In this research, carbon fiber sheet (CFS) substitute to lateral tie was used for torsional strengthening of PC member. To investigate the mechanical properties of CFS strengthened PC member subjected to torsion and torsional reinforcement effects of CFS, monotonic and cyclic torsional loading tests were carried out with specimens which strengthened by lateral ties and unreinforced specimen for comparison. From both monotonic and cyclic loading test results, it was proved that the CFS can increase the ultimate torsional capacity and cracking torque. And it was also confirmed that the CFS had sufficient reinforcement effect, and for CFS strengthened specimen, the cracks of concrete were dispersed and widths were small. Mechanical properties such as torsional rigidity retention, residual twist, resilience and ductility were excellent. As for three-dimension finite element method analysis, analysis results matched the results of monotonic loading tests well and tracked the cyclic torsional loading tests when both nonlinear properties and hysteresis properties of each material were applied. A calculation concept including torsional effective cross-sectional area and thickness of shearing flow for the torsional capacity of CFS strengthened PC member was proposed.

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This paper presents the results of un-stiffened cantilever column subjected to incremental or constant amplitude cyclic loading. The objectives of this study are to investigate the extremely low cycle fatigue life of the column and verify the proposed strain based approach. During the test, fatigue cracks initiated from the weld toe at the corner and propagated along the weld toe. Finally, the column ruptured without a local buckling. The failure of low cycle fatigue induced by large cyclic deformation has been elucidated. In a further step, the crack initiation life was estimated based on the local strain by proposed simple approach. It is indicated that correlation between the test result and the estimated life was good enough.

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For the retrofitting works for fatigue damaged connections in steel bridge bents, plates were attached by using bearing type bolts. In this study, in order to establish a modeling technique in FEM analysis of bearing type bolts, behaviors of bearing type bolt joints were examined by experiments.

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It is known that the bending strain at the head of a vertical, cylindrical fixed-head pile can be minimized by an adequate pile radius, called optimal pile radius, when the kinematic interaction dominates. In general, however, the pile may be influenced by local nonlinearities in soil, such as failure of the soil surrounding the pile. Therefore, This study focuses on the optimal radius of a pile embedded in cohesive soil under local nonlinear conditions. The Seismic Deformation Method (SDM) is used in this study. The SDM is well known as a static method that can appropriately estimate the bending strain at the head of the pile. The results of parametric analyses show that the optimal pile radius tends to increase as the degree of nonlinearity increases.

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Seismic response analysis of reinforced concrete pile foundation-soil coupled system was conducted using full-3D nonlinear finite element method. Detailed response and damage of pile foundation were investigated by comparing the result from 3-D dynamic analysis with those obtained by 3-D static pushover analysis and 2-D FE dynamic analysis. The static analysis gave different results in terms of deformation, damage and sway-rocking behavior of foundation. In addition, it was clarified that the two-dimensional model with a thickness equal to the width of footing give almost an equivalent result to the three-dimensional model.

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Many major and minor damages were found in the 2004 mid-Niigata earthquake, especially for the embankments of the Kan'etsu expressway and the Hokuriku expressway. Using both the actual damage data and detailed spatial distribution of seismic intensity, this study conducts the statistical analysis on the relationship between the damage ratio of expressway embankment and seismic intensity to construct fragility curves. Based on the obtained results, major damages that affect the serviceability for traffic are found in the area where the JMA seismic intensity is larger than about 5.1.

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The number of corrugated steel web bridge has steadily increased in terms of its structural rationality and labor-saving. On the other hand, the shearing behavior of corrugated steel web which is fixed all edge by concrete cannot be said that it has been already clarified. Thus, experimental research using full scale model and half size model of actual box girder was carried out to solve it. That research showed that the contribution of corrugated steel for shear increases accompanying with progress of cracking in concrete member and after reaching to yield shear stress, that contribution decreases gradually. And shear buckling behavior of the corrugated steel which is restrained by concrete progresses slowly, not suddenly.

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Much fatigue damage has been observed in connections between stringers and floorbeams in initially-welded steel railway bridges. In this study, analysis of fatigue cracking, stress measurement and finite element analysis on the actual bridges were carried out to identify the mechanisms of fatigue damage, in order to develop life extension methods for connections between stringers and floorbeams. In particular, it was noted that position of the train load influenced stress at crack locations. As a result, we were able to explain characteristics of stress and deformation primarily responsible for fatigue cracks in this type of bridge.

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Intelligent gas meters that stop gas supply during an earthquake are deployed for individual customers in the area where Tokyo Gas Co., Ltd. provides the service. However, there still remains unclear points in the seismic shutoff characteristics of gas meters. In this study, to reveal the shutoff characteristics under seismic motion, shaking table tests were conducted. In addition that, the relationship between the earthquake motion and gas meters' shutoff rate was investigated using about 200,000 monitored archive data that shows the shutoff situations under actual seismic motions.

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Base isolation systems are used to protect objects from damage due to seismic motion propagating from the ground on which they are supported. Although base isolation systems with low-stiffness laminated rubber bearings or roller bearings show a significant decrease in response acceleration, they may generate large lateral displacements when subjected to earthquakes waves. Such large displacements may exceed the available space, thus limiting the practical applicability. This study proposes a base isolation system incorporated with a so called "gyro-mass" device and a friction slider arranged in series. Numerical studies indicate that this system shows a significant decrease in response displacement as well as almost the same response acceleration as a conventional base isolation system.

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This paper presents an approximation method of path-independent M-integral by mapping of strain and stress fields along the integral path near the crack tip and the synthetic evaluation of kinked or curved crack model in two-dimensional linear fracture mechanics. The proposed M-integral method provides a significant improvement in the accuracy of stress intensity factors for static kinked or curved crack, and in the stability and rate of crack growth for the simulation of fatigue crack.

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The seismic performance of a bridge pier structure depends greatly on the properties of the plastic hinge region at the base of the RC pier. This means that the seismic performance of the RC pier can be enhanced by improving the properties of the plastic hinge region. Means to improve the properties of plastic hinge structures include the rational use of high-performance materials, such as high-performance concrete and high-strength reinforcing bars. This study proposes the use of ultra-high-strength fiber-reinforced concrete and unbonded bars to create plastic hinge structures that have large deformation capacity and are capable of behaving stably under earthquake loading. Cyclic loading tests and analyses concerning a RC pier incorporating the newly developed high-performance plastic hinge structure were conducted to elucidate its basic structural characteristics.

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In the authors' previous study, to investigate the time-dependent corrosion behavior for the steel structural members in boundary with concrete, accelerated exposure tests were carried out on model specimens. In addition, numerical simulations using referential spatial statistics were also performed on the models to predict the corroded surfaces corresponding to the service period.
In this research, fatigue tests were carried out to quantitatively clarify the fatigue behavior of corroded structural members in boundary with concrete. In the fatigue tests, specimens after accelerated exposure tests were used. Finite element stress analyses were also performed on the models based on the corroded specimens to investigate the stress concentration at the corrosion pit occurred in the boundary. From the experimental and analytical results, fatigue behaviors of corroded steel members in boundary with concrete were clarified. Quantitative evaluation and prediction methods for time-dependent stress concentration factor and fatigue life of the corroded members were also proposed.

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A method for the analysis of elastic half space by means of the volume integral equation is presented. The generalized Fourier transform is defined here in order to decompose the Green's function and the operator describing the fluctuation of the wavefield. The Krylov subspace iteration technique is employed to obtain the solution of the integral equation to which the generalized Fourier transform is applied. Several numerical calculations are carried out to verify the proposed method.

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This paper presents a multi-scale multi-physics analysis method for aged-deterioration of quasi-brittle materials involving micro-crack propagations. The mathematical homogenization method is applied for connecting the different state variables in micro-and macro-scale, and a weakly coupled solution method is employed for the approximation of bi-directional multi-physics phenomena particularly because of micro-crack propagations. We show the formulation of weakly bi-directional coupled problem, based on the homogenization method, between the diffusion of scalar potential and the deformation of solid. In this paper, the diffusion problem is considered as the heat conduction for the sake of simplicity, and the deformation problem involves crack propagations in micro-scale which can be analyzed by the finite cover analysis. After demonstrating the fundamental validity of the method, we present numerical examples of unsteady micro and macro coupled problems, and discuss the applicability of our method to aged-deterioration problems of quasi-brittle materials.

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This paper presents a dynamic experimental approach for the reappearance of bulge local buckling phenomenon of steel tubular stub column with nonuniform thickness around the thickness transition section. First, steel tubular stub columns are manufactured following the occurrence condition of bulge local buckling phenomenon which was previously investigated by the authors for geometric parameter (diameter to thickness ratio, thickness to thickness ratio, and length to diameter ratio). Then, the impulsive push-up test was performed for the specimens, and it is confirmed that the bulge local buckling occurrs around the section where thickness of the specimen changes, and external force conditions such as push-up veleocity and push-up forced displacement are investigated. Finally, a dynamic plastic local buckling stress formula is proposed based on the plastic local buckling load obtained from the impulsive push-up test by introducing strain rate effects into static formula, and the validity of the proposed formula is verified through the comparison with the test results.

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Much fatigue damage has been observed in connections between stringers and floorbeams in initially-welded steel railway bridges. In this study, static loading tests and fatigue tests on full-scale connections between stringers and floorbeams were carried out in order to identify fatigue performance, with the objective of improving fatigue performance so that life extension methods for the connections could be developed. As a result, it became clear that the existing connections were susceptible to fatigue damage in predictable locations, and that this low fatigue performance resulted in increased stress in the surrounding area. It was also found that a certain reinforcement method was effective in reducing stress in the fatigue damaged areas.

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A part of internal strain energy of rubber bridge bearing is transformed into thermal energy, so that temperature rise will be observed on high damping rubber bearing under repeated shearing deformation. It is, however, difficult to measure directly internal temperature subjected to large deformation. But internal temperature affects much on physical characteristics of rubber bearing. As the internal strains of rubber bearing under shear deformation are approximately condidered as uniform, so that energy absorption of rubber is assumed to be uniform. By the hybrid prediction analysis taking both experimental and numerical analysis into account, internal temperature distribution of rubber bridge bearing under repeated shear deformation, is analyzed.

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In performing seismic Probabilistic Safety Assessment (PSA) of structures, failure probabilities of the structures have been usually evaluated from seismic hazard and structural fragility curves. This paper presents a new methodology which can evaluate structural failure probability per year (seismic risk) precisely, by considering occurrence probability of the potential whole earthquakes and by conducting fragility evaluations consistent to the seismic hazard in the procedure. We introduce the physics of the earthquake ground motions, and structural dynamics at the maximum, and discuss a procedure to calculate directly P_f/year for any failure criteria of the considering structure model.

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The purpose of this research is to propose an early restoration method for lifeline systems after earthquake disasters. Road networks after earthquake disasters have an uncertain environment, that is, the restoring works are not progressing on schedule. An attempt is made to develop a decision support system of the optimal restoration scheduling by using Improved GA that can treat various uncertainties involved. In order to illustrate the efficiency and applicability of the proposed method, a numerical example is presented to compare with simple GA. It is confirmed that the proposed method can provide more robust solutions that can deal with the variations of seismic environment.

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Intermediate diaphragms are required for box girder bridges in order to keep the shape of cross section and reduce the warping stress due to cross-sectional deformation. The current design guideline of the intermediate diaphragms requires extraordinary stiff diaphragms because of assumptions for the design formula. This study aims at the rationalization of intermediate diaphragm design. FEM analyses with shell elements were carried out in order to grasp the structural behavior of box girders. In the FEM analyses, spacing and stiffness of intermediate diaphragms and curvature of curved girders are considered as parameters. FEA results showed that warping stress is not increased by increment of diaphragm spacing if stiffeners with relative stiffness of 0.02 are installed. Thus, there is no need to follow the required relative stiffness of intermediate diaphragms by the current design guideline. It was also showed that the accuracy of design formula will decrease by increment of the curvature in curved girders, especially if the curvature is greater than 0.01.

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To establish the estimation method of dynamic properties (frequency, damping, and mode shape) by ambient vibration measurement, multi channel observation data based vector AR model was proposed. In this paper, the vector AR model was introduced, and the relation between vector AR model with multi channel observation data and single point data was indicated. To verify the method's efficiency, simulation of ambient vibration for Langer girder bridge model, experiment of ambient vibration for 5DOF model, and existing Langer truss bridge were conducted.

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The purpose of study is to investigate the BMS in consideration of damage level, life expectancy, user cost and value of bridge structures. The damage level is carried out by analytic hierarchy process. The life expectancy is obtained by application of reliability analysis. UC is calculates from traffic assignment problem, and re-constructing cost is carried out for bridge value. The repair priority order of BMS is given by data envelopment analysis (DEA) from these parameters. It is considered that the analytical results are almost proper from these parameters. These analytical processes in this study have possibility of application for new type BMS in the future.

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The slip strength of perfobond strip is decided by yielding of perfobond plate or by concrete fracture. In the latter case, the strength will be effected by some factors restraining concrete crack around a hole. This paper clarifies the crack restraint factors enhancing slip strength of perfobond strip by conducting push-out and pull-out slip tests. It is concluded that the crack restraint factors are concrete covering of the connector, reinforcing bars set through or near the hole, and especially in push-out tests, the friction force between specimen and test bed which increases the slip strength greatly.

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In the seismic analysis of elevated bridges, the hyteretic behavior of pier base-to-footing connections has to be considered in case the magnitude of the pier base restraint is small or the connections are damaged during earthquakes. However, the hysteretic connection models presented so far are limited to those subjected to in-plane cyclic bending under constant vertical load. Herein, a versatile 3D connection model based on the component method is proposed for the behavior under cyclic biaxial bending and axial force fluctuations. This model is easily implemented in the customary commercial software. The validity of the proposed model is comfirmed by the experimental results under cyclic biaxial bending.

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Because of the development of high performance steel and the increasing attention on the performance based design in recent years, the application of hybrid plate girders have been investigated. However, it seems that there have not been sufficient experimental and analytical data to propose specifications for performance based design. In this paper, 17 hybrid girders were fabricated and statically tested with various combinations of moment and shear. The results indicated that there was no significant interaction between moment and shear strength based on stress distributions in web panels. In addition, the test results confirmed that the proposed equation by authors gives more reasonable estimation for the shear strength of hybrid girders.

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Recently, vibration control technologies have improved due to technological advancements in computers, sensors, and actuators. Concerning civil engineering structures, the advantage of passive control is larger than active control in the aspect of maintenance and reliability. However, bigger effects of structural response control can be expected regarding active control, and the adoption for important civil engineering structures can be expected in the near future. In this paper, we investigate an active control method using hyper vision technology, and derive recurrence relations for time integration including control forces. The feasibility of the active control method is confirmed by numerical simulations and by shaking table tests.

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This paper presents a new approximated formulation of Ogden model for isochoric deformation of rubber-like solids. In the formulation, the principle stretches in the strain energy function of Ogden model are approximated by Taylor series, and they are expressed by the invariants of material logarithmic strain. Then, the stress-strain relation and the elastic tangent moduli of the approximated model are developed together with their numerical implementations. Finally, accuracy of the model is evaluated in comparison with the exact Ogden model, and the necessary condition for proper approximation is shown on the basis of these results.

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Fatigue cracks have recently been observed at weld joints connecting deck plate and U-rib in an orthotropic steel deck. Some of the cracks initiate from the weld roots and then propagate through the thickness of the deck plate. If the deck plate are left unattended after fatigue-cracking, traffic accidents may be caused by partial sinking of the deck plate. In addition, considerable corrsion damage may also occur in the U-rib due to rainwater penetrating through the fatigue-cracked deck plate. The purpose of this research is to develop an experimental system for fatigue-cracking from the weld root in order to investigate the mechanisum of fatigue-cracking, the retrofitting methods, etc. Static and fatigue tests were carried out on model specimens of the orthotropic steel deck focusing on the scatter effect of traffic wheel loadings by asphalt pavement and on the service stress wave.

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The authors have been continuing the observation on 1 metre gauge measurement of strains induced at ground surface during earthquakes. In the present study, the array observations of ground surface strains have been conducted with the interval of each stations of about 17 metres and the maximum length of 100 metres. The pure shear strain condition was found to prevail at each station. It was also found that there was a specific direction of the principal strain. At one of the stations, the strain measurements were conducted at the vicinity of a ground water level. The strain amplitude at this location was larger than those at the other stations.

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The strains induced within the grounds are comprised of six components. The strains induced at the ground surface are comprised of four components. The authors have been continuing the observations of the three strain components induced at the ground surface during the earthquakes. In this paper, the observation of the remaining strain component, i.e. vertical normal strain, induced at the ground surface was undertaken using a gauge length of 1 metre. Based on the several earthquake observations, it was found that the vertical strain is similar in magnitude to the principal strain at the ground surface, and also has a tendency to be completely out of phase in time scale with respect to the vertical accerelation.

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