Repair of New Long-Span Bridges Damaged by the 1995 Kobe Earthquake

Abstract

The 1995 Hyogo-ken Nanbu (Kobe), Japan earthquake provided the world’s first experience with earthquake damage to new long-span bridges designed to 1990s seismic standards. This paper reviews damage and describes techniques used to repair three major steel bridges along the Wangan route (Bayshore route) in Kobe—the 885 m Higashi-Kobe Bridge, the 217 m Rokko Island Bridge, and the 252 m Nishinomiya Port Bridge. These bridges, in service for less than three years, were essential components in the highway transportation system in the Kobe region. Extremely large ground motions, and failure of bearings, connections, and seismic restrainers were principal contributors to the damage sustained by these bridges. Repairs utilized heavy-lift floating cranes (up to 4,100 ton capacity) and various jacks to stabilize the structures and to realign spans. In one case, reconstruction of a collapsed span was required, with lifting weight a prime concern. Significant constraints on the repair included confined working space and requirements for maintaining maritime navigational clearances. The closure times for the repair of the bridges ranged from three to nine months.