scope

Incheon Bridge will link the City of Incheon, which neighbours Seoul, with the Incheon (Seoul) International Airport. The US$1 billion toll bridge is a 12km long sea crossing.

The bridge is being constructed on a BOT basis by KODA Development Ltd, the concessionaire for the project, and the Halcrow-Arup-Dasan JV is provid`ing Contractor's Checking Engineer (CCE) services to the design and build contractor Samsung Construction JV.

The CCE role is unusual compared to a traditional independent checking role. Working within the contractors organisation, the CCE-JV is ensuring that the project stays on its fast track programme by carrying out parallel analysis and verification of the design and checking drawings before release to the Design Supervisor and Korean Highway Corporation for approval.

As well as reviewing key design reports and certifying the permanent works and major temporary works items, the CCE-JV also provided Samsung with technical evaluation of proposed refinements to the design basis of the bridge.

seismic design

The bridge is constructed in a seismically active region and is designed to resist a 1 in 1,000 year return period earthquake event which is the governing load case for the foundations and substructure Thick layers of soft marine deposits amplify earthquake motions in the bedrock leading to relatively high ground motions. The CCE-JV carried out time history site response analyses to confirm that the Korean standard adequately covers this site amplification.

All of the structures are checked based on multi-modal response-spectrum analyses. For the cable stayed bridge a state of the art analysis method was used based on assigning different levels of structural damping for each mode of vibration in the dynamic analysis according to the contribution of strain energy from the various structural elements.