Analysis of Local Variations in Free Field Seismic Ground Motion.
CALIFORNIA UNIV BERKELEY EARTHQUAKE ENGINEERING RESEARCH CENTER
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Earthquake engineers are often faced with the problem of determining the temporal and spatial variation of near-surface seismic motions in a site. This type of information is needed for the evaluation of soil-structure interaction effects, liquefaction potential and the effects of local site conditions on surface motions. Actual ground motions are due to a complicated system of body waves and surface waves. However, it is usually assumed that near-surface motions consist only of vertically propagating waves. In order to examine the validity of this assumption for engineering design a theoretical investigation has been made into the nature of near-surface motions produced by horizontally propagating waves. These include inclined P-, SV-, and SH-waves, Rayleigh waves and Love waves in horizontally layered sites over a viscoelastic half space. The research involved five phases 1 review of current knowledge, 2 development of new methods of site response analysis, 3 application to site response analysis, 4 application to soil-structure interaction analysis and, 5 evaluation of the relative importance of horizontally propagating waves in engineering design. Author