In CFRP bonded steel members, the shear stress is caused in the adhesive by temperature change, due to difference in coefficients of thermal expansion between steel and CFRP. CFRP strips are often separated from steel plates by the debonding shear stress, which is the high shear stress developed in the adhesive at the ends of the CFRP strips. In this research, the debonding shear stress induced by temperature change is theoretically analyzed for CFRP bonded steel plates and also for the case a glass fiber sheet is inserted under CFRP strips. The analytical results are confirmed by the measurements of the strains created by temperature change in CFRP bonded steel plates.

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Presented is the trial of road asset management supported by soil/water coupled finite element analysis. For the highway embankments on soft foundation, excessive long-term settlement and deformation are usually seen as a result of consolidation settlement The authors consider that settlement and deformation of highway embankments are the indicators effectively applicable to predict deterioration of highway. The soil/water coupled finite element analyses are conducted in analyzing the 20 years old existing highway embankments and its predictability of settlement and deformation during and after construction is verified. Based on the results of the simulation, the performance modeling of highway is carried out and the predicted life-cycle cost is compared with cost actually needed in the past 20 years.

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RC structural health monitoring (SHM) often includes two main concerns on local damage detection and global structural behavior. In our recent study, a novel packaged long-gage fiber Bragg grating (FBG) sensor for practical adaptation in civil SHM has been developed and verified to have the ability to obtain effective macro-strain distributions. This paper is dedicated to proposing an integrated SHM strategy for RC flexural structures by employing the developed sensors. Experimental investigations on a normal RC beam installed with the FBG sensors of different gauge length are first carried out. On one hand, the ability of distributed FBG sensors to detect the occurrence, location and extent of cracks has been testified in contrast with the results from foil strain gauges and crack gauges. On the other hand, a perfect linear correlation between the measurements from FBG sensors and those from displacement transducers has testified the sound performance of the developed sensors for global structural behavior evaluation. Numerical simulations based on section fiber modeling method with the plane section assumption are then performed to compare with the experimental results. Their nice agreements have further verified the ability of the FBG sensors to estimate structural parameters and evaluate structural global behavior. Regarding these meaningful investigations, the inverse analysis including load and structural parametric identification is carried out by utilizing the measured macro-strain distribution. An integrated SHM strategy based on distributed long-gage FBG sensors for RC flexural structures including local crack monitoring, parametric estimation and global behavior evaluation is proposed finally.

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A novel hybrid FRP-concrete sttuctural system was proposed in past study. In the study, high strength type of CFRP sheets is axially bonded on the bottom surface of the concrete core to cany tensile load while GFRP sheets with higher rupture strains are hoop-directionally wrapped to bear the shear load. The GFRP sheets also provide confinement to concrete core and delay the debonding of CFRP sheets. A minimum reinforcement ratio of steel rebars is used to control the localization and propagation of flexural cracks. In this study, a series of 4-point bending experiments were carried out to study the performances of the hybrid FRP with high modulus type of CFRP sheets, T grass fiber sheets and Dyneema fiber sheets and concrete hybrid beams. Based on the principles of strain compatibility and equihbrium, an iterative analytical model is developed to evaluate the flexural behavior of the hybrid beam specimens.

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This paper carries out a preliminary study on utilizing observation cameras to meet the demand for the quickness in evaluating urban earthquake disaster. The key issue is the examination of the high-accuracy and high-speed in measuring displacement by means of image analysis. The properties of the pixel data taken for buildings and building edges are quantitatively analyzed in this paper. The applicability of GIS to set a window for image analysis is proposed to reduce the computation cost. Also an experimental evaluation of sub-pixel edge detector is performed.

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The durability of concrete structures decreases easily due to such physical or chemical environmental effects as freezing-thawing process, chemical attack, fatigue or carbonation. The degree of damage in concrete is, in most cases, evaluated by a compression test and a rebound hammer test. For effective maintenance of concrete structures, it is necessary to evaluate not only the strength of concrete but also the damage degree. Quantitative damage evaluation system of concrete is proposed by applying acoustic emission (AE) method and damage mechanics. The procedure is named DeCAT, which is an abbreviation of “Damage Estimation of Concrete by Acoustic Emission Technique”. In this study, the relative damage evaluation of concrete by DeCAT in core tests. Core-samples were collected from a reinforced concrete water channel that had been used for 23 to 73 years. Mechanical properties of compressive strengths and Young's moduli were measured during the compression test, and dynamic Young's moduli were calculated from a longitudinal wave velocity. By estimating the concrete damage, it can be quantitatively evaluated from AE generating behavior under compression test and Calm ratio under cyclic loading test.

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This paper formulates the survival quantile model for analyzing the increasing hazard shape of a structural deterioration progress. The Gompertz model is specified in order to express the type of late-coming hazard of structural deterioration, and also the log-logistic model is specified to draw the type of peak hazard of deterioration. These models are applied to the bridge component and the pavement road surface and the paper shows the estimated results. The author mentions the maintenance policy implication for the irregular hazard shape of structural deterioration processes, for instance an index of time for peak point, structural monitoring scheme, maintenance scenario for an irregular hazard shape.

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Wave propagation in an infinite periodic railway track is investigated. In the analysis the constituents of a rail and sleepers are considered for the track model. Propagation modes of the periodic structure are described by virtue of the Floquet transform. This method makes it possible to reduce the infinite periodic problem to an eigenvalue problem for a unit structure with finite length. The rail is modeled by a Timoshenko beam and discretized by finite elements. Through numerical analysis the wave number-frequency curves for the propagation modes are obtained. It is found that the installation of sleepers causes a mode in which the propagation waves are accompanied by sleeper vibration. Besides, the influence of the stiffness of rubber pads on the propagation modes is discussed.

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Due to higher bridge piers and massive girder loads, long span bridges over rivers tend to have a longer natural period of equivalence. Therefore, during an earthquake, train-running quality is impaired on the railway long span bridges. In this study, the authors analyzed numerically dynamic behavior of the train-running quality on a long span bridge, and clarified the following items: Firstly, the train-running quality on the bridge becomes lower on girders in the middle of the bridge. Secondly, folding displacement at edges of the bridge did not largely affect the train-running quality. In addition, the authors studied on improvement measures by taking rigidity of piers and bearing as a parameter, and clarified that the train-running quality be improved with provisions of a large-size caisson or a sliding bearing.

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This paper presents a nonlinear spring multi-Winkler model for nonlinear seismic response of foundation and superstructure system using the fiber element method. The nonlinear soil reactions are modeled by using the spring coefficients per unit area of foundation surface with 3 components consisting of normal traction and two shear fractions on foundation surface. The shapes of monotonic curves and the hysteresis loops of the 3 springs are evaluated using the Mohr-Coulomb yield criterion and no rigidity of tension, and by the concrete crack model. The proposed spring model can incorporate such effects as separation and slippage at the soil foundation interface, and also the effect of coupling between the normal traction and two shear tractions on foundation surface. To demonstrate an applicability of the proposed model, a nonlinear seismic response analysis of cable stayed bridge supported by the two caisson foundations is performed and the effects of nonlinear behaviors of soil reactions are discussed.

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A dynamic horizontal loading system based on the wave theory was developed as a new on-site pile testing method. In this test method, the horizontal resistance of piles is calculated by applying an impact load in the horizontal direction to the pile heads using a hammer and conducting wave motion analysis of the measured acceleration and strain. A series of dynamic horizontal loading tests of steel-pipe piles was conducted and results were compared with those of a static horizontal loading test conducted at the same site. It was shown that the relationship between the load and pile displacement and the coefficient of horizontal subgrade reaction obtained by the dynamic horizontal loading test has relatively favorable compatibility with the values from the static test.

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Since the damage of structure increases by the effect of the aftershock, it is necessary to clarify the accumulated damage on the performance-based design due to earthquake. Because the damage of the structure may be closely related to the earthquake input energy, it is importanto carry out the accumulated damage assessment by means of the energy evaluation. In this present study, by applying the target performance due to demand strength spectra with the damage index, it is examined with cumulative damages which are given by aftershocks for the earthquake performance evaluation of the structure. It is shown that seismic performance evaluation is closely related to accumulative damage estimation due to aftershocks.

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This paper describes the validity confirmation of design to vibration control of Multi-direction Tuned Rolling Mass Damper (MTRMD) system by the vibration measurement of ITV pillars where MTRMD was given on site of city highway bridges. MTRMD system is the combination of the rotating ball and the hemisphere container which was made of the synthetic rubber. So far the simulation and experimental model tests have been done to estimate the abilities and the performance of MTRMD, the damping effect and the durability was confirmed by the vibration measurement for ITV pillars on site of city highway bridges in this time.

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This paper presents a newly developed procedure to solve the two-dimensional unsteady Navier-Stokes equations for an oscillating floating body. The main goal of this procedure is to investigate the unsteady viscous flow around a floating body at small amplitudes. Heaving motion and rolling motion are numerically simulated in order to compute the added mass and damping coefficients. The simulation results are compared to the values obtained by the inviscid-based potential theory. An experimental comparison is additionally carried out using the wave response, which is estimated from the added mass and damping coefficients obtained from the proposed N-S solver. The simulation results presented in this paper are remarkably similar to the ones computed from potential theory.

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This paper presents a newly developed numerical analysis program for second-order diffraction waves around a general shape structure using Green's function. In the developed program, the direct method to calculate the second-order velocity potential is used. A program based on the indirect method, but without considering second-order diffraction potential was previously developed. However, the indirect method does not allow the calculation of the pressure distribution nor the free surface elevation. Therefore, in this paper, a new approach using the direct method for calculation of second-order forces is numerically implemented and its results are compared with those obtained from the indirect approach. In the newly developed program, bi-directional waves with two different frequencies are considered.

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The dynamic response of an oscillating flexible riser involves a coupled phenomenon in which the nature and magnitude of the fluid forces acting on the riser highly depend on the structural riser's response. Therefore, the development of a response prediction model for oscillating flexible risers must consider the numerical modeling of fluid-structure interaction. In this paper a response prediction model for oscillating flexible risers using CFD-derived force coefficients is presented. A 20-meter riser model, sinusoidally excited at its top end using six different values of tension forces, is employed for its experimental validation. The computed maximum amplitudes in both in-line and cross-flow directions show good agreement with the experimental data considering the range of error commonly accepted for such implementations.

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In order to perform the reliable design of offshore structure, it is important to clarify the dynamic response characteristics due to severe dynamic forces. In the present study, the dynamic responses due to wave and seismic force which have different dynamic properties are examined. It is shown that the reliable evaluation can be carried out by clarifying effects which are caused by the nonlinear dynamic response and dynamic characteristics of external forces.

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