| The main difference between large-span structures and general structures’ seismic designanalysis is that the large-span structures need to consider the spatial differences in ground motion ofearthquake. When wave incident vertically, the effects of propagation along the horizontal direction ofseismic waves cannot be well considered and the spatial differences of the earthquake will beunderestimated. In addition, the soils always behave non-linear under strong ground motion, and thisnon-linear effect need to be considered in soil-structure interaction. Numerical analysis of P-wavescattering with linear and non-linear cases will be studied in this article, which will help to furtheranalyze the response of nonlinear soil-large-span structure system under oblique seismic waves.Specific works are as follows:(1) A numerical method of P wave scattering in a linear semi-infinite domain is proposed. Thefree-field motions when P-wave incident obliquely are obtained by transfer matrix method. Themotions of internal nodes and artificial boundary nodes can be obtained through the lumped-massfinite element method and the multi-transmitting formula (MTF in brief) respectively.(2) The nature of surface motion in and around a semi-cylindrical alluvial valley is investigated forthe case of incident plane P waves using the proposed numerical method. The displacement andspectral amplification are given, which significantly depend on the incidence angle of P waves.(3) Assuming boundary region is linear elastic, the proposed method can be used for nonlinear wavescattering analysis. Preliminary verification of the non-linear program is done through a free-filedanalysis example. Scattering of P plane waves by semi-cylindrical alluvial valley is analyzed whenthe valley soil are Mohr-Coulomb and Drucker-Prager elastic–plastic respectively. The results for theelastic-plastic cases are compared with those for elastic case.(4) Finally, the work of this study is summarized, and some suggestions for further research aregiven. |
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