In this study, fatigue tests of large-size out-of-plane gusset welded joint specimens with gusset lengths of 200, 400, and 800 mm, as well as main plate thicknesses of 9, 25, and 40 mm were conducted under axial tensile loading to investigate the effects of the geometric parameters on fatigue strength. As results of the fatigue tests, it was found that the fatigue strength decreases with increase in gusset plate length, while the fatigue strength does not always decrease with increase in main plate thickness. Crack propagation analysis, which was modified to correspond to the fatigue test results, was also conducted to confirm the size effect of the out-of-plane gusset welded joints on the fatigue strength.

 The stainless steels have high corrosion resistance than the structural carbon steels. The stainless steel structures can improve the maintenance performance. This paper proposes an evaluation method for interaction buckling strength of square hollow section columns made of Cr-Ni type stainless steels.

 First, the numerical analysis model was created by changing the slenderness ratio parameter 𝜆 and width thickness ratio parameter R. Second, the relationship between load and displacement of the stainless steel columns was compared with the results for the carbon steel columns. Then, the deformation of these columns was investigated and classified into overall buckling, local buckling and interaction buckling for each column parameters. Finally, a strength evaluation method was proposed for the interaction buckling of stainless steel columns based on the strength curve for overall buckling, considering the reduction in local buckling strength. The proposed evaluation method can evaluate the interaction buckling of stainless steel columns in the range of 92% to 111%, and is more reasonable than previous design methods.

 Measurement of ground deformation during shield tunneling is important. In this paper, we propose a method to measure ground deformation caused by shield tunneling in real time and nondestructively using ground penetrating synthetic aperture radar (GB-SAR). GB-SAR does not require the installation of targets or other equipment at the measurement points, and thus enables continuous measurement of ground deformation even under construction conditions where entry into the construction site is restricted. The usefulness of this method was verified using actual measurements obtained during a shield construction project that passed directly under an airport facility, which has many restrictions on the measurement of ground deformation, and the method was shown to control the radar wave irradiation angle, which controls the measurement accuracy of GB-SAR, as well as points to be considered to improve the measurement accuracy.

 The permeation grouting method is a ground improvement technology which is used as a liquefaction countermeasure for soft and sandy ground. For estimating the displacement and pore water pressure of the improved soil, on seismic response analysis, a commercial software FLIP (Finite element analysis program of Liquefaction Process) was used. On using FLIP, several parameters determining liquefaction properties of the elements should be used. In this paper, a proper setting method of the liquefaction parameters for the improved soils which has inherent liquefaction resistance are proposed by using unconfined compressive strength qu obtained from undrained tortional shear tests on hollow cylindrical specimens.

 Moreover, the ground improved by the permeation grouting method has a large spatial variability in material property such as shear strength compared to natural soil deposits. The spatial variability in the strength property of the improved ground is anticipated to affect the deformation property under seismic loading. Therefore, a seismic deformation evaluation based on the performance specification is required considering the spatial variability of the ground. In this paper, a random field theory is used to represent the spatial variability of shear strength of the improved ground, and a seismic response analysis is conducted by Monte Carlo simulation using the dynamic finite element method on quay wall with liquefaction countermeasures for the back ground. The effect of spatial variability of the improved ground on the seismic deformation of quay wall is discussed stochastically and statistically. In addition, a post-deformation verification method was proposed to account for uncertainties that depend on the quality of the ground improvement and the number of samplings in the field survey.

 We have developed an autonomous UAV (Unmanned Aerial Vehicle) that can efficiently and safely perform inspection work of communication manholes for long-term maintenance of underground structures. In order to make UAVs fly autonomously in the underground space, we constructed a method to estimate the self-position of UAVs using laser and ultrasonic distance measurement sensors and cameras, and a flight method using the estimated self-position information. We also examined the guard structure of the UAV suitable for flying in a small space such as a manhole. As a result of the flight verification of the UAV in the actual size manhole, it was confirmed that a series of flight operations from the ground to the inside of the manhole, the movement and imaging in the manhole body, the exit from the manhole, and the landing were realized completely automatically, and images for inspection could be taken. This enables the inspector to inspect the manhole using the UAV’s image without entering the manhole.

 It has been pointed out that public opinion in Japan is negative toward public works projects. In addition to countermeasures against disasters such as frequent heavy rains, more advanced social infrastructure is required, and public works projects must be implemented with the support of public opinion. On the other hand, looking at other countries, public works expenditure is on the increase in many developed countries, while Japan's downward trend is unique. The purpose of this study is to clarify the characteristics of public opinion toward public works in Japan in comparison with the United States and the United Kingdom. A questionnaire survey was conducted on a sample of 310 residents in the capital cities of each country. The analysis revealed that public opinion in Japan is characterized by the correlation of negative issues such as inefficiency and wastefulness of projects, as well as low trust in the government and construction companies.

 The purpose of this study is to obtain suggestions that will be key to expanding the use of business aviation in Japan. Business aviation operations and user attitudes in Japan and abroad were surveyed, compared, and analyzed. The results showed that the market for business aviation in Japan is growing, but is still small compared to the U.S. or Europe, and that the concentration of needs at Tokyo International Airport is a bottleneck to increased use. The study also showed that there are differences in attitudes toward business aviation between Japan and the U.S., with spontaneity, such as personal interest and motivation, being the major factors in Japan. From these findings, concluded the key points needed to expand the use of business aviation in Japan from the perspective of airport improvements and user awareness.

 In order to clarify the suppression mechanism of paint blistering of corrosion resistant steel for paint containing W, Cu, Ni, and Sn, rust analysis and electrochemical measurement were conducted. As a result, it was found that W, Cu, Ni, and Sn refine rust particles, W gives rust cation selective permeability and Sn and W prevent the Fe dissolution by inhibitory effects. The corrosion resistance of welded joints made of corrosion resistant steel was equal to or higher than that of the steel plate, and the mechanical properties of the steel plate and welded joints satisfied the standard values of each strength grade of JIS G 3106. The life cycle cost of repainting bridges with corrosion resistant steel is reduced by 64% compared to conventional steel.

 Using the database of construction record of RC abutments of bridges in the quality attainment system of Yamaguchi prefecture in Japan, thermal stress analysis was conducted to create a crack probability curve, which was compared with that in the Standard Specifications for Concrete Structures (SSCS) of JSCE. When the curve created based on the JCI guideline was compared to that in SSCS, it was found that the position of the former curve was shifted toward the left side compared to the SSCS curve. This was thought to be caused by much higher value of thermal expansion coefficient used in the analysis compared to thermal expansion coefficients measured from specimens made in 21 ready-mixed concrete plants in Yamaguchi prefecture. The authors calculated another curve using the measured thermal expansion coefficient which almost matched the curve of SSCS.

 When all available data of abutment lifts was used to make a curve assuming normal distribution for tensile strength and tensile stress, the coefficient of variation for tensile strength and tensile stress was 19%, which was higher than reported in previous studies. When the data was divided into two, that is, before 2010 and after 2010, obtained two different curves showed different shapes. It was found that the coefficient of variation before 2010 was 15%, and this coefficient reduced to 12.5% after 2010 when Yamaguchi system was sophisticated and improved. The reduction in coefficient of variation was thought to be due to that good concreting work was conducted according to Yamaguchi quality attainment system, resulting in improved quality of concrete.

 The freeze-thaw resistance of concrete is significantly lower in salt water than in fresh water. Concrete deteriorates through repeated freezing and thawing, but in salt water, freezing alone leads to destruction. This paper investigated the effect of calcium hydroxide in concrete on the failure of concrete under such low temperatures. Calcium hydroxide precipitates at the interface between aggregate and cement paste due to the hydration reaction of cement. The lower the temperature and the higher the concentration of salt water, the more calcium hydroxide dissolves. From mortar, more calcium hydroxide is eluted in salt water than in fresh water. This accelerates the deterioration of mortar and concrete due to freeze-thaw action. Mortar and concrete using ground granulated blast furnace slag produce less calcium hydroxide. In mortar and concrete using blast-furnace slag sand, calcium hydroxide precipitated around the aggregate reacts with cement paste and blast-furnace slag fine aggregate to modify the interface. From these results, it was clarified that concrete using blast furnace slag exhibits high freeze-thaw resistance even in salt water.

 The paper aims to develop a fatigue life prediction method based on the failure mechanism of reinforced concrete slabs subjected to cyclic moving wheel-type loads. In this study, the failure modes of RC slab were classified into three types, and the fatigue life was evaluated based on its failure mode. First, a residual shear strength reduction model based on the fatigue failure mechanism of the beam-formed members of RC slabs was developed by experimental approach. Then, a fatigue life prediction equation for RC and PC slabs subjected to cyclic moving wheel-type loads was proposed, which can take into account effect of transverse reinforcement ratio, compressive strength of concrete, and support conditions. The proposed method consists of a shear capacity equation and an S-N curve equation, and can evaluate both constant loads and stepped incremental loads. The applicability of the proposed method was verified by evaluating the experimental results. The model showed better accuracy in fatigue life prediction than the existing prediction equation.