When steel structures exposed to atmospheric environment are repainted, corrosion product containing chloride tends to be left on the surface. As a results, under-film corrosion will occur in an early stage after the repainting. In author's previous studies, an anticorrosive method with Al-Zn sacrificial anode material and fiber sheet which has functions of continual water absorption and retention has been developed as anticorrosive method without a high quality surface preparation. The purpose of this research is to investigate the anticorrosive effect and practicability of the developed anticorrosive method. Tensile strength tests were carried out on deteriorated Al-Zn sacrificial anode plates to clarify the mechanical properties. In addition, atmospheric exposure tests were conducted on the model specimens with the anode plate holes of various diameter and arrangement to quantitatively evaluate the influence of alloy composition of casting plate and water-absorbing route on current efficiency of the anode material. Furthermore, the practicability was also investigated by applying the method to hot-rolled H-section steel that simulated an actual structure and a steel I-section girder bridge of which almost paint coating has deteriorated and disappeared.

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 An estimation of a rail tilting under the design load is an important factor in a rational design of rail fastening systems. A rail tilting has been estimated by the practical solution based on the torsion theory. However, the recent study has reported that the rail tilting estimated by the conventional solution does not agree well with the experimental values.
 The purpose of this study is to establish a practical and high-accuracy solution for a rail tilting. First, a FEM model for a rail tilting was proposed and the validity of the model was examined by comparing the analytical values with the experimental values. As a result, a rail tilting estimated by the model was in good agreement with the experimental values. Therefore, it is found out that the model is available for predicting the response of a rail and its fastenings. Secondly, the model was applied to determining the loading condition of the performance test of rail fastening systems. Thereby, it is made possible to evaluate the performance of rail fastenings with high accuracy as compared with the conventional evaluation.

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 Decomposing the earthquake motion phase into the linear delay part and the fluctuation part from it, we investigate the stochastic characteristics of the phase difference in the fluctuation part. The probability density function of the Newton's difference quotient of phase (approximation of the group delay time), which is defined as the quotient of phase difference with respect to the discrete circular frequency interval, is expressed by a unique stable distribution for any arbitrary circular frequency intervals. Because the variance of the stable distribution cannot be defined it is analytically derived that the group delay time, as well as the phase difference, are the discontinuous function with respect to the circular frequency. The earthquake motion phase, therefore, is the continuous but undifferentiable function with respect to the circular frequency. We propose a new type of stochastic process being able to represent these stochastic characteristics of phase difference by the use of Lebesgue-Stieltjes type integral formula. In which the Kernel plays a role to realize the self-affine and auto correlation nature of phase difference and the integration function represents the main stochastic characteristics of earthquake motion phase. Comparison of several numerical simulations with observed earthquake motion phase differences results in the efficiency of the newly proposed stochastic process to simulate a realistic earthquake motion phase.

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 It is important to evaluate the amount of airborne sea salt adhered to each member of a bridge accurately and quantitatively for effective maintenance and management, because airborne sea salt have large influence on their durability especially at coastal regions. On the other hand, local governments have to maintenance and manage many bridges simultaneously. Therefore, it is preferable to obtain corrosion environment of each bridge without any on-site observation and/or monitoring to conserve their budget.
 First, in this paper, the authors calculated wind speed, wind direction and airborne sea salt concentrations using the meso-scale atmospheric model WRF. Second, the study bridge and the simplified surrounding topography were realized in computational domains to calculate steady flows in each approaching wind direction using the CFD technique. Finally, in addition to these results, on the basis of the proposed quantitative evaluation method of the amount of airborne sea salt on a surface, the authors evaluated the salinity amount in vicinity to each member of the study bridge. The authors achieved a certain result to regard with the WRF simulation and the evaluation of the salt amount, and expect that more accurate estimation will be realized with some improvements.

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 In this study, the structural design of railing post affecting road landscape was investigated. Bridge beam-type railing post is often made of aluminum-alloy because it has high durability and the extrusion process is possible to produce an arbitrary shape. The optimization of extruded shape was performed by a genetic algorithm using multiple objective functions of mechanical performance and economy. By changing dimensional parameters used in the optimization, the effect of each parameter on the optimization was examined. Based on the optimization results of separated extrusion models, the shape optimized for bulk extrusion models that require the latest developed extrusion machine was also examined.

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 In this research, a method which is able to analyze corrosion damage condition such as local thickness reduction or formation of rust layer of steel members of steel members at same time has been investigated. Considering eddy current testing which uses especially low frequency eddy current such as 1~1000Hz, corrosion damage condition analysis method which performs inspection from only one side of steel members has investigated to become easy non-destructive testing method. Firstly, differences of dynamic magnetic field characteristics due to damage form was clarified using numerical simulation, and further data analyzing method to obtain the differences was investigated. Then sweep wave and frequency step wave were designed as induced wave and analysis using both detected voltage and wavelet coefficient was performed. Based on results of all process, a corrosion damage condition analysis method was proposed. Finally, in the applicability of proposed method was clarified by experiment.

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 This paper presents development of a hood to mitigate penetration of noise accompanied by passages of the ultra-high-speed trains that has higher mitigation performance than the conventional upright noise walls. First, through on-site measurements for a pioneering type hood, it was found that air blown out from the openings such as gaps, slits, or structural joints had a significant effect on the noise level, and thus needed to be prevented. After the improvement on the openings, a hood of a segment frame structure that withstands the aerodynamic pressure fluctuation caused by the train passages is proposed. During the development, the future possible practical advantages of the hoods were also carefully considered, such factors as simpler construction and the easier maintenance. After several laboratory tests to confirm the noise mitigating performance of the local parts of the hood were conducted and the detailed structures were determined, a hood was experimentally constructed on the Yamanashi test line. Through the field measurements with this hood to investigate its effectiveness, it was finally confirmed that the noise level measured outside the hood was maintained low enough to satisfy the noise standard for the conventional high-speed rails targeted.

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 This paper presents an evaluation method of the strength of bearings supports for bridges subjected to the tsunami-induced force, to propose an estimation of the effect of the tsunami on the bridge function ability. The tsunami-induced force applied to the bearing supports was studied through the previous flume tests and numerical analyses conducted by authors. Based on a comparison with the performance of bridges affected by the tsunami caused by the 2011 Great East Japan Earthquake, an effectiveness of the estimation method of the tsunami effect on bridges was verified.

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 The soil classification method based on the natural period of the ground is used to estimate the design earthquake at surface. Although the natural period could express a predominant period of earthquake motion if the ground behavior is in region, it cannot take the nonlinear behavior into consideration. So, in this study, the soil classification method for a large-scale earthquake motion was proposed. The proposed method classifies the ground by using both a natural period and the strength of the whole ground. Thereby, the soil classification considering the nonlinear behavior of the ground is possible. The proposed method was applied to the various ground models. It was verified that the coefficient of variance of the structural response decreases significantly by using the propose method compared with the method using only natural period. This method makes it possible to estimate the ground and structural responses more precisely without any supplemental surveys. Furthermore, the proposed method is applicable also to the various earthquake levels. The proposed method is effective as the soil classification method in order to carrying out a rational seismic design and seismic reinforcement.

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 In this study, FE analysis for the girder ends with corrosion has been carried out in order to understand the failure mode and failure process . These collapse mechanism are analyzed from the analytical results, such as shapes of the deformation mode, stress distribution, and load-deflection relationships and so on. Using the load-deflection relationships diagram plotting the events such as buckling, tables of the failure modes, and a flow diagram of a failure process, the analysis cases were classified into six types of the failure type. By comparative analyzed of the failure mode and the the failure process and the difference of structural parameters to analyze the impact of the collapse, we examined the collapse mechanism of the corroded damaged steel girder end.

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 In orthotropic steel decks stiffened by closed section ribs, fatigue cracks resulting from large vehicles have been observed with the increase of the service years. The cracks found in trough-deck welds are bead-penetrating type. Several repair methods have been studied for these bead-penetrating cracks so far. However, effective methods that is applicable from the underside of the deck are still under development. In this paper, development of the repair method using Thread Rolling Screw from the underside of the deck and fatigue test results are described.

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 More reasonable seismic design can be achieved by considering the input loss effect of the soil-foundation interaction. However, there is no practical evaluation method of the input loss in the seismic design by means of the static analysis method for the foundation widely used in the railway field. Therefore, we examined a practical evaluation method of the input loss effect for the static analysis method. First, we conducted sensitivity analysis by varying the conditions of both the grounds and the piles, and the input loss effects caused by the pile foundations were investigated. Them, we proposed a practical method for calculating effective input coefficients by means of a seismic deformation method and that for calculating response spectra based on the random vibration theory. Furthermore, the applicability of these methods was verified through comparison between the dynamic analysis results and the evaluated results.

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 In this paper, an evaluation method is proposed for determination of planar shear deformation of a shear wall, considering the three-dimensionality, which is a part of an underground box-type structure such as screen chamber and pump chamber of important outdoor civil engineering structures in nuclear power plants. In underground box-type structures, as a result of large-scale ground motion side walls that are perpendicular to the direction of ground motion is pushed by the ground, hence soil pressure acting on the side wall centre is reduced by the deformation (deflection) occurred due to the decrease in the rigidity. On the other hand, acting soil pressure on the side wall end and the shear force acting on the shear wall surface is increased, resulting in in-plane shear fracture of the shear wall, which can lead to cases where critical breakage of the entire structural system occurs. In this case, a method for calculating the limit value of deformation angle (limit deformation angle) is proposed by applying the index of structural member's deformation angle to the damage index of the shear wall of an underground box-type structure, and the validity of this method is verified by utilising it in a seismic evaluation.

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 The objective of this research is to clarify the characteristics of corrosion resistance and anti-corrosion of interface between Al-5Mg thermal sprayed coating and heavy duty paint coating. Accelerated exposure tests were carried out on steel plates with the overlapping and butt layers with introduced linear or strip steel base-exposed portions. In addition, the AC impedance measurements, elemental analyses using EPMA, etc. were also conducted. Their results indicate that the deterioration of the overlapping layer at the steel base-exposed portion occurs earlier than that case of only Al-5Mg thermal sprayed coating. And then, the anti-corrosion performance would be lost after the thermal sprayed coating deteriorates and peels off from steel surface. The overlapping layer deteriorates in an earlier stage and then anti-corrosion performance is easier to decrease as the width of the steel base-exposed portion increases.

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