A new extension of the Applied Element Method (AEM) for structural analysis is introduced. This paper deals with the large deformation of structures under dynamic loading condition. As no geometric stiffness matrix is adopted, the formulation used for large deformation is simple and it can be applied for any structural configuration or material type. A new technique based on determining the residual forces due to geometrical changes is proposed. The accuracy of this technique is verified in small deformation range by eigen value analysis. In large deformation range, the collapse behavior of structures and the rigid body motion of the failed structural elements can be followed accurately.

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If rigid body displacements are properly separated from a finite-displacement small-strain problem, the remaining deformation is within the scope of the small displacement theory. For this purpose, the rigid body displacement of each sufficiently small subdomain of an elastic body must be removed independently from other subdomains before the actual deformation occurs. This paper presents a rigorous and straightforward theoretical formulation for a numerical solution procedure based on this concept. The simplicity of the formulation is due to the fact that it is developed for a general three-dimensional solid rather than structural elements as in the past works.

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A variety of cable structures are supposed to be analyzed in the displacement method. In this study, the elastic catenary is considered to be utilized as a displacement-method element. The flexibility relations are studied, in relation with its potential, and especially on the singularity exhibited in a veritically hanging state. A counter treatment of those singular states is presented to deal with any configurations of a cable structure. In the solution procedure, one iteration method is introduced to obtain the tension components in each of the elements at any nodal positions, both theoretically and in numerical examples.

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In this paper, alongside ground vibrations induced by high-speed trains and the mitigation measure are discussed from the computer simulation. The track loading is assumed by a set of harmonic moving function of different frequencies in view of a train geometry and in addition sleeper distance. The 2.5 dimensional FEM method developed by the authors is used for the analysis. The simulated ground vibration due to a train system of axle loads is interpreted from the knowledge of wave propagation in layered soil. The vibration reduction rate by the proposed X-WIB based on thus obtained information is demonstrated for the wave field before and after the installation.

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In seismic design of railway structures, it is verified whether plastic deformation capacity, what is called, ductility of structural members may exceed seismic response. Authors have already proposed a method to quantitatively evaluate ductility correspondent to damage levels for concrete-filled tubular steel column members. On the other hand, seismic response should be evaluated through dynamic analysis with computers. In those cases, the reliability of calculated response depends strongly upon hysteresis model of structural members, so that the study on hysteresis model is one of important research issues. In this paper, based on the results of alternate loading tests, which have been performed by authors, a hysteresis model of concrete-filled tubular steel column members was proposed and the validity of a hysteresis model was verified through the pseudo-dynamic tests.

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Large scale shaking table experiments of pile foundation have been carried out to investigate dynamic interactions between pile and soil. The deposit of K asumigaura sand, naturally dried, is prepared in a laminar box of 12m, 6m and 3.5m in length, height and width, in which 4 steel piles of 6m and 0.32m in length and diameter are installed. The force of interaction between soil and pile is calculated from the 2nd derivative of moment on the pile, the relative displacements between the deposit and piles are obtained from the accelerations measured. It has been found that the coefficients of dynamic interaction increase with depth proportionally, decrease with shaking level but vary slightly with the frequency. Most of damping is attributed to the nonlinearity of soil so that damping ratio increases with shaking level.

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This paper proposes an evaluation method of stress vs. strain relation of a rubber shock absorber for a seismic countermeasure of bridges. Compression behavior of the absorber subjected to an extremely high compression, induced by poundings between adjacent bridge decks, was studied. A high compression loading test was conducted with a strain as large as 70% was conducted. Finite element analysis with the Mooney-Rivlin stress vs. strain relation was conducted, and based on the results, an evaluation method for stress vs. strain relation was proposed. It was found from the comparison with the test data the proposed method predicts the stress vs. strain relation of the rubber shock absorber with acceptable accuracy.

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This paper presents an effect of inelastic behavior of cables on ultimate behavior and strength of cable-stayed bridges based on elasto-plastic finite displacement analysis. It is found, since the girder is subjected to the large compressive axial force, that the plastic elongation of the cables leads to the collapse of the bridge. The load parameter at ultimate state due to able plastic elongation can be estimated by calculating the ratio of the yield stress to produced maximum stress in the cable. From a viewpoint of in-plane buckling instability, the possibility of the reduction of the safety factor against proof stress from 2.0 to 1.7 is presented.

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This paper presents the slip verification method for the tank with the seismic magnification factors of both horizontal and vertical directions. The equation is derived from an analytical model for the tank slip including the effects of anchor straps and the responses to the ground acceleration in both directions. Since an application of the seismic magnification factors for the tank slip verification implicitly neglects the coincidence between the ground acceleration and responses to them which considerably affect tank slip behavior, two coefficients which express their coincidence are determined to compensate for the deficiency. Since relationships of the coincidence to their probability of occurrence are clarified, the design vertical ground acceleration and vertical response acceleration based on the allowable probability of excess are introduced to the slip verification method. The proposed method accurately approximates the slip commencement of the tank.

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In this paper, we carried out 2 points loading tests of 23 specimens of the open sandwich members which consist of concrete and embossed steel plate with headed studs. The experimental parameters of specimens are existence of embossments, ratio of shear span length to member height and arrangement of the studs. The main purpose of this study is to examine the possibility to reduce the required number of the studs by using embossed steel plates. From the results, we discuss each parameter's influence upon their load carrying capacities and corresponding failure modes subjected to bending and shear. Moreover, we propose a design method for the composite members considering the effects of the embossments.

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This paper presents a simulation method of earthquake motion. The proposed method is based on the nonstationary process model composed of not only evolutionary spectrum but also nonstationary phase that is named “time-varying phase”. Characteristics of simulated earthquake motions by the method are revealed in terms of peak values, their occurrence times, response spectra and evolutionary spectra. These are compared with the values of actual earthquake records as models of simulation and those of simulated earthquake motions by the conventional simulation method are also examined. As a result, it is found that simulated earthquake motions reflecting more closely characteristics of the original models can be generated by the proposed method than the conventional method.

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The present research is a basic research for development of a cable with good aeroelastic performance. A proposed cable in the present study is a multi-strand cable from viewpoint of cost performance. Wind tunnel tests were conducted to examine the aeroelastic performance of the multi-strand cable with or without helical strand. As a result, it was made clear that multi-strand cable with helical strand had better performance for redudng amplitude of aeroelastic vibrations and that the helical strand makes the drag and the lift forces decrease.

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This paper provides general theory of nondeterministic analysis of offshore structures subjected to the wave and the current simultaneously. The equations of motion are derived and nonlinear drag force in hydrodynamic force is presented The dynamic wave forces and the structural response to them are assumed to have zero-mean, Gaussian characteristics when suitably linearized. The linearization an the drag force with current velocity is carried out using the least square method The damping on the generalized coordinate is diagonalized and the structural responses are calculated by the random vibration approach. It is suggested that the current velocity has significant contributions on the wave force evaluation and the dynamic response of the offshore structures.

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In order to investigate the instability of the separated shear flows around a circular cylinder, a series of linear stability analyses was carried out. The analyses confirmed that the fluctuation with the transition wave frequency is enhanced most efficiently in the separated shear layer. It is also found that the vortices induced by such fluctuation frequently merge in the separated shear layer due to the increase of their wave number and the decrease of their phase velocity. Furthermore, these strong vortices change the flow instability just behind the cylinder and then alter the characteristics of the Karman vortex-shedding.

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The design wave loads on offshore structures subjected to both the current and the wave is examined with a random vibration approach. To ensure their extreme value adequately is essential to design them reasonably. Although random vibration analysis which is corroborated by reliability provides accurate estimation of the structural response, it is obviously impractical to carry out it in the design process. In this study, the design wave loads with current effect which corresponds to the static analysis design scheme is examined based on the maximum expected value of wave forces and structural responses.

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After forming tie reinforcements into the desired shape, plastic deformation may be induced in the ties because of the cold working. Thus, the ties with residual strain are subjected to tension when a bridge column develops inelastic plastic deformation. Since few investigations have been conducted on the effect of the plastic residual deformation of ties on the lateral confinement of concrete, a series of uniaxial loading test was conducted for circular concrete cylinders confined by ties with the residual plastic strain and those confined by ties in which the residual plastic strain was eliminated by annealing. It was found from the test that the residual strain increases the secant stiffness of concrete between ε_cc and 2ε_cc, in which ε_cc represents the concrete strain at the peak stress.

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This paper presents the condition of the damage to the pile foundation of a bridge caused by the 1995 Great Hanshin Earthquake, and examines the cause of the damage by means of the three dimensional finite element method taking into account soil liquefaction and the lateral spreading of the liquefied soil. The damage to the pile was mainly caused by the ground motion during the earthquake. It was expanded by the lateral spreading of the liquefied soil which occurred in succession after the main shock causing large residual deformation to the piles. Countermeasures involving the adoption of sand-compaction-piles or steel-pipe-sheet-piles were investigated in order to assess analytically the level to which the damage could be mitigated. It was found that the steel-pipe-sheet-piles constructed between the foundation of the pier and the quay wall can withstand strong motion, liquefaction and the lateral spreading it induces.

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This paper presents an investigation of a tuned liquid damper (TLD), for which heavy mud is used instead of water as the liquid. The viscosity of heavy mud is higher than that of water and can be adjusted within a certain range to meet the optimal design value of liquid sloshing of TLD. In addition, the heavy mud has a higher density than water, hence more effective mass is available.
The experimental results showed that the heavy mud TLD is more effective than a conventional TLD using plain water. The simulations, using a modified theoretical model with equivalent damping of heavy mud, showed good agreement between the measurement and the prediction. The heavy mud TLD was applied to a high RC bridge pier under constmction for reducing wind-induced vibration. It was found that the damping ratio of the pier was increased from about 1% to 3%.

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The differential quadrature method (DQM) is a numerical method of which has been successfully employed in a variety of problems in engineering and physical sciences. The DQM is accomplished by expressing at each grid point, the calculus operator value of a function at any discrete point as the weighted linear sum of the values of the function at all the discrete points.
This paper presents an application of the semi-analytical differential quadrature method to analyze vibration of annular sector Mindlin plates with two opposite radial edges simply supported. The convergence and accuracy of the present method are demonstrated to be compared with those obtained by other numerical methods. Good accuracy is obtained. The effects of sector angles and simple supported models on the frequencies of annular sector Mindlin plates are analyzed for the different radii ratios and ratios of width to thickness.

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The equations of motion for a beam with solid rectangular cross-section are derived from the displacement field of Rayleigh-Lamb plate theory. Cross-sectional properties, such as the dynamic moment of inertia, cross-sectional area and the radius of gyration of the cross-section, are investigated as functions of frequency. It was found that as the elastic surface wave in any medium converges to the Rayleigh surface wave in the limiting case of infinite frequency, the dynamic radius of gyration for a half-infinite medium can be defined in spite of being unbounded. The dynamic radius of gyration for the first mode of phase velocity in a beam in the case of infinite frequency converges to 68% of static values. The same radii converge to zero for modes of phase velocity higher than the second. This result indicates that only the first mode of phase velocity of a flexural wave survives on the surface of a beam medium as a Rayleigh surface wave in the case of infinite frequency.

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Among various limit states, serviceability limit state has not been fully investigated, because serviceability is not a fatal phenomenon in comparison with a collapse or a damage of structures. This study applies to a vibration as a serviceability limit state. Dynamic response of highway bridge under a moving vehicle is analyzed by simulation method and means of nonstationary random vibration theory, taking account of roadway roughness and coupling vibration of bending and torsion. Root mean square (RMS) values of a velocity of girder are calculated and considered as a vibration stimulus for pedestrians, and limit state probabilitv of human vibration sensibilitv is calculated. And also maintenance criteria of road roughness are examined.

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Studied herein is an experimental and analytical assessment on the modeling of pounding behavior in girders of elevated bridges, paying attention to the energy loss and the impact force during the pounding. The effect of rubber shock absorber on the reduction of impact force is also discussed. The pounding of girders is examined experimentally by colliding the two steel specimens each other with relative velocity ranging from 1 (m/s) to 3 (m/s). Experimental results are compared to those through the response analysis carried out by using the spring-mass-dashpot model including the linear spring for the pounding. It is recommended that a nonlinear spring for pounding should be developed in order to consider properly the energy loss during the pounding.

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An averaging method, Mori and Tanaka's theory, predicts the upper and lower bounds by Hashin and Shtrikman by exchanging material properties of the matrix and inclusion. However experimental results of porous media are very close to the upper bounds, and are also consistent with a numerical result of a body with periodic micro-structures. Here we propose a new approach using Mori and Tanaka's theory in which two materials are included into the matrix but the volume fraction of the matrix material is taken to be zero as a limit. Results show that either upper or lower bound by Hashin and Shtrikman is a probable estimate when the volume fraction of one material is very small.

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