In this study, focusing on the welded box section steel applied to the diagonal and chord members of steel truss bridges, compressive tests were conducted using short columns with local buckling and long columns with overall buckling. The purpose was to investigate the effect of corrosion near the weld on the reduction of compressive strength and to recover the compressive strength by bonding carbon fiber sheets. As a result, it was clarified that the load carrying capacity did not decrease significantly if the weld bead remained even the corrosion occurred near the weld, and that the load carrying capacity decreased significantly if the weld broke. However, even in the case of corrosion near the weld and weld breakage, it was possible to recover the resistance to near soundness by attaching carbon fiber sheets in the axial direction and aramid fiber sheets in the circumferential direction. In addition, the thickness reduction and weld breakage near the weld and the evaluation method of the load carrying capacity after reinforcement were studied.

 There have been many accident reports of damage to transmission towers, such as member buckling caused by excessive load due to strong winds and/or foundation displacement due to ground deformations. In this study, we examined the progress of damages and the ultimate strength of transmission tower subjected to severe external loads using 3D finite element analysis, especially focusing on the distribution of damaged members and the accompanying strength degradation. We then performed repairing analysis of the damaged tower, which simulated repair measures by replacing damaged members and removing foundation displacement, and thereby evaluated the degree of strength recovery after the repair. The analysis result revealed that the efficacy of repair significantly depends not only on the repair methods but also on the distribution of damaged members associated with the cause of damage. This implies that the proper choice of repair measures according to the damage type is of crucial importance for effective repair to recover the tower strength. Finally, we examined the member forces after different repairing scenarios to elucidate the mechanical cause of the difference in the degree of strength recovery.

 This paper investigates fatigue strength of various orthotropic steel deck types based on hot-spot stresses under moving traffic loads. The load positions and the load ranges were decided from finite element analysis result to simulate maximum hot-spot stress ranges of longitudinal to transverse rib connections which can occur under the actual traffic condition. Results show that non-slit connections between longitudinal and transverse ribs were of high fatigue strength. Especially, the orthotropic steel deck with plate-type longitudinal ribs and the non-slit connections were of higher fatigue strength than the strength equivalent to 1.0×10⁷ cycles of design fatigue load.

 This paper verifies the validity of the method for simulating the fracture behavior of reinforced concrete involving the bond behavior of steel bars. To reproduce the different bond behavior, we first conduct pull-out tests of round bar and deformed bar and examine the material parameters of the interface between steel bar and concrete by comparing the numerical and experimental results. Then, we conduct four-point bending tests of RC beams with different failure modes and compare the numerical and experimental results. The comparison reveals that the different failure modes of RC beams can appropriately be reproduced by changing the geometry of the steel bars without changing the material parameters.

 Sea levels had been observed at Fukuyama Port during about two months to investigate the local meteorological effects on the oceanic variations. Fukuyama Port is the long and narrow channel that extends about 8.5 km inland from the coast of the Seto Inland Sea. In this inlet, I observed the local meteorological effects such as the inverted barometer effect due to atmospheric pressure changes and the wind set-up effect due to easterly winds toward the deepest part of the port. These effects can cause over one meter rise in sea level under the extreme weather conditions such as approaching typhoons. In addition, the suboscillations with a period of about 42 minutes had been constantly observed in the port. The suboscillations caused a sea level rise about 0.4 m during the typhoon passing in September 2021. Therefore, in case that a typhoon would approach at high tide, the sea level could rise more than 3 m above the mean sea level due to the addition of the inverted barometer effect, the wind set-up effect and the suboscillations.

 Many clay roof tiles have been used until now, and a large number of tiles that have reached the end of their useful life will be discarded in the near future. In addition, a certain amount of defective roof tiles are produced when clay tiles are manufactured. However, these unnecessary clay roof tiles are not recycled much except as recycled material for clay roof tile. Therefore, in this study, the applicability of crushed roof tile, which is recycled material made from defective roof tile, as a backfill material for civil engineering structure was studied through laboratory model tests and full-scale field tests. As a result of the study, it was clarified that crushed roof tile can be expected to reduce the horizontal earth pressure acting on civil engineering structure because that has lightweight and high frictional properties. In addition, it was clarified that crushed roof tile can be expected to have high bearing capacity even without reinforcement, reinforcing effect due to geosynthetics, and the range of influence of the vertical load on the crushed roof tile was almost the same as that on the pit sand. Therefore, crushed roof tile can be fully applied as a backfilling material for civil engineering structures.

 There are cases of bridge pier foundation construction that require rapid construction in narrow areas, especially in urban areas, but it is difficult to use the conventional construction method from the viewpoint of occupied area and construction period. Therefore, we focused on the construction method of RC foundation by using steel segment press-fit method of shaft construction technology suitable for the above. However, the existing steel segment was a temporary underground wall, and it was necessary to construct the RC foundation separately. Then, the authors proposed a rational structure to construct bridge pier foundation rapidly in narrow areas by changing hoop of RC foundation to steel segment. In this study, the proposed structure is embodied and the reversed cyclic load test was carried out using the scale test specimen of the conventional RC foundation and the proposed structure, and it was confirmed that the proposed structure had the same or better seismic performance than the conventional RC foundation.

 Rainfall infiltration behavior and storage capacity on 18 years passed embankment composed of Shirasu soil (volcanic ash sand) were investigated to verify influence of degradation by measuring water content, suction, temperature, rainfall and surface runoff. The dry density and fine content of embankment soil at a surface area had especially been decreased to small value. The delay time to increase water content maximum and to occur surface runoff from beginning of rainfall at wood planted term was longer than that at non wood planted term by leaf storage. Water retention capacity in subsurface area had been tended to decrease during these 18 years.

 In this research, questionnaire survey was conducted for the child-rearing generation in order to clarify the factors of population growth in cities in Aichi Prefecture, where population growth and population decline are progressing at the same time. In the analysis of satisfaction and importance, the safety of the sidewalk was cited as the strongest improvement problem item. In the regional comparison by population and satisfaction indices, the overall evaluation of satisfaction was highly correlated with the population growth rate, and it was found that the fertility rate was related to natural richness. There were different trends between population indicators. The comprehensive evaluation model of multiple regression analysis indicates that it is important to obtain overall satisfaction such as local security, disaster safety and so on.

 Wide-range ultrasonic testing (WUT) is often used to estimate the grout filling-condition of post-tensioned PC bridges. To improve the accuracy of inspection by WUT, the fundamental characteristics of elastic waves propagating in concrete were examined. Elastic waves transmitted from the probe were propagated in a triangular prism concrete specimen. The propagated elastic waves were analyzed in the study. The result shows that transmitted waves were obviously observed in the range of 20-45° of the incident angle though it decreased in the range of 45-90°. In addition, spectrum peaks in reflected waves indicated 60-90 kHz approximately. The probe placement to observe reflection-waves of the direction angle of smaller than 45° is effective for WUT.

 Probabilistic risk assessment is useful and practical because large uncertainties are involved in the assessment of damage and it is difficult to assess the damage deterministically. This study proposes a support methodology for optimal placement of protection structures against rockfall based on minimization of the total cost (the construction cost of protection structures and the risk) and shows an example of cost-benefit analysis for a model site. The risk is defined as the product of the probability of exceedance of the limit state and the consequence. A reproduction analysis of the rockfall behavior by the lumped mass method is performed to obtain input parameter of the model for the arrival position obtained from the large scale rockfall experiment. The rockfall hazard is evaluated based on energy of each rockfall when the falling rock reaches to the road. An optimal selection of protection structures against rockfalls is shown based on minimization of the total cost with budget constraint. Finally, we perform a cost-benefit analysis and indicate optimal placement of rockfall protection structures that minimizes the total cost with and without the budget constraint.

 Asbestos had been widely used for building materials in past, and has been banned. In case the buildings are demolished, the ambient concentration of asbestos fibers is monitored by local governments because the scattering of asbestos fibers from building materials is concerned. In order to rapidly make the countermeasure to scattering of asbestos fibers, it is important to rapidly measure the ambient concentration of asbestos fibers. In this study, a new asbestos detection and counting method using a convolutional neural network (CNN) model is proposed as a more rapid measurement method. The method can automatically count the number of asbestos fibers in the image of phase contrast microscopy. The model was fine-tuned by teacher data created by samples obtained at the site of building demolishing, and samples made in laboratory. The model showed good performances in both of detection (F-score is 0.83) and counting (relative error is 11%).

 For evaluating reductions of automobile emissions by the regulations, automobile emissions of CO, NO_x and HC were estimated from 2000 to 2019. The estimated emissions were compared with emissions in the case of constant emission factors equivalent to the long-term regulation established before 2000 and analyzed for the annual trend with forecasted emissions. Emissions controlled by the constant emission factors were lager than several times of emissions estimated under normal conditions. However, emissions controlled by the constant activities were comparable to the ordinary emissions. The reduction trends of emissions were -4.4, -3.4, -5.0% per year in the order of HC, CO and NO_x. In the case of the forecasts to 2030, the reduction trends of pollutants were -3.1, -3.0 and -3.3% per year. From the results, although the reductions of pollutants by the regulations were different by the beginning periods and phases for the chemicals, the difference in the reductions was smaller in the long term.

 This study investigated the relationship between energy education and children’s energy conservation behavior by using a questionnaire survey of teachers and children in Sapporo, Japan. The results of the questionnaire survey for teachers confirmed that all schools are implementing energy education and feel the need for energy education. The results of Welch’s t-test on the responses to the questionnaire survey for children revealed that the level of knowledge and energy conservation behavior varied depending on the subjects and practices of energy education. No relationship could be confirmed between the presence of renewable energy sources in schools, the number of hours of energy education classes, and children's energy knowledge, interest, and awareness of energy conservation. In future energy education, rather than increasing the number of classes, it is necessary to consider how to improve the quality of energy education through the use of supplementary materials and the implementation of active learning.