The manifold method is a recently developed numerical procedure. Based on the original first-order Manifold Method, the second-order one together with corresponding computational code is developed in the present paper. Application examples include calculation of stress distribution of a circular ring, analysis of contact stress of a cylinder compressed between rigid plates, large deformation problem of a cantilever and failure of a slope with discontinuities. The results show that the second-order manifold method is capable in analyzing structure deformation and contact problems with relatively high accuracy and has priority in simulating large deformation problem and failure process.

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This paper has dealt with the nonlinear behavior of pile-supported bridge during earthquake motions. The formulation takes the FEM-BEM technique; the FEM for the near structure zone while the BEM for the far field zone. The analyses addressed to the parameter studies of component influence on the behavior of the total superstructure-pile-soil system for the total rational design practice. The results are interpreted with regards to: (1) inelastic behavior of superstructure or/and substructure; (2) different superstructure properties and vertical excitation conditions; and (3) soil layering effect on pile response with emphasis on kinematic and inertial interactions.

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This paper proposes an algorithm to control seismic response of structures by using information on predicted external force. The proposed control rule is composed of stationary feedback term and feedforward prediction terms. Numerical simulation in one degree of freedom system having one control system is used to clear the efficiency of this method. It shows that feedforward prediction terms act as bandstop filter of seismic wave and that the proposed method has more effective in control efficiency than stationary feedback control.

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Nonlinear seismic response analysis of the two steel bridges with continuous girders and steel piers (single columns or rigid frames) was performed. As the result, it was understood that the tensile axial forces that exceeds the tensile strength of the set-bolts affected the steel support bearings. The collisions of the bridge girders with the bearing supports were simulated by the impact analysis using velocity and acceleration that were obtained by the total system analyses. These results are close resemblance to the actual damage situation. In conclusion, the fractured set-bolts of bearing by tensile force were first damages, and after that the collision of the girders with bearing supports caused secondary damages.
This paper also verified of the effectiveness of the seismic isolation for these two bridges.

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To investigate the effects of stress-strain relation of steel on seismic performance of steel-pipe bridge piers, three types of loading test are performed using small pipe-pier models, which are: static monotonic-loading test; static cyclic-loading test; and base-vibration test. Here, three kinds of steel are used which are of different level of yield stress and of with/without yield-plateau. The results obtained from this study are: 1) the steel-pipe without yield-plateau are of bigger capacity of ductility and of bigger energyabsorption than those with yield-plateau; and 2) dynamic ultimate strength of the piers can be rationally estimated by using those static ultimate strength under monotonic-loading.

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This paper presents both experimental and analytical approaches of the flexural strength and the ultimate deformation of concrete filled steel tube beams subjected to high speed loading. First, a uniaxial high speed loading test of the filled concrete for various steel tubes was carried out to investigate both the confined effect and the strain-rate effect of materials. A prediction method of the stress-strain relationship considering the confined effect and the strain-rate effect is proposed based on Popovics' formula. Second, a high speed loading test of the concrete filled tube beams was also performed to investigate the structural member behavior. A dynamic elastic-plastic analysis method of concrete filled tube beam was developed taking into account for the confined effect and the strain-rate effect. The proposed method predicts very well the test results of the dynamic elastic-plastic behavior of the beams.

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This paper provides general theory of nondeterministic analysis of practical offshore structures subjected to the wave, that is located parallel to the wave direction and possess wide spans, multiple-piles, horizontal and slant bracing. In accordance with linearized equation of motion, its structural responses can be obtained by the random vibration approach. The linearized wave excitation matrix consists of cross-spectral density function of wave height, which is the product of one-dimensional sea spectrum and directionality function. To account the fact that the same wave forces do not occur simultaneously over the entire structure, a hydrodynamic admittance, the products of average values of directionality function, is introduced. It is suggested that the hydrodynamic admittance have significant contributions on the dynamic response of the offshore structures.

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A method of stochastic evaluation of the strength of structural members is developed by the bifurcation theory. Knowing that the strength of slender specimens/members is governed by the so-called hilltop bifurcation point, which implies the coincidental double critcal point of limit and bifurcation points, we derive a system of bifurcation equations for the local behavior at this special double critical point. On the basis of this system of equations, we formulate an imperfection sensitivity law and, in turn, the probability density function of critical loads, assuming that initial imperfections are subject to a multi-variate normal distribution. In addition, the associated formulas for a limit point are presented for comparison. The validity of the theoretical developments is assessed through its application to a simple truss structure, whereas the feasibility and capability of the proposed method is demonstrated for the data sets obtained in actual experiments and numerical simulations of structural members.

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In this study a hybrid coupling method for the dynamic analysis of dam-foundation-reservoir system has been developed. With this method, 3-D dynamic analyses were carried out to simulate the actual earthquake behaviors of an existing concrete gravity dam at the Kushiro-oki Earthquake (1993. M7. 8). As the results, the dynamic shear modulus of the dam was evaluated to be 11, 032N/mm², and the material damping factors of the dam and the foundation are evaluated to be 5%. With the identified analytic model, the revaluation of the seismic stability of the dam against very strong earthquake was done considering the non-linearity of dam and foundation materials. Furthermore, it is pointed out that the interaction between dam and reservoir exerts an important effect on the dam responses, and the added mass method can not give an accurate solution.

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With the results of field investigations and outdoor exposure experiments of painted specimens, time-lapse deterioration of paintings was statistically analyzed by using “Automatic Evaluation System for Paint Film Deterioration” in order to establish deterioration curves logically. Quadratic curves were found to be well fitted to the paint film deterioration within the practical period of 10 to 20 years. Estimation curves were established for three corrosive environments such as mild environment, seashore environment, and tropical environment (hot and highly humid).

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In this study, based on the results of the experiments, a model for the laminated rubber bearings is proposed. At first, to understand the mechanical property of rubber bearings, uni-axial and bi-axial loading experiments are done over a wide range of shear strain. Then the Ozdemir's elasto-plastic model is extended to accommodate the experimental results by adding a nonlinear spring, isotropic hardening and stiffness degradation. A simulation by this model can reproduce the load-displacement relation of the uni-axial and bi-axial experiments well. The performance of this model for predicting the seismic response is verified by comparing the simulation with the results of hybrid seismic response experiment of the rubber bearings.

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Aerodynamic sound radiated from rectangular cylinder with side ratio B/H=1, 3, 5 and 7.5 was studied experimentally in a low-noise wind tunnel at wind speed 15m/s and 30m/s. Peak Strouhal number is almost same at different speed, and increment of sound pressure level (SPL) is corresponding to U⁶ law. Angle of attack where SPL had peak value was α≈2°, 0°, 5°, 9° with B/H=1, 3, 5, 7.5 respectively, but peak value is almost same. On the other hand, variation range of SPL with different angle of attack is about 20dB for each case. The present data was compared with existing data by adjusting difference in experimental condition with Curle's equation.

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In the seismic design, the ultimate behavior of steel piers are usually predicted by the nonlinear Bernoulli-Euler beam model where shear deformation is ignored. Here, the validity and accuracy of the Bernoulli-Euler beam model is examined in comparison with the nonlinear Timoshenko beam model that takes into account the effect of shear deformation. First, we identified two structural parameters that govern the accuracy of the Bernoulli-Euler beam model. Then, an equation is derived to estimate the accuracy of this beam model in terms of the two parameters. From this equation, it is shown that the shear deformation has a big influence on the ultimate behavior of steel piers and cannot be ignored for the stocky piers. In contrast to the shear deformation, the geometrical nonlinearity can be normally ignored except for the steel piers with extremely large slenderness ratio and high axial force ratio.

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This paper presents the flexural design way of breakwaters by means of reliability based design method. By using the probability distributions of design parameters such as wave force, deadweight, material strength and so on, distribution of safety indices against ultimate flexural failure of breakwaters designed with conventional design method has been clarified. Target safety level has been determined in terms of comparison of life cost of breakwaters for external safety and internal safety. Code calibration has been carried out and safety factors for level 1 reliability design method have been proposed.

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Early earthquake damage evaluation is very important for the disaster-related organizations to take prompt action in order to minimize the hazard negative impact. This paper presents a methodology to evaluate the earthquake damage to buildings and dwellings using monitored power supply before and after the event. The electric power demand was used to evaluate regional characteristics and a high correlation was found between the demand changes and the earthquake damage. The proposed method allows a feasible real-time damage evaluation and can be readily implemented with little investment. Furthermore, the proposed method application is not limited by the weather conditions or time.

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This paper presents static and high-speed tri-axial compression fracture analysis of concrete specimen by using a mixed RBSM (rigid body spring model)-FEM model. A new RBSM model proposed here in has 3 couples of spring normal to and parallel to the failure plane located at the center of the element with an arbitrary angle, and 4 nodes at the out side comer of the element so that this element an be installed in the FEM platform without any interface. This model can take into account the bilinear elastic plastic gap behavior and Mohr-Coulomb slip behavior including softening in elastic plastic behavior. After formulating the basic equation of this model test piece compression test results that include the localization and softening behavior is simulated by using the proposed model. It is found that the proposed method can express very well the softening curve and residual resistance induced by localized fracture plane. Furthermore, the high-speed loading test results are simulated by the proposed method. It is also found that rate effect on the concrete strength and softening rate is also expressed well by considering those effect in the constitutive laws.

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Inverted L-shaped steel bridge piers under out-of-plane cyclic loading are studied experimentally and numerically. Four specimens are tested. The cross-section of models is non-stiffened box section and stiffened one. The width to thickness ratio of the component plate was changed as a main parameter. The eccentricity ratio e/h (the ratio of the distance e between vertical load and vertical pier axis to the height of pier h) is 0.4. The results of FEM analysis are compared with the experimental results. The failure behaviors of FEM analysis agreed well with those of the experimental test.

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The present study concerns the application of microtremor array observation to the evaluation of average S-wave velocity of the ground. Twenty-two sites were picked up for the study, at which distributions of S-wave velocity were known. Average S-wave velocities estimated with the microtremor observation have been compared with those obtained by the elastic wave exploration; the result shows very good coincidence. It is concluded that from the viewpoint of easiness and cost-effectiveness, microtremor measurement is highly applicable to the evaluation of S-wave distribution of the ground, which is essential for earthquake resistant design of the structures and seismic zonation.

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The S-wave velocity is one of the most important parameters in seismic response analysis of soil layers. However, PS-logging, which measures S-wave velocity in borehole, is not so frequently carried out. Hence the S-wave velocity is often estimated using SPT N-value and other soil parameters. In this paper, the results of comprehensive geological surveys conducted at K-NET sites and Yokohama seismometer network sites are employed to propose reliable estimation models of S-wave velocity. Based on a multiple linear regression analysis, the S-wave velocity is expressed as a function of N-value, soil type, and geologic age. The proposed equations are then compared with existing relationships.

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The seismometer network has been enhanced along the expressways since the 1995 Kobe earthquake. However, recent studies on earthquake damage have revealed that expressway structures are not seriously damaged under the current regulation level of seismic excitation. Hence, we may think of relaxing the regulation of the expressway closure. Before doing this, we need to examine the effects of shaking to automobiles on expressways since the drivers may encounter difficulty in controlling their cars and trucks, and traffic accidents may occur. In this study, a vehicle model with six degrees-of-freedom was made and its responses were obtained under several seismic motions and the effects of seismic motion to the dynamic response of the vehicle model were analyzed.

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The seismic records observed from 52 stations in Miyazaki Prefecture are currently used to grasp the distribution of seismic intensity of the surface ground in the prefecture soon after the occurrence of an earthquake. However, the number of instruments may not be large enough to capture the detailed seismic intensity distribution. Hence, microtremor measurements were conducted to estimate site response characteristics of the seismic observation stations and other locations. The horizontal-to-vertical (HIV) Fourier spectral ratios were calculated for seismic records and microtremor, and their similarity was confirmed. Using the H/V spectral ratios of microtremor, the velocity response spectra for earthquake ground motions at microtremor sites were estimated and their applicability was discussed.

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Wigner distribution is a useful tool to detect the time varying frequency characteristics of the signal, and it has many advantages. There is also a problem, however, that generally Wigner distribution can not be converted to the time series signal. This paper proposes a method to compose a time series signal from an arbitrary Wigner distribution by using the orthnormal wavelet functions. By using the proposed method, a strong motion record is divided into the body wave component and surface wave component based on its time-frequency characteristics represented by Wigner distribution. The computation results verify the applicability of the proposed method.

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The results of tests conducted on 14 concrete-filled steel tubular columns are reported. The primary test parameters were the radius and thickness of test specimens, the concrete strength, the concrete height, the position of diaphragms and the loading conditions. The local buckling were observed at the top of concretes or at the bottom of test specimens. Its position depend on the concrete height. New parameters are proposed to predict the maximum lateral load of concrete-filled steel tubular columns. The validity of the present parameters is confirmed through the present and existing experimental results. With the use of the present parameters, the optimum height of concrete filled in the columns is also proposed.

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We applied a free-vibration-based identification method of unsteady aerodynamic forces of bridge deck based on finite state approximate formulation to modal information data obtained by wind tunnel experiments on a thin box girder. This paper also discussed two kinds of the objective functions and their weight factors in the identification procedure as an optimization problem in detail. The results show that modal information and flutter derivatives can be estimated accurately, even though the experimental data contain relatively large error. It is also found that the application of the maximum-likelihood method based on the residual on modal information is effective in determining the weight factors of objective functions.

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A lot of rigid frame elevated bridges with reinforced concrete have been constructed as railway structures from the economic viewpoint. On the other hand, the omission of formworks and placing rebars under limited working conditions makes it possible to improve the safety during construction and reduce the total construction cost. A hybrid railway rigid frame elevated bridge of concrete filled steel tubular columns can simplify the construction and shorten the term of works. At the same time, high seismic performances can be expected because of a composite effect of steel and concrete materials. This paper shows an example of seismic assessment for a hybrid railway rigid frame elevated bridge composed of composite structural members, based on a method evaluating the performances of structural members which authors have already proposed.

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