Assessment of Performance of Bolu Viaduct in the 1999 Duzce Earthquake (2001-2002)

The Bolu viaduct is a 2.3 km long seismically isolated structure whose construction was nearly complete when it was struck by the 1999 Duzce earthquake in Turkey. It suffered complete failure of the seismic isolation system and narrowly avoided total collapse due to excessive superstructure movement. This paper presents an evaluation of the design of the viaduct’s seismic isolation system and an assessment of its performance in the Duzce earthquake. The evaluation revealed that the seismic isolation system did not meet the requirements of the AASHTO Guide Specifications for Seismic Isolation Design. Analysis of the viaduct with motions scaled in accordance to the AASHTO Guide Specifications resulted in a displacement demand equal to 820 mm, which is far more than the 210 mm displacement capacity of the existing isolation system. Analysis of the viaduct for a simulated near-fault ground motion with characteristics consistent with the site conditions resulted in an isolation system displacement demand equal to 1400 mm. This indicates that even if the isolation system had been designed in compliance with the AASHTO Guide Specifications it would have still suffered damage in the earthquake.