Seismic Design and Retrofit of Bolu Tunnels and Asarsuyu Viaduct

Location: Turkey

Client: High Point Rendel

Dates: 1999-2001

Following the two earthquakes in Turkey in 1999 (Ms = 7.2 & 7.4), the Turkish Ministry of Highways imposed stricter seismic design criteria to structures close to the North Anatolian Fault Zone. Bolu Tunnels and Asarsuyu Viaducts are key structures on the Motorway linking Ankara to Istanbul, which were still under construction. A seismic design review was required to match the new design criteria.

GCG were retained as experts by High Point Rendel who was acting as the Engineer for the Turkish Ministry of Highways. GCG’s role was to work within a panel of experts to address all engineering and seismology issues. This included:

  • Update of site specific seismic study;
  • Development of design ground motions;
  • Seismic screening of tunnels;
  • Detailed dynamic assessment of tunnels and viaducts
  • Development, costing and reporting necessary repairs and retrofit measures.

GCG also provided site supervision overseeing retrofit and construction of the new seismic designs, including a section of tunnels crossing an active fault, designed to accommodate future fault offset displacements.