Standard earthquake analyses of civil engineering structures use uniformground motions even though considerable variations in both amplitude and phasecan occur along the foundation interface for long-span bridges and large dams. Theobjective of this thesis is to quantify the effect that these nonuniformities have on thestructural response.
The nonuniform, free-field motions of the foundation interface are assumed tobe caused by incident plane body waves. The medium in which these waves travel isa linear, elastic half-space containing a canyon of uniform cross section in which thestructure is placed. The solutions for the free-field motions that are due to incidentSH, P and SV waves are calculated using the boundary element method.
An analysis of Pacoima (arch) dam located near Los Angeles, California, isperformed for both uniform and nonuniform excitations. The important effect ofnonuniformities in the free-field motions, sometimes leading to a decrease in the damresponse and sometimes to an increase, is quantified.
