The fundamental bending strength characteristics of channel section beams are studied by a numerical analysis and checked with respect to the effects of loading conditions, type of cross sections and initial imperfections. The slender type of high depth channel to be likely used in plate girder structures and the compact section type for hot-rolled shapes are adopted here. Mainly emphasized are the effects of prevention of twist at the loading point and the warping restraint at beam ends. The reduction of bending strength due to lateral-torsional buckling is significantly improved by the end warping restraint and prevention of twist at the loading point. Finally, it is concluded that the channel section beams can be used as main structural members.

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This paper presents a method for optimal control of flood propagating through a reservior of river channel using the combination of the finite element method and optimal control theory. The numerical model of the flood propagation can be expressed by the linear two dimensional shallow water equation and the equation can be solved by the two step explicit schemes. For the control theory, the method presented by Sakawa and Shindo is effectively used. It is shown that the water elevation can be controlled as flat as possible by adjusting the discharge of the dam gate. This method is also adaptable to the control constraining the control outflow within the limit of inflow into a reservoir.

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A procedure to generate the impedance matrix of foundation resting on an elastic layered half-space medium is proposed. The prescribed harmonic loadings due to the foundation are decomposed into an infinite Fourier series with respect to the azimuth. For each Fourier component, the analytic solution is obtained by solving the differential equations of wave propagation satisfying the prescribed boundary conditions, and the stress and the displacement continuity conditions at the horizontal interfaces in the layered system. Using this analytic solution, the impedance matrix is obtained by applying the variational principle and the reciprocal theorem with the assumption that the interaction stresses between the foundation and the soil is piecewise linear in the radial direction of cylindrical coordinates. An example of a two-layer system is often presented.

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For the purpose of simulating acceleration response as well as displacement of irregularly bounded surface ground with three-dimensional geological structure, the extended quasi-three-dimensional ground model is proposed. The new model presented here treats fundamental through N-th mode of shear vibrations of a surface layer, while the conventional one takes only fundamental shear mode into consideration. The equation of motion for the model is induced and examples of earthquake response analyses using the proposed model are introduced as well as those by finite element procedure and its applicability is verified.

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This paper describes the results of basic experimental studies performed to evaluate embedment effects on the dynamic characteristics of a rigid foundation and correlation analyses between the test results and the calculated results. Field tests of a rectangular concrete block are carried out with the purpose of obtaining the basic data for verification study on analysis codes. In the correlation analyses, the methods used here are the sway-rocking model and the axisymmetric finite element model. Frequency-dependent dynamic stiffness is examined comparing those values obtained from the field tests and the elastic theories. Furthermore, the embedment effects are confirmed through earthquake observation data.

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The objective of this paper is to construct a method of evaluating the dynamic collapse of an SDOF system with the degrading restoring force characteristics under random excitation. Firstly, an extensive parametric study is carried out to investigate the duration up to the dynamic ultimate state of the system and the power, when the system is subjected to the combined harmonic disturbing force. Secondly, through the results, a method of evaluating the dynamic collapse of the system subjected to a random excitation is proposed, in which the random excitation is replaced by a harmonic disturbing force of the resonance frequency. Finally, numerical examples are developed to illustrate the application of the method.

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This paper describes numerical simulation studies on the bent collapse of the Cypress Viaduct during the Loma Prieta Earthquake and on the seismic performance of the same type bent retrofitted. The purpose of the 1st simulation is to identify bent damage due to ground conditions and structural types and that of the 2nd simulation is to estimate seismic performance of the retrofitted bent. Systematized analyses provided following conclusions: 1) Amplified ground motion was appropriately predicted based on the multiple reflection theory, 2) Finite element nonlinear analyses provided good agreement with test results both of pre-retrofitted and retrofitted bents, 3) Nonlinear dynamic response analyses provided quantitative explanation on the relationship between ground conditions, bent types and bent collapses and also ensured sufficient seismic safety of the retrofitted bent.

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A finite element method for the multiple level analysis of tidal current flow considering an open boundary condition is presented in this paper. The incident wave condition which does not cause spurious reflective waves on the open boundary has been proposed and it has been applied to the boundary condition in the multiple level tidal current analysis. To determine the reflective wave component, the subdomain located adjacent to the open boundary is introduced. The reflective wave component on the open boundary can be extracted by computing on the subdomain. The numerical results are compared with the analytical solution and the observed data. Both results show well in agreement.

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To evaluate the wind resistance of suspension bridge, it would be necessary to know the vibrational characteristics, such as natural frequency, mode shape and structural damping, of actual bridge.
Some dynamic field tests using two special vibrators were conducted at the Ohnaruto Bridge, the Ohshima Bridge and the Minami Bisan-Seto Bridge.
At the tests, the vibration of large amplitude was excited, and some interesting vibrational properties as regards natural frequencies and damping values were obtained.
This paper describes the test results and some studies.

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Not by means of mathematical expansions, but on the basis of a physical decomposition of its total freedom into the parameters of position as a rigid and those of deformation, an explicit discretization is developed for the 2-D triangular element with large displacements. While the material is assumed elastic even for finite strains, any geometrically nonlinear effects are taken into account, systematically and rigorously.

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The elastic-plastic bifurcation phenomena are complicated due to the difference of the loading and the unloading characteristics of materials. Hutchinson applied Hill's theory to examine with considerable generality the theoretical aspects of the plastic bifurcation of continuum body and presented a perturbation method to analyze it. Although the method is theoretically exact, its application is restricted to simple problems due to the complicated mathematical operations. Further, the equilibrium paths can be obtained accurately only in the vicinty of the bifurcation points. In view of practical importance, we here present a versatile numerical method to analyze the elastic-plastic bifurcation of multiple discrete systems including the post-bifurcation range.

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This paper investigates the elasto-plastic behaviors of cantilever columns with variable cross-section subjected to horizontally cyclic load under the condition of constant vertical one. The numerical results based on the plastic zone theory show that the different collapse modes may appear in such columns every half cycle. This phenomenon occurs due to the interaction between the accumulated residual deformation of column by cyclic bending and PΔ effects by vertical load. It is also observed that such kind of columns have the transition region of collapse modes

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This paper deals with the ultimate strength of transversely compressed plate with longitudinal stiffeners. Firstly, the influences of initial deflection, residual stress and patterns of stress distribution on the ultimate strength of the stiffened plate are investigated analytically. Then, an approximate method is proposed for predicting the ultimate strength of stiffened plate, through a parametric study by means of the elasto-plastic and finite displacement analyses. Finally, this approximate method is verified in comparisons with numerical and experimental results.

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This paper presents an estimation method for the energy transmission factor of a rock onto the rock-shed in order to perform the safety check for the collapse of a rock-shed from the view point of energy criterion. The energy transmission factor means the ratio between the absorption energy of a rock-shed and the kinematic energy of a rock. At first, the three relationships of rock-sand cushion-rock shed are modelled into the three-degrees of freedom and, the transmission energy onto a rock-shed has been calculated as the time response. Herein, the model parameters of various sand cushion have been determined by the dynamic identification technique and derived as the regressive formulation which may be applied in various situations. Finally, the energy transmission factors of steel and RC rock-sheds have been estimated this method and, the safety check for the steel rock-shed has been performed by the energy criterion.

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Eigenvalues of TMD-structure 2DOF nonproportionally-damped system are obtained using pertubation technique. Explicit formulas for TMD design under various types of loading are proposed on the basis of the approximate eigenvalues and optimization of TMD is discussed. It is shown that the formulas are accurate enough under the practical range of the TMD parameters.

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Lagrange polynomials are widely used as interpolation functions in engineering. But polynomials of high degree exhibit occasionally considerable oscillation, hence calculated values by polynomials are often inaccurate. Indeed, C. Runge proved that equidistant interpolation over |x|≤5 to the function f(x)=1/(1+x²) diverges for |x|>3.63…. In order to improve an accuracy of the approximation, new interpolation functions using finite Fourier series are proposed. Several numerical experiments are performed to check the validity of the proposed method. It is found that the present interpolation functions are more reliable and efficient than Lagrange polynomials.

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A back analysis using extended Kalman Filter-weighted local iteration-finite element method (EK-WLI-FE method) has been developed in geotechnical engineering problems, where the extended Kalman Filter-weighted local iteration procedure which was previously proposed by the present authors is used incorporated with the finite element method in order to identify unknown parameters.
Numerical analysis are carried out to show the usefulness of this method in identification of elastic modulus of soil foundation.

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Geotechnical engineering problems in coastal area are often related to the behavior of the porewater. Typical examples of these problems include consolidation of soft clay and liquefaction of loose sand. In this report the dynamic response analysis for saturated layered media influenced by drainage condition and loading rate is presented. Saturated ground is dealt with as a two-phase material based on the formulation of Biot. A thin layered element for describing the dynamic behavior of a fluid saturated porous layered medium is developed. The dynamic stiffness and wave propagation characteristics of the saturated two-phase grounds are given comparing with those for dry soil by using developed method.

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The ultrasonic spectroscopy is known to be one of promising techniques for non-destructive evaluation of defects in structures. Conventional ultrasonic testings have an essential drawback on the applicability to composite structures, because the technique is basically associated with the arrival time measurement. The spectroscopy deals with information in the frequency domain, instead of the arrival times in the time domain. As a result, spectral responses of composite members possibly identify crack information without stained by the inhomogeneity effect.
In the present paper, the spectral responses of plain concrete and reinforced concrete (RC) members are investigated analytically by the three-dimensional boundary element method (BEM) and are compared with experimental results. To analyze a notched concrete member, a multi-domain BEM procedure is employed. In addition, BEM-FEM coupling procedured is applied to model a RC member with a notch. Spectral responses between 1kHz and 20kHz are determined on plain concrete and RC specimens with artifical cracks of several depths. Analytical results show close correlation with experimental results. It implies that the present method is promising for the evaluation of crack depth in composite materials.

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A method is presented to improve the convergency of solution for identification of soil properties by Successive linear Programming (SLP), using vertical array records of earthquake motion. Identification problem of shear wave velocity and quality factor of each layeris formulated in the frequency domain on the basis of multiple reflection and refraction method. In numerical analysis we showed that the modified SLP, which has been presented here, performed very good. Convergency and accuracy of solution is dramatically improved using both SLP and modified SLP.

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A new type of wire strands were developed for stays on cable-stayed bridges. A precoating strand consists of slightly helically twisted wires with high fatigue sockets. Bending tests and fatigue tests in bending for these socketed cables were presented. Cable secondary bending stress and fatigue lives in bending were obtained.

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Recently in Japan, there has been a marked tendency toward longer spans in cable supported bridges (suspension bridges and cable stayedbridges). However, towers have been designed in accordance with each public corpolation's own code, and common standards for tower design methods have yet been established. Therefore, we conducted an investigation into stability design procedures of towers for long-span bridges in Japan. We could obtain useful results, clarifying the characteristics and practical problems of the standing codes regarding towers. We believe that it will be possible to use these results in order to establish a new design procedure in the future.

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