The Earthquake Engineering Online Archive

Investigation of the response of Puddingstone and Cogswell Dams in the Whittier Narrows earthquake of October 1, 1987; Volume Two - Cogswell Dam

Boulanger, Ross W.; Seed, Raymond B.; Bray, Jonathan D.

UCB/GT-90-02, University of California, Berkeley, Geotechnical Engineering, 1990-06, PDF (1.( MB)

The Whittier Narrows Earthquake of October 1, 1987 shook the CSMIP-instrumented Cogswell Dam, a relatively tall, concrete faced rockfill dam in a steep walled, V-shaped canyon. Maximum recorded crest acceleration was 0.15g. The report presents dynamic analysis studies of the response of the dam and the subsequent back-calculated estimates of the in-situ dynamic properties of the rockfill materials. Dynamic modulus degradation relationships as a function of shear strain were found to be better modelled by relationships proposed specifically for gravelly soils. Results also suggest that three dimensional effects are significant for this type of dam geometry and that these are not well modelled by two-dimensional analysis methods.

Available online: http://library.eerc.berkeley.edu/documents/GEOTECH/UCB-GT-90-02.pdf