Scientific Cause of 'Gwangju Collapse Accident' Identified... "Timing of Disciplinary Action Under Discussion"

Direct Cause of Accident: 'Arbitrary Structural Modification and Repeated Impact Loads'

[Asia Economy Honam Reporting Headquarters Reporter Park Jin-hyung] The police investigating the collapse accident at Hwajeong I-Park in Seo-gu, Gwangju Metropolitan City are expediting the detention process for those booked in connection with the case. This comes as scientific evidence and analyses clarifying the cause of the accident are being systematically organized.

The Investigation Headquarters for the collapse accident at the newly constructed apartment in Seo-gu, Gwangju (Gwangju Police Agency) announced on the 7th that it has received the "Disaster Investigation Opinion Report" sent by the Korea Occupational Safety and Health Agency under the Ministry of Employment and Labor.

Based on the official accident cause investigation results analyzed by an authorized institution, the investigation headquarters is moving closer to proving negligence and is considering the option of arrest warrants. Discussions with the prosecution regarding timing and scale are ongoing in close cooperation.

Currently, a total of 19 individuals have been booked, including those from the primary contractor HDC Hyundai Development Company, subcontractors, and supervisors. They are suspected of violating their duty of care in the workplace, resulting in the death of workers at the construction site.

The direct cause of the collapse, according to the report, was identified as "arbitrary structural modification."

The subcontractor, in consultation with the primary contractor Hyundai Development Company, constructed seven counterforts (vertical walls) weighing tens of tons on the PIT (equipment space) floor to serve as supports, and installed special formwork called deck plates on top.

In other words, the installation of concrete supports for the deck altered the load-bearing structure of the floor, which became the starting point of the accident.

On the three floors below, without reinforcing the props (supports), the upper concrete load exceeded the design load of the lower floor, causing deflection and eventual collapse.

The reason 16 floors collapsed simultaneously was due to "sequential impact loads."

For example, if 1 ton of concrete debris falls 3 meters within 0.2 seconds, the load increases to 3.8 tons. A representative from the investigation headquarters explained, "According to calculations by Lee Seong-min, Deputy Director of the Korea Construction Quality Research Institute, the continuous impact loads caused the collapse up to the 23rd floor."

The use of a "flat slab structure," which minimizes columns or walls instead of a wall-type structure, also had a significant impact.

In the column-type flat slab structure, there were few load-bearing walls to sufficiently share the additional upper load.

Another cause pointed out was "poor concrete quality."

Due to poor quality control such as winter curing of concrete, the design standard strength was not achieved.

The Korea Institute of Construction Living Environment Testing, upon police request, measured the strength of samples collected from the site and found that some parts of the collapsed 23rd to 39th floors fell below the standard of 24 MPa (megapascals).

Normally, 75-85% of this standard should be met.

It is also presumed that local (partial) quality defects led to reduced bonding strength with the rebar.

The investigation is also looking into whether water was added excessively, instead of using a proper plasticizer, during the use of Concrete Pacing Boom (CPB) equipment that pumps concrete to upper floors to reduce costs.

The reason for adding water was to make the concrete more fluid so it could be pumped upwards before hardening. A subcontractor representative reportedly testified during police questioning that "the primary contractor ordered it."

An investigation headquarters official said, "There are still aspects to investigate regarding poor quality control and local quality defects, and we have yet to receive analysis results from the Construction Accident Investigation Committee and the National Forensic Service. We will conduct a strict investigation to ensure those responsible are punished accordingly."

This content was produced with the assistance of AI translation services.