Presented herein is a transient response analysis of a VLFS (Very Large Floating Structure) due to impulsive landing of an airplane by Finite Element Method. The wave absorption filter which consists of sponge layer and Sommerfeld boundary is applied to open boundaries with irregular waves, and has been found to be efficient. The dynamic deflectional configuration caused by the landing of an airplane appears to be axisymmetric with respect to the point of landing for a few seconds after the landing; however, after that, the response becomes non axisymmetric depending on the shape of the floating body.

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A finite element formulation for the large displacement analysis of three-dimensional solid beams is proposed. It is based on the degeneration approach: the governing equations for a general solid are directly discretized. The assumptions of the Timoshenko beam theory are implemented in the discretization process by devising a 9-node beam element and utilizing the penalty method. The shear stiffness is adjusted by introducing two shear correction factors into the constitutive equations. The formulation is quite simple and straightforward, mainly because rotations are excluded from nodal variables. Several example problems are solved to demonstrate the validity of the present formulation.

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Flutter and buffeting of the Akashi-Kaikyo Bridge were analyzed using a newly developed analytical tool, which is able to consider fully aeroelastic and aerodynamic coupling effects among modes. The analysis well demonstrated the behavior of a wind-tunnel model and particularly could capture the mode-coupling effects. Six primary modes dominated the flutter of the Akashi-Kaikyo Bridge where significant mode couplings of the 1^st torsional mode with three vertical modes were observed. The multi-mode analysis also provided insights into the coupling mechanism in buffeting in which strong aeroelastic and aerodynamic interactions between vertical and torsional modes were observed.

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In order to evaluate accurately fatigue life of weldments under variable amplitude loading, load interaction effect due to load sequence has to be clarified. A simple case is the fatigue crack growth retardation effect resulting from single or periodic overloads. In the present study, fatigue crack growth rates were measured under single and periodic overload conditions on center-cracked tension specimens of structural steel SS400, SM520B and HT780. Effects of several parameters including overload ratio, stress ratio, yield strength of material and interval between overloads on fatigue crack growth retardation were investigated.

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The purpose of this study is aimed at improvement of system reliability for the Neuro-Fuzzy Bridge Rating Expert System, by investigating representative problems related to knowledge-base refinement. In this paper, the previous empirical knowledge (teaching data) acquisition method is reviewed, and a reliable method which can extract the intrinsic fuzziness from questionnaire survey results, is proposed. And, in order to represent experts' inference flow for user, a user information system is newly developed, and installs into the expert system. Furthermore, by applying the improved expert system to an actual in-service bridge rating, it is verified that the proposed teaching data acquisition method and the user information system are effective.

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Considering the improvement of steel properties, it will become important to use new detail where stresses are applied in steel thickness direction for rationalization of steel bridge structures. In this study, considering the welded anchor detail of hanger cable of suspension bridge, which connect pin-plate to deck-plate of steel orthotropic deck, thickness direction properties of steels are studied from some points of view, such as static strength, fracture toughness and fatigue strength. In addition, effects of chemical composition of steel, especially of sulfur, are discussed. As a result, using SS400 for deck-plate has very low strength and has much possibilities to characteristic fracture mechanism which is very similar to lamellar-tearing. On the other hand, using SM400A-S which control amount of sulfur has good behavior.

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Tuning method of plural TMD with equal dynamic characteristics, which are attached to several arbitrary points, is presented and a numerically determining method of optimal attaching positions of each TMD and optimal allotment of total mass to each TMD, under which maximum response of 1st mode is kept within the limit amplitude and sum of the absolute value of each maximum response in resonance of 2nd and 3rd modes is minimized, is proposed using the optimal design method (Feasible directions method). Usefulness of the optimal tuning procedure of plural TMD is demonstrated from numerical applications for suppression of 1st, 2nd and 3rd vibration modes of simply supported beam and cantilevered beam and optimal number, attaching position and allotment of total mass of plural TMD for both beams are revealed.

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In order to evaluate deterioration degree of steel bridge painting quantitatively, image processing technology is applied to this research instead of visual observation method. Especially, “Grayscale Morphology Processing”, which can extract deterioration area precisely from various types of pictures, was chosen among a lot kinds of image processing methods. The result of extraction test with some 13620 of actual bridge pictures indicated that deterioration degree of painting can be calculated quantitatively by using image processing technology, and the possibility of measuring accurate estimation of the time for repainting is also indicated.

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Emergency control of spatially wide-spread facilities is an important measure to prevent damage spread in earthquake disaster. This study presents a probabilistic method to realize optimum subdivision of an extended system using control devices which are potentially used in emergency so that the immediate function of the system is most reliable in an earthquake emergency. Firstly, for a linear structure with random occurrence of damage, the expected length without functional interruption has been derived in continuous and discretized form. The DP (Dynamic Programming) algorithm is then employed to find optimum allocation of arbitrary number of control devices. Some illustrative examples have been demonstrated.

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The equivalent vibration system of liquid in TLD will be of great use in the analysis of coupled vibration of TLD-structure system. While the cases of the equivalent vibration system of linear vibration have been studied widely, scarcely have those of nonlinear vibration been researched until now. In this paper, the equivalent vibration system representing vibration phenomenon approximately is proposed when liquid in a rectangular TLD is oscillated forcefully in horizontal direction nonlinearly and, by using the result, it is shown that the calculated vibration characteristics of liquid in TLD and TLD-structure system agree considerably with the results obtained from the experiment and the calculation by means of FEM.

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Tests of stiffened steel cylindrical shells subjected to cyclic lateral load have been performed to study the effects of longitudinal stiffeners on the ultimate strength and ductility of the shells. The buckling pattern observed in this study was the elephant foot bulge. In the present test, a crack was observed along the welded portion of the longitudinal stiffeners. The direction of this crack is different from that observed in the Hanshin-Awaji earthquake. A new parameter is proposed to predict the ultimate strength of cylindrical shells with varying thickness. Using the new parameter the accuracy of the prediction method was confirmed through existing experimental and numerical results. It is shown that good correlation is obtained between the ductility and the nondimensional load of cylindrical shells.

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A modification of the engineering beam theory for static problems of thin-walled box girders is presented that accounts for cross-sectional distortion and the shear lag effect. The shear lag effect is considerd using the Timoshenko beam theory, which can be regarded as an equation of any order. A cantilever constructed of a 4-cell box girder is examined as a numerical example. The results obatined using the proposed theory are compared with known results from elasticity theory and are found to be in good agreement.

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An identical formulation by using distinctive finite elements with displacement discontinuities across internal surfaces for modeling of cracks in composite material systems and other discontinuous problems in composite structures such as reinforced concrete structures is developed in this paper. First, the governing finite elements equation is derived in a condensed form without increasing any extra degrees of freedom based on an extended principle of virtual work. It can be used easily to incorporate the elements into a general purpose displacement based finite element code, because it does not disturb the basic form of standard nonlinear finite element method. Consequently, a discontinuous interpolation function is designed for numerical analysis. Some examples such as crack propagation and bond-slip interfaces between steel and concrete are tested to demonstrate the effectiveness and versatility of the proposed computational model.

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This paper presents a three-dimensional numerical analysis for wave response of large floating structures using finite element method. Up to now, wave response analyses using finite element method had not been studied because this method required a large computer memory and had to deal with the infinite boundary condition. At the present time, progress in computer is remarkable, so it is possible to perform such an analysis by finite element method using the infinite element. The aim of this study is to develop a method for wave response analysis of large floating structures by finite element method. The model stricture has a length of 1000m, a width of 500m, and a height of 4m. Finally, Effects of important parameters such as the direction of incident waves, the incident wave length and plate rigidity on the response of the structure are discussed.

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In this paper, a 3D elasto-plastic large displacement analysis of long-span cable-stayed bridges is proposed. In the analysis, cable tensions are determined based on the condition that the bending moment in girder is nearly zero, and the condition for closure of the girder is taken into account. Elasto-plastic behavior of 3D beams are compared with those obtained by other researchers in order to confirm the validity of the proposed method. Using a 1400-meter cable-stayed bridge model, the ultimate strength analysis of the bridge under distributed loading is carried out. It is found that the collapse of the model is due to the rapid increase of the horizontal compressive displacement of the girder and that of the vertical displacement at a point in the girder, where the large axial force is produced. It is also shown, for identifying the ultimate strength, that geometrical nonlinear effect should be taken into account, while it is small until the applied load reaches the collapsed load.

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In this paper, the shear transfer capacities of embossed steel plates as “Steel products for composite construction” has been examined through the experiments of 84 specimens under a direct pull-off shear loading with constant confinement stresses. Ordinary plane plates, checkered and ribbed plates with various heights, spacings and numbers of embossments were used in the specimens. Some of them also had a headed stud connector. The empirical equations to estimate the shear transfer capacities of those plates have been proposed. A simple accumulative shear strength of embossments and stud connectors and a simplified numerical modeling of the ribbed plates are also discussed.

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This paper introduces an idea of controlling a shaking table so that soil-structure interaction effect is incorporated. In order for the interaction effect to be reflected in a shaking table test, the signal equivalent to the soil-structure interaction motion is added to the input base motion. It is shown herein that a variety of flexibility functions of bases or soil mediums overlaid with structures are closely approximated by rational functions of imaginary circular frequency, s, . These rational functions are easily simulated by means of analog circuits. To all intents and purposes, an analog circuit loses no time in responding to its input signal. This method thus has the potential to be applied to a variety of experiments of soil-structure interaction without preparing any physical soil model.

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Stability investigation of dynamic response analysis of nonlinear bending oscillation with softening of M-Φ curve, is dealt with in this paper.
One method which can stabilize the nonlinear response analysis under softening is proposed taking the balance between kinetic and internal histeretic energy into account. Numerical results of energy response and phase plane at the top of the column are compared with that of linearlized M-Φ curve method. And the comparison of dynamic nonlinear response between numerical simulation and experimental result is also shown.

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In this paper we applied new methodology, which can reduce the influence of numerical viscosity due to the higher-order upwind scheme in large eddy simulation (LES), to the flow around a square cylinder. Here we focus on two parameters, the filter width of LES and the coefficient of numerical diffusion terms of the third order upwind scheme, and their effects on computed turbulent flows and aerodynamics were studied in comparison with experimental data. It is shown that two appropriate parameters can improve computational results such as the reducing of overestimated drag coefficient. The accuracy of simulating the development of the shear layer of the sides has strong correlation with the improvment of the drag coefficient.

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Control of unstable vibration of tethered satellite at retrieval phase is studied both analytically and experimentally. First, optimal control method to stabilize the response by adjustment of tether lenghth is proposed Nonlinear equation of motion at retrieval phase is linearized and optimal control theory is applied to construct control law. Then, the validity of the control method is verified by aground experiment which is conducted on a inclined rotating table to simulate the Coriolis' effect and gravitational gradiant. The experiment is shown to well approximate the on-orbit dynamics, and proposed control law is proven to be effective in controlling the unstable vibration.

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Failure of solar panel array of SFU (Space Flyer Unit) during retrieval due to folding of some of the panel is investigated. Its retrieval behavior is studied experimentally in microgravity environment created by a dropshaft type facility, and then, analyzed by searching the minima of potential energy of the system. The flexural rigidity of the membrane, which is usually small and neglected, is found to strongly influence the deformation of the membrane in the microgravity environment. The failure is shown to be a kind of snapthrough phenomena, where structural deformation during deployment and retrieval follows different paths. Based on these findings, several countermeasures to prevent this type of failure are also proposed.

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Many localized deformations are observed in the ultimate state of structural and geotechnical materials. Since it is important to predict how such localized deformations are initiated and developed, we propose a constitutive model which is represented by small number of parameters and yields no difficulty in numerical calculations. The model includes a micro-slip mechanism as the second inelastic part of deformation after the condition of localization of deformation by Hill is satisfied. The micro-slips are formulated by the double-slip theory. Numerical check with standard tensile tests shows stable numerical calculation up to very large deformation state. Compression tests and indentation problems are solved to show eligibility of the present model.

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The hyperspace division method proposed by Katsuki and Frangopol is modified to get a more accurate solution with less computational effort. First, the advanced centerline generation method using synchronized polar coordinates parameter combination method is proposed to divide more precisely the standard normal random variable space into the radial subdomains. Secondly, two step hyperspace division method is proposed to compute the failure probability more efficiently in multiple random variable space by adopting an importance sampling methodology. Thirdly, the proposed method is applied to the plastic reliability analysis of truss structures. The accuracy and efficiency of the proposed methods is verified by comparing with the Monte Carlo simulation and/or the directional simulation results of some mathematical numerical examples, i. e., linear and nonlinear element or system reliability problems. Finally, the plastic reliability analysis of the three bar truss and the check dam structure are shown as application of the proposed method.

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Shaking table tests and the three dimensional distinct element analyses were carried out to investigate the rotation response of tomb stones, which are excited by seismic motion. It is clarified that rotation response of a rigid body is caused by two reasons, one is the rocking caused by one directional input motion and the other is caused by the rotation of particle motion of input motion. The rotation response of a real tomb stone was simulated using the accerelation record observed during 1994 Sanriku-Haruka-Oki Earthquake. It is concluded that, except for special cases, the direction of rotation of a rigid body represents the reverse rotation direction of particle motion of seismic motion.

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The earthquake response of the rubber devices to distribute the seismic lateral force for the multi-span continuous girder bridge to substructures was studied using the hybrid (pseudo-dynamic) testing technique. First, the force-displacement relationships of the two types of rubber devices; the natural rubber device and the high-damping rubber device, were compared from the loading tests of the specimens. Then, the earthquake responses of the multi-span continuous girder bridges with the rubber devices were obtained from the hybrid tests. The results showed the highly nonlinear responses with hardening phenomina of rubber material, however, they showed good agreement with the numerical simulations using the multi-linear hysteretic models for the rubber devices.

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Conventional flutter analysis formulation using unsteady aerodynamic forces based on sinusoidal oscillation has a problem that the oscillation condition of aerodynamic forces doesn't correspond to the eigen-solutions. This paper discussed flutter analysis of bridge deck using unsteady aerodynamic forces based on general damped oscillation and examined the influence of formulation of aerodynamic forces and equation of motion on the analysis results. It is found that the flutter derivatives and the flutter analysis results based on general oscillation tend to differ from the results based on sinusoidal oscillation as the damping value increases and that the finite state approximation model of aerodynamic forces functions as forces based on general oscillation in flutter analysis.

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Ultrasonic testing will be applied to evaluate field welded butt joints of steel girder bridges. The detectability of planar defects such as cracks is a serious problem because cracks may do damage to structures without appropriate treatment. Characteristics of flaw echoes from planar defects were investigated by doing numerical simulations and experiments. Considering multiple paths of ultrasonic wave, synthetic aperture focusing technique was conducted to reconstruct a planar defect.

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This paper proposes a new bridge restrainer system with fiber reinforced rubber-rolled pin and examines the efficiency of it for the shock absorber device by the experimental approach. First, static and impact loading tests were performed in order to examine the mitigating effect in elastic range. Second, high speed loading test was performed to compare the energy absorbing capacity of rubber-rolled pin system with steel pin system. It was confirmed that the rubber-rolled pin could decrease about 1/4 the responding strain of bridge restrainer plate compared with the case of steel pin system. In addition, it was also found that the ultimate limit displacement and energy absorbing capacity of rubber-rolled pin were larger than those of the steel pin system.

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A computational program by the tangent stiffness method has been developed for plate & shell structures. By this program, we can obtain strict equilibrium solutions even in the case of extremely large deformation, because our new calculation method considers exact spatial finite rotation of each node. The method expresses the total rotation by the composition of two coordinate transformational matrixes. In some computations, it has been evident that the application of this new method in order to renew the rotational vector us the nodal displacement causes so much improvement of the convergence.

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Steel weight of bridges reflects their structural features. The paper first constructs the data-base by collecting more than eight thousand weight data and then analyzes statistically from various points of view. Comparisons by structural types provide valuable information to engineers for selecting the most suitable type. Further, comparisons by years describe the change of design specifications or design concept which comes from the social situation. The current design for rational girder bridges is compared with other similar types of ordinary design. The influence of the change of the live load is also discussed.

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The purpose of the study is to make up a standard design method for tuned mass dampers. That is, by random vibration theory, using the H₂ norm and H_∞ norm as evaluation functions, then the design methods based on different theories can be integrated to a standard method for optimal design of tuned mass dampers. For the conditions where the analysis method are difficult to be used, this paper presents an optimal design method that can be commonly used by numerical computation.
In this paper, a method of optimal design of a tuned mass damper, for a structure of 1-degree of freedom, is given by using H₂ norm and H_∞ norm method. The validity of the method is confirmed by analytical and numerical calculations.

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New cable tension adjustment method has been developed by introducing the concept of satisfaction to reduce the weight of cable-stayed bridges. The degree of satisfaction is defined in such a way that when the aspire of a designer is completely achieved, the satisfaction degree is one, and when the aspire is not achieved at all, the satisfaction degree is zero. Evidently, because the satisfaction is related to engineering knowledge and judgement, the proposed method can provide us with more practical solutions. In order to treat the satisfaction in the formulation, fuzzy mathematical programming is employed, in which the satisfaction degree is related to the determination of the membership functions for the designer's allowable demand range. Practical applications of realized models and existing cable-stayed bridges show the efficiency and usefulness of the method developed here.

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In this paper the thin plate bending problem of residual stress which is generated due to the change of loading after the partial displacement constraint is given under a loading is analyzed. Then the crack initiation due to the residual stress and the change of loading is investigated. The rational mapping function and the complex variable method are used. The solution of residual stress is obtained by superposing the solution of uniform bending of an external force boundary value problem and that of uniform bending of a mixed boundary value problem under partial displacement constraint. Clamped supported and simple support boundaries are treated as the displacement constraint. Stress distributions before and after the crack is initiated by residual stress from an end of the displacement constraint are investigated. Occurrence of a crack and its direction are investigated using the energy release rate of crack initiation under the initial loading and that after the crack initiates.

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Three-dimensional and two-dimensional simulations of the unsteady flows around a rectangular cylinder are carried out by means of IBTD+FS Finite Element technique without any turbulence model. In case of the three-dimensional simulations, it is confirmed that the aerodynamic characteristics of a rectangular cylinder with a side ratios of breadth/depth(B/D) of 4.0 is good agreement with the experimental result. We have succeeded in simulating the detailed behaviors of the shear layer and the vortex motions around a rectangular cylinder. The relation between the structures and the aerodynamics of the rectangular cylinders is also investigated.

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We investigated the effect of pier base restraint on the ultimate behavior of bridge piers subject to severe earthquake motions. For this purpose, we implemented our pier-base connection model referred to as ‘a semi-empirical model’ in the nonlinear dynamic analysis for steel piers. From this numerical analysis, it is observed that the reduction of pier base restraint decreases the damage to steel pier but increases the damage to anchor bolts. Therefore, there exists an optimum pier base restraint that minimizes the maximum response displacement and residual displacement. For the design purpose, we discussed a necessary pier base moment capacity where the damage to pier base will not exceed that to steel pier. Furthermore, we examined the applicability of the static analysis based on the Newmark's energy conservation principle as an alternative to the nonlinear dynamic response analysis.

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This paper presents characteristics of substation facilities' damage caused by recent earthquakes and their seismic countermeasures in order to realize future subjects. Damage to substation components and functional loss of electric power systems caused by 1993 Kushiro-Oki, 1994 Northridge, 1994 Hokkaido Toho-Oki, and 1995 Hyogoken Nanbu earthquakes are carefully examined. Existing seismic countermeasures related to substation components and power system operations are also examined. After that, future subjects of seismic countermeasures are discussed on the basis of these examinations.

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In order to examine the fatigue crack propagation rates of stainless clad steel which is considered to be useful for increasing the resistance of steel structures against corrosion, fatigue crack propagation tests have been carried out by using CCT type of specimens made of mild steel, stainless steel and stainless clad steel. On the basis of the experimental results, an expression for fatigue crack propagation rates of stainless clad steel is proposed in consideration of a difference in a Young's modulus of steel from stainless steel.

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