Koror-Babeldaob Bridge
Encyclopedia
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 built by Socio Construction Co. of Korea
.
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 Alfred A. Yee and Associates. It was constructed by Dyckerhoff & Widmann AG, contractor was Palau based Korean company, Socio Construction Co. It was the world's largest bridge of its type, until its record was broken by the 260 m span of the Gateway Bridge in Brisbane
, Australia
, finished in 1985.
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.
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.
international Co-operation Agency) 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.
By 1990, a physical phenomenon called creep
had caused the midline of the bridge to sag 1.2 meters, causing discomfort to drivers and concern for officials. The Palau government commissioned two studies by Louis Berger International and Japan International Co-operation Agency. They both concluded that the bridge was structurally safe though 1m more of creep would occur in the future. Based on the studies, the Palau government decided to counteract the cosmetic damage caused by creep with resurfacing and reinforcement of the bridge.
According to British civil engineers Chris Burgoyne and Richard Scantlebury, the reinforcement operation had 4 main components.
The most probable progression of the collapse began with a weakening of the Babeldaob side. This caused a shear failure, resulting in all of the weight of the continuous main span coming to rest on the Koror side. This unbalanced moment caused the backspan of the Koror side to fail and tipped the bridge into the channel. The new design of the bridge hastened the bridge's collapse, but did not actually cause the fatal weakening of the Babeldoab flange. The ultimate cause of collapse remains unknown. The repair and resurfacing operation may have contributed to the bridge failure, but since the lawsuit over the collapse was settled out of court, no final cause has ever been definitively published.
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 Japan
ese construction company, and was completed in December, 2001. It was named "Japan-Palau Friendship Bridge" on its opening ceremony on January 11, 2002.
Palau
Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...
that connects Koror
Koror
Koror is the state comprising the main commercial centre of the Republic of Palau. It consists of several islands, the most prominent being Koror Island ....
and Babeldaob
Babeldaob
Babeldaob is the largest island in the island nation of Palau. Its area, 331 km² , makes up over 70% of the area of the entire country, and about 30% of the population, with about 6,000 people living there...
Islands. It is a reinforced concrete
Reinforced concrete
Reinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...
, portal frame
Portal frame
Portal frame construction is a method of building and designing structures, primarily using steel or steel-reinforced precast concrete although they can also be constructed using laminated timber such as glulam. The connections between the columns and the rafters are designed to be...
, cable-stayed bridge
Cable-stayed bridge
A cable-stayed bridge is a bridge that consists of one or more columns , with cables supporting the bridge deck....
with a total length of 413 m. It was built by the Kajima Corporation of Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
in 2002, to replace the former, collapsed bridge built by Socio Construction Co. of Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
.
Collapse of the former KB Bridge
The original Koror-Babeldaob Bridge was a balanced cantileverCantilever bridge
A cantilever bridge is a bridge built using cantilevers, structures that project horizontally into space, supported on only one end. For small footbridges, the cantilevers may be simple beams; however, large cantilever bridges designed to handle road or rail traffic use trusses built from...
prestressed concrete
Prestressed concrete
Prestressed concrete is a method for overcoming concrete's natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete...
box girder bridge
Box girder bridge
A box girder bridge is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises either prestressed concrete, structural steel, or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section...
with a main span
Span (architecture)
Span is the distance between two intermediate supports for a structure, e.g. a beam or a bridge.A span can be closed by a solid beam or of a rope...
of 240.8 m and total length of 385.6 m (1265 ft). It was designed by Dyckerhoff & Widmann AG
Dyckerhoff & Widmann (Dywidag)
Dyckerhoff & Widmann AG was a construction company based in Munich, Germany .-History:...
and Alfred A. Yee and Associates. It was constructed by Dyckerhoff & Widmann AG, contractor was Palau based Korean company, Socio Construction Co. It was the world's largest bridge of its type, until its record was broken by the 260 m span of the Gateway Bridge in Brisbane
Brisbane
Brisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, finished in 1985.
This led to two studies carried out by Louis Berger International and the Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
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.
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
State of emergency
A state of emergency is a governmental declaration that may suspend some normal functions of the executive, legislative and judicial powers, alert citizens to change their normal behaviours, or order government agencies to implement emergency preparedness plans. It can also be used as a rationale...
. By request of Kuniwo Nakamura
Kuniwo Nakamura
Kuniwo Nakamura was the President and foreign minister of Palau from 1993 until 2001.-Background and early life:Nakamura is the son of a Japanese immigrant from Matsusaka, Ise Province and a Palauan chieftain's daughter. He was studying in his second year of primary school when the surrender of...
, then the country's President
President of Palau
-List of Presidents of Palau:-Latest election:-See also:*Vice-President of Palau*High Commissioner of the Trust Territory of the Pacific Islands...
and foreign minister, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
provided emergency aid as well as a temporary bridge.
Reason for the collapse
The 18-year old, Koror-Babeldaob bridge (KB bridge) collapsed abruptly and catastrophically. The failure occurred during benign weather and loading conditions, less than three years after two independent teams (Louis Berger International and the JapanJapan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
international Co-operation Agency) 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.
By 1990, a physical phenomenon called creep
Creep (deformation)
In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....
had caused the midline of the bridge to sag 1.2 meters, causing discomfort to drivers and concern for officials. The Palau government commissioned two studies by Louis Berger International and Japan International Co-operation Agency. They both concluded that the bridge was structurally safe though 1m more of creep would occur in the future. Based on the studies, the Palau government decided to counteract the cosmetic damage caused by creep with resurfacing and reinforcement of the bridge.
According to British civil engineers Chris Burgoyne and Richard Scantlebury, the reinforcement operation had 4 main components.
- The bridge midspan was modified, changing the originally non-weight-bearing hinged joint to a continuous block of concrete.
- Eight prestress cables were added to straighten the span.
- Eight flat-jacks were added to the center of the structure to add additional prestress, loading the center of the bridge.
- The bridge was resurfaced to smooth out the sagging road.
The most probable progression of the collapse began with a weakening of the Babeldaob side. This caused a shear failure, resulting in all of the weight of the continuous main span coming to rest on the Koror side. This unbalanced moment caused the backspan of the Koror side to fail and tipped the bridge into the channel. The new design of the bridge hastened the bridge's collapse, but did not actually cause the fatal weakening of the Babeldoab flange. The ultimate cause of collapse remains unknown. The repair and resurfacing operation may have contributed to the bridge failure, but since the lawsuit over the collapse was settled out of court, no final cause has ever been definitively published.
Japan-Palau Friendship Bridge
Official development assistance
Official development assistance is a term compiled by the Development Assistance Committee of the Organisation for Economic Co-operation and Development to measure aid. The DAC first compiled the term in 1969. It is widely used by academics and journalists as a convenient indicator of...
. Its construction began in 1997 by Kajima Corporation, a Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese construction company, and was completed in December, 2001. It was named "Japan-Palau Friendship Bridge" on its opening ceremony on January 11, 2002.
External links
- Photographs of collapsed original bridge - Photographs
- Cambridge Univ. Research Projects - Research of the KB Bridge collapse
- Pacific Island Report - KB bridge suit revived in Palau
- The Collapse of the K-B Bridge in 1996 A MSc Dissertation at the Imperial College London Matthias Pilz report