Effects of horizontally travelling waves in soil-structuat interaction

Phenomena related to horizontally travelling waves are normally not considered in soil-structure interaction. Only vertically incident S- and P-waves are commonly assumed. To determine the influence of this very basic assumption, the responses of a massless basemat, of a massless structure, of a basemat with mass and of a mass-spring system connected to a basemat with mass are parametrically analysed for harmonic and transient excitations for all wave forms (SH-, P-, SV- and Rayleigh waves). Comparisons of the results of the same structures, calculated for the standard vertically incident body waves of the same amplitudes are made. Various possibilities of combining P- and SV-waves to create specified horizontal and vertical free-field motions are examined. By way of illustration, a reactor building and the through-soil coupling of a reactor and a reactor auxiliary building are examined in detail, using the J-145 record of the 1971 San Fernando earthquake as a travelling wave. The effect of a flexible basemat on the structural response is discussed. (orig.)