Equations of Boussinesq problem for a semi-infinite body are extended by increasing number of boundary constraints so that more flexibilities can be obtained in solving several practical problems for which original equation can not be applied.

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For the ultrasonic nondestructive evaluation, it is important to understand the wave propagation process from defects. In this study, the scattered waveforms from a cavity are calculated by the boundary element method and the wave motion in the vicinity of the cavity is visualized. It is shown that the first pulse is produced by the reflection of incident wave at the front surface of the cavity and the second pulse is the creeping wave along the surface of the cavity. The diameter of the circular cavity is estimated from the time delay of these two backscattered pulses.

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A boundary element method (BEM) is developed for a quasi-static analysis of crack growth in an anisotropic body. The regularized integral equation is formulated using the higher order fundamental solution for a general anisotropic solid in conjunction with the Galerkin method. Two crack problems are solved as numerical examples. The first example is a stationary kinked crack subjected to a shear loading in an unbounded anisotropic solid. The stress intensity factors and the energy release rate are calculated as a function of kinked angles. The solutions obtained by the present method show a good agreement with other numerical results. The second example is a crack growth simulation, which is the crack extension analysis adding to the crack tip small straight elements in a direction predicted by the fracture criterion of maximum K_I and maximum energy release rate G. The effect of anisotropic material and fracture criteria on crack paths is discussed.

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In recent years, data accumulationh as been remarkablyi ncreased, and it is pointed out that it is necessaryt o restored ata in order, and to discoverr ulesh iddenb ehindd ata. The notion of data mining is firstc larifieda nd is interpreteda s a non-structurailn verseo ridentificationp roblem. Then, within the scope of data mining, n umerical analysesare carried out to find out rules on three sets of data whose featuresare different, that is, (1) occurrence of ared tide in Tokyo bay, (2) causalr elationship of water qualityin Lake Shinji and Nakaumi. Finally, aneural network algorithm is found that the usefulness of a data mining procedure for non-structural system identification.

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In this paper, a virtual work error estimator is defined to express the discrepancy between a real structure and the analytical model, with which a system identification scheme is developed. Moreover, an adaptive parameter grouping method is applied to deal with the sparsity of data. In order to obtain the relationship between the input error and the output error, Monte Carlo method is used to simulate the measured data with error. Based on the identified results, the normal distribution of estimated parameters can be assumed. As a statistical approach, Hypothesis test is introduced for damage assessment. Using one solution in the sample, the status of an existing structure is statistically evaluated by locating and assessing the damage of elements. The proposed scheme is proved effective through numerical example.

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A linearized inverse scattering method based on the Born approximation has been developed for the reconstruction of a defect shape in an elastic solid. In order to fully recover the shape of the defect, the Born inversion approach requires that the information must be measured at all frequencies and from all aspect-angles with respect to the scatterer. For a defect in a plate, however, the data cannot be measured at all directions and the complete information is seldom available.
In this paper, the aspect-limited problem of the Born inversion is investigated for the inverse scattering of antiplane waves. After the formulation of the Born inverse method is described, the method is applied to numerically simulated data with limited aspect-angles for a defect in an infinite domain as well as for a defect in a plate. It is found that the illuminated portion of the defect can be reconstructed even using a limited amount of data. The defect shape in a plate can, therefore, be recovered very well by utilizing the reflected waves at the bottom surface.
Pulse echo ultrasonic experiments using SH probes are conducted for a cylindrical cavity in a steel block. The Born inversion is applied to the data which include the direct back scatter by the cavity and to the data which include the back scatter due to reflection at the bottom of the steel block. It is found that the reconstructed result when both sets of data are utilized is far superior than those reconstructed by the individual data. It is also shown that even with the limited amount of data, the Born inversion can produce much better image of the defect than the aperture synthetic approach can.

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A new inversion method of identifying stress, called the stress inversion, is developed. The stress inversion method finds a stress distribution from a strain distribution, by using Airy's stress function that produces self-equilibrating stress components. It is shown that a boundary value problem can be posed for Airy's stress function when one stress-strain relation is assumed. Since the weak form of the boundary value problem uses displacement instead of strain, the method is suitable when actual measured data are used. As an example, the stress increment distribution of the Japanese Islands is predicted by using the nation-wide GPS array that measures daily displacement increment. Some discussions are made on the applicability of the stress inversion method to the GPS data.

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The Convex Linearization method (CONLIN), that is a dual optimizer based on the convex approximation concepts, is often used to solve the structural optimization problem, recently. The CONLIN optimizer has many benefits, for example, the handling of constraint conditions is easy as well as the SLP method, and the performance of convergence is excellent as well as the optimality criteria method (OC). In this paper, the CONLIN optimizer is applied to the topology optimization problem of three-dimensional structures. The density approach is used to obtain the optimum topology, and the filtering method proposed by the author is used to obtain the clearer topology. In the optimization problem, the total volume and the value of the gravity function which is used for the filtering are constrained. The validity of the CONLIN optimizer are clarified by comparing with the OC method. Some examples of bridge design are shown to demonstrate the effectiveness of the CONLIN optimizer for the topology optimization analysis.

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In this paper, the plate bending analysis using overlaying mesh method is presented. In general, when the plate bending problem is analyzed based on the Mindlin-Reissner theory, the reduced integration method is used to prevent the shear locking phenomenon. However, in the overlaying mesh method, the effectiveness of the reduced integration is lost because the integration points are increased by the overlaying local mesh. Therefore, the shear locking phenomenon cannot be prevented by using the regular reduced integration method when the overlaying mesh method is used. The object of this paper is to propose the effective method to solve this problem. In the present method, the interaction stiffness for shear is neglected. However, the interaction of the shear stiffness between the global model and the local model does not lose, because the influence of the shear stiffness is transmitted each other through the pure bending stiffness. Some examples are shown to demonstrate the effectiveness of the present method.

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A new analysis method, called Hybrid Finite Cover Method (Hybrid-FCM), is developed based on the modified variational principles with relaxed continuity requirements. The method is formulated for the characterization of the mechanical behavior of multi-phase materials, which possibly involve interface fracture. Due to the introduction of Lagrange multiplier to satisfy the continuity conditions for displacement vectors on the interface, the proposed Hybrid-FCM provide much more realistic solution than those of the conventional FCM with penalty method and of the image-based FEM. The performance of the proposed method is well demonstrated by the nonlinear analysis of interface fracture.

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A computational method has been proposed for viscous incompressible flows with QSI (quintic spline interpolation) scheme. This method is based on general curvilinear coordinates and collocated grid arrangement, which allows us to deal with moving boundary problems. In order to confirm the validity of this computational method, it was was applied to the rectangular and polar cavity flows. In addition, it was also applied to small amplitude standing waves and free-surface flows within a cavity. As a result, it has been shown that the predicted results are in good agreement with the theory and other computational results and that the QSI scheme is effective to predict various fluid flows with sufficient accuracy.

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In this paper, we investigate the accuracy of MPS (Moving Particle Semi-implicit) method on dam break simulation with simplified boundary conditions which values of weight function mean the existence of fixed dummy particle instead of setting them. The result of comparison between the calculation and an experiment shows that MPS method with this simple boundary conditions works well. Then, this method was applied to the mixing process of two-phase flow fields on dam break simulation. The result shows that this method can calculate the violent mixing motion of collision between two-phase flow. And the layer separation process could be calculated. Theses results show that MPS method is very useful for treatment of multi phase flow.

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This paper presents a parallel finite element for the analysis of non-linear free-surface flows. The incompressible Navier-Stokes equation based on ALE description is employed for the basic equations. The stabilized FEM based on the SUPG/PSPG method is employed for the descretization. Parallel implementation of the unstructured grid based formulation is carried out on the PC cluster. The present method is applied to the sloshing problem of a rectangular tank and actual dam. The effect of parallelization on the efficiency of the computations are examined using some different network environments.

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A stable mixed Petrov-Galerkin finite element approximation employing the trilinear element with a scaled bubble function is presented in this paper. It turned out that present approximation prompts stabilized method in certain problems such as steady advection-diffusion and viscous fluid flows. In this paper, we disscuss how stabilization of bubbles' effect acts on unsteady problems in incompressible Navier-Stokes flows through a firm theoretical and numerical foundation.Conseqently, present approach possesses better stability properties than conventional Bubnov-Galerkin appriximation employing MINI element.

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Awavelet-weighted Gauss quadrature formula is developed to reduce computational work in wavelet BEM. The non-orthogonal wavelet constructed by the authors is used as the basis. This wavelet is defined as a spline, which requires us to divide an interval into several subintervals in calculation of integrals corresponding to the basis. Besides, the number of the subintervals increases in propotion to the order of vanishing moments. The computational work for generating matrices thus is expensive, in particular, in application of numerical integration. The present formula enables us to carry out numerical integrations without division of the interval, since the wavelet is also employed as a weighting function of the formula. The number of integration points is determined a priori based on estimation of the integration error and a prescribed accuracy. In wavelet BEM, the error tolerance can be given by a threshold for matrix compression. Through numerical experiments, availability of the present method is verified.

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The scattering problems for periodic array of scatterers are formulated by taking advantages of the geometrical periodicity. For planar array of scatterers, reflection and transmission coefficients are derived as integrals over a surface of the single scatterer in the reference unit cell. In order to determine the physical quantity on the surface of scatterer, the boundary integral equation is used. The fundamental solution in a form of integral with rapidly convergent integrand is adopted for the numerical analysis. The accuracy of the reflection and transmission coefficients is confirmed by the energy balance. The reflection and transmission coefficients are applied to determine the dispersion relation for the triply periodic scatterers.

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An inverse problem of determining the elastic wave produced by an ultrasonic transducer from laser velocimetry data is considered. The quality of the inversion is tested via a comparison between experimental data and simulation results obtained with a 3 dimensional time domain elastodynamic BIEM using parallel computing. The agreements of these results are satisfactory. The feasibility of the determination of defects based on the laser measurements is also investigated. The size and location of an unknown defect are determined with high accuracy.

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Analysis of cracks and fractures in various materials is one of the major issues for the numerical method of applied mechanics. This paper presents a method to simulate the interaction between cracks which distribute on different planes in three-dimensional space. Displacement discontinuity (DD) method is applicable to the long-time computation on fluid-coupled solutions for a hydraulic fracturing, which may lasts several hours, or even days and months. The final fracture size could reach several hundreds meters, involving all fracture planes.
In the present paper, basic theory and numerical procedure are given with examples of the analysis of fracture interaction.

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The interpolation functions using the finite Fourier series fit the curved boundary shapes accurately, and also have features that the shapes of equations are almost the same without relating for the order of differentiation. This paper presents a structured grid generation method using finite Fourier series. The region defined in physical domain is mapped into computational domain of rectangular grid, and partial differential equations are calculated numerically in the transformed computational domain. The validity of the proposed method is examined for some numerical problems.

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An approximate method is used for analyzing the free vibration problem of isotropic and anisotropic right triangular plates with various aspect-ratios and variable thickness. In this paper, a right triangular plate is considered as a kind of equivalent rectangular plate with point supports. Therefore, the free vibration characteristics of any triangular plate can be obtained by analyzing the equivalent rectangular plate. The differential equations of the equivalent rectangular plate with point supports are established based on the first-order shear deformation theory. By transforming the differential equations into integral equations and using numerical integration, the solutions of the partial differential equation can be obtained in discrete form. The Green function, which is the discrete solution for the deflection, is introduced to obtain the characteristic equation of the free vibration. Frequencies and mode shapes are shown for some triangular plates with various aspect-ratio and variable thickness. The effects of boundary conditions and the fibre orientation on the frequency parameters are considered. The efficiency and accuracy of the numerical solutions by the present method are investigated.

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Wood is known as a complex material having both anisotropic and viscoelstic properties from a theoretical standpoint. The moduli of elasticity of wood easily varies with the variation of temperature and water content.
This paper presents vibrations of wood plates with varying thickness using the spline element based on the orthotropic Mindlin plate theory. The convergence and accuracy of the present method are demonstrated to be compared with those obtained by other numerical methods. The effects of taper ratio, thickness ratio and variation of moduli of elasticity on the frequencies of wooden plates have been investigated

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This paper aims to clarify the effects of transverse stiffeners on local vibrations in component plates of thinwalled steel members caused by a high-speed traveling load. The dynamic responses of the component plates with a transverse stiffener are calculated by means of finite strip method. The component plates and the transverse stiffeners are divided into a number of finite strips which are at right angles to the longitudinal direction of the component plate. The results from the analyses are as follows: 1) the local vibrations of the component plates are reflected in the transverse stiffener; 2) the maximum amplitude of the local vibrations of the component plates with the transverse stiffener increases when the speed of the traveling load approaches the minimum value of the phase velocity curve

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In order to clarify the nonlinear dynamic response characteristics of semi-rigid steel frames, second-order elastic dynamic response analysis is performed for semi-rigid portal frame under sinusoidal wave excitation. Semi-rigid connection is represented by a discrete rotational spring whose stiffness is given by a three-parameter power model and whose hysteretic M-θ, curve is approximated using independent hardening model. The characteristics of displacement response spectra and hysteretic loops of M-θ, curve of connections are discussed. The results obtained from this study are as follows: 1) the bigger the input acceleration amplitude is and/or the smaller the connection moment capacity is, the smaller the dynamic response amplitude is; and 2) even so, by inputting acceleration with excessively high amplitude, the response spectra of the frame may be greatly increased due to the influence of zero tangent connection stiffness.

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In the two or three dimensional beam problem, if only the sizes of meshes are similar, the stiffness matrix of each elements is similar and the subparts made from the stiffness matrices of elements are similar too, This paper presents a mesh generation method in the Finite Element Method, which divides a given system into the subparts with the similar stiffness matrix under the concept that the stiffness matrices are the same independent of the sizes of the subparts, if only the shapes of the subparts are similar, Validity of proposed method by using similar mesh element is shown by numerical results.

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An analytical procedure to estimate both the buckling strength and the mode shapes of thin-walled members with round corners when subjected to the axial loads is presented using the transfer matrix method. As the analytical models, both box-section members without and with stiffeners are introduced. The transfer matrices are derived from the differential equations for the plate and shell panels composing the cross section of the members. The extended transfer matrix relating the state vector of the cross section and that of the stiffener are used to allow the transfer procedure over the cross section of the thin-walled members with stiffeners. The buckling strength of the members is obtained for various sizes of the round corners. And the effects of the round corners of the cross section on the buckling strength are examined.

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Nonlinear finite element (FE) analyses are performed to simulate the behavior of top- and seat-angle connections. Contact model with small sliding option is applied between contact pair surfaces of all connecting elements. Bolt pretension force is introduced in the initial steps of analysis. Numerical analysis results together with the prediction by Kishi-Chen power model are compared with experimental ones to examine the applicability of proposed analysis method and power model. The study is farther extended by analyzing the models varying connection parameters, material properties of connection assemblages, and magnitude of bolt pretension. The following results are obtained: 1) bolt sustains additional tensile force due to prying action; 2) prying force develops more quickly due to increment of bolt diameter, gage distance from angle heel to the centerline of bolt hole, and reduction of angle thickness; and 3) bolt pretension increases the initial connection stiffness.

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The volumetric change accompanying with plastic shear deformation causes the dependency of q on p where p and q respectively represent the hydrostatic pressure and the equivalent deviatoric stress in yielding. Their dependency is called yield curve or yield function. In geomechanics Cam-clay and cap models have been frequently used as yield curve. In the last report we examined the shapes of yield curve based on the deformation behaviour observed in the published experiments where a parallel piped specimen was compressed under plane strain condition or a cylindrical specimen was extended in axial direction increasing confining pressure. In many cases the shape of yield curve were different from those in Cam-clay and cap models. In this paper the inverse prediction is discussed where the deformation behaviour is predicted according to the yield curve and hardening charcteristics obtained in the last report. First, the method of the inverse treatment is proposed, and then the comparison is made between predicted behaviour and the observed one. On the whole the inverse prediction is successful, but an abnormal prediction arises in the case that the term ƒ_r+α tends to zero or to be negative where ƒ_r;, represents the ratio of compressive volumetric strain rate to distortional strain rate and a is the hardening ratio constant. So far geomechanics has been developed under the condition of α=0. In such framework the abnormal prediction can be brought about at positive volumetric strain rate, and so introducing of hardening ratio constant must be considered. Stress point (p, q) moves with progressive deformation. Under plane strain compression the stress point approaches to the critical state line with the increase of deformation, and finally reaches to it. It is proved that the movement of stress point always stops on the critical state line regardless of the hardening characteristics of deforming soil.

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The hollow rock cylinders of andesite were tested under uniform inner pressure due to expansive demolition agent in the center hole without outer pressure. The pressure distribution in the center hole and the stress distribution on the outer surface of the specimen were observed during from the beginning of failure to the whole fracture under tensile stress field. At the same time, the measurement of acoustic emission and the visualization of failure within the specimen by the X-ray CT scanner were performed. Based on these results, failure mechanism of rocks under tensile stress field was discussed.

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In this study, we apply the finite element method utilizing section partition method to the analysis of the behavior of the reinforced concrete beam under relatively low speed impact. At first, the method isconcretely shown with some assumptions e. g., dynamic increase factors considering the strain rateef fects both steel and concrete. Successively, we introduce impact tests under some kinds of conditionsand their results, which had been done by authors. It is shown that this method is fairly reproduciblefor the failure in bending of concrete beam under impact is shown with notice after comparisons with experimental results and considerations. At last, we show the application example of this method in which a design verification of the reverse L-type rock-shed is done under some assumptions.

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In the present study, a cyclic viscoelastic-viscoplastic constitutive model for clay based on thekinematic hardening rule was proposed, which in corporates three-element viscoelastic componentin the cyclic elastic-viscoplastic constitutive model. From cyclic undrained triaxialtest results and numerical simulations, it was found that viscoplastic approach is significantin the large strain level as approaching a failure state while viscoelastic approach is notablein the small strain level. Moreover, it can be seen that the proposed model can well describeboth viscoelastic and viscoplastic behaviors of clay in the wide range of strain level and isapplicable for earthquake response analysis and/or liquefaction analysis.

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A lattice type model is employed to simulate the shear deformation and failure of uniform and non-uniform materials. Uniform materials are modeled as assembleges of a number of unit cells, which undergo bifurcation buckling to express the local softening behavior of materials. Nonuniform materials are represented with the use of the image-based geometry modeling with the consideration of micro-macro scale model to simulate the formation of a cross shear band.

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Soil deformation is largely controlled by the migration of the pore water. The self-boring pressuremeter (SBP) testdata on clayis often interpreted based on the conditions that the soil remains in the undrained condition during the pressuremeterexpansion and that the soil deformation is one-dimensional. The former condition is related to the expansion rate and thepermea bility of the soil, whereas the latter condition is related to the pressuremeter geometry. Soil-water coupledfiniteelement analysis using the finite deformation theory was performed to investigate the validity of the assumptions used ininterpreting the SBP data. The effect of permeability and expansion rate on the SBP strength was examined for differentplasticity clays with different overconsolidation ratios. The various effects caused by pore water migration on the SBP strengthwere clarified.

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The infinitesimal deformation analysis of the rate-independent Sekiguchi-Ohta model is formulated to include a class of two-invariant stored energy function considering initial state of stress. Elastic shear modulus is assumed to depend on pre-consolidation pressure and increase exponentially with strain-hardening parameter after yielding by taking damage effect on energy conservation into account. The principle of maximum plastic dissipation is connected to the associated flow rule while hardening/softening law is described by the hardening potential function defined to suit the model. The implicit integrative scheme is return mapping algorithm based on the Closest Point Projection method. The nonlinear analyses for stress-strain-strength under UU and CU tests were carried out to test the performance. It was found that the method is proven to robust, stable and accurate even in very large strain increments

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In this study, numerical simulations on the boulder breakage by the hydraulic breaker were carried out by using Distinct Elements Method (DEM). The boulder consisted of 4106 elements and two kinds of chisels were used in this simulation. One is a flat type chisel and the other is a wedge type chisel. These chisels were penetrated into the boulder and the generation and development of the fractures in the boulder were simulated. It was confirmed through this simulation that the flat type chisel broke the chisel largely although the large impact force and hitting number are necessary. On the other hand, the wedge type chisel needed small impacting force, and hitting number to break the boulder was also small.

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3-dimensional numerical simulations are carried out for material deterioration of the hybrid rigid connection between steel girders and reinforced concrete pier. The constitutive relation for concrete is taken account of the void damage theory, and the confinement effect of steel cover plate on concrete rigid connection is included. As a result, the deteriorated process and concentrated portion of rigid connection are made clear, and the confinement effect by steel cover plate is quantitatively estimated.

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Nowadays, void slab, two-way slab and half precast concrete plate are employed in order to control the creep or time-dependent behavior of large-span concrete slab. Additionally, barrierfree type slab that has very complicated shape to remove a difference in grade is appeared to respond the strong request for handicapped people. The mechanical behaviors of these new slabs have not been well considered yet. Above all, the non-linear behaviors due to cracks are not investigated and the linear analysis is employed to analyze their mechanical behaviors. Thus, in this article, a non-linear constitutive model for the void slab is proposed and its behaviors are analyzed by the proposed analytical method. As the low-tension constitutive equation in the region of tension stress introduced, the numerical result has good accordance with the real behavior.

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In this paper, to establish a proper method for analyzing failure mechanism of RC beams flexural strengthened with Aramid FRP (AFRP) sheet, three-dimensional non-linear numerical analyses were carried out using DIANA code. Here, predetermining crack distribution based on the experimental results and applying interface element for these cracks, debonding mechanism of AFRP sheet is precisely analyzed. From this study, following results were obtained: 1) loaddisplacement curve and strain distribution can be predicted with good agreement; 2) failure type of the RC beams can be identified; and 3) it is analytically made clear that AFRP sheet is debonded due to peeling action of a concrete block formed in the lower cover concrete.

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In this paper, we examine a new method of implicit finite element analysis of soil/water coupling problems. It consists of two main schemes: One scheme is an implicit return mapping scheme and another is a scheme which employs the consistent tangential modulus. The implicit return mapping scheme is based on the notion of the elastic-plastic operator split that consists of the elastic predictor and the plastic corrector. A tangential modulus consisting with the integration algorithm is developed for a well-known Cam-clay model for soils. Some examples of the implicit method show the high accuracy and much reducing the total CPU time.

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The conventional elastoplasticily is based on the idealization that the interior of the yield surface is a purely elastic domain. This idealization would not lead to unrealistic prediction of hardening behavior but would cause unrealistic prediction of softening behavior which is observed typically in over-consolidated soils, while metals and normally-consolidated soils exhibit hardening behavior. On the other hand, the unconventional elastoplasticily disusing the idealization enables to describe the plastic deformation due to the change of stress inside the yield surface exhibiting the smooth elastic-plastic transition and thus is expected to descnbe pertinently softening behavicr. In this article the capabilities of the conventional and the unconventional elastoplasticity for the description of softening behavior are examined, comparing the Drucker Prager model as the conventional one and the subloading surface model as the unconventional one for the prediction of deformation behavior of over-consolidated soils. Then, it is concluded that the unconventional elastoplasticity has to be adopted for the prediction of softening behavior.

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The failure of ground or specimens in the laboratory is caused by formation of the slip surface, which is recently regarded as thin layer called as shear band. The accurate prediction of the shear band formation is required because the bearing capacity of the ground is estimated from the shear stress on the shear band. The mathematical condition of formation of the shear band with no volume change has been derived. It is being found out, however, that volume change is localized in the shear band as well as shear deformation. In this paper, the condition for shear band formation with volume change under plane strain compression is derived. Then, this condition is applied to non-coaxial Cam-clay model and influence of non-coaxiality on the shear band formation is examined.

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The mechanical response of the elastoplastic constitutive model for soils is examined, which is based on the subloading surface model with tangential stretching describing the inelastic stretching induced by the stress rate component tangential to the yield/loading surface. The stress rate response to the imposed stretching under triaxial condition in not only hardening but also softening states on the meridian and the deviatoric planes is shown firstly. Then, it is indicated that the stress rate response in the deviatoric stress rate plane is decreased to the tangential direction of subloading surface by the tangential stretching effect. Further, a nose is predicted in the response envelope to the imposed stretching inducing the axisymmetric deformation and the response envelope in the softening state exhibits a crescent form.

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Observing numerical results obtained by Granular Element Method, we discuss the incremental stress-strain behavior of granular materials. We assume a periodic boundary for the numerical experiments to avoid disturbances caused by boundary controlling. Stress-probe tests starting with the intermediate data of a bi-axial compression test give a set of incremental stress-strain relationships. The result indicates that the flow direction for plastic loading is not constant as is assumed in the classical plasticity theory and depends on the direction of the stress increment. Comparing the numerical results with a proposed flow rule, we conclude that the origin of the direction dependency is the volumetric component of plastic strain.

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In order to clarify analytically mechanical behavior of sand ground-structure system under cyclic central or eccentric loading condition, a series of FEM analysis and model test were performed. In this study, a technique of analysis for lateral deformation of sand deposits is proposed. The characteristics of elastic modulus of ground were detailedly investigated in advance and were quantifed. The results obtained from this analysis, which is based on the change in rigidity of ground, are also compared with those of the model test. It was found that the behaviors of settlement and lateral flow deformation can be simulated by means of FEM analysis with changes in the elastic modulus of ground.

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Mori-Tanaka theory is used to predict average behaviors of yielding of composite materials and polycrystals. Comparison with experimental results quantitatively shows the characteristics of such an average yield stress. Results indicate the hydrostatic pressure dependence onto yielding and the anisotropy of yield loci. Furthermore a type of non-associativeness of the flow and a corner development on the yield loci of polycrystals are shown as an approximate example.

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In this paper a simplified method, in which a group of piles is viewed as a single equivalent upright beam, is presented for expression of the dynamic stiffnesses of grouped piles subjected to lateral force and bending moment. An effective computer program with very little memory, based on the Thin Layered Element Method, is used for this purpose. The results of the program are compared with those calculated by the 3-dimensional Finite Element Method for several cases of large-scaled grouped piles. The results obtained lead to the conclusion that the simplified method that is presented is sufficiently accurate for the purpose of preliminary evaluation of the pile cap stiffnesses for sway and rocking motions of large-scaled grouped piles.

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Ground vibrations due to surface loads and incident waves are considered. The reduction of the vibration is achieved by using a wave impeding barrier. The considered structure is the foundation of a building. For incident waves from below the current investigation shows that a wave impeding barrier is not a proper reduction measure. Ground vibrations due to the surface load can be strongly reduced by the wave barrier. The effectiveness of the wave barrier can be improved by increasing its length and stiffness.

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RC members that have terminated main reinforcing bars with inadequate anchorage length become the week points of the RC structures because a significant shear failure is likely to develop at the middle part of them. So, the development of the seismic inspection method and the seismic strengthening method of the RC members with termination of main reinforcing bars is very important. In this paper, Non-linear numerical simulation of the failure mechanism of the RC bridge piers whose main reinforcing bars are terminated is carried out and in addition to that on the effect of the seismic strengthening of the piers with steel jacket is also studied. The applicability of Applied Element Method as the evaluation tool for the seismic performance and the effect of seismic strengthening of bridge piers is tested.

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In this study, elasto-plastic and dynamic response analysis is carried out to investigate the influence of applied seismic acceleration and the flexural rigidity of longitudinal stiffeners onto damage to steel bridge piers having single thin-walled box columns and the relationships between the extent of the damage and the limit states, such as serviceability limit, repairable limit and ultimate limit of the bridge piers. Firstly, a method for estimating the proper flexural rigidity of longitudinal stiffeners is dealt with. Secondly, a parametric analysis is carried out by varying types of the seismic acceleration waves and the flexural rigidity of longitudinal stiffeners in order to investigate the definition of the limit states.

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In order to simulate the formation process of surface earthquake faults, we develop a new stochastic finite element method for an elasto-plastic body with randomly varying material properties and apply it to the 3D Drucker-Prager model. The method is based on the Karhunen- Loeve expansion and Polynomial chaos expansion to efficiently estimate complete probabilistic characteristics of responses, such as average, variance, and a probability density function. Also, it is shown that the proposed stochastic finite element method is able to simulate complicated bifurcation phenomena associate with the fault formation process.

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The formation of surface earthquake fault is a hot topic in earthquake engineering, as it could cause fatal damage to near-by structures. This paper presents results of numerical experiment of the reverse fault formation using granular materials. The numerical experiment is carried out by using the simulation of Modified Distinct Element Method (MDEM). The deformation of shear bands and the incremental distribution of maximum shear strains are observed to vary in the displacement speed of bedrock fault and the rigidity of surface grounds. It is shown that displacements of the top surface and positions reaching the top surface of shear bands hardly vary in the cohesion of surface grounds.

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