NEW IABSE Publication

International Association for Bridge and Structural Engineering IABSE Association Internationale des Ponts et Charpentes AIPC Internationale Vereinigung für Brückenbau und Hochbau IVBH

2015-05-19/SN

PRESS RELEASE Contact: Sissel Niggeler Phone: +41-44-633 3150 . Email: [email protected]

NEW IABSE Publication: The Story of the Koror Bridge by Man-Chung Tang IABSE Bulletins, Case Studies 1

IABSE Bulletins is the name of a new series covering various types of publications. The first case study in this series has been published: ‘The Story of the Koror Bridge’ by Man Chung Tang, USA.

The Koror Bridge, connects the islands of Koror and Babeldaob in the Republic of Palau. The design of the bridge began in 1974 and was based on the prevailing AASHO Standard Specifications at that time and was supplemented by ACI and CEB-FIP design recommendations on an as-needed basis. When the Koror Bridge was opened to traffic in April 1977, it was the world’s longest concrete girder span. A few years later, the bridge began to deflect more than had been anticipated. The owner commissioned a Japanese engineering firm in 1985 and then a US engineering firm in 1993 to conduct in-depth investigations of the structure. Both firms came to the same conclusion that the bridge was structurally safe and that the excessive deflection was an unexplainable phenomenon.

Nevertheless, in order to improve the driving quality of the bridge deck, the owner decided to repair the bridge. The repair scheme made changes to the structural system and added a large amount of post-tensioning force to the bridge. Unfortunately, less than three months after the repair, late in the afternoon on 26 September, 1996, nineteen and a half years after it was opened to traffic, the bridge collapsed. Thereafter, most of the documents were sealed as a result of litigation between the various parties and the debris was cleared. For a long time, it was impossible to study the facts surrounding the bridge’s collapse. Only recently, through continuous probing by a group of engineers, were these documents mad accessible to researchers.

‘The Story of the Koror Bridge, by Man-Chung Tang’ IABSE Bulletins, Case Studies 1

100 pages, in English ISBN 978-3-85748-136-9 Format: 170 x 240 mm Published: December 2014

Hardcopy: IABSE Member CHF 40.- / Non-Members: CHF 70.- Order at: www.iabse.org/onlineshop ./. International Association for Bridge and Structural Engineering IABSE Association Internationale des Ponts et Charpentes AIPC Internationale Vereinigung für Brückenbau und Hochbau IVBH

The International Association for Bridge and Structural Engineering (IABSE) was founded in 1929. The mission of IABSE is to promote the exchange of knowledge and to advance the practice of structural engineering worldwide. IABSE deals with all aspects of planning, design, construction, maintenance and repair of civil engineering structures. To fulfil its mission, IABSE organises conferences and publishes a quarterly journal, Structural Engineering International, as well as books and reports. The Association has a number of technical groups and presents awards in recognition of outstanding contributions in the domain of structural engineering.

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