This paper describes newly developed measurement techniques of the three-dimensional (3D) behavior of an actual ballast stone.A field experiment was performed on a railway line using aspecial ballast sensing stone with piezoresistive triaxial accelerating sensors for measurement.Two accelerometer chips are embedded in a crushed stone separately. The average value of the two acceleration measurement values indicates the to acceleration;the difference of the two acceleration measurement values yields off the rotational acceleration. The ballast grain receives an impact load imparted by a running train and generates a high-frequency translational motion together with the high-frequency rotational motion.We recordeda large amplitude signal immediately after loading;the high frequency of several hundred Hertz was rapidly attenuated. Regarding the reproducibility of high damping performance, this paper also proposed techniques for parameter determinationin the dynamic discontinuous deformation analysis based on the results of a field measurement experiment on an actual railway track.

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Spatial distributions of strains in granular media were investigated by numerically simulating an idealized assembly of two-dimensional particles. The objective of this investigation is to provide insight into the change in the microstructure of granular materials during a loading process. In particular, the spatial association of the relative displacements of particles during the loading process was examined by the spatial analysis. The distinct element method was used for simulating an idealized assembly. Using the calculated relative displacements of the particle, the local strain increments were calculated within triangle elements which were defined by particle centers. The spatial analysis indicated that the spatial autocorrelation distance of the local strain increment varied during the loading process and the strain localization zone occurred prior to the peak stress ratio.

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This paper presents a 3-D visualization and quantification of granular packing structure using a micro x-ray CT at SPring-8. SPring-8 is the world's largest third-generation synchrotron radiation facility where a high-resolution x-ray CT system is available. Specimens of Toyoura sand and Glass beads for dense and loose packings are used in the study. A newly-developed image analysis procedure enables to automatically identify each grain in the specimen. The accuracy of the identification reaches around 80% or more even in the dense packing of irregularly-shaped grains. The obtained grain information is further processed to quantify 3-D grain shape and contact point statistics.

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Understanding the rate of aggregation of colloidal particles is very important to consider the transport of substances in water environments. Theoretical investigations on aggregation kinetics have been perfonned by using trajectory analyses to elucidate the influence of electrochemical and hydrodynamic interactions on aggregation. So far, however, this analysis has not been fully applied to the aggregation between unequal-sized particles with opposite sign of surface electric charge in a shear flow. In this study, the rate of shear hetemaggregation between oppositely charged and unequal-sized particles was evaluated by using the trajectory analysis. The calculated results indicate that the rate of heteroaggregation increases with decreasing salt concentration and that the effect of attractive electric double layer force is more significant at higher shear rates. At low salt concentrations, in addition, the present evaluation reveals that larger values of scaled capture efficiency were found not for the homoaggegation between equal-sized particles but for the hetemaggregation between unequal-sized particles. The calculation also suggests an experimental plan, that is, pure heteroaggregation without electric double layer effect can be obtained by using the binary mixture of oppositely charged and unequal-sized particles in 1-10mM aqueous solutions.

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In Japan, there are many precipitous mountains. Because of it, mudflow often occurs in rainy and typhoon season. Countermeasure for mudflow is required as soon as possible, but prediction system of mudflow has not been established yet. The purpose of this study is to establish the simulation of mudflow that is useful for countermeasure for mudflow. In flowing mudflow, boulder comes floating and it moves ahead of a flow. This phenomenon has been confirmed and published. But it has not been figured out. In this paper, this phenomenon is reproduced by the DEM simulation. And, the new measurement method for verifying the validity of a simulation is proposed. Electromotance is used for this system to be able to sense position of invisible boulder.

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Flow behaviors of granular materials on slope were discussed by model tests and Distinct Element Method in two-dimension. DEM simulation results can simulate the tendency of model test results. The relationships between macro and micro behaviors on typical phenomena such as the velocity distribution in depth and lift up of the coarse particle in the flow were examined on the basis of the numerical results. We focused the stress-chain formed in granular materials. It was found that the distribution of averaged coordination number was corresponded to the distribution of velocity indicating three layers structure. In addition, it was revealed that at the changing points of their distributions, both of the void ratio and the mean normal stress attach to critical state.

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he sloshing phenomenon might be caused by long-period ground motion. As a result of it, the storage liquid might overflow. The pool of the nuclear waste storage overflowed due to the Niigata Chuetsuoki Earthquake is the recent case. In this paper, shaking experimentation was conducted by setting up small tank of rectangular section on shaking table to make this cause clear. In addition, the effect of setting the net in small tank inside as one of sloshing measurement is explained.

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This study aimed to clarify the influence of sloping wall to sloshing in a reservoir by numerical analysis called the SPH method. We compared SPH simulations with some theoretical equations and with some experiments. Finally, we proposed the equation which gave the natural circular frequency as the function of slope angle. The equation means that the natural circular frequency of sloping wall reservoir is almost the same as that of rectangular tank which has the same surface length as the intended sloping wall reservoir. We considered the reason is the velocity distribution of water particle is similar between these systems.

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The liquid sloshing in petroleum tanks is one of severe problem against huge earthquakes such as the Tokai Tonankai and Nankai earthquakes. In this study, we are developing a damper to reduce sloshing. The damper consists of partitions with slits which gives resistance to liquid moving in the tank. The model experiment and numerical simulation are performed to determine the optimum layout of the damper As the results we find the optimum layout which can reduce the sloshing height to one-tenth. Furthermore, by the results of the real-scale numerical simulation of cylindrical tank with the layout, we confirm our damper is effective to reduce sloshing under the condition of the seismic motion in the 2003 TOKACHI-OKI earthquake.

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This study analyzed the extent of tsunami propagation and the behavior of tsunami water level into the river through the study of Mukawa River and Sanikawa River that face the Pacific Ocean. For the study of tsunami propagation into the river, tsunami runup form at the river mouth was necessary and 2-D non-linear long wave was applied in this study. For the analysis of tsunami propagation, the consideration of undular bore fission was necessary. 2-D analysis of dispersive waves of tsunami was favorable for this purpose, but it was not easy due to the limitations of computing situation. In this study, 1-D non-linear dispersive long wave model and 2-D non-linear long wave model was introduced by taking consideration of the applicability and the limitation of those models.

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Uplifting of sewage manholes is one of the typical and striking damage pattern observed in the area being hit by large earthquakes. A simplified method to estimate the maximum uplift displacement of a manhole and settlements of backfill soil under liquefaction is derived based on the mechanism of uplift of a manhole under undrained condition of backfill soil. The method is capable of evaluating effectiveness of countermeasures against uplift by considering excess pore water pressure ratio and/or unit weight of backfill soil. In the present study, the applicability for the case without countermeasures is investigated through comparison with experimental results. Results show that measured uplift displacements and settlements are within the range predicted by the proposed method.

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A method of estimation of earthquake ground motion using nearby earthquake ground motion record and microtremors horizontal to vertical (H/V) Fourier spectral ratio is presented. In this formulation, an earthquake ground motion is estimated from the earthquake ground motion recorded in the nearby observation site by using the correction factors which consist of the difference correction factor between the H/V spectral ratios of the strong motion record and the microtremors at the strong motion observation site β, the normalized microtremors H/V spectral ratio of the both sites by their peak values, and the site factor of vertical ground motions γ. By using the observed microtremors and earthquake ground motions in the Miyazaki and Fukuoka Prefectures, the presented estimation method is examined. This examination demonstrates a potential capability of the presented method in the frequency range from 0.5Hz to 10Hz, especially around the predominant frequency of the site.

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Recently, many reinforcement measures have been developed to prevent gravestones from overturning. In this study, we focus attention on the interlocking reinforcement measure using steel bars. This reinforcement measure is widely used, but there are no specifications as to how long, how thick and how many steel bars should be used. To clarify the adequate size and installation method of steel bars, 3-dimensional shaking table tests of full-scale Japanese.type gravestones are conducted. Seismic waves with seismic intensity of 6, 6+ and 7 are used as input ground motions. Seismic behavior of four gravestones, one without reinforcement, one with a long and thick steel bar, one with a short and thin steel bar, one with two short and thin steel bars, are compared. Moreover, numerical simulations of gravestones are done using 3DDEM, and effective reinforcement measures are discussed.

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Stone masonry houses are the most common type of construction in the Alpine Himalayan Belt across Pakistan, India and Nepal. However, the seismic resistance of these houses is highly questionable if constructed without any form of lateral support In this paper, the effectiveness of wooden bond beams as a retrofit solution has been examined. Dry stone masonry houses have been modeled by finite element method considering stones as linear solid and interfaces as joint elements. The joints are allowed to open and slide satisfying the Mohr-Coulomb criteria. To calibrate the values used in the numerical modeling an experiment using a small scale wall made of wooden blocks was shaken in small custom made table. The corresponding parameters which showed good agreement with experimental results were taken as inputs for the non linear dynamic analyses of various model houses. The results showed that wooden bond beams can be an effective technique for upgrading low strength masonry homes in low seismicity regions

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Since significant damages during 1995 Kobe Earthquake, one of urgently needed countermeasures is to retrofit frame type timber structures. In responding, the authors have proposed Arc-Shaped Dampers with aluminum. In order to investigate seismic performance of the proposed damper installed at the beam column joint, cyclic loading tests were conducted focusing on hysteretic characteristics and effect of damping. Following results were obtained: 1) Maximum load in compression is smaller than that in tension and during 1/15 drift angle, rapid load increase is observed in tension. 2) the proposed damper has enough effect of damping over 1/30 drift angle. 3) In seismic response analysis, the proposed damper can makethe maximum displacement reduced by a half.

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Seismic safety evaluation against fault displacement induced by surface earthquake fault is an important subject for long and large structures. However, a method for evaluating seismic safety against surface fault displacement has not been established yet Therefore, we have studied and devised a 3-D dynamic analysis method for evaluating discontinuous behaviors of dam and surface earthquake fault by applying progressive wave analysis. And, in order to examine an applicability of the method proposed, we have made 3-D dynamic analyses in regard to the discontinuous behaviors of concrete gravity dam against surface fault displacement It can be concluded that the method proposed is effective for evaluating discontinuous behaviors of the coupled dam-foundation-surface earthquake fault system. The proposed method can be broadly applied for various kinds of structure-foundation rock-fault system.

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Structural safety for earthquake waves emitted by a nearby fault is a major concern in Japan. For high accurate estimation on seismic structural response, it might be desired to estimate its seismic response by analyzing a fault-structure system: a full three-dimensional model in which a source fault and a target structure are modeled so that fault processes, wave propagation and amplification processes, and resulting dynamic responses of the structure can be computed numerically. To analyze this fault-structure system, this paper presents a proposal of an efficient approach based on multiscale analysis and examination of the validity of the proposed approach. Discussions are presented to describe the usefulness and applicability of the proposed approach to estimate the seismic structural response.

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This paper presents a methodology of data conversion from GIS to urban area models which are used for the numerical simulations of natural disasters. The key point of the methodology is the use of intermediate data, i. e., GIS is converted to the intermediate data from which the models are constructed. Two kinds of intermediate data are developed, and they are converted to models for non-linear seismic response analysis and for flood and volcano eruption simulations. The robustness of the data conversion is examined, and commercial GIS is successfully converted to urban area models for earthquake, flood and volcano eruption simulations.

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The purpose of this research is to propose an early restoration for lifeline systems after earthquake disasters. Here, two issues are focused on, the first of which is such an allocation problem that which groups will restore which disaster places, and the second is such a scheduling problem what order is the best for the restoration. In order to solve the two problems simultaneously, Genetic Algorithm (GA) is applied, because it has been proven to be very powerful in solving combinatorial problems. However, road networks after earthquake disasters have an uncertain environment, that is, the restoring works are not progressing on schedule. The actual restoring process should be performed by considering various uncertainties simultaneously. In addition, the restoring works should be performed by not single group but multiple group in order to make the progress more effective. In this study, an attempt is made to develop a decision support system of the optimal restoration scheduling by using the improved GA to consider uncertainty.

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Consideration of nonlinear response of structures is essential in the dynamic response analysis for the performance based design. Due to technical difficulties, however, they are not sufficiently considered in the current seismic design schemes. This paper proposes a method to estimate an input ground motion from the time-frequency characteristics of the nonlinear response of sys-tems, by using wavelet transform. Performance of the proposed method is verified by numerical simulations.

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Ministry of Land, Infrastructure and Transport recommends that the water level difference in pool-and-weir fishway must be in the range between 0.1m and 0.2m without any verification. In this study, the water level difference in a pool-and-weir fishway was changed between 0.05m and 0.425m and migration rates were obtained. It was found that Zacco platypus and Zacco temminckii migrate with swimming under the condition that the water level difference is lower than 0.2m and also that Zacco temminckii only migrates with jumping under the condition that the water level difference is in the range between 0.275m and 0.425m. Migration rates concern with the velocity in the orientation area, because the fishes orient in the favorable velocity area.

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A new estimation method of discharge hydrograph during floods, which numerically solves the shallow water equations using multipoint water level hydrographs, is applied to a flood in the Minochi river. The physical environmental data of the river is so limited that topographical surveying using GPS, total stations and 3-d terrestrial laser scanning has been carried out along with continuous observation of water levels at several stations. Concurrently a stage-discharge curve in the river reach is produced by 2-d numerical simulations for relatively low and steady flows. The two methods are applied to a flood discharge in 2007 in the river. It is shown that the new discharge estimation method can give discharge hydrograph, whose peak value agrees well with that estimated by the stage-discharge curve.

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The Chiyoda Experiment Channel, a section of the Chiyoda New Channel, is Japan s largest hydraulic experimental facility. It is capable of generating artificial flooding with a maximum discharge of 170 m³/sec. Experiments using this channel are planned to start in 2009. In 2007, we performed preliminary experiments to clarify the basic characteristics of the channel. The experiments used various types of observation instruments to measure the water level, discharge and sediment transport. The behavior of sediment in Chiyoda Experiment Channel was studied by examining bed load the channel bed height before and after water was introduced to the channel, and the bed materials, at varying discharges. The results were used to select the appropriate equation for calculating sediment transport in this experiment channel from among currently used equations of sediment transfer.

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Seepage erosion has been hypothesized as one of the dominant factors of channelization in both sediment and rock. However, the actual erosion mechanism responsible for seepage erosion is not fully understood. Recently, the importance of seepage erosion in rock is widely discussed. As a reason, this study aims to fulfill a lack of the fundamental knowledge in the seepage erosion mechanism. A series of the experiments on seepage erosion in wide chamber is conducted with varying sediment layer thickness, chamber slope and discharge. Artificial plastic pellets are used as cohesionless sediment. Channelization is found to be strongly influenced by water discharge. Amphitheater head of channels are observed in every experiment. The effects of chamber slope and sediment layer thickness result in different characteristics of channelization.

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A lot of non-overflow groynes that do not sink under the water at the ordinary water flow are used, and it is known to it does working that keeps away the water current form the river bank.On the other hand, when the water level is surpassing of the height of the groyne, it becomes to sink. In this study, the height of the groyne was made constant, depth was changed systematically, and it aimed to clarify the characteristic of the bed level variation and the flow velocity profile of the flowfield with a single groyne by the laboratory experiment under the condition to assume the Froude number to be 0.2. As a result, the maximum depth of scour has become small as the relative groyne higher. The groyne height when relative height grows, the ratio of the main flow velocity to the mean flow velocity has grown.

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Small-scale fluvial bed waves such as dunes and antidunes formed on river beds during floods increase the bed resistance, causing rises in water levels. Therefore, it is important to obtain detailed information on the conditions for the formation of bed waves. One of the purposes of this study is to extend the existing linear stability analysis of the formation of small-scale bed waves to the case with active suspended sediment transport. The analysis reveals that the critical Froude number for the formation of dunes is reduced, and the dune formation tends to be inhibited with increasing suspended sediment load.

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A doubly meandering compound channel is one in which both lower and upper channel meander. This paper examines the 3-D flood flow structures in terms of primary velocity distribution, stream-wise velocity distribution and secondary currents in a doubly meandering compound channel under dominant relative depth. The relative depth is the ratio of the depth of water over the floodplain to the total depth of water while the dominant relative depth is the relative depth at which the difference in discharge between the rising and falling stages takes the maximum value. The dominant relative depth of a doubly meandering compound channel is found to be 0.17. The primary velocity distribution under the dominant relative depth appears to be essentially the same for both rising and falling stages. The exchange of flow between main channel and floodplain results in the retardation and deviation of flow fields. The extent of retardation and the angle of deviation of the stream-wise velocity vary in the rising and falling stages. The maximum retardation occurs in the cross-over section at the floodplain level for both rising and falling stages. The maximum deviation occurs at the bend apex section for both rising and falling stages. The magnitude of the secondary current under dominant relative depth can be as high as 30% of the bulk velocity. The evolution and decay processes of secondary currents during rising and falling stages are essentially the same but only differ in strength.

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In this paper, eco-morphological model is proposed to simulate morphology at tidal environment with vegetation growth. Two numerical experiments such as vegetated scenario and unvegetated scenario were performed to clarify influence of vegetation on morphological evolution. This model was applied to a square tidal flat and calculations were conducted for 350 days. Computational results show that a complicated channel network is formed on tidal marsh and natural levees were appeared around the channel network in both cases. In addition, the vegetation propagated along the natural levees. In vegetated scenario, sediment deposition was enhanced by effect of vegetation on natural levee in comparsion with unvegetated scenario. Therefore, these results indicated that tidal channels are formed more clearly due to vegetation.

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It is commonly known that the flat bed is unstable in open channels in the range of small and large Froude numbers, in which the presence of the free water surface is important to the instability. However, instability of the flat bed without free water surface has not been well understood. In this study, we perform a linear stability analysis of the boundary between sediment and water in pipes transporting sediment with the use of the mixing length turbulent model. The analysis reveals that the governing parameter is the Euler number, and that the boundary is unstable in the range of relatively small Euler numbers.

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In general, it is said that the fridge in 2-box girders is excellent in the wind-resistant stability. However, the wind-resistant performance is changed by the difference between the additional materials. In this paper, the difference of the aerodynamics forces and the flow field by the presence of the wind-resistant stabilization material is calculated quantitatively and qualitatively by using computational fluid dynamics (CFD). Furthermore, the vibration generating mechanism and the wind-resistant performance improvement factor is examined, and the effectiveness of the wind stabilization material added to 2-box girder bridge is suggested.

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A computational method for multiphase fields, MICS, was applied to estimate the shielding effects on the fluid forces acting on a complicated-shaped object surrounded by other objects. In the MICS, arbitrarily-shaped objects are treated with tetrahedron elements, through which the momentum interactions between objects and fluids are accurately taken into account with a tetrahedron sub-cell method. The applicability of the MICS was discussed with the experimental results obtained in some arrangements of the objects which surround a target object in a flume equipped with a wave generator. As a result, it was shown that the MICS enables us to predict reasonably the shielding effects on the fluid forces in all cases of the present experiments.

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Large eddy simulation (LES) of a flow past a typical trussed structure has been conducted. The method is so calleda n implicit LES with dissipatived ifferencingo f the nonlineart erms but standard Smagorinskym odel is used for the sub-grids cale stress. The sizes of the structure members are very small and the detailed shapes of the members are not resolved accurately. However, t he simulatedf lowf ieldi s plausiblew ith the drag forcen ot too far off empiricalf ormulaa nd the wakea nd vortexs tructuresa re predictedw ell. It is thoughtt o be due to the fact that the resistanceo f thesef rames tructuresi s dominatedb y the form drag on individuasl olidm embersr athert hant he viscouss kin-frictiond rag.

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In the present study, two doubts concerning the wind tunnel experiment by using the scale model were investigated. First, the comparison between an I-type hot wire probe and a split film probe was paid to attention in the eddy region. In the case using the I-type probe, a negative value is not reproduced for the mean velocity profile. Consequently, when the I-type probe was used, it became the result of overvaluing a true value. Next, the influence that the surface roughness of the scale model gives to the wind speed at the hub height was examined. The influence of the ruggedness did not appear remarkably when about 1/2800 scale models were used.

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A computational method has been proposed to predict the interactions between free-surface flows and elastic bodies submerged in the flow. A solid model, whose deformations due to fluid forces are solved with a finite element method, is introduced into the MICS, which is a computational method for incompressible multiphase fields. A solid object submerged in the flow is divided into multiple tetrahedron elements, through which fluid-solid interactions are taken into account using a tetrahedron sub-cell method. The experiments on the wave flows acting on a partly submerged elastic plate were carried out in a laboratory flume in order to confirm the applicability of the proposed numerical method. The fluid forces acting on an elastic plate and its deformations were measured. The developed computational method was applied to the experimental results and the fluid forces and the deformations of the plate were compared with calculations. As a result, it was shown that the experimental results are adequately predicted with the present numerical method.

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Experimental study was performed on flow structure variation with arboreal vegetation composed of stem and crown. The stem part was formed with circular cylinders (1cm diameter, 7cm height) arranged at 10cm intervals on the channel bed. The crown part was modeled with coarse-meshed material, which was set on the top of the stem part. It is found that the difference of discharge and depth does not cause velocity difference in the crown, but it causes difference in the stem part. This is because of the difference of flow resistance. In the upstream end of the vegetation, the velocity profile is immediately shifted from that of the log-law to that of equilibrium state in vegetation, which generates remarkable downward flow. In the downstream end of the vegetation, a separation zone is formed behind the crown, which generates reverse flow along the water surface and increases Reynolds stress remarkably.

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The gas transfer of CO₂ at the air-water interface when regular surface waves run up a sloping flat bed is investigated experimentally. The CO²absorption process is visualized by using a laser-induced fluorescence te chnique (LIF). We found out in the vicinity of the air-water interface, or ganized vortices whose rotation direction is opposite to that of the offshore vortex train, which was reported by Matsunaga et al. The counter-rotating vortices are found to promote efficiently the gas transfer at the wavy air-water interface in the offshore zone. The local gas transfer velocity is obtained from an image processing for LIF images. It is quantitatively confirmed that the transfer velocity increases due to the organized vortices.

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This paper describes the fundamental characteristics of vertical heat transfer due to thermal convection during the cooling period (September to February) in the northern part of Lake Biwa. The seasonal variations of the vertical water temperature and water quality distributions are firstly shown with the comparisons of calculated results by 1-D model and observed ones to explain the fundamental features of heat and mass transfer occurring in Lake Biwa through a year. Based on the examination of these results, it is pointed out that the thermal convection during the cooling period is the main mechanisms of DO transfer from the water surface to the bottom of lake. Then the mixing mechanism caused by thermal convection is investigated in detail numerically using 3-D CFD model. It is shown that thermal convection cells are observed in the computational domain, changing the positions of submerging portion temporally and promoting the mixing near the interface between the thermally stratified two layers. It is also pointed out that a fractal structure is observed in the flow generated by thermal convection.
A stochastic model with Monte-Carlo simulation, which is similar to Ising model and forest gap model, is proposed to consider the results of numerical experiments. It is pointed out that the spatial flow structures can be simulated by the stochastic model qualitatively.

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A simple and inexpensive system is developed to generate an oscillatory flow in a closed conduit, which simulates sea-bottom boundary layer induced by a solitary wave. A relationship has been established between theoretical quantities and system parameters in order to facilitate practical application of the present system. Preliminary experiments have been carried out in a laboratory to check the validity of the present system and excellent agreement has been found between theory and experiment The system can be utilized effectively for further experimental studies on various topics such as turbulence structure and sediment movement induced by a solitary wave.

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To understand the detailed processes of rainfall infiltration into 2-layered ground, the lab-scale experiments were conducted by using sand and decomposedg ranite. And the two phase flow and the saturated-unsaturated see page analysis were carried out to reproduce the experiments, and compared results of these analysis methods. In the experiments, when the surface layer has low permeability, pore pressure increased as soon as the rainfall was started. On the other hand, in the case of reverse layer system, pore pressure increased after the wetting front reachedt he sensors. It seemed to be no influence of pore air, but the two phase flow analysis reproduced the experimental results better and the results of the analysis showed the increasing of the pore air pressure obviously.

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The effect of pressure gradient on the dune-flat bed transition is studied in terms of linear and weakly nonlinear stability analysis. We employ the Kovacs & Parker bedload transport formula extended to incorporate the effect of pressure gradient on the lee side of dunes proposed by Yamaguchi & Izumi.The linear anlysis reveals that the critical Froude number is slightly increased due to the effect of pressure gradient. The nonlinear stability analysis reveals that the effect of pressure gradient renders the bifurcation pattern at the dune-flat bed transition subcritical in the range of relatively large resistance coefficients.

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An Unsteady Reynolds Averaged Navier-Stokes (URANS) calculation method has been applied to open-channel flows past a trench downstream of a vertical drop which involve oscillating hydraulic jumps. The basic turbulence model is a low-Reynolds number two-equation model that can be used to calculate the near wall flow down to the surface using a fine calculation grid. This method has been found to reproduce unsteady fluctuations for which standard high-Reynolds number models can only give steady results. The reproduced fluctuations agree qualitatively well with the experimental observation. The represented unsteadiness is due to large scale oscillation instead of turbulent motions and is due to more two-dimensional coherent fluctuation much like unsteady vortex shedding off bluff bodies.

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Unsteady numerical simulation is carried out for 3D velocity field of a turbulent trailing vortex using non-linear κ-ε model. The general features of vortex decay as well as the different time periods of turbulence growth/decay captured in present simulation are discussed. The self similarity in the radial distribution of tangential velocity and circulation profiles are examined for trailing vortex. The simulation is also performed using standard κ-ε model, and comparison is shown with non-linear model. Since the rotational effects of vortex were not captured by a standard κ-ε model, it predicted extremely rapid and strong turbulence growth and causes a rapid decay of tangential and axial velocities. However, the non-linear model shows good agreement with previous DNS data. It is observed that the decay rate of axial velocity is much higher than tangential velocity. Five different time zones are observed in the growth/decay process of turbulent kinetic energy. In the matured stage of a trailing vortex, the turbulent normal stresses show two types of anisotropic behavior depending on the radial distance.

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By installing a side cavity section to a relatively narrow open-channel flow, water surface oscillation is generated within the side cavity and main channel. It has been found that there exist several modes of oscillation that depends on the aspect ratio and the Froude number by the authors; however, the three-dimensional flow structure has not been clarified so far due to the complexity of flow. In this study, by using a LES model capable to represent surface oscillation, three-dimensional unsteady flow structures and the mass transfer between the side cavity section and the main stream are examined. It was found that for a mode showing a strong correlation between surface and velocity variations, the mass exchange at the side cavity zone becomes significant. It was also made clear that as the decrease of the side cavity width, the three dimensionality of the flow becomes evident.

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This paper presents the micromechanical modeling of fiber bridging constitutive laws of a discontinuous fiber reinforced composite (DFRC) under monotonic and cyclic loading with the effects of fiber fatigue rupture. Based on the considerations of fatigue damage on randomly distributed fibers under the fatigue loading of constant crack opening amplitude, the monotonic and cyclic fiber bridging constitutive laws are derived. It is shown that, as fiber fatigue rupture proceeds, maximum bridging stress as well as crack opening displacement at which bridging stress vanishes are decreased. Also, the critical normalized number of cycles, n^*_crit, at which crack bridging degradation takes place, is analytically derived, and its role is explained for the design of a DFRC against fatigue.

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For rapid repair and strengthening of steel members, carbon fiber reinforced polymer (CFRP) strips can be conveniently used. However, their deboding mechanism and design parameters are still to be clarified to prevent any debonding problem. Bending tests of steel plates with bonded CFRP strips are carried out to see the debonding stresses and failure mechanism. Then, differential equations are derived to express axial and shear forces in CFRP strip and steel plate, as well as shear and normal stresses in adhesive. It is shown that the debonding strength of CFRP bonded to steel plate in bending can be evaluated by the maximum principal stress developed in adhesive at the end of the CFRP strips.

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In order to realize lightening and repair/reinforcement for existing steel I-girder, whose lower flange was corroded, it was proposed that the damaged flange was replaced by cutting and welding with inverted T-shape member composed of high strength steel (HT780). And the soundness of the girder applied this method was diagnosed. In the case that the dead weight was decreased 7% by this method, the bending stiffness and yielding load was kept the same and ultimate load was increased 14% as the existing girder. In the case that the dead weight was kept the same, the bending stiffness was 34%, yielding load was 27%, ultimate load was 29% increased compared with the existing girder.

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The change in mechanical characteristics of mortar due to degradation was investigated. Degraded specimens were prepared by mixing expanded polystyrene (EPS) beads with mortar, and sound specimens include no beads. These EPS beads are very soft compared with mortar; they have a diameter of 0.22 cm and a density of 0.03 g/cm³. Uniaxial compression test and a splitting test were carried out with these specimens. The mechanical behaviors are investigated on the basis of the differences between each type of material (degraded and sound), load (monotonic and cyclic), and failure (compression and splitting). The stress-strain relationship was examined, by which the damage parameters are determined.

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This paper presents a method of measuring restoring force characteristic of a structure using synchronized accelometers to estimate degree of damage which is caused by an earthquake. The restoring force characteristic is obtained as relation between measured acceleration and displacement which is computed by integration of the measured acceleration. A set of acceleration data for an 11-storied building which has been monitored in 3 years are used. It is shown that the restoring force characteristic can be measured by the present method. Numerical experiments are carried out to examine the sampling rate and the data length that are needed to accurately measure the restoring force characteristics. It is shown that the minimum sampling rate and data length are 200 [Hz] an 16 [bit].

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An examination of characteristics of landslide by acceleration with static sensitivity was performed. Landslide experiment was performed by large scale rainfall system. Four acceleration sensors settled in the upper, lower, right and left side of experimental slope. Not only the sensor worked instead of inclinometer by 3-dimensional components of gravity acceleration but also results of analysis of measured signal could indicate characteristics of landslide process in detail. The indication of landslide was observed as drift of the acceleration signal caused by condition change of the sensor. Wavelet analysis of measured signal was performed. Results of that showed relationship between soil mechanics on landslide and frequency characteristics. A feeble indication of landslide was detected. According to these results, we could clarify that the acceleration sensor on landslide could measure the behavior of landslide. And the Wavelet analysis of the measured signal on landslide is useful for early-warning system of landslide.

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It is reported that the sound noise in a low frequency range is generated mainly by the spread of the vibration due to impact power caused by the passing vehicle. As one example of the measured bridge shows the vibration mechanism in which resonance of the girder web plates is taking major part of this sound noise. In this report, the noise of a low frequency range is specified mainly by local measuring, and analyzing the vibration mode of the noise intended for a real fridge, and whether the collaboration repair has the effectiveness of the noise measures as a measures idea that suppresses the vibration on the web side is examined.

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