The mechanical behavior of a particle assembly is described based on Cundall's Distinct Element Method (DEM) which uses an explicit numerical scheme. The DEM is a numerical technique specifically designed to solve problems where continuity cannot be ensured throughout the analysis. We used this method to study the flow mechanism of dry rock avalanches which frequently take place following strong earthquakes. On the basis of the results obtained from a numerical simulation, we conclude 1) that the largest pieces of rock float up to the surface of the flow and 2) that they become concentrated at the front of the flow.

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This paper proposes a simple and effective method for determining the vibration characteristics of cylindrical shells with either internal or external fluids. The fluid region is treated analytically, and the collocation method is used to solve the integrodifferential equations which govern the motion of the shell. The reliability and accuracy of the proposed method is illustrated through several numerical examples. Furthermore, a numerical study of the frequency characteristics of the shells is carried out. Finally, a simple equation which accurately predicts the fundamental natural periods of a wide range of shells in the swaying mode is presented.

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A steel sheet pile in marine environments may have been damaged greatly by corrosion. Reinforced concrete covering is an effective repair technique for such damaged steel sheet piles. The repaired part of the sheet piles can be designed as a composite structure with reinforced concrete and the steel. Its design method and structural details have to be made clear. Loading tests on eight test specimens have been undertaken to investigate their mechanical properties and to verify the design formulae. Through the loading tests, ultimate strength, crack development, and so on depended on the arrangement of shear connectors and concrete cover length.

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This paper describes an expert system for selecting the types of superstructures and substructures of river-crossing bridges, and deals with the knowledge of expert designers and rules of Japanese codes as the knowledge base. This expert system can automatically determine span arrangements satisfying the River-Crossing Structure Law, and uses the fuzzy set theory for pile type selection to express the ambiguous knowledge of expert designers. Moreover, in this system, the online data communication system between workstation and host computer is utilized for more accurate evaluation of substructure construction costs.

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The mechanical properties of large sockets in which cable terminals are secured with zinc-copper alloy were studied and a design method for this type of socket was proposed. When sockets for large cables are designed by applying the conventional design method, one inevitable consequence is insufficient wall thickness, which leads to large deformations of the socket itself under the cable breaking load. Since the mechanical properties of a large socket are different from those of small one, the conventional design method is inapplicable to such a socket. The new design method studied in this work introduces the concept of rigidity for ultimate strength into large socket design.

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This paper deals with the development of sensitivities of structural parameter estimates with respect to model errors and measurement noises.
Structural identification algorithm is normally developed based on the concept of least square method. Then the determination of parameters is treated as an optimization problem and the parameter estimates are an optimum solution of the problem. Hence the sensitivities of the parameters with respect to errors and noises can be formulated in the manner similar to sensitivities of optimum solutions.
Numerical examples are presented to demonstrate an effectiveness of the method proposed.

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The advanced periodic Galerkin method for the shallow water equation is presented using the exponential function for the constituents decomposition including the conjugate complex function. The steady flow which is caused due to the existance of periodic flow can be solved by the present method. To verify the effectiveness of the present method, the numerical calculation in one-dimensional problem of which the analytical solution is known is performed. The numerical results are well in agreement with the analytical solution. The residual flow analyses both in the model basin and in Tokyo Bay are carried out. The numerical solutions are well in agreement with the experimental data and measurements. Accordingly, the present method is shown to be adaptable for the analysis of the combined problem between the steady and harmonic flows.

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In order to examine the fatigue strengths of welded bridge details subjected to traffic loading, four large-scale welded girders were tested with various gusset details, transverse stiffener and cover-plates. The results were compared with the fatigue strengths of joint specimens and the allowable stresses in some specifications. Furthermore, the applicability of drilling holes as a retrofitting technique was investigated.

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The Uyashinai bridge is located on the Uyashinai forest road in Akita Regional Forest Office. This bridge is a glued-laminated grillage girder bridge with timber deck panels and steel diaphragms. The present paper is concerned with the development of an analytical model and studying the field hehavior of the bridge. A method of incorporating the rigidity of the diaphragms in the analysis is presented. Full-scale tests of the Uyashinai forest road bridge are studied experimentally and are compared with the numerical solutions. Through the comparison with field test results, the accuracy and the efficiency of the proposed method is verified.

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Method of Lee and Trifunac (1985; 1987) for the synthetic generation of translational, torsional and rocking accelerograms has been generalized to enable computation of strains at ground surface during passage of strong earthquake ground waves. Variations of strain with time resemble ground velocity components in corresponding directions. The Fourier spectrum amplitudes of strain are proportional to the spectrum amplitudes of the corresponding velocity components divided by the representative phase velocities.

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A practical method for the stochastic analysis of the effect of spatial randomness of earth dams on the seismic stability is proposed, where attention is paid particularly to the shear strain in the horizontal cross-section due to relative displacement of the dam along its longitudinal axis. The method takes into consideration both spatial variabilities in the dam material and geometry and randomness of the earthquake motion. The proposed method is used to determine the depth-wise distribution of shear stress in the horizontal cross-section of the dam as well as that in the transverse cross-section. Such a distribution of a shear stress is in turn used to examine their effect on the seismic stability of the dam.

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A simplified 3-D finite element method is newly proposed in order to simulate seismic wave propagation in a vast sedimentary basin Eigenvalue analyses for 2-D and 3-D ground models with Poisson's ratio 0.25 or 0.40 are carried out to check validity of the method. The 2-D analyses demonstrate that Love wave modes can be accurately calculated in both cases. Rayleigh wave modes can also be calculated satisfactorily except for those with shorter wavelength and Poisson's ratio 0.40. In 3-D eigenvalue analyses by the present method, computational time is reduced to 1/170 of the similar analyses by a conventional method.

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A new regression model of strong-motion spectra is derived by incorporating the conception of the dummy variables to the conventional regression model. The dummy variables are available not only to obtain the amplification factors due to local soil conditions of each observation site but also to estimate the non-linear dependences of spectral amplitude on earthquake magnitude and hypocentral distance. The new regression model is applied to 228 strong-motion spectra obtained in Japan. The regression results are used to estimate the source spectra, as well as being discussed in detail, in particular, from the view points of faulting and wave propagation mechanisms. It is finally coneluded that the specific barrier model is more connected with the present statistical source spectra than the stochastic ω-square model.

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Construction of shield tunnels (segmented tunnel) is growing in recent years for traffic, water supply, sewerage and common utility ducts in urban area. Because they are extremely important as lifeline facilities, development of seismic design method suitable for shield tunnels is quite important. Stiffness of the tunnel exhibits highly nonlinear behavior, i. e., stiffness of the tunnel in tension depends on the stiffness of the ringjoint, while the stiffness of the tunnel in compression depends on the stiffness of the concrete segment. Furthermore, interaction between the segment and concrete lining generally placed inside the tunnel make the behavior of the tunnel extremely sophisticated. Therefore, to study the deformation and failure pattern of shield tunnels, axial loading tests under alternative tension and compression were conducted. This paper presents a result of the loading test on the deformation and failure pattern of the shield tunnels subjected to alternative axial loading.

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Large elasto-plastic deformation around a blunting crack tip is analyzed with help of the theory of physically based crystal plasticity. A boundary value problem is formulated by use of boundary layer analysis under the condition of small scale yielding. The results are compared with those predicted by the usual macroscopic (J2) plasticity. It is shown that deformation tends to localize when crystal plasticity is used. The effects of microstructures on the ductile crack growth are also discussed.

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This paper presents a method to determine both every value of various partial safety factors and the range of a variety of concrete structures designed by applying these values, in order to establish a design code based on the Partial Safety Factor Design, taking account of both safety and economy. The method consists of two parts. The first part shows how to define partial safety factors satisfying safety on the condition that the values of the same partial safety factor for the same design variable don't have much disparity in different designs. Another part shows how to estimate a waste of economy caused by applying the same set of values of various partial safety factors to the designs of different concrete structures. In this estimation, we use “Fuzzy Set”.

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Thin-walled hollow steel columns with box or circular sections have been popularly used hitherto. In recent years, polygonal section columns have been increasingly used for point of aesthetic reasons, especially in cities or in the suburbs of cities. However, few studies have been reported on the stability of steel polygonal section columns.
The purpose of this paper is to experimentally investigate local buckling strength of cold-formed steel polygonal section columns with rectangular, pentagonal, hexagonal, heptagonal and octagonal sections. Based on the tests, an empirical design formula is presented to predict the local buckling strength of steel polygonal section columns.

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In the present paper, the analytical treatments of dynamic behavior of beams with moving loads are shown by using of transfer matrix method to determine the natural frequencies and mode shapes of the beams and application of the mode superposition technique.
We adopt the analytical theories such as Classical, Timoshenko's and Levinson's theories for the computations of dynamic behavior of simple and multispan beams, in which the latter two theories take into consideration of the shear deformation and rotatory inertia of the beams.
The accuracy, dynamic responses and dynamic magnification factors of multispan beams are illustrated through several numerical results by using of the three theories.

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In this paper, the equations of motion in linear viscoelasticity of Voigt type are directly solved with the boundary-initial conditions, instead of employing the displacement potential theory and the integral transform technique for reducing the time variable. The problem treated is the transient wave propagation in an infinite viscoelastic layer overlaying on a viscoelastic half-space, which is excited by concentrated normal loads at the surface and inside. The solution is obtained by the use of Hankel transform and separation of variables for eigenfunction expansion based on the elastic frequency equations. The displacements and stresses generated by the sudden application of concentrated normal loads are computed. Numerical results show the wave propagation including reflection, refraction and transmission of wave front at the interface as a Love wave

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This paper presents some considerations on longitudinal motion of girder of cablestayed bridges with longitudinally elastic or free support conditions. The structural design factors that affect natural frequency corresponding to the longitudinal motion are investigated through a simulation analysis, using two cable-stayed bridge models with longitudinally different cable arrangements.
From the results of a simulation analysis, a simplified method of estimating this natural frequency can be proposed. Numerical examples are also worked out to demonstrate the efficiency of the proposed method.

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A bridge restrainer plate resists seismic loads to prevent the fallout of girders from piers or abutments. The ultimate strength and mechanical properties of a plate are studied by suitable elasto-plastic analysis. Emphasis is marked on the shape and the frictional resistance acting between a pin and a plate. Numerical results show excellent coincidence with the experimental studies reported before. Parametric study reveals that shape and frictions exerts direct influence on the failure mode of a plate, and, in turn, the ultimate strength and ductility. These results help the establishment of the more rational design of a plate based on ultimate strength and ductility.

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This paper presents results of theoretical analyses on in situ vibration test results of large-scale rigid foundations on bedrock, and estimation method of interaction characteristics of foundation on bedrock, where attention is paid to the layered structure of the bedrock. Stiffness and damping of the foundation estimated from theoretical analysis using ground material properties based on elastic wave detection proves to compare well with experimental ones. Using the results of parameter survey with two layered ground model, damping characteristics of the foundation on layered bedrock is shown to be estimated by simple two-layered ground model.

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In assessing the seismic stability of slopes and breakwaters, the evaluation of the seismic force to them is one of the most important factors. The object of this research is to establish evaluation method of seismic coefficient that is used in the estimate of seismic stability of slopes and breakwaters. Numerical analysis is conducted by computing the displacement of a sliding mass in the slope using a simple model of a rigid block on a slope. And the general relationship between the displacement of the sliding mass and input earthquake motion is obtained using several models of slopes and breakwaters with different cohesive resistance. In this report, the evaluation method of the effective value of earthquake motion is proposed in which the slip displacement of sliding mass is taken as an index.

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This paper presents a practical evaluation method with respect to the stress of underground structures laid through two different ground rigidity during earthquake.
In this method, considering the effect of each ground of surface layer under the elastic wave theory, the ground displacement in the horizontal direction is obtained. Displacement, axial force and bending moment of the structure are analyzed by applying the seismic deformation method.
Additionally, we discuss herein the earthquake behavior in the homogeneous or inhomogeneous ground and the relation between the apparent propagation velocity of the input earthquake motion and the strain of the surface layer where two different soils are existing.

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In this paper, we, first, obtained resistance and spring constants acting on buried pipelines when subjected to ground settlement due to liquefaction by an experiment of lifting up pipes in liquefied ground. Second, we investigated the suitability of the spring constants by comparison of the result by a different experiment using a dual sinking soil box with results of non-linear analyses using transfer matrix method. Furthermore, we proposed design formulae and equivalent spring constants of the liquefied ground. The formulae were obtained by beam theory on an elastic foundation and the equivalent spring constants were determined such that calculated values of pipe responses by the proposed formulae are well matched with the result of non-linear analyses.

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This report deals with the seismic design of the Higashi-Kobe Bridge, which is a long-span cable-stayed bridge. In this bridge, the main girders are supported by all towers and piers in such a way that the girders are all movable (herein referred to as “all free”) in longitudinal direction. This supporting method was adopted with an aim to lengthen the fundamental bridge period to a reasonable long period. By using this supporting method, the effects of the inertial force of the superstructure on the bridge towers and the caisson foundations were greatly reduced, thereby resulting in a more rational and economical bridge design.

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This study aims to construct a practical forecasting model for the seismic damage restoration of city water supply functions by using experts' empirical knowledge as well as the functional data of the characteristics of water supply networks. The model itself is so simple and tedious computational time for the complicated network interlinkage analysis can be avoided. This forecasting model has been designed for the practical use that it can not only present a solid output of information reguired for planning for seismic damage prevention but also be a useful training device for personnel engaged in water supply operations.

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A strong motion database is developed for a dense seismometer array in Chiba Experiment Station. The array system consists of a three-dimensional arrangement of borehole accelerometers and a complementary observation system for pipe and ground strains. The array system has been operating successfully and more than 160 events have been recorded since 1982. In order to utilize these valuable data effectively, the database including 27 major events has recently created. Because of the dense arrangement of seismometers, the recorded motions may be especially useful when evaluating the spatial correlation characteristics of seismic waves as well as examining soil amplification theory. Using a typical event in the database, the spatial variation of ground motion is demonstrated.

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A displacement type seismograph of the Japan Meteorological Agency (JMA), a velocity type seismograph developed by Muramatsu and a piezoelectric accelerometer were installed on the ground floor of the observation building at Chiba Experiment Station of Institute of Industrial Science, University of Tokyo, to obtain a better and more comprehensive understanding of the earthquake ground motions recorded by different kinds of seismographs. Simultaneous observation using these three kinds of seismographs has been conducted since December, 1985 and a total of 47 earthquake events have been successfully recorded. Using these earthquake records, the performance of the JMA displacement type seismometer and piezoelectric accelerometer was examined with the aid of the coherence function, transfer function and phase lag between the records.

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A FE-BE method in time domain adaptable to dynamic interaction analysis of a dam-foundation-reservoir system is developed. In order to formulate the method, FEM is applied to the dam and the part of reservoir near the dam, and BEM is applied to the foundation and the part of reservoir away from the dam. The role of BEM is to satisfy the radiation conditions of waves which include elastic waves traveling from the dam to the foundation and fluid pressure waves generated at the interface of dam and reservoir. Basic equations in time domain of each region; that is dam, foundation and reservoir, is coupled by a method of weighted residuals, and an algorithm similar to the Newmark's beta method is obtained.
An advantage of this algorithm is the capability of taking into account all the effects of dam-foundation interaction, dam-reservoir interaction, and reservoir-foundation interaction.

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Dynamic responses of highway bridges induced by moving vehicles are taken into consideration of impact in design of bridges, namely multiplying live loads by impact coefficient which is a function of span length or loading length of live load. Relationship between live load and impact coefficient is not independent of traffic condition, because traffic speed varies with traffic volume and traffic congestion often occurs due to traffic accidents and traffic signal.
In this paper, static and dynamic responses of highway bridges corresponding various traffic modes are calculated by Monte Carlo simulation and it is clarified that the maximum response is given by traffic congestion mode in case of a bridge with a longer span, therefore, the effects of impact are ignored in such case.

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The intermediate supports in side spans are expected to increase the total rigidity of cable-stayed bridges. Therefore, it is significant to examine the effects of intermediate supports on the dynamic behavior of this type of bridges.
In this paper, natural frequencies of cable-stayed bridges with and without intermediate supports are compared with respect to nondimensionalized parameters, in order to get the simplified method of estimating natural frequencies of the three-span continuous type cable-stayed bridges having intermediate supports in side spans. The validity of this method is also confirmed by comparing the results by means of the eigenvalue calculation.

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