PREDICTION OF NONLINEAR STRUCTURAL EARTHQUAKE RESPONSE BASED ON HYBRID METHOD CONSIDERING LOCAL SEISMIC ACTIVITIES AND UNDERGROUND SOIL CHARACTERISTICS

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A direct 2.5 dimensional boundary element method is applied to evaluate strong ground motions in two-dimensional sedimentary basin due to a three-dimensional Haskell-type fault to estimate the amplification characteristics of the ground motions in the heavily damaged belt zone in Kobe City during the 1995 Hyogo-ken earthquake. The effects of different types of cross-section of the sedimentary basin on the strong gound motions in the basin are examined in detail.We discuss a three-dimensional fast multiple boundary integral equation method for crack problems in Laplace's equation. The proposed implementation uses a new multipole expansion proposed by Hrycak and Rokhlin in conjunction with collocation in the solution of a discretised hypersingular boundary integral equation for crack problems. The resulting numerical equation is solved with GMRES(generalised minimum residual method) in connection with FMM(fast multipole method). It is found that the obtained code is faster than a conventional one when the number of unknowns is greater than about 1300.We present a method to evaluate time-varying nonlinear dynamic soil resistance to a pile when subjected to horizontal excitations on the top of the pile. In the procedure only bending moments at some points on the pile are assumed to be given in advance by observation. Special consideration to a data processing method, which combines a smoothing procedure for given data and introduction of regularization with a penalty matrix, is made for improving the accuracy of the estimation from the observed data including measurement errors. The validity of the proposed procedure is studied and confirmed through numerical examples.