and Investigation:
The process of collecting and testing the steel samples from the collapsed building has not been without challenges. The rescue operations at the site have made it difficult for officials to access the area and gather additional materials for analysis. Despite these challenges, the Thai Industrial Standards Institute plans to continue its investigation and collect further samples to ensure that all potential issues with the building’s construction materials are identified.
According to Ekniti Romyanon, the Inspector General of the Ministry of Industry, collecting samples from the collapsed building site has proven to be difficult due to safety concerns and logistical issues related to the ongoing recovery efforts. However, officials remain committed to the investigation and will continue to work with local authorities to ensure all necessary samples are gathered.
Implications for Thailand’s Construction Industry:
This investigation has raised serious concerns about the quality control procedures in the Thai construction industry. The use of substandard steel in such a critical building underscores the importance of rigorous testing, quality assurance, and regulatory oversight to prevent such incidents. As the investigation progresses, it is expected that the Thai Industrial Standards Institute (TISI) and other regulatory bodies will strengthen their inspection procedures to ensure that only certified, high-quality materials are used in construction projects.
This incident could lead to stricter laws surrounding construction materials, and steel quality specifically. The Thai government may also implement tighter regulations to ensure that steel suppliers maintain high standards and that construction companies adhere to these requirements. Additionally, contractors and engineers may face increased scrutiny in the future when selecting materials and working with suppliers.
Key Takeaways:
• Two steel samples from the collapsed State Audit Office building in Thailand failed critical quality tests, raising questions about the role of substandard materials in the disaster.
• The 32-millimeter deformed bar failed the yield strength test, while the 20-millimeter deformed bar was found to have insufficient mass, both compromising the building’s structural integrity.
• Both faulty samples originated from the same steel supplier, which had been ordered to cease production by the Thai Industrial Standards Institute (TISI) in December 2024 for failing to meet safety standards.
• Steel quality is crucial for the safety of a building, and failing to meet the required strength or mass standards can lead to catastrophic failures.
• The investigation is ongoing, and authorities are focusing on determining if there were any illegal activities related to the distribution of substandard steel.
• The incident highlights the need for stronger regulations and better quality control in the construction industry to prevent future structural failures.
