This paper proposes a method for determining fracture mechanics parameters of concrete usingnonlinear finite element analysis and response surface methodology. Three-point bend tests of notched concrete beams are used as the experiment to estimate the parameters. The nonlinear finite element analysis with a damage model validated based on the verification and validation is applied to simulate the experimental responses. A surrogate model based on the response surface methodology performs Monte Carlo simulations for calibrating the numerical result to the experimental response. Applying the proposed method to six test results demonstrates that good agreement between the numerical and experimental results can be found, and the material parameters of concrete can be determined with a low computational cost.

This study proposes a validation method for in-situ experiment. The in-situ test was the HE-E experiment conducted at the Mont Terri rock laboratory in Switzerland to understand the coupled behavior of Thermo-Hydro-Mechanical coupled behavior. Focusing on the THM coupled behavior, a method for validating the reproducibility of relative humidity was investigated. The material uncertainty was quantified by applying the MCMC method. The uncertainty of the experiment was quantified by focusing on the accuracy of the measurement equipment. We proposed that the validation method in ASME V&V 10.1 can be applied by quantifying the uncertainty with the above method.

A beam theory with cross-sectional deformation due to torsion applicable to arbitrary cross-sections is proposed. In this theory, the magnitude of the warping, which is independent of the angle of twist, is introduced. The cross-sectional deformation mode is obtained numerically by a finite element analysis of the representative volume element with periodic boundary conditions. This homogenization process makes the present theory applicable to arbitrary cross-sections. The deformation mode is used to obtain the cross-sectional parameters appeared in the derived governing equations. The result of the proposed method for a beam with heterogeneous cross-section shows good agreement with the result of finite element analysis.

This study proposes a method for extracting cracks from concrete surface images using a naive Bayes filter. The naive Bayes filter, a simple machine learning technique, is used to probabilistically classify crack and non-crack regions by evaluating the size, color, and shape characteristics of regions appearing in binary images. The analysis results demonstrate that the proposed method is capable of extracting crack regions by visualizing the calculated crack probabilities from the naive Bayes filter. Additionally, the proposed method has the potential to improve classification accuracy by estimating the probability density function based on a small amount of training data without the data collection costs.

In a non-destructive estimation using topological derivatives, candidate cracks are found from the distribution of the toological derivatives. A determination of correct cracks from the candidate cracks using LASSO is considered in this paper. We compute the coefficient matrix using BEM for 2D Laplace crack problems in two ways and determine the correct cracks solving the algebraic equation for the sparse vector. By solving numerical examples, we can estimate the correct cracks in two cases of the coefficient matrix. Moreover, in the case of candidate cracks having similar directions and very close location, we can determine the correct crack with sufficient accuracy assuming the presence of one of each candidate cracks in the domain and calculating the coefficient matrix.

This study aims to develop a data-driven method for seismic response analysis based on the simultaneous analysis of seismic acceleration records at the ground surface and engineering bedrock. Seismic response analysis involves dealing with non-stationary earthquake input motion and the nonlinearity of geomaterials. To address these challenges, we propose a method that combines time-delay embedding and dynamic mode decomposition for time-series data observed in real space. The proposed method aims to construct a high-dimensional linear model that accurately represents the time evolution of seismic response. In this study, we apply the proposed method to field observations and demonstrate its effectiveness for extrapolation estimation by constructing a high-accuracy linear model replicating the seismic response.

Behavior of the rail neutral temperature due to the movement of an object shadow driven by diurnal motion of the sun is discussed. For this purpose, theoretical steady-state solutions are derived for two simple track longitudinal resistance models of the rigid plastic and the linear elastic models. A numerical method is also applied to the present problem. Simulation with this method consists of two problems: the rail thermal analysis considering the time variation of both weather and solar radiation, and the mechanical analysis of rail tangential displacement considering the nonlinearity in the track resistance. Based on these analyses, some fundamental characteristics of the rail neutral temperature are investigated. It is found that the movement of shadow is very important for evaluation of the neutral temperature.

In hierarchical Bayesian model updating, the inherent variability of the model parameters is represented by a probability distribution. Its hyperparameters are then updated by minimizing the stochastic discrepancy between the model outputs and observations. To avoid subjective hypotheses in hierarchical Bayesian updating, the authors have considered applying the staircase probability distribution. The staircase distribution can discretizely and arbitrarily approximate a broad range of distributions. In this study, we aim to calibrate dependent parameters with modeling the joint distribution by a copula and its marginal staircase distributions. Bayesian model selection is also used to determine the optimal copula from several candidates that represent different correlation structures. The proposed approach is demonstrated using a three degrees of freedom spring-mass system. The results show that the proposed approach is capable of quantifying uncertainties in correlated parameters from limited prior information and available observations.

In this study, we investigated the feasibility of using a Hierarchical Bayesian Model (HBM) to estimate geotechnical parameters and provide engineering interpretations of soil properties. The study focused on estimating geotechnical properties of soft foundation soils at an offshore airport in Japan. We compared a basic HBM utilizing a global geotechnical investigation database (Generic database, GDB) with an HBM that employed a refined GDB based on similarity. The HBM with similarity refinement, incorporating geotechnical engineering knowledge at the soil layer level, demonstrated superior estimation accuracy and enhanced geotechnical insights. However, we observed that the accuracy of the estimates is contingent upon the quality of the GDB and may significantly decrease under certain conditions. We emphasized the importance of incorporating geotechnical engineering knowledge into the labeling and management of the database and highlighted the need for expanding the database in future endeavors.

This study conducts a comprehensive analysis of the recorded data on ground deformation during the construction of an offshore airport embankment, with the aim of exploring the potential for real-time future prediction and feedback control. Considering the presence of measurement errors and missing data in the observed records, this research investigates the signal reconstruction method based on Dynamic Mode Decomposition (DMD) and examines the feasibility of developing a ground deformation prediction model. The effectiveness of mrDMD, incorporating a multi-resolution representation, is validated for effectively separating local heterogeneity within the observations. Moreover, the introduction of DMD-C (a time-invariant system) highlights its compatibility with linear control theory, thereby demonstrating the feasibility of constructing a future prediction and control model for ground deformation.

This study presents an efficient approach to estimate the track profile and detect the unsupported sleeper using train vehicle responses. A half car model is used to represent the bouncing and pitching motions of the vehicle, and an augmented state space model is defined that includes the input track profiles in the state vector. A Kalman filter and Rauch-Tung-Striebel smoothing are then applied to estimate the track profile using the vehicle response observations. In the Kalman filter procedure, both the process noise covariance matrix and the observation noise covariance matrix are sequentially updated using the Robbins-Monro algorithm. The half car model parameters are also updated deterministically by solving an optimization problem based on constraints on the estimated track profiles. Furthermore, unsupported sleepers are detected by a large difference between the track profiles estimated using train vehicles with different weights. A statistical index is proposed to quantitatively identify the unsupported sleeper and distinguish it from random errors between two track profile estimates. The proposed approach is demonstrated on a numerical example using multi-body simulation.

It is known that chain link wire netting, which is used as one of the energy-absorbing components of rockfall protection structures, undergoes partial strain hardening due to plastic processing during manufacture and shows anisotropy in terms of deformation properties. It is necessary to confirm the mechanical similarity of chain link wire netting with these characteristics in order to carry out reduced-scale model experiments of rockfall protection structures in the future. In this study, as a fundamental study, reference dimensions (full scale) and reduced model specimens of chain link wire netting were fabricated and statically tested in the in-plane and out-of-plane directions of the chain link wire netting. Numerical analyses of the experimental results were also carried out. The experimental and analytical results confirmed the mechanical similarity of the rhombic wire mesh according to the replica law, based on the load-deformation relationship of each test and the load-tension relationship at the wire mesh constraint.

Bonding carbon fiber reinforced plastic (CFRP) is one of the repair methods for corroded steel tube members. In this research, loading tests were conducted for the steel tube with cross-sectional loss repaired by CFRP bonding. As a result, it was confirmed that the effectiveness of the repair method decreased compared to the calculated values of the composite theory for the sectional forces shared between the defective steel tube and the CFRP. This is caused due to sectional force transfer by the adhesive. For CFRP bonding repair, a shear-lag theory has been proposed to evaluate the sectional force transfer through the adhesive. However, there is no theoretical solution for steel tube with cross-sectional loss repaired by CFRP bonding. Therefore, in this study, the shear-lag theory was applied to a steel tube with cross-sectional loss repaired by CFRP bonding to derive the shared sectional forces. The derived shared sectional forces were in good agreement with the results of axisymmetric analyses based on finite element analysis and loading tests.

This paper proposes a method for creating a three-dimensional (3D) mesoscale model of concrete using the weighted discrete Voronoi tessellation. The weighted discrete Voronoi tessellation is used to generate Voronoi elements with curved surfaces. A database of coarse aggregate models is prepared by generating a large number of 3D coarse aggregate models close to the actual coarse aggregates. After correcting the statistics of the database to the grain size and shape distributions of the coarse aggregates contained in the actual concrete, the coarse aggregate models selected in the database are arranged randomly in a 3D space to create a mesoscale concrete model. The proposed mesoscale model is compared with an actual concrete, and the results demonstrate that the actual coarse aggregates’ size, number, and shape can be reproduced with high accuracy.

A validation experiment for reinforced concrete beams was carried out to validate the computational models in the verification and validation (V&V). The specimens were prepared simultaneously under the same conditions to reduce uncertainty in the experiment, and the experiments were performed in a short period. The non-linear finite element analysis was used to specify the uncertainty affecting the experimental results. The numerical and experimental results revealed that the main factor of uncertainty involved in the experiment was the variation of concrete material properties.

Particle methods such as the SPH and MPS methods have problems in that the approximation accuracy decreases due to disorder in particle arrangements and it is difficult to treat accurately curved bottom surfaces such as seabed surface. Regarding the first problem, we proposed the SPH(2), which satisfy the second order convergence in space and maintain its accuracy against for particle disorders. In this study, the second problem, the treatments of the curved bottom surfaces, has been improved using a coordinate transformation with the SPH(2)'s second derivative model Although the theory for the coordinate transformation was established in the MPS method, its accuracy did not give the desired accuracy because of the numerical errors of the second derivative models. Therefore, the numerical errors in these coordinate transformations were overcome by applying the second derivative model of SPH(2) to the coordinate transformation formulas. The superiority and validity of the proposed coordinate transformation using SPH(2) are demonstrated through validation examples such as hydrostatic pressure problems and dam breakage problems.

For simulating the fluidized ground during landslides, a new ISPH using the fully implicit time integration has been developed to decrease total simulation costs for highly viscous fluid simulation in non-Newtonian fluids. With the help of the proposed fully implicit ISPH, μ(I) rheology model, which is one of the reliable non-Newtonian fluids for dense granular materials, can be implemented with lower numerical costs than the semi-implicit ISPH keeping the same accuracy. The fully implicit ISPH method was implemented on a GPU computer to speed up their heavy computations and achieve stable and fast analysis by combining hardware speed-up and software improvement. Finally, comparing numerical and experimental results for sand flow supports the usefulness of the μ(I) rheology model and fully implicit ISPH method for granular flow.

Various damages to SUS panel tanks have been reported due to the earthquakes. These causes are due to the bulging. The bulging is a coupled vibration interacted the wall structure and fluid by short-period seismic motion. However, there are no design standards for bulging, and it is necessary to establish those standards. In this paper, we carried out the time history response analysis using the natural frequency of the bulging for the real SUS panel tank. This analysis clarifies the center part of the tank wall and the corner members is the weak points of the real SUS panel tank. As for the stress, peeling off occur at the welded parts and buckling occur at the corner members.

In the numerical computation of incompressible fluids, the solution of the discretized pressure Poisson equation at each time step accounts for most of the total elapsed time, and the load is particularly large in three-dimensional domains and density flows. On the other hand, the elapsed time for the simultaneous linear equations can be reduced by applying preconditioning to the Krylov subspace methods. In this paper, we investigate the effect of applying preconditioning using SOR and Multigrid methods to the Bi-CGSTAB method for solving the pressure Poisson equation in thread-parallel computation of 3D cavity flow and dam-break problems using collocated grids. The TVD scheme and the QSI scheme, which is accurate but time-consuming, were applied to calculate the convection terms appearing in the equation of motion. As a result, it was confirmed that the Multigrid method preconditioner reduced the elapsed time of the pressure Poisson equation regardless of convection term scheme, and the pressure calculation was up to 15 times faster when 128³ grids and 16 threads in parallel.

This paper presents a noise evaluation system based on the finite element method using impulse response analysis and its auralization. The time-variant convolution is employed to treat the moving source problem such as traffic noise. The PML boundary condition is employed to treat the open boundary condition. The system exposes to users the computed noise level with both the auditory information using sound source signal and the visual information using CG image. The present system is applied to the construction noise and traffic noise problems with various type of sound insulation wall. The computed results are compared with the measurement results in VR space.

In this study, we propose a credibility factor to evaluate the credibility of material model and its parameters calibrated from material tests, based on the concept of credibility evaluation of simulation models presented in ASME V&V-40. In solid simulations, it is common to identify material parameters so as to reproduce the response obtained in material tests, so the reproducibility of this response alone is not sufficient to evaluate the credibility of the simulation model. This paper proposes a new credibility factor and its gradations, checking the reproducibility of responses that are not used for parameter identification. Using 4-point bending tests on plastic materials and wood as examples, we will show the difference in credibility evaluation for calibrated model that only identify parameters and one that confirm the reproducibility of other responses.

In recent years, the damage to the spread foundation piers due to local scouring has been increasing by heavy rainfall and typhoon disasters. If the damage is of a medium scale that causes foundation settlement or tilting, the foundation can be repaired and restored in a short period through emergency restoration. Therefore, in order to make a quicker decision on the restoration of the foundation, it is important to understand the mechanism of the development of the residual bearing capacity. In this paper, the rigid-plastic finite element method (RPFEM) was applied to the bearing capacity problem of the ground after local scouring, in order to evaluate the bearing capacity characteristics immediately after the disaster. In addition to, Meyerhof’s effective footing width was introduced for scoured ground to discuss the analytical results. The numerical results showed that the decrease in ultimate bearing capacity due to scour was mainly due to the effect of the effective footing width and secondarily due to the effect of the slope near the foundation due to scour.

There are examples of extended finite element method (X-FEM) studies of crack initiation and propagation in slopes under static and quasi-static conditions. However, there are no studies on dynamic slope failure caused by earthquakes. In this study, the dynamic initiation and propagation of tensile cracks in rock slopes are analyzed using the X-FEM with enrich freedom representation closed in element. In the dynamic analysis of a rock slope, differences in crack patterns due to different input accelerations were observed, which is caused by differences in vibration modes. This suggests that the possibility of quantitative evaluation including the difference of the failure process by the vibration mode, which are not fully considered in conventional slope stability analysis.

To evaluate the loads due to dry bulk cargoes on the inner hull of bulk carriers, effects of the particle-wall frictional properties on internal lateral pressure during sway motion using Discrete Element Method (DEM). The dynamic load distribution shape in the lateral excitation analysis differ from that of liquid cargo. The results of the analysis using realistically set coefficients, the internal friction of the cargo and the friction between the cargo particles and the wall surface, demonstrated that the dynamic pressure decrease at the side wall where the particles collide because of shearing force on the walls. However, there was no significant difference in their decreasing effect in the range of realistic friction coefficients.

It has been pointed out that corrosion cracking conditions influence the shear capacity of RC structures. To elucidate this, it is necessary to systematically study the relationship between the visualization of corrosion cracks and the stress transfer situation during loading. This study demonstrates the effectiveness of an X-ray computed tomography (CT) system that can take images under loading conditions for visualizing cracks and shear deformation near corroded steel bars in mortar. In the experiments, X-ray CT images were acquired during electrolytic corrosion tests and loading tests of specimens with shear surfaces along the round steel to investigate the section reduction rate and crack propagation in the round steel, and the change in the stress transfer mechanism at the shear surface with or without corrosion during loading. The results showed that the relationship between the arrangement of the round steel bars and the degree of corrosion, and the three-dimensional distribution of corroded crack widths could be calculated from the X-ray CT images. The changes in the stress transfer mechanism due to corrosion cracks were also clarified from the load-displacement relationship inside the specimen with or without corrosion of the steel bars.

In recent years, a cable type open Sabo dam has been proposed as a countermeasure for small scale streams. However, there is no design method for the cable type open Sabo dam, and it is necessary to evaluate its load bearing capacity under debris flow loads. Therefore, the impact resistance of a cable member supporting an open Sabo dam under lateral impact is investigated. The maximum tensile strength in the impact is not different from the tensile strength in the static tensile test. Furthermore, the applicability of the elastic plastic analysis used in this study is confirmed by reproducing the experimental results using the cable specifications obtained from the static tensile test. The cable type open Sabo dam is then evaluated using this analytical method and is found to bear the existing design load. Furthermore, the energy distribution of the main member of the dam and cables is generally clarified by considering the energy classification at the impact velocity.

Improvement effects of fatigue strength by post-welding treatment methods, for instance grinding and hammer peening, have attracted considerable interest. Improvement of the weld toe shape and compressive residual stress are considered to enhance fatigue performance of welded joints. However, individual effects are not clear, since those treatments change simultaneously the local residual stresses and the weld toe shape. Recently, the authors studied on a method to predict the fatigue crack initiation life by using the local strain approach and extended it to assesst the crack propagation life, handled as continuous behavior of crack initiation life. The prediction of the inelastic deformations has been investigated by means of an unconventional elasto-plasticity model called the Fatigue SS Model (hereafter, FSS model). The FSS model is based on the Subloading Surface theory, which was enriched by including the elastic boundary and cyclic damage concepts for the description of strain softening behavior within macroscopically elastic stress state. The FSS model was used to investigate the inelastic response of the material under different cyclic loading conditions. The aim of this paper is to study the welding residual stress and shape effects on the fatigue performance of welded joints. In this study, finite element analyses were conducted to assess the fatigue crack initiation and propagation lives of a non-load carrying welded fillet joint by using the local strain approach. The results show that the fatigue life of welded joints can be enhanced by removing tensile welding residual stresses, or reducing welding deformation, or improving weld toe shape. In particular, the most effective improvement on the fatigue life is obtained by reducing the welding deformation.

Due to the progress in urban planning, our country has experienced an increase in the expansion of transportation networks, which has exposed the road network to the risk of rockfall disasters. A wire supported rockfall protection fences have been constructed as one of countermeasures. But it is necessary to examine the performance of a wire supported rockfall protection fences using impact load experiments. This study examined to simulate full scale collision experiments of wire supported rockfall protection fences using elasto-plastic analysis. Additionally, the weak points of the rockfall protection fence were investigated using simulation. The results reproduced the deformation response observed in the experiments with maximum tension falling within the safety range. Moreover, it was shown that analysis parameter of reproductivity analysis was feasible for analysis with different collision positions.

Recently, multiple fatigue life extension techniques have been proposed utilizing crack closure for pre-existed cracks against a backdrop of the structural design philosophy changes. However, their reports are mainly for experimental phenomena, not for numerical analyses, which work for the understanding of their mechanism. On the other hand, the authors have been inventing an unconventional elasto-plasticity model called the Fatigue SS Model and proposed the assessment method on crack propagation life based on it. This study aims to follow numerically fatigue crack propagation experiments considering the corrosion effect and establish assessment methods. The result shows good agreement with the crack propagation behavior caused by crack closure. Moreover, the applicability of the same conditions to different test cases is verified, which shows the phenomena could be reproduced in a unified manner.

The accuracy of the model for estimating soil-water characteristic curves (SWCC) proposed by Sako et al. is discussed in this study. Specifically, the correlation between the parallel translation index (I_pt) and properties of grain size distribution are investigated. The relationships between fine fraction content, uniformity coefficient, and I_pt was discussed, and linear approximations equation were derived from the relationships. The accuracy of the approximate equations was examined by conducting soil water retention tests on soils of several different grain sizes and comparing laboratory results with calculations. The results showed that the I_pt tended to be larger for the soils with higher fine fraction content and uniformity coefficient. This suggests that more pore water in the soil contributes to suction when the soil has a higher fine fraction. Calculations using the I_pt obtained from the approximations were close to the test results for volcanic sandy soil with fine fraction content of 16%, and 20%. The accuracy of the estimation of soil water retention can be improved by using approximate equations obtained relationship between the properties of grain size distribution and I_pt.

In order to reproduce large shear slip behavior beyond the initial element network and contact behavior between crushed fragments in the process of fracture and collapse of concrete structures subjected to extreme actions, the authors introduce a method for updating the network between elements in the authors' proposed rigid-body spring model (RBSM) with geometric nonlinearity. Specifically, the polyhedral elements of the RBSM are represented by multiple contact spheres, and a new RBSM-equivalent reduced integral Timoshenko beam element is placed between elements that are determined to be in contact in the process of large displacement and large rotation behavior analysis to represent contact behavior. The validation analysis shows that the proposed method can reproduce the behavior from the crack penetrating the cross-section through the large-rotational behavior of the member to the contact with the other member and the formation of a new resistance mechanism.

The stress concentration is widely known that has a significant influence on fatigue performance, but the calculation cost is high when using FEM or other methods when to evaluate the stress concentration for geometries measured with a 3D scanner. Although several simple formulas have been proposed to estimate the stress concentration factor, no method has yet been established to uniquely and automatically determine all geometrical parameters that serve as input parameters for Kt equations. In this study, an automatic evaluation system for shape parameters and fatigue performance based on Kt of welded joints was developed. Accuracy verification using an ideal model confirmed that the system can predict the weld geometries in a sufficiently high precision. Comparison with the results of manual measurement confirmed that the stress concentration factors were evaluated to be equivalent or on the safe side.

In excavating works using temporally retaining walls under low-permeable ground with confined aquifer, the installed length of the wall often depends on the study of the stability against the heaving of bottom ground. In this study, pore water pressure and effective stress obtained by 2-dimensional soil-water couped finite element analyses were examined and the possibility of usage of the predicting method about heaving was clarified. Furthermore, instead of use of finite element analysis, the calculation method of earth pressure based on the classical soil mechanics was examined for evaluating the stress condition under the bottom ground of excavation. The calculated vertical and horizontal stress coincided with them obtained by finite element analyses, so the applicability of the proposed method was validated as the use of predicting method of the occurrence of heaving.

The binary granular mixture consisting of two types of particles, large particles and small particles, are divided into three types of properties: small particle skeleton structure, intermediate skeleton structure, and large particle skeleton structure. The properties of the intermediate skeleton structure vary with the large particle content, so it is important to understand the micromechanical state of the intermediate skeleton structure. In this study, DEM was used to reproduce the angle of reposed experiment conducted on binary granular mixtures, and the visualized strong contact vectors, contact forces for each contact type, and distances between the centers of gravity of the large particles were analyzed. The results show that the strong contact vectors visualized started to appear from the large particle content where the intermediate skeleton structure begins, and developed toward the top of the mountain as the number of large particles increases. The contact forces between large particles and large particles, between large particles and small particles increased in the intermediate skeleton structure, while the contact forces between small particles and small particles decreased. The distance between the centers of gravity of large particles was shorter in the vertical direction than in the horizontal direction.

Recent abnormal weather conditions have resulted in large-scale debris flow, causing damage to steel pipe open Sabo dams. Particularly, unprecedented cases have been reported where the downstream components of a steel pipe open Sabo dam were damaged by overflow of boulders. It is necessary to investigate and implement measures regarding the reinforcement of downstream components and the slope of the downstream. This study analyze the factors causing damage to steel pipe open Sabo dams utilizing DEM and referring to cases of damage caused by overflow of boulders. Field boulders exceeding 1.0 m boulder were modeled, and boulder collision was examined. It is revealed that a 5.0 m boulder would accumulate near the top, repeatedly colliding with downstream components due to subsequent boulders flowing from behind, leading to their destruction. Moreover, a 5.0 m boulder would flow towards the diagonal members, causing their rapid collapse. Therefore, even in the event of overflow of boulders, it is necessary to reinforce the overflow components or employ joints capable of withstanding such conditions to prevent damage to the diagonal members.

In this study, experimental and numerical investigations were conducted to examine the impact resistance of polyurea resin coated RC slabs subjected to repeated projectile impacts. The results revealed that the polyurea resin coating on RC slabs were highly effective in preventing the scattering of scabbing fragments, and scabbing occurred at lower energy than the scabbing limit energy at a single projectile impact. Numerical investigation was carried out to reproduce the impact behavior of the polyurea resin coated RC slabs.

In risk assessments of slopes after rainfall, to quantify the amount of fluid outflow from the system, obtaining the amount of evaporation is essential, which is ground surface moisture flux boundary conditions. This paper focuses on the bulk method to estimate evaporation and discusses the calculation method of evaporation efficiency, an essential parameter of the bulk method, under natural convection. Firstly, the exchange speed necessary for calculating the evaporation efficiency is examined from thermodynamics, and the calculation method considering the difference in heat capacity between soil and water is proposed. Secondly, from the laboratory experiments, evaporation efficiency is calculated using the exchange speed based on the above-proposed method, and its validity and applicability are evaluated. As a result, it was confirmed that the evaporation efficiency can be calculated as below 1, which satisfies the variational range by using the proposed method. In addition, a method for organizing the data to eliminate the influence of the initial conditions of the laboratory experiments on the evaporation efficiency is presented.

The objectives of this paper are to make clear the vibration characteristics of the road information board fixed by the F type support and to evaluate their sensitivity of eigen frequency to the damage. First, the accelerations of the road information boards in service are observed at three ground sites and three superstructure sites. The observed accelerations are analyzed with ERA (Eigensystem Realization Algorithm). As a result, four common vibration modes are found, and their estimation accuracies are evaluated. The analyzed results also show that the eigen frequencies depend on the site condition. Second, full-scale damage experiments are conducted to investigate the temporal changes in the eigen frequencies due to several patterns of damage. The results show that the failure of anchor bolt in the tension side gives the detectable change in the eigen frequency. Since the full-scale experiments represent the ground site only, the temporal changes in the eigen frequency in the case of a superstructure site are estimated using a simple numerical model that is a cantilever beam with a rocking spring. The simulation results show that the temporal change in eigen frequency is smaller when the rocking spring is softer. Even though the softness of rocking spring in the superstructure site is considered, the failure of anchor bolt might be detectable from the temporal change in eigen frequency.

Bulging is a coupled vibration between tank wall and content fluid. This phenomena is induced by seismic ground motion. In Japan, many cases of water storage tanks due to bulging have been reported with an intensity index over 6. Seismic design against bulging is introduced just at 2022, which will activate various kind of engineer’s interest on it. That is e.g. possibility of phenomena occurrence for existing tanks. In this study, microtremor measurement and natural frequency analysis are conducted to estimate the natural frequencies of the real scale SUS panel tanks, which are considered to have natural frequencies below 10 Hz, the frequency at which bulging damage is expected to occur. As a result, the calculated natural frequency of bulging is consistent with that of the actual tank, indicating the possibility of bulging occurring in the tank. The microtremor measurement method is shown to be particularly effective for SUS panel tanks, which are considered to have natural frequencies below 10 Hz.

The purpose of this paper is to roughly evaluate the impact of torsional vibration on bridge design and maintenance management when a high-speed train passes through a double-track railroad girder, which has not been studied in the past. First, a standard cross-sectional model of railway double-track girders implied that a ratio of the natural frequency of the torsional mode/bending mode is about 1.2 to 1.3 times for open section concrete T girder, and 3 to 5 for closed section PC box girder or composite box type. As the results of theoretical approach, the 1^st torsional resonance may be occur in the ultra-high-speed region, while no significant resonance of the torsional mode occurs in the conventional speed range up to about 300 km/h. the dynamic response on railway structures above girder may increase due to the amplified acceleration due to torsional resonance, although the conventional design method does not evaluate the displacement response to the dangerous side without considering tortional mode.

We propose a detailed method for standardizing the seismic evaluation of gas pipelines. Firstly, a ground model is built based on the surveys, which is then converted into a FEM model to perform three-dimensional nonlinear seismic response analysis. Based on the analysis results, the behavior at the gas pipelines can be determined and the pipe strain can be analyzed through another analysis. With this method, it is possible to quantitatively evaluate the pipe strain caused by the assumed seismic motion in the area, which is useful for maintenance, management, and repair planning of the facility.

The onboard bridge deflection estimation method of railway bridge based on track irregularities have been developed. However, the existing method, for a single bridge, could not apply to 2 bogie track inspection vehicles since the track irregularity measured by it is physically affected by the deflection of the adjacent bridge. In this study, a novel bridge deflection -track irregularity conversion program is developed to cond uct fundamental investigations to establish the bridge deflection estimation method based on track irregularities measured by 2 bogie track inspection vehicles. The program outputs the difference between track irregularities (DTI), which cancels out static track irregularity and depends only on bridge deflection. The effect of the adjacent bridge on the DTI of the target bridge is investigated through the numerical calculation in the section which consists of 7 consecutive bridges of 13m beams.

Railway poles vibrate significantly when high-speed railway passes. There are the reference values to avoid damage to the electrical wires. However, the reference values do not take into account the non-linearity caused by the wire restraint. This study proposes a Time-Varying Auto Regressive with eXogenous (TV-ARX) model that clarifies the pole natural frequency, which increases instantaneously with wire restraint. The proposed model is obtained by reformation of the existing model, such that the railway bridge deformation is replaced by the excitation force on the railway pole. The proposed model is applied to the measured displacement response of the railway pole and the railway bridge when a railway passage. It was shown that the relationship between the railway pole displacement and the estimated railway pole natural frequency. In addition, it was clarified that the current reference values are also valid for the pole on operating lines.

Agricultural-steel-sheet-pile walls have thickness reduction due to corrosion. This leads to pitting corrosion and buckling of steel-sheet-pile walls. This study aims to a non-contact evaluation of steel-sheet-pile thickness using infrared measurement based on the temperature variation of a steel sheet pile according to the thickness. In analytical procedure, the temperature of steel sheet piles is calculated based on meteorological data. Surface temperatures is estimated by applying the theory of heat balance on the ground surface. In experimental procedures, steel-sheet-pile samples were set under meteorological conditions. The temperature fluctuations of the steel sheet piles were detected by a combination of heat-balance simulation and infrared measurements to determine the thickness. As a result, it was found that the relationship between standardized temperatures and steel-sheet-pile thickness showed a negative correlation during the temperature increase process and a positive correlation during the temperature decrease process.

In order to clarify and quantify the mechanism of the increase in the dynamic response of the bridge due to the passage of a train through a rail joint, this study conducted a numerical analysis of a conventional railway bridge, which is considered to be particularly affected by rail joints. The results showed that the dynamic response due to the passage of a rail joint is amplified by the resonance that occurs when the excitation frequency with the passage of two wheelsets in a bogie and the natural frequency of the bridge coincides, and is clarified the relationship between the resonance and the rail joint parameters. The impact factor at resonance was also found to be reduced due to the dynamic interaction between a train and a bridge. Furthermore, it is shown that the impact factor decreases with a decrease in the natural frequency of the bridge or an increase in the span, and that the impact factor is less than 0.05 for spans longer than 30 m.