Seismic response characteristics of two types of base-isolated buildings are investigated by using identification techniques. Equivalent linear system was first assumed in connection with the dynamic behavior of the structural system, then the nonlinear Bouc-Wen's model was also assumed as second stage to model the isolation system and estimate the hysteretic damping of the system. Both “modal minimization method” and “Extended Kalman Filtering techniques” are used for structural identification. The natural frequency of the isolation system of Law and Justice Center Building was designed greater than the natural frequency of the building while the natural frequency of the test building of Tohoku University was designed smaller than the natural frequency of the building. These results are obtained from identification.

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The following expression of the factor of safety against liquefaction is found useful:
F_le=√W_l0/W_e0
where W_l0 is the energy accumulated in the pore-water from the initial state until liquefaction; W_e0 is the work done to the pore-water by the ground motion. F_le can be directly related to the pore-water pressure ratio. From the historical data of liquefaction sites and earthquakes, compiled by Kuribayashi and Tatsuoka, the effect of the ground motion is found to be captured by the quantity X=SA_C, in which S is the slip displacement of the unit mass with critical acceleration of sliding A_C. The procedure for evaluating F_le statistically from the JMA magnitude, epicentral distance, effective compressibility of the pore-water and critical angle of dislocation is presented.

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A new experimental technique to visualize the dynamic behavior of particle assemblage is developed. According to the proposed method, a granular structure model, made of particles of crushed glass and immersed in liquid with the same refractive index, consequently becomes invisible. An intense laser-light “sheet” (LLS) is then passed through it, illuminating the contour lines of all the particles within a cross-section. Scanning the model with LLS allows a 3D image of every discrete particle's shape and motion to be obtained as well as the whole-field deformation of the model.

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In this paper, a dicsrete method for analyzing the geometrical nonlinear problems of rectangular plates is proposed. The solutions of partial differential equations of rectangular plates are obtained in discrete forms by applying the numerical integration, and they give the transverse shear forces, twisting moment, bending moments, rotations, deflection, in-plane displacements and membrane forces at all discrete points. The nonlinear problems are solved by the iteration and the load incremental procedure.
As the applications of the present method, geometrical nonlinear bending and post-buckling problems of rectangular plates with some of boundary conditions are calculated.

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In this paper, cases of rhombic rigid inclusion with two symmetrical debondings, two asymmetrical debondings and one debonding are analyzed as the mixed boundary-value problem of plane elasticity. Stress singular values at the debonded tips are obtained under uniaxial and biaxial loadings for several cases on corner angles of the rhombic inclusion, length of debonding and poisson's ratio. Properties of the debonding propagation are investigated in respect with these factors.

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A computational method is developed to solve coupled problems of incompressible viscous flows and motion of an elastically mounted rigid body. The moving interface between the body and the fluid is described in terms of the arbitrary Lagrangian-Eulerian formulation. The streamline upwind/Petrov-Galerkin method is applied to the ALE Navier-Stokes equations to yield finite element equations. The coupled matrix equations with respect to the fluid and the body are solved by means of a predictor-corrector-type time integration method. The improved stability of the proposed method in comparison with the author's previous one is demonstrated by numerical examples. Computational strategies to reduce the computational time are also presented.

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A numerical method is proposed in order to generate mesh deformation patterns for ALE finite element analysis of fluid-structure interaction problems. Nodal proportional constants to give a mesh deformation pattern are obtained by solving the Laplace equation using the same finite element mesh for the fluid-structure interaction analysis. From this initial set of the proportional constants, distortion is evaluated element by element. The Laplace equation is solved again using the element distortion as the weight for each element. Numerical examples show that the proposed method generates mesh deformation patterns with less element distortion for arbitrary finite element meshes.

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This paper presents the result and consideration of a field vibration test performed on the Hitsuishijima Bridge, a long-span cable-stayed bridge. In the test, large exciters were used to vibrate the bridge to a certain level of amplitude.
The dynamic properties, especially damping characteristics at large amplitudes, in the lower significant modes of this bridge were measured. By the comparison of the measured values with assumed ones at the design of these properties, dynamic design of the bridge was verified. In addition, coupled vibration which was observed between the girder and the cables was also examined by the analysis.

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This paper presents a study on the ultimate strength of plate girders with two longitudinal stiffeners. The static loading tests were carried out with 18 full size scale specimens under pure bending, shear or combined bending and shear loading. We investigated ultimate strength, behavior and failure patterns of web panels experimentally and compared the test results with some strength formulas and other experimental data.

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This paper proposes a design method to estimate the shear lag phenomenon concerning L-and T-shaped corner parts of steel rigid frames with bi-symmetrical box cross-section. Firstly, the fundamental beam model is explained to apply the beam theory to the beam and column members with corner part. Secondly, an approximate method is derived to calculate the additional normal stress due to shear lag through the stress analysis by using this beam model. Finally, an approximate method for ultimate strength of corner parts is proposed by the application of the ultimate strength of box cross section subjected to bending moment and shearing force. The validities of these propositions are confirmed in comparison with the test results.

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This paper describes parameter identification and prediction of consolidation settlement on peaty soft deposits using Extended Kalman filter. Consolidation settlement on peaty soft deposits shows non-stationary behaviour under the periodical loads of under ground water levels. At first, this non-stationary consolidation behaviour is assumed to be a regularly intervaled stationary process
Secondly, this procedure is applied to the parameter identification and prediction of consolidation settlement using observational data.
Finally, numerical analysis of observation data is carried out to show the usefulness of this procedure of parameter identification and prediction of consolidation settlement on peaty soft deposits.

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Seismic observation is carried out from February, 1981 to June, 1985 to evaluate the dynamic behavior of the underground transmission line constructed in soft ground in Noubi plane. Velocity of the ground and strain of the reinforcing bar along the axial direction of the structure are mesured. It is found that the dynamic behavior of the structure which is constructed in horizontally layered ground structure has a selectivity of surface wave including in seismic wave; axial deformation is predominant among the axial and bending deformation and that spring constant is 65% to the value obtained by the existing seismic code.

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