Did the 33rd floor shake because the idol danced?Mystery of vibration of skyscraper = Korea | Joongang Ilbo | JoongAng Ilbo

Ⓒ JoongAng Ilbo / JoongAng Ilbo Japanese version2022.01.24 10:34

“It was the first time I felt the building sway up and down.”

On the 20th of this month, an office worker who was working in a 33-story office building in Seoul complained of anxiety while recalling the vibrations he felt inside the building. This afternoon, there were a series of reports that “vibration was felt” at the building of Acro Seoul Forest D Tower in Seongdong-gu, Seoul. As a result of a safety diagnosis by the contractor and the authorities, vibration from the dance lesson room of the entertainment agency that moved into the building was designated as the main cause.

◆ Construction owner “No stability problem”

DL E & C, the building builder, commented on the 21st, stating that “as a result of the emergency safety diagnosis, there is no relationship between vibration and building stability.” Professor Park Hong-gun of the Department of Architecture, Seoul National University, who participated in the diagnosis, said in a report that “it is presumed to be vibration caused by a specific activity inside the building” and “the level of vibration is considered to be minute vibration that does not affect the safety of the building.” Will be done. ” This building was completed in December 2020 and is an office building with 7 basement floors to 33 floors above ground. In addition to the comprehensive logistics company “Hyundai Glovis”, the entertainment agency “SM Entertainment” and the car sharing startup “SOCAR” etc. Is moving in.

Currently, there are dance lesson rooms in the entertainment agency on the 9th to 11th and 18th floors. Experts explain that the vibration generated when dancing in a group in this lesson room may match the natural frequency of the building and the vibration may be amplified more than usual. The fire department dispatched on the day of the report also confirmed the seismic detector under the building, but found that there was no separate vibration.

◆ Resident “The building shook because of the idol’s dance …”

Despite the explanations of the contractor and the authorities, the staff members of the resident company cannot hide their anxiety. “I think it was a sloppy construction from the beginning if the building shook because of the idol’s dance,” he said. Employee A said, “It was a violent vibration that made me feel that an earthquake had occurred. I can’t understand the explanation that the building shook up and down because dozens of trainees danced at the same time.”

On the 20th, a photo of a cracked ceiling or a broken glass window was posted on the office worker’s anonymous app “Blind”. However, some photographs turned out to be unrelated to vibration in time. On the 23rd, the DL E & C side told the JoongAng Ilbo by telephone that “water leaks from the ceiling and damage to the glass windows are phenomena that occurred during the interior process after moving in and have nothing to do with the vibration this time. It has nothing to do with the building structure layer because of the problem. “

He continued, “It is only the opinion of an outside expert that the vibration was caused by the dance, and it is not yet clear what the cause is. Why did the building shake through monitoring and simulated experiments in the future? I plan to investigate it properly. “

◆ Inquiries about the “Technomart Incident” 11 years ago …

Some have analyzed that this phenomenon is similar to the vibration turmoil that occurred in the 39-story building “Seoul Techno Mart” in 2011. At that time, Techno Mart sensed vertical vibrations that caused the building to sway up and down, and restricted access to all floors for three days. As a result of the investigation, it became clear that the vibration generated by about 20 people dancing aerobics dance at the fitness center on the 12th floor was the cause of the shaking.

“Recently, residents of high-rise buildings have to feel uneasy due to the collapse of a new apartment in Gwangju,” said Ahn Hyun-jun, a former president of the University of Architecture, Konguk University. If you feel vibration as a whole, you need an additional anti-vibration design. “

He added, “After careful analysis of the vibration cycle and structure of the building, a device that reduces the transmission of vibration should be installed at the required position.”