National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2015

Case study for tsunami design of coastal infrastructure: Spencer Creek Bridge, Oregon

Yim, S.C., Y. Wei, M. Azabakht, S. Nimmala, and T. Potisuk

Journal of Bridge Engineering, 20(1), 05014008, doi: 10.1061/(ASCE)BE.1943-5592.0000631 (2015)

The absence of tsunami load provisions in coastal infrastructure design has led to unchecked resistance capacity of bridges against one of the most eminent natural hazards on the U.S. west coast. The Spencer Creek Bridge, which was completely rebuilt on the Oregon coast in 2009, is a unique example to demonstrate development and implementation of site-specific tsunami loads during the design stage. Two tsunami models, the Cornell Multigrid Coupled Tsunami model (COMCOT) and the Finite-Volume Wave model (FVWAVE), defined the flow fields from three rupture configurations postulated for a Cascadia earthquake, which has a moment magnitude of 9.0 consistent with the seismic design of the bridge structure. Although both models produce comparable surface elevations at the site, the finite-volume formulation of FVWAVE provides higher flow speed because of its capability to conserve momentum and mass even with formation of tsunami bores. The FVWAVE results define the input to the computational fluid dynamic module of LS-DYNA. The computed time history of the horizontal and vertical loads on the bridge deck, in turn, provide the input to a finite-element model of the bridge structure for capacity comparisons and damage analysis. It is concluded that the earthquake design specifications used for this particular bridge provide more than sufficient strength to resist the maximum tsunami horizontal force. The margin of safety is much smaller for the uplift force, but still remains in an acceptable range.

Feature Publications | Outstanding Scientific Publications

Contact Sandra Bigley |