Seismic response of the Eureka Channel Bridge-Foundation system

Recorded earthquake motions from the highly instrumented Eureka Channel bridge-foundation system have been compiled and made available by the California Geological Survey. During eight seismic events, more than 20 data channels have been documenting the seismic response of the bridge, abutments, and adjacent ground surface. Of special interest is the response of one of the bridge piers with records at the deck level, pile cap and within the underlying pile foundation. In this paper, records from the strongest to date 2010 Ferndale earthquake (PGA of about 0.25 g), along with other available low-amplitude events (2007-2014) are employed to evaluate the ground, pile foundation, and overall bridge seismic response. Spatial variation of the recorded motions is examined. Linear and nonlinear response of the ground and the bridge are assessed using system identification techniques. Finite Element (FE) modeling is employed along with the optimization software framework SNOPT, to derive salient response characteristics of the bridge system and its foundations. As such, the FE model is calibrated using the recorded data. On this basis, estimates of the column and foundation lateral stiffness during the low amplitude and the strong shaking phases of seismic response are derived. Results of this study, complement those reported earlier for the nearby Samoa Channel Bridge and geotechnical downhole array. In this regard, the Eureka Channel Bridge differs in geometry, foundation layout, and supporting soil profile.

Automated summary

This paper utilizes earthquake motion data from the Eureka Channel bridge to evaluate the seismic response of the ground, foundation, and overall bridge. Spatial variation of recorded motions is examined, and Finite Element modeling with optimization software is used to analyze the characteristics of the bridge system and its foundations.