Maintenance Of Social Infrastructure Research Articles

Analytical Study on the Load-Bearing Performance of RC Beams Subjected to ASR Expansion

The alkali–silica reaction (ASR), a major cause of cracks in concrete, is a critical issue in the maintenance of social infrastructure. In this study, a concrete mesoscale model was meticulously developed, and a coupled stress–moisture model was also developed to reproduce ASR degradation. The aim was to investigate the effect of ASR degradation on the bending load-carrying capacity of RC beams. The concrete mesoscale model, specifically designed to reproduce ASR degradation, was modeled from three phases: coarse aggregate, mortar, and ITZ (interfacial transition zone). ASR was considered as the expansion of the coarse aggregate, and the objective was to reproduce expansion cracks with numerical analysis using the mesoscale model. Uniaxial compression tests were carried out on cylindrical specimens with ASR-accelerated deterioration to clarify the relationship between ASR deterioration and compressive properties, and the experimental results were used to identify material parameters in the mesoscale analysis model. The results showed that the model proposed in this study can reproduce the change in compressive properties due to expansion cracking. Finally, RC beams were constructed using the mesoscale model, and the effect of ASR degradation on the bending load-carrying capacity of the RC beams was investigated. The results showed that the presence of expansion cracks caused the initial stiffness of the load-displacement curves to decrease, but the bearing capacity tended to increase. This suggests that factors other than cracks, such as chemical prestress and boundary conditions in this model, have a strong influence on the load-bearing capacity of deteriorated RC beams.

Analytical Study on the Load-Bearing Performance of RC Beams Subjected to ASR Expansion

The alkali–silica reaction (ASR), a major cause of cracks in concrete, is a critical issue in the maintenance of social infrastructure. In this study, a concrete mesoscale model was meticulously developed, and a coupled stress–moisture model was also developed to reproduce ASR degradation. The aim was to investigate the effect of ASR degradation on the bending load-carrying capacity of RC beams. The concrete mesoscale model, specifically designed to reproduce ASR degradation, was modeled from three phases: coarse aggregate, mortar, and ITZ (interfacial transition zone). ASR was considered as the expansion of the coarse aggregate, and the objective was to reproduce expansion cracks with numerical analysis using the mesoscale model. Uniaxial compression tests were carried out on cylindrical specimens with ASR-accelerated deterioration to clarify the relationship between ASR deterioration and compressive properties, and the experimental results were used to identify material parameters in the mesoscale analysis model. The results showed that the model proposed in this study can reproduce the change in compressive properties due to expansion cracking. Finally, RC beams were constructed using the mesoscale model, and the effect of ASR degradation on the bending load-carrying capacity of the RC beams was investigated. The results showed that the presence of expansion cracks caused the initial stiffness of the load-displacement curves to decrease, but the bearing capacity tended to increase. This suggests that factors other than cracks, such as chemical prestress and boundary conditions in this model, have a strong influence on the load-bearing capacity of deteriorated RC beams.

Time distancing to avoid network microbursts from drones’ high-definition video streams

Maintenance of social infrastructure, such as utility poles and bridges, is a major challenge in the era of declining labor force. While remote maintenance with drones is expected to solve this problem, it requires high-quality images for error-free decisions by a remote maintainer and low-latency to prevent many retries of remote operations since they directly affect maintenance efficiency. For that purpose, low-compression video with low encoding delay and small distortion is a leading candidate. However, we found that such traffic with high-burstiness causes a microburst, which is a short-time congestion experienced at the aggregation point even though the network capacity seems to be sufficient. We also propose a congestion avoidance method by designating appropriate timing to the encoders without losing image quality and report latency reduction in 5G-NR simulations.

A New Type of Rotary Magnetic Actuator System Using Electromagnetic Vibration and Wheel

In recent years, large structures, such as bridges, which are a type of social infrastructure, have been constructed with increasing traffic volume. For this reason, inspection and maintenance of social infrastructures, such as large bridges and tanks, is important. In the present paper, a magnetic wheel actuator system capable of movement using a new principle of locomotion was proposed and tested. The experimental results indicated a maximum pulling force of 1.6 N. By on-off control of the attractive force of the magnetic wheel, the actuator system was demonstrated to be able to move on a step having a height of 10 mm. Furthermore, the proposed actuator system could freely rotate in horizontal and vertical planes of over angles of 360°.

Application of Monitoring Technology to Maintenance of Social Infrastructure

Application of Monitoring Technology to Maintenance of Social Infrastructure

社会インフラストラクチャーの予防保全と非破壊検査技術

社会インフラストラクチャーの予防保全と非破壊検査技術

長野県八ケ岳山麓・青森県八戸市周辺の冬季気象特性と凍害との関係

Even though aggravation of global warming, snow hazards or frozen occurred inland area in northern part of Japan annually. Worsen catastrophic heat made it difficult to forecast of meso-scale under statistical deviation or coefficient of variation. From curtailed budget, it is required to reduce allocation of additional wage based on forensic treaty, in order to establish countermeasure for frost heave from road management or slope stability efficacy.In this paper, the authors analyzed meteorological observation data Aomori, Nagano and Hokkaido including assimilated our data from Chino City Nagano, as to statistical period proximately two or three generation considering with deterioration of civil facilities. At first, we categorized each meteorological element on Dec., Jan., Feb. and Mar. adjust data of descriptive statistic for finding analogous characteristic results between Honshu and Hokkaido concern with cryogenic circumstances. Secondly, our research member scrutinized frozen ground with field survey, geo —morphological features and temperature focused on Nagano Pref. Finally, occurrence of frost heave and statistical analyzed climatic and hydrologic data, we concluded that several areas in Honshu Japan should be amended Hokkaido's maintenance of social infrastructure in order to alter or promote safety community swiftly.

骨材資源特集号 砕石資源と砕石業の課題

Although crushed stone is indispensable to building and maintenance of social infrastructure and a large amount of it (about 9.5×108t, in Japan 1990) has been used, few papers have studied crushed stone resources because of their abundance. In Japan, nevertheless, maintaining a stable supply against the increasing demand will become a serious problem. There are many problems in mining crushed stone and these can be classified as economic and social restrictions. Economic restrictions arise mainly from increases in both labor and transportation costs. Social restrictions include many environmental protection regulations by national and local authorities.In this paper, problems concerning crushed stone resources are classified as a part of geoscience and their deposits, demand and supply are considered. Efforts that should be made in the future to increase the potential of the quarrying business can be arranged into three categories, that is, automated methods of planning the mine site, efficient systems of transportation from factory to consumer, effective measures to deal with spoiled sight.