Investigators are closely looking into the structure and construction method used in the Yun Men Tsui Ti commercial and residential complex, which collapsed partially during the 6.4 earthquake in Hualien County on Taiwan’s east coast on Feb. 8. Nine of the 12 people killed in the quake were in this complex.

“After the rescue efforts are completed, we will subpoena the constructors, the architects and the contractors [involved in the construction of the four buildings] for questioning,” Hualien Chief Prosecutor Huang Ho-chun said. He has instructed officials to obtain the buildings’ blueprints, documents and data files submitted by construction companies to the Hualien County government for the initial phase of the investigation.

The  District Prosecutors’ Office  is also looking at alternations made to four of the worst-hit buildings, comparing the structures to building construction licenses, building use permits and owners’ applications for alterations. The buildings are the Yun Men Tsui Ti building and the Marshal Hotel and two apartment buildings. The Marshal suffered the most damage and was left leaning to one side after its bottom three floors crumpled.

Huang said prosecutors are looking for negligence or infractions such as shortcuts during construction, using inferior building materials or failing to comply with construction regulations. The idea is to determine if these factors contributed in the partial collapse of the buildings.

National government prosecutors have lent support in technical and legal issues. “In our Taipei office, we have 11 prosecutors with professional background and expertise in civil engineering and construction. They have been put on alert and will be dispatched to Hualien to provide support for the investigation into possible negligence and the legal responsibilities regarding the buildings’ collapse,” Taipei District Prosecutors’ Office spokesman Chou Shih-yu said.

The probe is taking place in the midst of serious concerns that have been raised by both ordinary citizens and architectural experts in Taiwan.

The head of a construction safety association, Tai Yun-fa, said the Yun Men Tsui Ti and the affected hotel did not have enough reinforced pillars at the lower levels, causing them to be “heavy at the top, but weak at the bottom.” This is what made them extremely susceptible to earthquake damage. These buildings were built before 1999, when a more comprehensive and strict building code came into effect. The buildings saw no reinforcements since then, Tai said. Their original designs for the two buildings were likely flawed in terms of column support at lower levels, he added.

An association of structural engineers has said that the method used to connect steel rebars in the building was a key contributor to the casualties reported at the site. Going by construction regulations, steel rebar used in the building should have been 1.3 times their actual lengths so they could be layered upon one another to enhance the building’s structural integrity. But the bars were not assembled in this manner, Tainan Structural Engineer Association Director-general Huang Chia-jui and association member Wang Wu-lung said. Taiwan’s Tainan city saw a major earthquake that killed 116 people in 2016.

'Columns Snapped Like Ropes'

“As a result, the columns snapped like ropes,” Huang said. Wang added that the way the steel bars snapped appeared “suspicious.”

Since the connection point between steel bars is not sufficiently strong, the law stipulates a method of making several connections converge at a point in order to enhance the sturdiness of beams and columns. The affected Yun Men Tsui Ti had “clearly fallen short” in this regard, Huang said.

Wu Tze-cheng, chairman of Yuan Public Construction Commission, said that steel bars were not layered property as evident in a preliminary review of the building. The disproportionately heavy upper levels of the building likely caused the columns to fail, he said.

National Taiwan University’s geology professor Chen Wen-shan said the Yun Men Tsui Ti structure, like all other residential buildings in its proximity, sits on the Milun earthquake fault. But since only one building has been affected, questions need to be asked about its construction quality.

The building collapsed in a roughly north-to-south direction, but it was the steel bars facing the north that were broken and exposed, indicating that that the building’s construction was likely flawed, New Taipei City Professional Civil Engineers Association chairman James Yu said.

Work on Weaker Structures Sought

Meanwhile, the country’s National Center for Research on Earthquake Engineering has called for new laws to encourage the reconstruction of weaker structures. Its director general Huang Shih-chien, pointed out that many of the buildings designed before 1999 have large open spaces in their ground floors and strong occupancy in the upper floors, making them more prone to collapse. Several people have property rights in such buildings which is hampering the processing of reinforcement or reconstruction of older buildings.

“If a consensus cannot be reached to move forward with reconstruction, I suggest property owners start with incremental, structural reinforcement,” he said.

Huang said high-tech industry operators, including Taiwan Semiconductor Manufacturing Co and United Microelectronics Corp, should network their systems with the Center to allow shutdown of equipment in the event of an earthquake, he said, adding this could prevent sensitive systems from damage.