Use of dense array data in the determination of engineering properties of strong motions

Abstract

A dense seismometer array in Chiba Experiment Station of the Institute of Industrial Science, University of Tokyo, was introduced including its complementary observation system for measuring soil and buried pipe strains. By using the dense array data, the variation of peak accelerations within a small area was examined. It was conclusively found that the axial pipe strain is almost equal to the surrounding soil strain in the pipe direction. The soil strains evaluated from dense array data were generally in good agreement with the directly measured soil strains and pipe strains even for a small finite element if the original accelerograms are processed through proper filters. For an incident wave of dominantly shear type, the pipe strain was found to be small, namely the pipe strain measured in 10 −6 being only 0.15–0.30 times the peak acceleration measured in cm/s 2.