Corps of Engineers Strong-Motion Instrumentation Program. Report 1. Earthquake Response Spectral Analysis of Arkabutla Dam, Mississippi
Abstract
This report provides permanent documentation for and analyzes accelerograms for the main shock (m sub b = 5.0) and aftershock (m sub b = 4.5) of the New Madrid earthquakes of 25 March 1976 obtained at the Arkabutla Dam. Both epicenters occurred in Arkansas. The main purpose of this study is to analyze the response spectra of acceleration, velocity, and displacement, the amplification factors, and the natural periods of foundation, dam, and abutment. All response spectra of longitudinal (L), vertical (Z), and transverse (T) components for the downstream (toe), crest, and abutment of Arkabutla Dam were presented individually. Five percent damped spectral amplitude-ratios of the L- component at the toe to those at the abutment and the similar crest to the abutment rates were 4.2 and 2.2, respectively, at the period of 0.35 sec or 2.9 Hz. Therefore, 0.35 sec is the natural period for both foundation and dam. Evidently, the spectral amplitude of the L-component at 0.35 sec on the crest of the dam was deamplified or reduced directly due to the dissipation (attenuation) of wave energy in the dam. The average amplification factor of the vertical component for the toe relative to the abutment is 3.22 for the period of 0.25 sec or 4 Hz; for the T-component it is 1.06 and 0.93 for 0.35 sec (2.9 Hz) and 0.40 sec (2.5 Hz), respectively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1990
- Accession Number
- ADA226231
Entities
People
- Frank K. Chang