Influences Of Uncertainty Of Shear Wave Velocity On Design Ground Motion Parameters

Shear wave velocity is an important parameter for estimating seismicresponse analysis of site. The existing studies have shown that it hassignificant uncertainty. How much are there impacts on the design groundmotion parameters? How should it be estimated quantitatively? These haveof important significance value for reasonably considering the effects of shearwave velocity uncertainty on the seismic design ground motion parameters. Toachieve the above goals, the work and results in this paper are as follows:(1) The studies of dynamic shear modulus ratio, damping ratio and theshear wave velocity are reviewed concisely and the uncertainty of shear wavevelocity on the design ground is summarized. The correspondingshortcomings are pointed out.(2) The one-dimensional equivalent linearization wave analysis methodand important improvements are introduced.Taking Tangshan Xiangtangthree-dimensionan stations as the basis, the4corresponding programs arecompared to verify their reliability and applicability.(3) Monte carlo method is used to study the effects of the uncertainty ofthe soil dynamics parameters (shear wave velocity and modulus ratio anddamping ratio) of the single-layer and double-layer soil. The results obtainedare compared with those of typical cases to determine the limit states ofseismic response.(4) Base on the different site classes of228actual engineering siteprofiles, the influences of the uncertainty of shear wave velocity on groudpeak acceleration, response spectrum platform value and characteristic periodunder different inputs are are studied and their laws are concluded, using aone-dimensional soil layer seismic response of the equivalent linearizationwave method. The correction formula for considering the influences of soilshear wave velocity’s uncertainty on the peak groud acceleration, platformvalue and characteristic period of response spectra are proposed, and theircorrection factor are obtained.