Koror-Babeldaob Bridge

The Koror-Babeldaob Bridge is a bridge in Palau that connects Koror and Babeldaob Islands. It is a reinforced concrete, portal frame, cable-stayed bridge with a total length of 413 m. It was built by the Kajima Corporation of Japan in 2002, to replace the former, collapsed bridge.

Collapse of the former KB Bridge

The original Koror-Babeldaob Bridge which collapsed was a balanced cantilever prestressed concrete box girder bridge with a main span of 240.8 m and total length of 385.6 m (1265 ft). It was designed by Dyckerhoff & Widmann AG and built by Socio Construction in 1977. [According to [http://en.structurae.de/structures/data/index.cfm?ID=s0001026 Structurae database] , the bridge was completed in 1978. However, there are also sources which describe it as in 1977.] It was the world's largest bridge of its type, [Troyano, L.F., "Bridge Engineering: A Global Perspective", Thomas Telford Publishing, 2003, p.426] until its record was broken by the 260 m span of the Gateway Bridge in Brisbane, Australia, finished in 1985.

Socio Construction had offered to construct the bridge at half the cost of a proven competitive company. Almost immediately, the bridge's durability was questioned and citizens took safety measures such as driving slowly across it or keeping windows open so as to provide an emergency exit in case of collapse.

On September 26, 1996, the bridge suddenly collapsed , and shut off fresh water and electricity between the islands. In addition, the collapse killed two people and injured four more. This caused the government to declare a state of emergency. By request of Kuniwo Nakamura, then the country's President and foreign minister, Japan provided emergency aid as well as a temporary bridge. [ [http://www.britannica.com/eb/article-9114428 Pontoon Type (Floating Structure with Flat Plates) bridge, Palau History; page 1] Britannica Online Encyclopedia] [ [http://www.everything2.com/index.pl?node=Palau the Japanese provided Palau with a temporary bridge to replace it.] Palau, everything2.com] [ [http://stuffedwombat.com/gallery2.html Picture of the temporary bridge] Stuffedwombat.com]

Reason for the collapse

The 385.6 m (1265 ft) long, 18-year old, Koror-Babeldaob bridge (KB bridge) collapsed abruptly and catastrophically on September 26, 1996. The failure occurred during benign weather and loading conditions, less than three years after two independent teams of bridge engineers had evaluated the bridge and declared it safe, and less than three months after completion of a strengthening programme to correct a significant midspan sag that was continuing to worsen. The present paper describes findings of an on-site inspection and structural analyses performed to assess long-term behaviour of the bridge, the increment of internal forces and deflections produced by the 1995 bridge retrofit repair, and principal factors that contributed to the collapse. Results of this investigation confirmed, both qualitatively and analytically, that the most probable cause of the KB bridge collapse was damage engendered by removal of the original concrete roadway surface.This led to two studies carried out by Louis Berger International and the Japan international Co-operation Agency. They concluded that the bridge was safe and the large deflections were due to creep and the modulus of elasticity of the concrete in place being lower than anticipated.

Japan-Palau Friendship Bridge

As the Palau government lacked sufficient funds to rebuild immediately, a new bridge to provide a steady transportation system was constructed with Japanese Grant Aid in ODA. Its construction began in 1997 by Kajima Corporation, a Japanese construction company, and was completed in December, 2001. It was named "Japan-Palau Friendship Bridge" on its opening ceremony on January 11, 2002. Ironically, Kajima had been a competitor of Socio. [ [http://www.pacificmagazine.net/issue/2002/03/01/pacific-notes Palau Toasts Bridge to the Future] Pacificmagazine.net, March 1, 2002] [ [http://www.britannica.com/eb/article-54026/Palau Palau History; page 10] Britannica Online Encyclopedia]

ee also

References

External links

* [http://www.ketchum.org/bridgecollapse.html Photographs of collapsed original bridge] - Photographs
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* [http://www-civ.eng.cam.ac.uk/cjb/cjbresearch1.html Cambridge Univ. Research Projects] - Research of the KB Bridge collapse
* [http://web.archive.org/web/20010121234800/http://pidp.ewc.hawaii.edu/PIReport/1999/March/03-04-04.html Pacific Island Report] - KB bridge suit revived in palau
* [http://www.uni-leipzig.de/~massivb/institut/lacer/lacer02/l02_06.pdf The Collapse of the K-B Bridge in 1996 A MSc Dissertation at the Imperial College London] Matthias Pilz report