The collapse at the Gwangju Metropolitan Library construction site in December, which left four workers dead, was found to be a man-made disaster caused by shoddy construction that deviated from the design—such as arbitrarily inserting rebar into welds—and poor inspection and oversight. The actual strength of the welded joints was only 22% to 31% of the design strength. The Ministry of Land, Infrastructure and Transport plans to pursue business suspension for the Sigongsa and the construction project manager and to refer the findings to investigative authorities.
The Ministry of Land, Infrastructure and Transport (MOLIT) on the 30th announced the findings of the Construction Accident Investigation Committee on the Gwangju Metropolitan Library collapse. The accident occurred on Dec. 11 last year at the construction site in Chipyeong-dong, Seo District, Gwangju, when the welded parts of the truss structure fractured during rooftop concrete pouring. Four on-site workers died.
The committee, composed of 11 experts from industry, academia, and research, investigated the cause of the accident through 20 plenary meetings, five on-site inspections, two hearings of related parties, and non-destructive testing and structural analysis of welded joints.
The investigation found that the direct cause of the collapse was defective welding carried out differently from the design. The machining to bevel the joint before welding, which is needed to ensure sufficient fusion of the steel, was omitted, and foreign materials such as rebar were inserted into some welds to fill voids. Visual inspections and corrosion tests also confirmed defective welding in multiple locations that differed from the design.
As a result, the actual strength of the welded joints was only 22% to 31% of the design strength. It was found that as the structural load increased due to rooftop concrete pouring, the weak joints failed to withstand the weight and fractured in succession.
The committee determined that the primary responsibility lay with the Sigongsa for shoddy construction and with the construction project manager for lax oversight. The Sigongsa failed to properly prepare detailed construction drawings specifying welding methods before work began and did not sufficiently verify the skills of the welders deployed on site.
The supervisor also did not properly review the inadequately prepared detailed construction drawings. It was found that verification of welders' skills and post-weld inspections were also deficient. Even after identifying welding defects, necessary additional tests were not conducted, effectively disabling the management and oversight procedures that could have prevented the accident, according to the committee.
A special inspection conducted in June by the Iksan Regional Office of Land and Infrastructure found failures to implement the safety management plan, poor management of quality-control technicians, and illegal re-subcontracting to unregistered firms. Construction that differed from the drawings and insertion of rebar into welds were also confirmed.
As measures to prevent recurrence, the committee proposed specifying standards and procedures for welding quality inspections and strengthening management and oversight of high-difficulty welding. It recommended requiring construction project managers to verify welding plans and post-construction inspection plans and to clarify criteria for verifying the qualifications and skills of on-site welders.
The Ministry of Land, Infrastructure and Transport (MOLIT) will pursue administrative measures, including business suspension, against the Sigongsa and the construction project manager based on the findings. It also decided to share the results with the police and the Ministry of Employment and Labor (MOEL) so they can investigate possible violations, including occupational negligence resulting in death and breaches of industrial safety laws. It plans to share the case with relevant ministries and local governments to strengthen safety management at construction sites.