In this study a 3D nonlinear parallel FEM formulation was derived for dynamic soil structure interaction problems. To express the nonlinear property of the saturated soil the simplified bounding surface model was used referring the Wolf and Crouch's study. In the implementation of the parallel processing algorithm for the 3D nonlinear FEM formulation, Domain Decomposition Method and Conjugate Gradient Method were applied. To see the validity of the proposed parallel analysis a seismic earth pressure test using a shaking table was simulated. The numerical results for the seismic active earth pressures and dynamic pore water pressures acting on the wall coincide well with those of the experiment.

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A seismic risk assessment procedure based on the fragility curve concept is proposed in this paper. First, damage criteria for gravity type quay walls in terms of normalized seaward displacement are proposed considering the restoration cost. Second, a procedure to generate the fragility curve for each damage level using Monte Carlo simulation is proposed. Third, the fragility curves are utilized for the risk assessment of a quay wall under certain conditions based on the result of seismic hazard analysis. Finally, the proposed risk assessment procedure is examined with a case history from the 2000 Tottori-ken seibu earthquake.

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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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A three-dimensional finite element modeling for High Damping Rubber bearings is studied. At first, the constitutive law for High damping rubber is formulated to derive the constitutive tensor. Then, a mixed finite element method is formulated, to which slightly compressible materials with rate form or incremental form of constitutive law are applied. Using the constitutive law and the finite element method developed here, a finite element model of High Damping Rubber Bearings is constructed and it has shown a good agreement with experimental results of the bearing. Finally, the torsional or rotational deformation of the bearing is simulated. In addition, simple and theoretical equations on these deformations are proposed for the design of bearings.

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A simple constitutive equation for saturated loose sand was developed to be able to express the phase change phenomenon between solid and fluid during liquefaction. This is named the fluidal-elasto-plastic constitutive equation, which combines a cyclic elasto-plastic behavior of sand and Newtonian viscous fluid characteristic of liquefied sand by defining a phase controlling function. Using the proposed constitutive equation and the finite element scheme, we conducted an element simulation to investigate basic behavior of the proposed constitutive equation and then applicability of this constitutive equation to practical problems is investigated by comparing the results of a centrifuge experiment with simulated ones.

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A pseudo analytical method for time-dependent system reliability analysis of nonlinear stochastic structural dynamics is investigated. This method is a class of linearization approaches that linearize approximately a nonlinear state vector equation to a discrete Gaussian and Markovian state vector equation, and the optimal state vector and covariances at times k and k+1 are estimated by the Kalman Filter algorithm with a set of numerically obtained response data. In this way, the probability of performance may be evaluated. Finally, a numerical example of a nonlinear structural system is demonstrated in order to examine the efficiency of the method.

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A centrifugal dynamic experiment and relevant numerical analyses have been carried out for assessing the seismic stability of a rockfill dam against strong earthquakes. The central core dam model was 40cm in height and both the upstream and downstream slopes were 1:1.8. A reservoir 32cm deep was coupled with the dam and the valley was alternatively modelled in a U shape or a V shape. The whole model was set at a gravity field 40G and shaken by various waves of the maximum acceleration 40G. Numerical simulations were performed for interpreting the experiment. Such work has resulted in an understanding of the seismic stability of the rockfill dam. The dynamic properties of the dam materials in large strain status have been quantitatively evaluated. The behaviors of excessive pore water pressure in rock zone have been examined. The damage process and the failure mode have been understood primarily.

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A series of compressive loading tests was conducted to clarify the effect of spacing of ties and cross ties on the lateral confinement of concrete. It is found that the peak stress and the strain at the peak stress of confined concrete decrease and the slope of the falling branch increases as the tie spacing increases. This is because the increase of tie spacing results in a decrease of confinement stress of concrete between ties. An empirical formulation for the peak stress, the strain at the peak stress and the slope of the falling branch was developed taking account of the tie spacing.

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With urbanization, the amount of electric-power consumption and its ratio to the total energy consumption have increased. Due to this increase, a possible power outage will have a severe impact to the affected urban area. In this study, we propose a quantitative evaluation method of the power outage effects. Power outage is defined as “a situation, in which people cannot do their usual activities” and a power outage effect index is evaluated as a total value of disturbance of various human activities. Proposed method is applied to Tokyo Metropolis and power load characteristics are analyzed. Prepared are maps of the power outage effects for each substation area.

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In order to establish the design method of the shear connectors, which is taken into account not only the longitudinal shear force but also the pull-out force due to the transverse bending moment of the slab, the loading test using full-scale models was carried out. The headed stud was selected as the shear connector, which has been generally used by reason of excellent executivity and the independent of the direction of the longitudinal shear force. In this paper, through the experimental study, we proposed the rational arrangements of the headed studs on the upper flange near the vertical stiffener of the steel girder in composite two-I-girder bridges.

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Using aerial television images taken after the 1995 Hyogoken-Nanbu earthquake, automated detection of building damage based on the maximum likelihood classifier was attempted. Each class for the classification was defined by four attributes of either including color information or only edge texture. In both cases, the estimated results were in good agreement with the actual distribution of severely damaged buildings and the results of previous studies based on the multi-level slice method. In particular, the method based on edge information can be applied not only to adjacent images but also to other images taken after other recent earthquakes without selecting training data. Finally, application of the automated damage detection methods to early damage assessment was discussed.

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In the field welding division for I-section girders, the web plate generally possesses semi-circular notches called as cope holes in order to avoid intersection of weld lines. The cope holes induce out-of-plate bending stresses caused by shear force in addition to membrane stresses by bending moment in I-section girders. Therefore, a local stress concentration occurs in the vicinity of a cope hole. This study aims at investigating fatigue strength of cope hole details in the mixed joint that were made both welded flanges and high strength bolted web. For this purpose, fatigue tests were carried out of on the large-scale girder specimens with cope holes in the mixed joints.

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This paper describes the load carrying capacity of the suspension bridge by considering the initial imperfection of the towers under various combinations of the safety factor of the main cable, hanger and tower. Rational combination of safety factors has to be established by considering both of the initial yielding state of each component and the ultimate state of the bridge. From results of this study, it is presented that the effect of initial imperfection is small, and we propose the combination values of γ_T=1.5, γ_H=2.2, and γ_C=1.8 as the rational safety factor.

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