Seismic Analysis of the Bonneville 1st Powerhouse

Madden, Dan; ,

Seismic Analysis of the Bonneville 1st Powerhouse

by Dan Madden, Corps of Engineers, Portland, United States,

Document Type: Proceeding Paper

Part of: Waterpower '91: A New View of Hydro Resources

Abstract:

The Bonneville 1st powerhouse monoliths were constructed during the period of 1938 to 1942 and were designed against seismic loads using the old lateral coefficient method. The Corps of Engineers Dam Safety Assurance Program provides for investigation of existing projects which may contain potential hazards in light of present day standards and knowledge. Since the project is 35 miles southeast of Mount St. Helens, which erupted in May of 1980, it quickly became a candidate for a dynamic analysis. A Portland District Corps of Engineers study established a new peak horizontal ground acceleration of 0.24g for the Maximum Credible Earthquake (MCE) and 0.09g for the Operating Base Earthquake (OBE) for the Bonneville area. The district contracted with Cornforth and Associates, Inc., of Tigard, Oregon to provide response spectra for both earthquakes, and with the Hydroelectric Design Center of the Corps' North Pacific Division to perform a Finite Element dynamic analysis of a complete generator bay.

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