Rolled steel plates were subjected to ultrasonic inspection in order to examine acoustical anisotropy and non-homogeneity along the thickness direction. Two vertical planes of the plate were observed under a microscope in order to investigate changes in microstructure. Shear wave velocities, which depend on both propagation and polarization directions, were measured for both 40mm and 26mm thick steel plates. Changes in the shear wave velocities V_L are found along the thickness direction. Especially, strong local anisotropy is found due to elongated ferrite grains in the near-surface zone. A high angle beam probe should be used carefully for ultrasonic testing on a plate exhibiting strong anisotropy.

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This research aims to determine the effect of loading pattern on the damage of a reinforced concrete bridge column. Five specimens were tested with uni-directional or bi-directional cyclic loading patterns combined with a uniform axial load. From the test results, the theoretical plastic hinge zone length was calculated considering the yield penetration effect and the energy dissipated by the specimens was obtained.

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By its geometrical nonlinearity, the realization of a desired suspension structure depends on the shape-finding procedure. In an actual suspension structure, cable members are usually combined with bending members. For a beam-cable structure, in this study, the displacement method is employed to deal with the structural equilibrium, but in which each cable member is treated as the elastic catenary through a force-method computation. Thereafter an iterative scheme of shape finding is developed for such a mixture of cable and beam members, which is based on the tangent coefficients to change of the cable natural lengths on each updated equilibrium configuration.

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In an earthquake, a standard reinforced concrete column develops plastic deformation in the plastic hinge region under a strong near-field ground motion. Although the lateral confinement is effective to enhance the plastic deformation capacity, it is likely that the damage has to be repaired after an earthquake. This study aims at development of a column in which a rubber layer is built-in at the plastic hinge so that the column has a 4% drift deformation capacity without damage in the concrete. Prestressing tendons are installed in the column in order to resist tension force in addition to reinforcing bars. A cyclic loading test is conducted for six reinforced concrete columns; one standard column and five rubber layer built-in columns. It is found from the test that damage of concrete in the plastic hinge region is extremely limited in the rubber layer built-in columns.

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Engineering viewpoints on reasonable and effective countermeasures against a surface active fault are discussed for three types of civil engineering structures, i. e. highway bridges, river dykes/road embankments/flat roads and underground pipelines. Considering characteristics of historical surface faulting, damages of structures and existing technology against relative displacements induced, three fundamental engineering concepts against surface faulting are proposed, and several examples of countermeasures to reduce damages by surface active faults for three types of civil engineering structures are shown according to four construction work-stages: planning, designing, activity just after an earthquake and restoration.

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In this study, high cycle fatigue damage analysis and life prediction of steel structural member based on continuum damage mechanics is proposed. Three-dimensional finite element implementation of a elastoplastic constitutive equation coupled with damage is employed. In case of high cycle fatigue, no plastic strain observable at a mesoscale, thus a two-scale model had already presented by Lemaitre. To apply this theory and obtain reasonable results, two kinds of identification method of damage parameter are considered. The fatigue failures due to the typical stress concentration are simulated, and confirmed the efficiency of this method with appropriate identification technique of damage parameter.

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Structural characteristics of the Old Tacoma Narrows Bridge which was collapsed in 1940 by wind was exactly investigated for both the eigenvalue calculation and the flutter analysis to grasp natural frequencies and the torsional flutter response characteristics of the Bridge. It was found from these numerical simulation analyses that 1st symmetric torsional flutter might have been presented if a pair of center stays was not broken, although 1st asymmetric flutter was excited in the Bridge. It was also found that 1st asymmetric torsional flutter, which was the same flutter mode in the destroyed Bridge, seemed to be induced in case that a pair of center stays was broken and that lower wind velocity less than 19m/s acted on half length of either side span.

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A series of cyclic and hybrid loading tests was conducted to clarify the effect of loading hystereses on the flexural strength and ductility capacities of circular reinforced concrete columns. In the cyclic loading test, 5 reinforced concrete columns with a diameter of 400mm were unilaterally loaded under a constant vertical force. A stepwise increase and a stepwise decrease loading scheme were used in the cyclic loading tests. It was found that the flexural strength at the same lateral displacement in the first push direction is about 10% larger in the stepwise decrease loading than the stepwise increase loading. The hystereses of the hybrid loading tests are closer to the hystereses of the stepwise decrease loading. It was also found that the Takeda degrading model does not provide a good numerical simulation for the hybrid loading tests when residual drift occurs.

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The behavior of tunnel lining versus the pressure fluctuations in the tunnel induced by a high speed train at over 500km/h was investigated in this study to realize the rational tunnel lining structure. Fullscaled measurements of the tunnel pressure and the concrete strain were conducted, in the Yamanashi Maglev Test Line, to comprehend the strength on the tunnel lining structure under the pressure fluctuations. Firstly, FEM based numerical model for the stress of tunnel lining were developed considering the drain material around the outer concrete lining and its validity was confirmed in comparison with the data obtained from the full-scaled measurements. Secondly, the stress versus the maximum set of pressure fluctuation, which was estimated as the design load of tunnel lining structure, was examined. Furthermore, the accumulated fatigue damage of the lining concrete over lifetime was evaluated based on the number of the pressure loading cycle derived from the maglev train oeration plan.

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As recent tendency of steel highway bridge consturction, 2 or 3 main girder bridges have been constructed. Flange plates of those bridges are welded as butt-welded joints at site. Fatigue resistance of those joints are considered sensitive to inside weld defects. It is important to clarify the weld quality requirements for evaluating NDT results. Fatigue tests of butt-welded joints with various sizes/types of intentionally embeded defects were carried out in order to clarify their influence on fatigue resistance. Based on the results, allowable defect size for butt-welded joints were proposed.

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This paper focuses on the measurement of ground deformation using fiber optic sensor, called Fiber Bragg Grating (FBG) sensor. A displacement transducer based on FBG sensors was developed and tested in the laboratory. Additionally based on experimental and numerical observations, an assessment on sensor arrangement of the transducer as well as the displacement estimation procedure was made. As a result of the experiment, it was found that FBG sensors agreed well with resistive gauges for strain measurement on vinyl chloride pipe and the proposed transducer estimated the displacement with an accuracy of about 6.7% in the bending test. It was also found from numerical evaluations that although there was no significant difference between two algorithms, the spline interpolation and the uniform sensor arrangement may be preferable for uncertianity in displacement distribution.

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It is well known that arbitrary amplitude and phase spectra cannot be assigned to simulate an earthquake motion with causality. We therefore have developed a new method to simulate earthquake motion which can take into account the causality characteristics. In this study we point out that we need to define not only the average and standard deviation of group delay time but also the correlation of group delay time between frequency. We demonstrate that a non-stationary earthquake motion can be synthesized from phase information reasonably by defining the auto correlation function of group delay time as exponential function type.

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Civil engineering and architectural facilities can be characterized as an asset to produce income. In this study, a discounted cash flow method (DCF method) considering a seismic risk is proposed, and a methodology on how to evaluate a discounted present value of the asset pricing is presented with a conditional exceeding probability function of the asset pricing. In the DCF method, an estimation of income is based on a random walk model where as the seismic risk is associated with structural damages is based on a probabilistic model, in which losses by one earthquake event during service time are considered. Finally, the usefulness of the proposed method is demonstrated through a numerical example of a commercial building.

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The objective of this paper is to investigate the applicability of the current static seismic analysis methods to the level 2 earthquake motion. For this purpose, we conducted the numerical analyses using dynamic FEM, static FEM and seismic deformation method, considering the nonlinearity of structures and contact surfaces between structure and soil, and then evaluated the ductility of the structures. As the results, in the case of considering the nonlinearity of the structures, we clarified that both of the ductilities by the static FEM and the seismic deformation method were in good agreements with those by the dynamic FEM quantitatively. On the other hand, in the case of considering both the nonlinearity of the structures and the contact surfaces, the less ductility by the seismic deformation method was obtained than that by the dynamic FEM and the static FEM due to the use of Winkler type spring.

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During 1995 Hyogoken-Nanbu earthquake, many bridges were damaged due to bumping behavior in girders, and which mechanism has been required to be elucidated. This study investigates the damping effect of shock absorbing rubber placed between girders and the modeling of girder-absorber system based on the impedance method. An elastic rod having apparent wave characteristics was employed as the girder model, and which was suspended by steel wires in order to make clear its energy balances in the bumping experiment. It was revealed that the energy losses, which become important for investigating the damping effects of shock absorbing rubber, could be estimated with high accuracy by the impedance method. This method also enables one to estimate the arising stresses at bumping, and confirmed that the bumping stress increases as the length of girder model increases.

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Hinge support steel rigid frame piers used in the important railway bridges that cross another railway or roads are needed to verify the seismic behavior. These piers are characterized by a) hinge support at the bases of columns, b) flange and web that are continuous by the beam-to-column connection, c) diaphragm that is diagonally attached at the comer connection panel, d) concrete filled inside the column members and e) cross section getting smaller toward the bases of the columns. In this study, we conducted the cyclic loading tests on the full-scale rigid frame specimen removed from real bridge used on Tokaido-Sinkansen for thirty-five years to verify the elasto-plastic behavior. Prior to this test, we measured the stress range caused by a trainload to clarify the existing of fatigue cracks and investigated whether the quality of manufacturing was appropriate, because initial crakes and quality of weld seriously influence the seismic performance. Furthermore, we investigated on the performance of the hinge supports that were damaged by cyclic-loading tests to verify the influence of the hinge supports on the seismic performance of the piers.

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Quaternary structure around Fukui plain was explored based on the microtremor observation. The observations were carried out every small grid that covered the Fukui plain. We could evaluate two kinds of predominant period from collected Fourier and H/V spectra of microtremor observed on the alluvial plain. It was confirmed that those predominant periods were originated by the basement of alluvium and diluvium respectively. By assuming S wave velocity structures, the thickness of Quaternary system of the sites were estimated based on the predominant periods. By comparing with kinds of inversion analysis results and boring data, the validity of the estimated structure was examined.

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There are many in-service structures that require to be improved their anti-seismic property. It is practical in them to be installed a number of small anti-seismic elements by reason of strength and/or space. In this study, we propose an approximate optimization, that consists of the nural networks of Radial Basis Functions, to get an acceptable better solution, not the best solution. We made an attempt to apply the method to a problem in which we investigate the efficient arrangement of additional mass for cables to control the motions of a cable-stayed bridge. The results show that the proposed method can find out not so bad solutions within 1/10 or less times of analyses than the conventional optimization.

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This paper proposes an analytical method for the seismic design of circular shield tunnels in the cross section based on the seismic shear deformation. Since the seismic deformation of underground structures is primarily the shear deformation in terms of the whole cross section, the seismic deformation of the circular shield tunnels is close to the elliptical shape. The study shows that the shear strain ratio of the shield tunnels to free field ground is the hyperbolic function of the shear stiffness ratio between the ground and the shield tunnels. The seismic shear deformation of the shield tunnels is estimated by both the shear strain transmitting characteristics and the push-over analysis of the 2-ring frame model that can evaluate the effects of the transverse and circumferential segment joints.

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It has been pointed out that the interaction of 3D components of earthquake waves plays a critical role on the ultimate seismic behavior of structures. In fact, numerical analyses have shown some results to support the importance of considering multi-directional nature of seismic loads. However, this fact has rarely been examined by experiments primarily because of the difficulty in applying 3D loads, not to say the difficulty in carrying out 3D pseudo-dynamic tests. Herein, we developed a 3D structural experiment system that is capable of conducting pseudo-dynamic tests and then, confirmed its validity by some cyclic loading tests and pseudo dynamic tests on thin-walled circular steel columns.

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In this paper, we investigate an inelastic behavior of viaduct systems, which consist of a superstructure, piers and bearings, under bi-directional earthquake motions. First, we construct a three-dimensional geometrical and material nonlinear dynamic analysis program. Next, when the viaduct system including adjacent structures is subjected to bi-directional earthquake motions, we investigate the effect of the bidirectional moments and torsional deformation on the dynamic inelastic behavior of the viaduct system. The resultant dynamic behavior is also compared with the one under the one directional earthquake motion. Furthermore, we investigate an applicability of the equivalent cantilever column model under bi-directional earthquake motions.

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Low cycle fatigue strength of welded joints was investigated by means of newly developed fatigue testing system in which image analysis technique was applied to measure the strain of specimens. It was validated that the strain measured by the image analysis was almost equal to measured value by strain gauge, and the low cycle fatigue strength of steel plate without welding was in good agreement with the results reported in former researches. After verifying the testing system, fatigue tests were carried out on welded joint specimens. The test results indicated that the low cycle fatigue strength of welded joints was much lower than that of plain material, and fatigue life was reduced by half.

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We propose a methodology to retrieve the up-going (incident) component of ground motion from borehole records by applying a backward calculation based on an effective stress analysis. Most of the available techniques to date are based on an equivalent linear analysis that is not accurate in cases of strong non-linearity. Numerical examples are conducted to examine the accuracy of the identified incident wave in cases of liquefaction. It is concluded from the results as follows: 1) The incident wave, as well as the stress-strain hysteresis and effective stress path of a liquefied layer, is retrieved from the noiseless record with high accuracy. 2) In case the observed record is not given at the sufficient depth, the accuracy of identified incident wave will decrease. 3) The proposed methodology can be applied to the records with white noise.

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The data on thickness and mechanical properties of structural steel plates for bridges distributed from domestic five steel making companies in 2001 were collected, and about 160, 000 and 80, 000 samples were acquired, respectively. The mechanical properties include yield point, tensile strength and yeld-tensile ratio. The mean value, standard deviation and histogram of samples were obtained for every steel grades. The correlation between mechanical properties and thickness was examined. The goodness-of-fit tests of thickness and yield point to typical probability functions were carried out. This paper presents the outline of the survey and the discussion on statistical characteristics of the data.

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Equivalent linearization of a phenomenological hysteresis model of laminated rubber bearings which is proposed by the authors, is studied. At first, the approximated equations of the equivalent stiffness and damping ratio of the hysteresis model is analytically derived. The advantage of these equations are that they include the effects of the amplitude-dependency of the hysteresis loops and the hardening phenomenon. Then, by comparing the derived equations with the simulated results of the hysteresis model, these equations are found to be more accurate than the present design code.

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In this study, the effects of multiple detonations on the damage of reinforced concrete (RC) slabs has been experimentally investigated to improve the design and damage estimation methods of RC shelters. One of main results obtained is that the crater and spall depths of the RC slabs due to two detonations may be relatively well predicted with the authors' method proposed for virgin RC slabs subjected to a single detonation.

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