Universitas Gadjah Mada along with ITB and ITS are appointed as an independent team to join a professional team in order to investigate the cause of the collapse of the Kutai Kertanegara (Kukar) Bridge). According to the plan, the team will work in the upcoming 30 days to collect facts and data about the causes of the collapse and make recommendations to anticipate similar incidents.
"At a meeting last night the House of Representatives and Government agreed that we would set up an independent team from universities and professionals. There are three universities involved, UGM, ITB and ITS. They did not rule out the addition from other universities," said Chairman of the Institute for Research and Community Service as well as expert staff to Minister of Public Works, Prof. Dr. Ir. Danang Parikesit, M.Sc., to the reporters to give information on the investigation results. Technical team members are Prof. Ir. Bambang Suhendro, M.Sc., Ph.D., Ir. Henricus Priyo Sulistyo, M.Sc., Ph.D., and Dr. Andreas Triwiyono Ir, Dr. Adhy Kurniawan, ST., and Ir. M. Nur Ilham, M.T.
Danang said that the day after the bridge collapsed, UGM immediately sent three people to review the condition of the bridge. They were Prof. Dr. Ir. Danang Parikesit, Dr. Adhy Kurniawan, ST., and Ir. M. Nur Ilham, M.T. According to Danang, the results of field investigation was scientifically analyzed to produce recommendations for the Ministry of Public Works to take further steps.
Nur Ilham mentioned the circulating rumors saying that the bridge was hit by a barge before it collapsed or that the bridge could not withstand the load that exceeded the capacity. "I saw the facts on the field. It is clear that the main cable imported from Canada was okay, cable hanger from Austria was okay, but the nuts and bolts had failed. Furthermore, on the connections of the bolts and nuts, there was locally produced old metal that had gone black and cracked," he said.
UGM Investigation Team Leader, Prof. Ir. Bambang Suhendro, M.Sc., Ph.D., said that there were indications of collapse. Over time, strength, stiffness, stability, and serviceability of the construction have degraded so they no longer meet the requirements. It is observable that before the collapse, the main components of cables, hangers, frame/truss of bridge, pylon, foundation and anchor blocks had functioned well. "The only vital component which had allegedly initiated or triggered the collapse was the connection system between the main cable to the hanger (wire hanger)," said Bambang.
The fact also shows that the clamp is still intact, but the nuts and bolts had shear failure. "The phenomenon of shear failure is the failure phenomena of material that is brittle, thus the sudden collapse that is not preceded by other phenomena such as enlarged deflection or deformation," he explained.
Despite the need for further evidence, the UGM technical team has hypothesis of why the connection on the nuts and bolts system had shear failure. "Keep in mind that if even there are only two or three connections that are experiencing material fatigue, the domino effect will happen," said Bambang.
The investigation team suggested that the ruins of the bridge should be secured in a museum as study materials. It would be better if you build a new bridge, but it is more ideal to build bridges with 'cable stayed' models, such as Suramadu Bridge, rather than a suspension bridge model like the Kukar bridge.