It is well known that a bluff body cross-section exhibits various kinds of aeroelastic instabilities such as vortex induced vibration, galloping and torsional flutter. Since these cross-sections are used in a long span bridge and tall building, it is important to predict their occurrence in wind resistant structural design. In this paper, the authors made a series of comparisons of unsteady wind forces, unsteady pressure distributions and free vibration responses between the previously conducted studies and the unsteady two-dimensional unsteady κ−ε model for rectangular cross-sections with cross sectional ratio of 2 and 4 in a smooth uniform flow in order to verify computational predictability of aeroelastic instabilities. As a result, the computation could successfully predict the onset velocity and response of these aeroelastic instabilities.

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  This paper presents design formulas for rotational deformation of natural rubber bearings on the basis of finite element analyses of the bearings. At first, a natural rubber often used in the bearings is modeled by hyperelastic damage model, based on several material tests. In addition, a material property, which is equivalent to elastic limit of tensile deformation of the bearings, is identified by simulating one of the tests. Then, critical angles of rotational deformation of the bearings are computed through simulations, where shapes-factor, vertical load and initial horizontal deformation are changed. From results of the simulation, simple formulas approximating the critical angles are proposed, and they are found to exhibit larger values in comparison with present design code. Finally, validity of the proposed formula is verified by fatigue test on rotational deformation of a bearing.

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  This study proposes a certain measure for decision making associated with the seismic retrofitting investment strategy preventing a large-scale malfunction such as water supply loss under seismic risks. Newly developed stochastic value index is adopted for the overall evaluation of social benefit, income, life cycle costs and failure compensation associated with the existing lifeline systems damaged by an earthquake during the remaining service period. Discussions are given for the optimal seismic disaster prevention investment of the existing deteriorated lifeline system. Finally, the present study can provide a performance-based design method for seismic retrofit strategies of existing lifelines which can be carried out through the target probabilities of value loss and structural failure.

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  A numerical model was developed to predict the dynamic response of a floating offshore wind turbine system in the time domain, considering the interaction between wind turbines and floater. The responses predicted by the proposed numerical model show good agreements with experiments. Morison's equation overestimates the heave motion of the floating structure with vertical column, while the hydrodynamic damping ratio proposed by Srinivasan et al. gives good predictions. The effect of the aerodynamic damping from the wind turbine is small in the survival condition since the effect of the hydrodynamic damping is significant, while in the operating condition the effect of the aerodynamic damping decreases the dynamic response. Elastic deformation plays an important role in dynamic response of the floating structure. The predicted response was underestimated when the elastic deformation is ignored. The nonlinearity of wave becomes dominant when the water depth is 50m and the elastic modes might be resonant with the higher order harmonic components of nonlinear wave, resulting in the increase of dynamic response of the floating structure.

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  A Serious fracture that extended halfway through the circumference of a steel pipe column was discovered in a pedestrian bridge across a prefectural road. A lot of pedestrian bridges have been designed and constructed according to the standard specifications. Therefore, there is a possibility that pedestrian bridges whose structural details are the same as those of fractured pedestrian bridges in this paper may exist. It is very important to identify the cause of the fracture for preventing the same failure mode.
  In order to identify the cause of the fracture, observation of crack surface, SEM observation, material property tests, measurement of strain and calculating histogram of the stress range and the frequency were carried out. Moreover, the fractured steel pipe column of the pedestrian bridge was retrofitted by applying bolted splice rings and plates.

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  Even though the aerodynamic derivatives associated to lateral motion is much smaller than the other derivatives associated to vertical and torsional motion, the results of Akashi Strait Bridge full scale model tests show better fitting to the results of 3DOF (vertical, lateral and torsional motion) flutter analysis than those of 2DOF (vertical and torsional motion) flutter analysis. In this study, the effects of lateral motion is investigated by using 3DOF or multi-mode step-by-step analysis. In consequence, the flutter of Akashi Strait Bridge can be characterized by aerodynamically 2DOF coupling and structural coupling between lateral and torsional motion, and can be described by 2DOF aerodynamic forces.

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  The hierarchical reinforced concrete element is proposed for efficient global analysis of steel-concrete mixed bridges with prestressed concrete deck slab. In this element, reinforcing bars that are represented by cable elements are embedded in a solid element, and a displacement function of the reinforcing bar is expressed by generalized displacements of a solid element. As such, the element division is not necessary at the position of reinforcing bars and many reinforcing bars can be arranged in any direction into the solid element. Furthermore, a curved tendon is represented by a mapping cable element considering the initial stress.

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  The fundamental of structural inspection is a visual examination of representative parts of the structure. Several accidents on bridges in Japan and USA two years ago have shown that not only the bridge inspection but also the estimation of structural safety by bridge experts are necessary. But it is almost impossible to perform that kind of estimation of structural safety due to economical condition of the local governments. In this paper, the synthetic safety estimation of infrastructures by SVM (support vector machine) is proposed. Generally SVM requires the input data of the training data like the estimation of the structural experts. In this paper the input data are the deterioration degrees of the structural parts and the output data is the working year of the structure. As numerical example, 2959 inspection data of the bridges in Hokkaido are used as training data and, for example, the health ranking of the bridges is shown.

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  The method that a slab covers ground surface above the foundation structures is suggested as a seismic retrofit method. The method makes it possible to reduce the term and the cost for retrofitting of the foundation structures by omitting excavation.
  It is known that this method will be more effective for seismic retrofitting of the foundation structures in case a slab has piles which fixes itself. Although, we worry about the interaction effect that the closer piles fixing a slab were to a footing, the less the effect of seismic retrofit would be.
  Therefore we practiced some experiments considering the relation of the lateral resistance due to a footing, soil, a slab, piles fixing a slab with centrifugal model test.
  This paper says that these experimental results give that ground-surface-slab increases the lateral resistance force of footing, and piles fixing a ground-surface-slab decreases the lateral resistance of footing in proportion to the overlapping area under the influence of a footing and piles.

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  A finite difference analysis method is developed to simulate outdoor sound propagation under the influence of inhomogeneous or unsteady meteorological conditions by applying the separable solution of aeroacoustics to the outdoor sound. It is verified that the perfectly reflecting boundary on ground surfaces and the nonreflective boundary to realize the sound transmission from finite domain to infinite domain virtually perform properly in the numerical analysis. Then the numerical analysis precisely simulated the advective effect of wind on sound propagation and the change of sound wavelength due to the difference of air temperature. Furthermore, a shadow zone of acoustic waves was identified from the computation of sound propagation with the nonuniform vertical distribution of wind flow.

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  In the Central Circular Shinjuku Route of Tokyo Metropolitan Expressway, a new construction method such that the ramp tunnels are connected with the main-way shield tunnels is employed. The connections are large-scale steel-concrete composite structures, in which loads are transferred by the main girders of steel segments embedded in the body of the ramp tunnel. As to the load transfer, the influences of the structural characteristics of connection, the cross section and the embedded depth of main girders must be clarified. The authors carried out finite element analyses and large-scale model experiments to examine the transfer mechanism of such forces as axial force, bending moment and shear force on the connection. Based on the analytical and experimental results, a design method of connection was proposed, the validity of which was verified by experiments.

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  For the Yokohama Bay Bridge, Rainbow Bridge and Tsurumi Tsubasa Bridge, long-span cable-supported bridges on the metropolitan expressway, seismic records have been collected intensively using numerous seismometers since their construction. This study examined how the modal parameters and seismic response parameters estimated from the acceleration records collected on the three bridges during the 2004 Chuetsu-Niigata earthquake could be reproduced by a seismic retrofit dynamic analytical model. Normal mode of vibration existed that could not be reproduced by the analytical model unless the effect of friction at bearings was taken into consideration. The periodicity of acceleration response was reproduced generally well despite variations in response level in the direction transverse to the bridge axis. Along the bridge axis, however, periodic elements existed that could not be reproduced by the dynamic analytical model used for seismic retrofit although corresponding seismic records were available. It was revealed that the existence of such periodic elements was ascribable to the effect of friction at bearings.

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  Inspection or test data of specific site as well as latest knowledge of degrading mechanism should be considered in order to perform accurate reliability estimation of existing structures. This study discusses the methodology to estimate limit state probability updated by inspection or test data. The formulation with sequential Monte Carlo simulation (SMCS) is introduced for updating of model parameters and limit state probability. After demonstrating the solutions by SMCS agrees well with theoretical solutions in a linear Gaussian problem, numerical examples on updating of chloride deterioration parameter of a RC structure and three kind of limit state probability are shown.

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  Concerning hydrogen embrittlement of corroded bridge wires, the effects of diffusible hydrogen concentration to corrosion progress and the effect of introduced stresses to high strength galvanized wires were investigated. Hydrogen concentration directly relates with hydrogen embrittlement. The three corrosion level specimens were produced and then the concentration of the diffusible hydrogen was measured by the gas chromatography with scanning temperature. The concentrations of the corrosion level 1 to 3 specimens and those with tension or non-tension were all between 0.1 to 0.2 ppm. This value is well below the critical diffusible hydrogen concentration of 0.6ppm to cause embrittlement.

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  The present paper proposes a ratio of effective acceleration A₀ to PGA(A₀/PGA) to evaluate periodic characteristics of earthquake ground motion by using JMA seismic intensity and PGA. A relationship between A₀/PGA and spectrum of earthquake ground motion was theoretically studied. It is clarified that the shape of spectrum of earthquake ground motion correlate with A₀/PGA. Next, a relationship between A₀/PGA and peak period of fourier and velocity response spectrum were examined. Moreover, it was found that A₀/PGA have a positive correlation to the relative amplitude of spectrum for period 1 to 2s. Finally, we proposed an equation of the average amplitude of velocity response spectrum for period 1 to 2s(S_v1-2) as parameters of A₀/PGA and logA₀. We verified that the proposed equation can evaluate S_v1-2 more accurately than that using only logA₀ or logPGA.

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  The authors clarified the aerodynamic characteristics of the pentagonal cross-section girder that might have enough aerodynamic stability without using additional devices and investigated the aerodynamic stable mechanism by conducting various wind tunnel tests in a static state. As a result, it was found that the aerodynamic characteristics of the girder depend on the lower flange slope because the magnitude of the flow separation from the lower slope portion depend on the lower flange slope and the pressure distributions are different based on the lower flange slope, and the girder corss-section with the lower flange slope of 12deg. is the most recommended for the girder for the cable-stayed bridge.

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  Various vibration control methods, including the skyhook control, have been proposed to achieve dynamic response reduction in terms of the absolute response. It is often observed that negative stiffness appears in the behavior of control devices following skyhook control. However, evaluation and the significance of negative stiffness have not been discussed in past research. In this study, negative stiffness appearing in skyhook control method is theoretically evaluated with the use of equivalent control parameters in the negative stiffness control. Based on the result, relevance of the negative stiffness control to skyhook control is discussed, and the optimal design of the negative stiffness control is proposed.

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  This paper proposes an experimental approaches on the fragment scattering behavior of concrete specimen subjected to about 2.0m/s velocity high speed loading, and analytical approaches on these behavior by using 3-dimentional distinct element method. First, the high speed loading experiment are carried out to the concrete specimens, which have different aggregate size and different water cement ratio. The fragment characteristics, i.e., shape, mass, and velocity are measured, and the kinetic energy conversion ratio is discussed. Secondly, the applicability and some modification of the distinct element method for this phenomena are discussed.

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  The present paper shows a recconnance report on the damage of bridges due to 2008 Wenchuan, China earthquake. Site investigation was conducted by the authors on August 10-14, 2008. Presented are damage of thirteen bridges as well as possible damage mechanism. Characteristics of three near-field ground accelerations and Chinese practice on seismic design of bridges are also presented. It is found from the damage investigation that insufficient intensity of seismic design force, inadequate structural detailing for enhancing the ductility capacity and absent of unseating prevention devices resulted in the destructive damage of bridges.

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  The liquid sloshing phenomenon of oil storage tank was excited by the 2003 Tokachi-oki Earthquake. This phenomenon caused severe damage to oil storage tanks at Tomakomai igniting fire and sinking floating roofs. After this accident, verification of various, dynamic behavior of a floating roof due to liquid sloshing have been begun and it has been desired to verify it with the tank at the real scale level. Then, we propose the experiment method of generating the sloshing phenomenon in the floating roof tank using a real tank. This method uses the excitation equipment of the liquid sloshing phenomenon by the Wave Generator with air cylinders which is set up and moves the fluid in the tank. As a result, we succeeded in the generation of the liquid sloshing in a real tank and obtained appropriate damping factor of the liquid sloshing.

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  When composite girder bridges are exposed to fire due to the traffic accident, doubt fire and so on, it is important to verify the damage of shear connections as well as the steel girder and RC slab. However, damages of the shear connection cannot be confirmed easily. Therefore, the authors carried out the static and fatigue push-out tests for headed studs which were naturally cooled after heating. From the test result, it was found that the fatigue strength of studs heated up to 700°C shows remarkable decrease. Based on the test data, the results of the fatigue verification under various conditions for studs damaged by fire and its considerations are reported in this paper.

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  The strong motion simulation technique using site-dependent amplification and phase characteristics was originally proposed by Kowada et al. and its applicability has been extensively studied by the authors. One disadvantage of the method, however, was that it cannot generate a ground motion that satisfies causality conditions, meaning a ground motion with zero amplitude at the beginning of the time history. In this article, the authors revise the method by introducing a smoothing technique in the procedure to generate Green's functions. It was confirmed that the revised method can generate causal ground motions, which are in agreement with the observed ground motions during the 2003 Tokachi-oki earthquake.

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