This paper presents the method of eigenfunction expansion to the impact response analysis of a transversely isotropic, thick rectangular plate with simply supported conditions, based on the theory of elastodynamics.The elastodynamic solution is decomposed into their quasi-static and dynamic components.The quasi-static solution is obtained by an exact analysis of the quasi-differential equations withthe time-dependent boundary conditions under the given impact pressure loading.The dynamic part is given in aninfinite series of the eigenfunctions (normal modes) which are derived from the free vibration analysis of the associated problem satisfying homogeneous boundary conditions. Stresses and displacements responses at transient and long-time states are shown graphically, and then influences of anisotropy on the dynamic response are revealed.

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Equations of vertical and horizontal displacements on a half space rock mass caused by a rigid plate loading test using concrete facing which restricts free horizontal displacements of the rock surface under direct contact with it, are developed. Young's modulus and Poisson's ratio of the intact rock mass can be simultaneously obtained by applying the equations to the test results.

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In this paper, we examine the existence of conditions that the mode II crack extensions occur under compressive loads. It is important to elucidate the fracture criterions under compressive loads such as the explanation of the existence and the creation of long faults, landslide in slope ground and so on. We find, by using the maximum energy release rate criterion, that the mode II crack extensions occur by the shear stress with the necessary parallel compressive stresses for a crack surface. We also find that the mode II crack extensions do not occur by the well-known maximum stress criterion.

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By employing the block-diagonalization method in the group-theoretic bifurcation theory, we develop a general procedure to estimate the number of periodic microstructures (cells) that should be contained in a representative volume element, in which the microstructural analysis in the nonlinear multi-scale homogenization analysis is performed. Since the problem of interest essentially involves the non-convexity of the total potential energy, we first provide some remarks on the multi-scale modeling strategy within the framework of the nonlinear homogenization theory. Next, knowing that the number of cells restricts possible bifurcation modes, we perform the bifurcation analysis for periodic microstructures by means of the block-diagonalization method. To demonstrate the proposed procedure, several numerical analyses are conducted on a cellular solid, which is one of the typical examples whose microstructural instability causes the macroscopic material instability. The proposed method can readily be applied to the characterization of the mechanical behaviors caused by micro-macro-coupled instability.

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Many materials are often observed to fail in a longitudinal splitting mode under far-field compressive loading with weak lateral confinement. An energy-based model is developed based on the principle of minimum potential energy and the evaluation of effective properties to obtain an analytical approximation to the critical stress for longitudinal splitting under compression in materials with a given microstructure. The analyticestimate for the compressive strength is used to illustrate its dependence on micromechanical properties and lateral confining pressure. The predictions of the model show good agreement with available experimental data.

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The objective of this paper is to characterize the failure in light-weight soil with air foam under unconfined compression using industrial X-ray CT scanner. In this study, a series of unconfined compression tests was conducted for both specimens made in laboratory and sampled at in-situ construction site. And then, the nondestructive testing was also examined under the process of unconfined compression for all the specimens. Here, image processing analyses in order to obtain the distribution of the density in the soil were conducted. According to those results, the change of soil property under unconfined compression was evaluated and it was also convinced that the industrial X-ray CT scanner may be a powerful tool in geotechnical engineering.

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In order to propose a numerical discrete model on structural element stiffness identification, a general framework of inverse analysis is first developed for the static parameter estimation problem as a nonlinear minimization of difference between the response of a real structure and the prediction of a finite element model of that structure. To enhance the identifiliability of the identification model for a large-scale structural system, a localized identification concept is proposed, and, a statical condensation method based on the cholesky decomposition approach is introduced to predict all the unmeasured nodal displacements for preparing the input data during the iterative identification procedure. Next the Hopfieled neural network is used as a minimizator for identification procedure.

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This study presents numerical simulation and experiment to investigate the vibration characteristics of a transducer used in an immersion ultrasonic testing. Firstly, the Rayleigh-Sommerfeld integral is used to numerically evaluate pressure waves excited by a transducer in a fluid, on the assumption that the velocity distribution on the vibration plane of the transducer is given. The results show that the velocity distribution influence the so-called ring source waves generated at the edges of the transducer. Secondly, an inversion method is developed to determine the vibration characteristics of a transducer when pressure waves are given at several points in a fluid. It is shown that the velocity distribution on the vibration plane is well reproduced by applying the inversion scheme to simulated near-field data. The inversion method is then applied to experimental data.

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An inverse method for estimating the non-stationary variations of soil rigidity and damping from observed array records is presented. The method uses basically the “Complex envelope method” for the time histories of stress and strain obtained from observed motion records. In this paper, the validity of the method is first confirmed based on both theoretical and numerical analyses. The method is further applied to the array strong-motion records that were observed at three sites during the 1995 Hyogoken Nanbu Earthquake showing different features of non-linear responses. It is finally concluded that the present method is quite effective in inversely estimating the non-stationary variations ofsoil rigidity and damping in comparison to the results due to the PS logging profiles.

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The linearized inverse scattering methods are applied to the shape reconstruction of defects in elastic body. The linearized methods are based on Born and Kirchhoff approximations for unknown displacement fields in the integral representation. To show the versatility of the methods, the experimental measurement is performed to collect the scattered waveforms from defects. The results show that the shape of defects can be reconstructed by the linearized methods with processed waveforms from ultrasonic measurement. It is shown that the scattered wave component in the low frequency range is important for the shape reconstruction.

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In this study consists of the following two topics, one is a basic considerationo n a data miningw hich is the power of currentd ataprocessingf unctions, o f interestingk nowledger ules from huge database.A nd the other, we introduced ata mining with a view to discuss applications of artificial life and decision tree procedures. Data mining procedures which, decision tree using information entropy theory and genetic algorithm are proposed, and red tide data from Tokyo bay were analyzed. Finally, it is found that the usefulness of these data mining procedures for non-strucural system identification

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When a rail-surface profile is taken into account as an excitation, in a numerical track vibration analysis, it is necessary to decide the irregularity which reflects the whole source of noise. In this study, identification of the rail-surface irregularity which reproduces observed acceleration is attempted. The identification method is constructed based on equations describing the relation between the observed acceleration and the rail-surface irregularity. Since the identification of the rail-surface profile is so called ill-posed problem, in order to augment the stability of solution the Tikhonov's method is employed. The identification is achieved using accelerations observed at the rail, sleeper, and substratum. The developed method is applied to a numerical model and to observed data. Through numerical experiments validity of the proposed method is investigated.

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In order to measure the surface roughness three-dimensionally, noncontact and portable 3D measuring system is developed. This system is composed of the two CCD cameras and laser beam, and is based on three types measure method, i.e. stereo-photogrammetry, spot-laser and slit-laser photogrammetry. As the applications of 3D measurement, the problem of construc tion joints of concrete and free vibration analysis for twisted thin cylindrical shell panels are investigated.

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Among some sophisticated interpolation techniques, Kriging is an attractive method because it is constrained by intrinsic hypothesis. In order to apply Kriging to actual data, however, it is required to choose the variogram or covariance function, which are representationo f spatial correlation.I t is well known that spatial autocorrelation of error terms in regression model is often encountered, for which error component models (ECM) have been suggested and applied. In this paper, an interpolation technique coherent with Kriging system by expanding ECM is developed.

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Scattering cross-sections for the parallel penny shaped cracks are calculated b the boundary element method. The multiple scattering effect of cracks is generally large in thecase of the vertically arranged parallel cracks. However, it is shown that the multiple scattering effect becomes small in the low frequency range when the distance of cracks approaches to twice as large as the crack diameter. It is also shown that the local resonance phenomena are induced in the low frequency range. The mechanism of the resonance phenomena is revealed by the crack opening displacement and the radiation pattern of the scattered energy.

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This paper discusses an application of FMM (Fast Multipole Method) using Wigner-3jsymbols to the BIE (Boundary Integral Equation) analysis of the three dimensional scattering of elastic waves by a crack. The boundary integral equation is discretised with piecewise constant shape functions. The resulting algebraic equation is solved with preconditioned GMRES (Generalised Minimun RESidual method). It is shown that FMM is more efficient than the conventional BIEM (Boundary Integral Equation Method) when the number of unknowns is larger than several thousands.

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The application of transformation methods such as the Fourier transformation is difficult, when the boundary condition is implicitly given and changes with time such as in time domain problems. We consider that solving this kind of problem by applying time subtraction solution method. When time subtraction solution method is applied, domain integration of theapparent body force requires a huge amount of computation. In this paper, the panel clustering method is applied for this domain integration, and the reduction of a huge. amount of computation is being attempted. This method is applied to the anti-plane wave field problem, and it is confirmed that the amount of computation was drastically reduced.

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Multigrid algorithm is developed for wavelet BEM. Since the wavelet bases have hierarchical structure, in the wavelet BEM using the wavelet bases as its functional bases, coefficient matrix and vectors include submatrix and subvector corresponding to each resolution level. Hence, one can readily apply the multigrid method to wavelet BEM. In this paper, V-, Sawtooth-, and FMV-cycles are considered. Numerical experiments show that these methods improve the convergence of iterative solution. As the iterative methods, Jacobi, Bi-CG, and GMRES methods are employed. It is found that the multigrid method can be an effective strategy for enhancement of convergence and stability of these iterative methods.

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The voxel analysis method and the meshless method have been proposed to relieve the formidable task of mesh generation of traditional FEM. The model generation of the voxel analysis is very simple, but how to get reasonable accuracy and avoid the sharp increase of degrees of freedom is a problem of the voxel analysis. On the other hand, the meshless methods can avoid the mesh generation completely. However, some difficulties limit the freedom of meshless methods very much. One of these difficulties is how to easily guarantee the linear independence of approximation functions.Recently a new meshless approximation method, Cover Least Square Approximation, has been proposed, by which the linear independence conditions can be simply satisfied. In this paper, it is implemented for linear structural analysis by distributing the covers using multi-resolution voxel data.

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In this paper, a fast numerical procedure to analyze fundamental behaviors of concrete materials by the mesoscopic simulation is proposed. Two improvements make the proposed procedure fast. One of them is a numerical procedure based on the multiscale method in which the microscopic displacement can be calculated from the prescribed macroscopic stress directly. Another one is an effective parallel solver for the linear system derived from the image-based finite element method. The numerical properties and efficiency of the proposed procedure are alsoevaluated on a PC cluster.

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We here introduce the displacement field of frame structures into the micro-scale problem in the multi-scale homogenization and develop its formulation within linear problems. The micro-scale structure is naturally modeled by the same mechanical model as that of the original macro-scale structure. However, considering computational efficiency especially for the nonlinear homogenization involving bifurcation, it is rational to discretize the microstructures which consist of thin walls like cellular solids by thin-walled structural elements, e.g. frame or shell elements. Some difficulties in the modeling of the cellular microstructure by the frame elements are manifested from several numerical examples provided here and are overcome by examining the characteristic function obtained for some cellular solids in detail.

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The differential quadrature method (DQM) is a numerical method which has been successfully employed in a variety of problems in engineering and physical sciences. The DQM is accomplished by expressing at each grid point, the calculus operator value of a function at any discrete point as theweighted linear sum of the values of the function at all the discrete points. This paper presents an application of the semi-analytical DQM to analyze vibration of rectangular Mindlin plates with two opposite edges simply supported. The convergence and accuracy of the present method are demonstrated to be compared with those obtained by other numerical methods. The effects of simple supported models on the frequenciesof rectangular Mindlin plates are analyzed for the different aspect ratios and ratios of width to thickness.

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On the thin-walled steel members of railway bridges, it has been clarified by measuring the vibration of a railway bridge actually that local vibration of the members increases suddenly with speeding up of train. This paper aims to elucidate the mechanism of the sudden increase of the local vibration. Firstly, the phase velocity and group velocity of the local vibration in steel component plates of thin-walled steel members are computed. Secondly, the dynamic responses of the steel component plates under high speed moving loads are analyzed. The relation the local vibration with the speeding up of the moving loads are investigated on wave form, time histories, reflection and propagation of local vibration of the plates.

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This paper presents dynamic characteristics of curved pair members tied with struts subjected to axial compression. Numerical calculation was performed by using the natural frequency analysis method (QR method) changing the end support conditions, rise-tospan ratio and the axial load to check the practical use of the proposed paired structures. The effects of the end support conditions of those structures on the natural circular frequencies and the natural mode shapes were clarified using non-dimensional parametric analysis. It was found that curved pair members with both “fixed” or “hinged” endssubjected an axial load have higher natural circular frequencies in comparison with the usual straight structures with under the same conditions.

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FEM analysis is commonly used in wide range of industrial design works such as machine design, aeroplane design. There are some experimental studies about the application of FEM combined with optimization methods in order to accommodate complicated mutuary related phenomenon or to accomplish optimization automatically. In this study, optimization methods, FEM and design code inspection program are linked together to automatically seek and generate optimum structural dimension for objective steel bridges. It is discussed that Possibility of conversion of design method from traditional beam theory design to FEM based design where three dimensional structural behavior are easily considered.

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This study presents the numerical procedure for static and seismic stability analyses of slope based on the shakedown theorem in plasticity. The stability of slope has been defined as a reduction coefficient in shear strength for the limit state of slope mass. Firstly, the applicability of proposed method to the static slope stability analysis was investigated. The obtained factors of safety were compared with those of the conventional methods. It was clearly shown that the proposed method could evaluate the stability of slope properly. Secondly, the seismic stability of slope was investigated against sine wave accelerations excited at the bedrock of subsoil. The proposed method was shown to estimate the factors of safety by taking account of the effects of frequency in enforced acceleration and vibration properties of slope mass as damping and resonance.The obtained factor of safety for low frequency wave acceleration coincided with that of pseudo-static stability analysis and, on the other hand, the factor of safety approached that of static stability analysis for high frequency wave acceleration. Thirdly, the combined stability method which composed of deformation and stability analyses was conducted. The comparison between combined stability and proposed methods in cases of natural slope and embankment was investigated.It was found that the minimum factor of safety for natural slope obtained by the conventional method, however, gave an almost coincident factor of safety by the proposed method. But, the significant difference appeared in case of embankment problem. The possible engineering meaning of time dependent factor of safety obtained by the combined method was clarified.

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The modified Boussinesq equation model which was proposed by Madsen et al was applied for wave motion and nearshore current fields and its applicability was discussed. Numerical simulations of the circular reef, half-unlimited breakwater and beach topographies with an offshore breakwater were performed The accuracy of this model was verified thorough comparison with laboratory experiments and previous theory. Furthermore, numerical analysis of wave transformation for typhoon No.9918 in the vicinity of the Kumamoto New Port were carried out Results demonstrated that wave height increased in the estuary of Shirakawa river and the velocity scale of nearshore currents was as large as that of tidal currents.

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This paper presents a Space-Time finite element method for shallow water flows with moving boundaries. For the stabilization techniques, the streamline upwind/Petrov-Galerkin (SUPG) is employed and the shallow water equation based on conservation variables is used for water equation. In order to determine the position of shoreline accurately, an iterative algorithm is used. Wave run-up problems are solved for numerical example and the computed results are compared with experimental results. This method is shown to be a useful tool for the analysis of shallow water flows.

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Numerical solutions of the shape identification for the circular cylinder is treated with in this paper. The Sakawa-Shindo method is employed for minimization algorithm. The unified computation approach to the simulation of the flow and the shape identification is presented. As the numerical approach for the spatial discretization, the mixed interpolation by the bubble and linear elements is applied for velocity and by linear element for pressure, respectively.

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A new Petrov-Galerkin formulation employing the MINI element with a non-confirming bubble function for an incompressible media governed by the Stokes equation, which is to be equivalent to the stabilized finite element method, is proposed. The new formulation possesses better stability properties than conventional Bubnov-Galerkin formulation employing MINI element. In this aspect, the stabilizing effect of this formulation is evaluated by stabilizaing parameter determied by both shape of trial and weighting bubble functions.

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On geotechnical problems, many localized deformations are observed before the ultimate state. In such cases, it is important to predict how such localization is initiated and developed. In this study, the localization of deformation is simulated numerically using a constitutive model with a non-coaxial plasticity and a double-slip mechanism. Results show that material properties such as dilatancy and boundary conditions affect the local development of localization, and that the scale effect on the bearing capacity can be quantitatively predicted. As another example, this constitutive model is applied to fault problems.

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TBM (Tunnel Boring Machine) is an useful machine to construct the tunnel. In the excavation by TBM, the rock is broken by the disc cutter installed on the cutting face of TBM. Recently, the round tip disc cutter has been widely used. This paper describes the rock breaking by use of actual size disc cutter. It was confirmed through this experiment that hard rocks can be broken by the round tip disc cutter. Furthermore, the internal of the rock sample was measured by X-ray CT equipment. It was observed that the fracture was generated horizontally from the dip made by the rolling of disc cutter. If the fracture is connected with the fracture generated from the neighbor dip, the chipping is excepted. If the chipping is occurred by this mechanism, flatfragments of several millimeters thick are excepted to obtain. In this experiment, the same shape fragments were actually obtained.

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Soil has the characteristics of volume change accompanying with plastic deformation, differing from metal. Hence, the equivalent deviatoric stress q at yielding depends on pressure p. The dependency of p on p is referred to as yield curve or yield function. In soil mechanics Cam-clay model and cap model have been frequently used as yield curve. However, it does not seem to have been examined whether the shapes of these yield curves are consistent with the soil behaviour observed experimentally. So far several experiments have been carried out in compressing a parallel piped specimen under plane strain condition for obtaining the information on the onset of shear banding. For predicting yield curve by referring to their results, the following assumptions are set up. Yield curves expand similarlyin shape with plastic de formation and yield function plays as plastic potential. Yield curve prediction needs two kinds of physical values measured in tri-axial compression tests, for example axial stress, volumetric strain and so on. Under a certain condition the yield curves predicted have the similar shapeto that in Cam-clay model. In these procedures modified hardening characteristics were used, and it was found that the characteristics also are very similar to that in Cam-clay model.

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Unsteady open channel flows with viscous fluids caused by instantaneous gate removal, so-called dam break flows, were studied theoretically under the assumption of self-similarity of hydraulic variables. Fundamental flow characteristics such as the propagation velocity of front position of a flow, the attenuation rate of flow depth, etc. were derived by using the depth averaged flow equations, and were compared with the results of numerical simulations. Theoretical results were applied to a flow of high flow concrete, which is classified as Bingham fluids, induced by slump flow test. It was pointed out that in the case of high flow concrete with large plastic viscosity, the similarity laws derived for viscous fluids can be observed clearly in the temporal variations of depth and front position.

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In compression tests of geomaterials, many patterns of localized deformation are observed depending on initial imperfections and boundary conditions. In this paper, especially the developments of such localized deformation are traced numerically using a constitutive model with non-coaxial plasticity and double sliding effect. As a typical result, the final patterns of localization with initial imperfections lose their symmetry and the body shows global softening even though the local constitutive law holds hardening. Furthermore many phenomena like mode-switching are also observed along their loading paths.

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Naturally deposited soils are mostly found in structured and overconsolidated states. To describe mechanical behavior of the soils, the original Cam-clay model was newly placed not on the classicalbut on the “unconventional plasticity” theory by introducing super and subloading yield surfaces. Theformer yield surface lies outside the Roscoe Surface and stands for the structured state, while the latterexists inside the former surface and represents overconsolidated state.
Two evolution laws are newly introduced to the constitutive law. One is to govern the rate of theloss of structure, while the other, the rate of the decay of overconsolidation.The difference betweenthese two rates gives a clear distinction between clay and sand.
Both the loss of structure and the decay of overconsolidation proceed with ongoing plastic sheardeformation in the naturally deposited soils. The former proceeds at a much slower phase than thelatter in natural clays while the former progresses more rapidly in sands.

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Adopting the constitutive relation taken account of the void damage theory, the numerical simulation of material deterioration by a few times of cyclic loads is attempted up to the failure stage when the void volume fraction reaches the critical value. The accumulation of damage and progress of void by the repetitive loading is the major concerning of this study. As a result, it is found that the void damage theory can reasonably analyze the material failure by very-lowcyclefatigue with plastic deformation especially without considering the void declease under compression.

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We first examine the mesh independence of the finite element analysis making use of a damage model with incompatible elements that include a displacement discontinuous surface inside. This method is based on a strong discontinuity analysis with an assumed enhanced strain method. We then examine the independence of the width ofa discontinuous band. Finally, we estimate the method by means of verifying the accuracy of the energy release rate calculated by the J-integral and the E-integral, which are path independent integrals. As a result, we find that, by using the E-integral method, the strong discontinuity analysis is appropriate and high accurate in view of the energy release rate. We also find that the well-known J-integral is not useful to show the accuracy of the strong discontinuity analysis.

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The aim of this study is to clarify experimentally the vibration behavior of rigid body placed on dense sand ground surface in resonant condition. The rigid bodies with variable mass, inertial moment and base size were prepared, and their vibration behavior was observed in a series of forced vibration tests. From the observed behaviors, the resonant and natural frequencies and amplification factors were analyzed. It was found that the natural frequency and amplification factor in resonant condition are dependent on the contact pressure of footing.The stiffness coefficients of springs modeling the interactive mechanical behaviorbetween rigid body and ground were assessed from the analysis of coupled horizontal and rotational vibrations. The influence of base pressure and base size on the spring coefficients is also discussed.

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Deformation behavior of clay specimen modeled as a viscoplastic model with second order strain gradient during shear is numerically analyzed by a soil-water coupled finite element method. In addition, effects of permeability and strain gradient term on growth rate of fluctuation were obtained by the linear instability analysis. It isfound that the strain localization pattern and stress-strain curve greatly depend on the initial inhomogeneity and the permeability.

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Bearing capacity characteristics of a multi-footing system subjected to repeate and combined loads are investigated in this study. As an analogy of a statical shakedown analysis based on Melan's theorem, rigid-plastic shakedown analysis is newly proposed. Theoretical consideration of the proposed method is done, especially in comparison with elasto-plastic statical shakedow nanalysis. As an example, bearing capacity characteristics of a three-footing system is estimated by the proposed method. Reduction of bearing capacity for repeated loads can be estimated numerically. Instead of theoretical ambiguities, it may be useful for concise design procedure.

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A strain-based criterion can possibly serves as a direct and convenient approach for the stability assessment of geo-structures. The purpose of the present study is to experimentally verify the applicability of 2 strain-based failure criteria: 1) critical tensile strain criterion (Fujii, 1994) and 2) critical strain criterion (Sakurai, 1982) to rocks and concrete.Effects of confining pressure, pore pressure, intermediate principal stress, strain rate on the critical tensile strain εTC andcritical strain ε0 have been investigated by triaxial tests and true triaxia tests for 2 kinds of Shirahama sandstone and 4kinds of concretes with different aggregate sizes. The experimental results show that tensile strain εTC and the criticalstrain ε0 are not affected significantly by confining pressure, intermediate principal stress, strain rate and maximum aggregatesize under low confining pressure and intermediate principal stress. However, the critical strain ε₀ become higherthan the maximum strain at failure ε_1f when σ₂>100MPa, which suggests that critical strain criterion (Sakurai, 1982) mayover-estimate load-carrying capacity of structures. In view of this, a new definition of the critical strain has been proposed, which takes the effect of intermediate principal stress into considerations. The proposed definition has a clearerphysical meaning and affected by the intermediate principal stress to a less extent than the original one.

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The object of this study is to investigate the notch and the deformation rate effects on theload-displacement relation experimentally and numerically.Especially the comparatively highpermeable loose sand is adopted.Triaxial tests are carried out with perfect and imperfectspecimens to examine the shear modulus, the peak and the residual strength, and their relationswith the deformation rate and its mode.The finite element analysis of soil-water coupledproblem is also performed to consider the notch effect of geometrical boundary condition inthe frame work of the finite deformation theory.The numerical results are confirmed with theexperimental facts as follows.The notch makes the peak strength reduced and promotes themore wealthy compressibility in the pre-peak deformation process.At the post-peak state, theload reduces depending upon the specimen's shape that is governed by the deformation rate.

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A series of centrifuge model tests were carried out to investigate effectiveness of toe drainage as countermeasureagainst failure of embankment and behavior of slopes reinforced with geotextile due to seepage flow, and to evaluatethe contribution of reinforcement to the stability of these slopes. It was found that the toe drainage contributes for thestability of the slopes and the embankment which reinforced with toe drainage fails suddenly along a well-defined andlarge slip surface. In the case with reinforced with geotextiles, smaller shear deformation in the toe area ofembankment and the smaller settlement at the top of embankment were observed. It indicate that the pull-outresistance of reinforcements make the slope stability increase. Especially, the embankment that installed non-wovenfabrics, which has lager tensile stength, with less reinforcement spacing is highly stable in this study. The factor ofsafety that obtained by means of limit equilibrium could not accurately evaluate the stability of embankments whichinstalled geotextiles. The reason is that in the stability analysis that on the basis of limit equilibrium, the deformation ofembankment that is required to produce the reinforcement force of geotextile was not taken into account

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Semi-rigid connection structure made by I-section steel girder and reinforced concrete column is dealt with in this paper. Nonlinear behavior of the connection and internal stress transfer mechanism are analyzed by experiment and numerical calculation. Good agreement between experimental result and numerical estimation was obtained and the results on the stress distribution from elastic to plastic deformation are shown in the figures. And interaction behavior between steel girder, reinforcement bar, stud and concrete is analyzed in some cases.

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Multi-layer neural network has been regarded as a useful algorithm in identification and dynamic control of structures. As one of the existing researches, the active vibration control for structure-actuator coupled system consisted of a tendon system controlled by a signal hydraulic actuator using multi-layer neural networks has been studied. Active Mass Driver (AMD), as another kind of control device, has been studied on the concept of conventional control methods and control design. In this paper, a coupled system consisting of a four-story frame structure and an AMD driven by a electrohydraulic actuator was investigated. Firstly, considering the dynamics of electrohydraulic actuator, the dynamic equation of a structure-AMD coupled system was formulated. Secondly, an emulator neural network with suitably chosen input variables corresponding to the structure-AMD coupled system was established and trained for the purpose of non-parametric identification. Lastly, a neurocontroller was set up and trained with the aid ofthe trained emulator neural network to control the dynamic response of the structure-AMD coupled system subjected to earthquake loading. Because accelerometers can readily provide reliable and inexpensive measurement of absolute structural acceleration at strategic points on a structure, development of identification method based on acceleration feedback is presented. The effectiveness of the identification and control is evaluated through numerical simulations.

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The combined behaviors of the local and overall buckling deformations of the U-section members subjected to the axial loads are analyzed by the finite element method. In the finite element method, isoparametric degenerated shell element is adopted, and only the geometrical nonlinearity is considered based on the Green Lagrange strain definition. To solve the nonlinear equation, the displacement incremental scheme employed, in which the incremental axial displacements are added to the ends of the members. As the initial imperfections, four types of initial imperfections are introduced, 1) the bulge type of imperfection, 2) the local type of imperfection, 3) the global type of imperfection, and 4) the combined imperfection of local and global ones. For the local type of imperfection, the buckling mode corresponding to the local buckling load obtained by the transfer matrix method is introduced.

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Oscillation damping system using ER fluid (Electro-Rheological Fluid) from which viscosity changes by applying voltage is analyzed by experiment and the hysteretic damping characteristics is analyzed as nonlinear dynamic problem in this paper. Modeling of the synthetic combination of damping material and damping mechanism was dealt with especially, and the approximation formula which express change of the damping characteristics by change of voltage, frequency, etc., was verified by the comparison with an experimental result.

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The behavior of beam-to-column connections is crucial in the design of a steel moment frame, since large resultant forces and stress concentration can take place there.The elastic design based on the analytical study of stress concentration has been the standard method for the connections.However, such a design approach is not practical against large earthquake, and much remains to be researched for establishing the seismic design of connections.In the present study, connections with.several types of haunch are analyzed numerically.The results show that a haunch influences the strength and the ductility of a connection considerably; the way it works depends on the size and the yield strength of the haunch.

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The considerably non-linear deformation behavior of granular materials is controlled by grain properties and microstructure formed. Grain properties are assigned by grain shape and resistant friction angle between grains. Microstructures in granular material are formed as contact paths of grains. In this paper, the deformations of granular media with different grain shapes and friction properties were simulated by DEM in twodimension. On the basis of analysis results and observation of the formation of microstructure under isotropic compression and bi-axial shear, the relationships between macro deformation and the formation process of microstructures were discussed in detail.

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