A new formulation of an inverse problem of identifying a material property distribution is proposed. The formulation is based on the equivalent inclusion method which solves a heterogeneous body problem using a homogeneous body. Two linear inverse problems are obtained, and, due to the linearity, the limitation of identifying the distribution is clearly seen. Two illustrative problems are studied. For the first problem, quantities which can be identified and those which cannot be determined are clarified. For the second problem, the stress distribution is obtained by measuring strain distribution, even though the constitutive relation is not known.

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The purpose of this study is to develop the multiscale analysis method for heterogeneous media with periodically distributed fissures. The formulation of the homogenization based upon the method of two-scale asymptotic expansions provides the variational inequality which governs the microscopic mechanical behaviors while the homogenized structure yields the nonlinear elastic media without fissures. The numerical algorithm to solve the multiscale problem is presented using the mathematical notions and the computer program is developed to solve both the contact problem in a microscale and the nonlinear global behavior in a macroscale. Several numerical examples justify the current formulation and provide insight into various engineering applications.

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Hierarchical finite element method using the two phase dynamic condensation method is proposed for the fee vibration analysis. In the two phase dynamic condensation method, the assembly procedure of the global stiffness and mass matrices is the same as that of stress analysis and the required memory size is comparable to that in the usual static condensation method. Therefore, this method is applicable to large eigenproblems. From the results of numerical calculation, it is found that very accurate solutions are obtained with one hierarchical element in the free vibration analysis of thin and thick plates and the hierarchical element analysis using the two phase dynamic condensation method is very effective for large eigenproblems.

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Numerical flow analyses of a box-type bridge section were performed using two and three-dimensional finite element models. Computed results, such as aerodynamic coefficients, pressure coefficients, and flow patterns around the section, were compared with wind tunnel results using a rigid model. In 2D case, evaluated flow characteristics did not agree with experimental values, except the drag coefficient. The computed flow structure in 3D well represented separated shear layer of the wind tunnel model, consequently the numerical results were in good agreement with the experimental values. It was found that the spanwise flow disturbance in 3D analysis played an important roll in weakening strong vortices generated in 2D case. Thus, the advantage of 3D flow analysis against the box-type bridge section has been confirmed.

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There are two opposite viewpoints on flutter speed of long-span bridges in a turbulent flow. One is that it is destabilized with consideration of build-up time to flutter. The other is that it is stabilized due to the loss of spatial correlation of aeroelastic forces. In addition, both viewpoints were confirmed by wind-tunnel studies. In this research, executing flutter analyses with the loss of aeroelastic-force spatial correlation and comparing the results with a fullmodel wind-tunnel test of the Akashi Kaikyo Bridge performed in smooth and turbulent flows, effects of wind-speed fluctuations in a turbulent flow on flutter speed of long span bridges were investigated. As a result, the analysis showed flutter-speed increase due to the loss of correlation, however the evidence was not observed in the wind-tunnel test.

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The present study deals with the difference of the aeroelastic responses of a square prism with rounded corners. The previous studies showed that the aerodynamic behavior changed at non-dimensional curvature of R/B=0.2 by wind tunnel tests and two dimensional simulations. In this paper, we conduct two and three dimensional flow simulations of the aerodynamic force of a square prism with rounded corners at windward portion to compare with wind tunnel tests. The behavior due to variation of flow condition was also investigated through flow visualization by tufts.

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This paper presents the evaluation of earthquake ground motion severity for the sloshing design of LNG inground storage tanks in the Tokyo Bay areas. A pseudo-velocity response spectrum for the sloshing design (for primary sloshing periods of 8-10 sec.)is proposed from the analysis of sloshing using earthquake ground motion records and artificial earthquake records generated by a semi-empirical method using small earthquakes recorded in the area. Safety level is examined in consideration of the variation of LNG level during the operation of the storage tank based on a reliability analysis. From these analyses, a uniform velocity response spectrum of 180cm/s can be proposed for the above period range as the recommended value for the sloshing design of LNG inground storage tanks in the Tokyo Bay areas.

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When a large earthquake occurs, plastic deformation is developed not only in the reinforced concrete piers but the pile foundation of a bridge. Since the nonlinear behavior of the pier and that of the pile foundation is interacted, it is required to evaluate the lateral load which should be applied to the pile foundation in the push over-analysis, considering the flexural strength of the pier. This paper describes a series of nonlinear analysis and the push-over analysis for a bridge. It is found from the analysis that the push-over analysis provides sufficient accuracy for evaluating the deformation of the piles if the contribution of damping force, in addition to the flexural strength of pier, is considered to evaluate the lateral load, and if the deformation of the surrounding soils is considered.

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Based on Biot's two-phase mixture theory and the paraxial approximation, the absorbing boundary conditions in the time domain for u-w formulations are presented for the dynamic analysis of fluid-saturated porous media. Applying the absorbing boundary conditions to the liquefaction analysis of 2D dipping layer model, the efficiency of the proposed method is evaluated by comparing the response results with the reference solution defined as that of large scale ground model equivalent to infinite ground. Numerical results for the- several parameters regarding the structures of the model ground and input seismic waves show the accuracy and efficiency of the proposed absorbing boundary conditions even for the nonlinear dynamic analysis of infinite fluid-saturated porous media.

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Strong-motion characteristics on soft rocks in the southwestern part of the Tokyo metropolitan area are evaluated and classified into six source regions. Accelerographs obtained at vertical array observation sites are used to identify S-wave and Qs profiles. By using the identified profiles, site amplification characteristics are removed to obtain incident spectra on soft rocks. A spectrum referred to as ‘residual spectrum’, which is obtained by dividing the incident spectrum by idealized source and propagation spectra, is defined. A method using the residual spectrum which includes regional source and propagation characteristics is presented. The method is shown to have a good accuracy to predict strong-motion characteristics on soft rocks in the southwestern part of the metropolitan area.

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This paper presents an analysis on the importance of clarifying the difference of column ductility factor and system ductility factor for two bridges which are supported by flexible elastomeric bearings. Assuming a column-foundation-elastomeric bearing-deck system, the relation of column ductility factor and the system ductility factor is presented. It is found from a series of nonlinear and linear dynamic response analysis that the deck accelerations evaluated by the force reduction factors based on the system ductility factor are closer to the deck accelerations computed by the nonlinear dynamic response analysis while the deck accelerations evaluated by the force reduction factors based on the column ductility factor are extremely underestimated. It is also found that the deck displacements evaluated by the displacement increasing factor based on the column ductility factors are overestimated. It is thus concluded that the system ductility factor should be used to evaluate the force reduction factor for deck accelerations and the displacement increasing factor for deck displacements.

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This paper summarizes results of both an experiment for earthquake-proof U-PVC pipeline subjected to uneven ground settlement and its numerical simulation. Through the ground settlement experiment, in which 50cm uneven ground settlement was acted on buried U-PVC pipelines, pipeline deformation and joint expansion behavior were observed. As a result, it was clarified that axial strain of the pipeline was redused due to sliding of the rubber ring type joints and slip-out preventer of the joint worked well. Furthermore, in the numerical simulation based on beam theory, relationship between transient settlement zone and pipeline response was examined.

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To evaluate the effectiveness of earthquake preparedness education visually, we improved software “Quake Busters” which we had developed before, by introducing S-P curves, Caution Index and Item Relational Structure Analysis (IRS). When users such as elementary and junior high school students answer quizzes which are given by improved “Quake Busters”, the score to these quizzes are stored in the software and S-P curves are made automatically from the score. Furthermore we examined appropriate contents to be learned about earthquake preparedness by using IRS. We could judge improvement in understanding earthquake preparedness by comparering the shapes of S and P cureves and Caution Index before and after the use of Quake Busters.

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This paper deals with the noise reduction by the wavelet transform when the signal contain the noise of the impulsive and Gaussian components.In the case of the impulsive noise component, the algorithm of the noise reduction is the inverse finite impulsive response (IFIR). The estimate time of the IFIR is treated by the wavelet odd (or even) coefficients. On the other hand, the reduction of Gaussian noise component is carried out the treatment of low pass filter for the wavelet Fourier spectra. The effects of this method are investigated by the numerical calculation and are confirmed for the impulsive noise component. In addition, we apply the method for the seismic wave involved the impulsive noise and obtain the good results.

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The purpose of this study is to evaluate seismic performance of steel bridge piers with and without a seismic isolator, and to perform a parametric study for such structures. Concrete-non-filled and filled steel bridge piers are modeled as single degree of freedom systems. Discussed and compared are the calculated response and damage of such structures. On the other hand, concrete-non-filled and filled steel bridge piers with a seismic isolator are modeled as two degree of freedom systems. Similarly the damages of such structures are compared and discussed. Finally, a proposal of seismic design method for steel bridge piers is presented based on the results of the elasto-plastic seismic response analysis.

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This paper has dealt with the computer simulation of the high-speed train induced ground vibration. The track loading is assumed by a set of harmonic moving function of different frequencies in view of a train geometry (axle distances of a car and connection of cars). Besides, sleeper distances and other vibration factors involved are of essence for the periodicity of alongside vibration so that an inverse analysis is introduced to the measured data for the Shinkansen train running. The 2.5 dimensional FEM-BEM method developed by the authors is used for the analysis. Thus simulated ground vibration results in a good prediction for the attenuation of alongside vibration acceleration value (VAL) in case of flat track and an acceptable prediction for embankment track.

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A prestressed concrete bridge with subtended stay cables has many advantages compared with an ordinary prestressed concrete bridge with external cables. But it also has some problems to be solved for practical use. The purpose of this study is to clarify the ultimate strength and behavior of this type of bridge theoretically and experimentally. Developed numerical method is based on FEM with beam-column elements, and is able to consider finite displacements and plasticity of materials. Also, the ultimate strength and behavior of this type of bridge were studied by big scale model tests. Results of the test have been compared with those of numerical analysis.

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In order to establish a rational elasto-plastic impact analysis method on reinforced concrete (RC) beams with statically bending failure mode, an applicability of three-dimensional finite element method (FEM) with a simple constitutive law is discussed. The applicability is confirmed by comparing with the experimental results on thirteen RC beams obtained from a steel weight freely dropping impact test. From this study, it is seen that the dynamic responses of displacement of RC beam, reaction force and impact force occurred in a steel weight can be estimated with good accuracy by using the proposed method.

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A lot of alternate load tests have been performed mainly in the architectural research field in order to examine the bearing capacity and ductility of concrete encased steel column members. However, in the field of civil engineering, the research focusing on the ductility is still few. Then, the alternate load tests under the constant axial compressive force and bending moment were performed by using the test pieces taken into consideration the loading condition and section parameters for railway structures. In this paper, based on the above-mentioned experimental results, a method of quantitatively evaluating the ductility of concrete encased steel column members was developed.

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The approximate algorithm for stochastic interpolation and extrapolation of conditional non-Gaussian fields proposed in this paper produces a nonlinear unbiased estimator with the characteristic minimum variance of errors. The extended Kalman filtering procedure is then used for solving the conditional estimation problem transformed into the Gaussian stochastic field. A lognormal stochastic field is taken up as an example. The accuracy and efficiency of the proposed method is discussed compared with the theoretical solutions of Simple Kriging. It is found that the proposed method does not suffer from the difficulties associated with computing the optimum estimator and estimated error variance.

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Web gap plates, connecting between upper flange of plate girder and its cross beam, were fatigue-cracked due to concrete slab deflection. Semi-circular cut-out in the plate is one of the retrofitting measure, since it decreases the stresses in the upper edge of the plate. Fatigue tests were carried out on the three kind of 3-points bending model specimens of web gap detail with or without the cut-out. Finite element analyses were also carried out on an actual plate girder bridge model with or without the cut-out, and then fatigue life was calculated on the basis of their results.

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Ultrasonic testing could be applied to evaluate field welded butt joints of steel girder bridges. It is, however, a difficult problem to detect planar defects like cracks. Cracks should influence on the fatigue strength of the member of structures. Hot cracks are formed in the first weld path. In case of groove weld, hot cracks are located near the surface. Numerical analyses and experiments were carried out to investigate the detectability of planar defects near the surface. Experiments on a field welded joint specimen were also conducted to investigate detection and sizing of a planar defect.

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This paper deals with an interpretation on stochastic combinatorial optimization algorithm using Markov process and Information theory. Combinatorial optimization problems are essential for seeking a specific set among other alternatives. These problems cannot be solved by standard optimization techniques such as the Newton method. And, these problems are almost always exposed to the danger of falling in local minima. Under these circumstances, techniques which integrate biological evolution process, physical process, and stochastic processing have been developed. These techniques are usually cast into a probabilistic and information framework via such paradigms as conbinatorial optimization, stochastic-based algorithm.

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The authors previously proposed the method to assess the design of steel highway bridges using the deviation of steel weight statistics. Further, they estimated the weight increase when designed using the new live load (B-Load). The present paper collects the data of steel weight for the bridges designed using B-Load and analyzes statistically. As a consequence, the deviation for simple supported plate girder bridges becomes 53.8 which is very close to the predicted deviation 53.1. The weight increase for simple supported box-girder and continuously supported plate girder bridges are small, and the deviations are 51.5 and 50.5, respectively.

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