The results are discussed of experiments to test the adequancy of various approximate methods of estimating relative motion. The methods considered were characterized by the follwing: (a) the relative displacement is twice the maximum ground displacement; (b) the relative displacement is no greater than the maximum positive displacement minus the maximum negative displacement; approximation of the relative motion by an equation (given); (b) the propagation of body and surface waves through an elastic medium and the evaluation of expressions for relative motion and strains in various directions; (e) if the motion consisted of a single sinusoid, the maximum displacement would occur when b/c (distance between two points of earthquake motion; time lag between the motion of the two points) is exactly one-half the period of the wave. Direct calculations from accelerograms from 3 earthquakes showed that: method (a) is very conservative for all b/c; method (b) provides a reasonable upper value of R, it is very conservative for b/c, and use of the displacement, dm alone is inadequate; method (c) without the acceleration terms and method (d) provide a conservative but reasonable estimate of relative motion when it is less than dm; method (e) severely underestimates the possible relative motions.

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  • Accession Number: 00148204
  • Record Type: Publication
  • Report/Paper Numbers: ASCE #12536
  • Files: TRIS
  • Created Date: Mar 15 1977 12:00AM