AIJ Journal of Technology and Design, Volume 30 (2025)

Experiments were conducted on the physical properties of lightweight aggregates using discarded asbestos and sludge, and on the properties of concrete using these aggregates. I got the following results. (1) The density of aggregate A, a was approximately 0.9, the 24-hour water absorption rate was approximately 17%, and the BS10% crushing value was approximately 40 kN. (2) Concrete using aggregate A had a gradual increase in compressive strength as the cement-water ratio increased and the age of the material increased. (3) Concrete using Aggregate A exceeded the demolding strength specified in JASS14.

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The transition of standards of chemical admixture was investigated by literature survey. Japanese standards were affected by mainly ASTM until the 1960s, but have followed their own path until international harmonization in the late 1990s while referring overseas standards. In the 1960s various organizations established their own standards, but after that the commonality of standards was promoted, and many of them were integrated to JIS A 6204. Since the late 1990s JIS standardization of new chemical admixtures has not progressed. There is a tendency to respond by adding new performance to the name while assuming the conformity with existing standards.

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Properties of high strength mortar using mineral admixtures and cement-based powder extracted from sludge separated from ready-mixed concrete was examined for the purpose of assisting effective treatment of returned concrete. The results are as follows. 1) From the viewpoint of mortar fluidity, it was found that mortar with a high mass replacement rate of mineral admixtures in the binder has a faster flow rate. 2) From the viewpoint of mortar compressive strength, it was found that products using mortar with ground granulated blast furnace slag do not tend to lose strength even if the recycled cement replacement rate is high.

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In this study, the influence of concrete temperature assuming extreme hot season on strength properties, adiabatic temperature rise properties, and thermal stress analysis were investigated. The results showed that the strength properties were equivalent to those during the normal hot season. Although the adiabatic temperature rise properties had a difference between some measured and estimated values in the range of high-strength concrete, the influence of the difference between the measured and estimated equations for adiabatic temperature rise properties on the thermal stress analysis results was small.

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This report presents the findings from a questionnaire survey aimed at clarifying the actual conditions of formwork construction using softwood plywood. It covers various factors, including the configuration of wall formwork, storage conditions, reuse times, and common defects. The survey revealed that in formwork construction using softwood plywood, there is a decrease in the reuse times of plywood and an increased propensity for the formwork to warp. Additionally, based on the survey results, we have organized the challenges and considerations for using softwood plywood in conventional formwork methods.

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The purpose of this study is to clarify the progress in recycling of finishing material waste after the enforcement of construction recycling law in 2002, and to further consider the future direction of recycling. The progress of recycling over the past 20 years has been clarified by comparing the surveys conducted in 2021 and 2001. The status of recycling methods and recycling rate in production process, construction work and demolition work was compared.

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To establish an accelerated corrosion test method for steel under soil exposure environment, exposure tests were conducted with quantitative levels of factors affecting the corrosion of steel. By measuring the corrosion mass at each level, effective conditions that accelerate the corrosion of steel in the soil exposure environment were determined, and a new accelerated corrosion test method for steel under soil exposure environment was established.

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In this study, on site, the moisture conditions of concrete slab for targeting poured at different times were determined using humidity test paper and capacitive moisture meter until finishing floor covering. As a result, color chart value showed the same variation as that of temperature and humidity, indicating the possibility of being easily affected by the measurement environment. Moisture meter reading decreased with the lapse of lumber age, suggesting that it is not easily affected by the measurement environment.

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To clarify whether the bond behavior of FRP rods fabricated by 3DP can be evaluated, a pull-out test was carried out with CF incorporation rate and the height of ribs(H) to the spacing of ribs(L) (H/L). As a result, it was found that the effect of increasing CF incorporation rate on the improvement of FRP rod bond performance is small, and bond stress showed a different trend from that of reinforcing bars. In addition, it was suggested that the effect of H/L on bond stress in FRP rods can be evaluated by appropriating CF incorporation rate.

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In recent years, the use and preservation of historic brick buildings have attracted attention. However, little technical data exists regarding the material properties of brick buildings, and a method of estimating the corresponding compressive strength for seismic evaluation has not been established. Therefore, technical data was collected in this work to develop a method for estimating the compressive strength of brick buildings. Drilling tests were conducted, and the results confirmed the feasibility of estimating the compressive strength of bricks and joint mortar.

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In the construction industry, the number of noise complaints is increasing along with the growth in demand, and the aluminum alloy system formwork method (hereinafter referred to as (Aluminum formwork) construction method is also expected to be effective in reducing noise. Therefore, we compared the noise between the aluminum formwork method and the conventional formwork method. Noise measurement results from slab formwork dismantling, which generates the loudest noise during formwork work, showed that the aluminum formwork method was approximately 3.7 dB lower than the conventional formwork method, indicating a noise reduction effect.

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This study presents a method for calculating the probabilities of collision with buildings due to airplane or helicopter crashes. Probabilistic models are presented based on ISO 10252. The probabilities of collision are generally expressed as the product of accident probabilities and strike probabilities. Accident probabilities are sourced from domestic public databases on aircraft accidents, limiting to accidents affecting buildings. The calculated results are compared to the reference values of ISO 10252. This paper also provides an example of the calculation of strike probabilities to evaluate aircraft impact risk.

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This study presents a method for calculating the probabilities of collisions between vehicles or trains with buildings, by multiplying two probabilities: accident occurrence and subsequent reach to buildings. Data for accident occurrence probabilities were sourced from domestic public databases, and the estimated values were found to be comparable to those in ISO 10252. The reach probabilities were calculated using ISO 10252’s mathematical model, applied through Monte-Carlo simulations. The paper also provides an example of the calculation of collision probability, which combines the expected value of the occurrence rate of accident with the integration of the reach probability along the path.

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This study validated the accuracy of the action difficulty evaluation method based on the relationship between the results of seismic response analysis and the results of the questionnaire survey for residents in more than 20 super high-rise residential buildings of different building types, for which questionnaire surveys on action difficulty were conducted after major earthquakes. Shaking table boarding tests were conducted using simulated acceleration of floor responses in earthquake-resistant and seismically isolated buildings. Differences in the physical sensation depending on the aseismic types of buildings were discussed.

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Wind forces acting on high-rise buildings are usually evaluated from wind tunnel tests. With recent improvements in computational capabilities, wind forces can also be evaluated from computational fluid dynamics (CFD). In this report, the response of high-rise buildings calculated by time history analysis using wind force from CFD is compared with the response calculated by time history analysis using wind force from wind tunnel tests and the response that can be calculated from the load guideline. The results show the usefulness of using CFD to evaluate wind forces acting on high-rise buildings.

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In this paper, a method to obtain the “inverted membrane shell” advocated by Heinz isler using elastic large deformation analysis using the particle method is proposed. Several analytical examples and their numerical analysis are provided to demonstrate the effectiveness of the method. A shape equivalent to a catenary curve, which is a two-dimensional hanging shape, is generated and the feasibility of the hanging shape is determined. Then numerical analysis is used to verify whether tensile stress is generated by membrane stress and whether greater membrane stress is than bending stress.

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In Japan, there are no legal provisions for the limit state design of piles in buildings less than 60 meters in height. Guidelines, such as the Recommendations for design of building foundations published by the AIJ, leave the choice of analytical models up to the discretion of structural designers. This report conducts push over analysis of the typical building, using the modeling of piles and foundation beams as parameters. Differences in analysis models for piles and foundation girders are investigated focusing on the seismic stress and deformation of piles.

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This study investigates effects of variation in soil on bearing capacity of piles. Resistance factors of shaft friction and tip resistance are estimated with using N-value measured at several points in a site. The resistance factors decrease with increasing variation of N-value. This trend is more remarkable in tip resistance than in shaft friction. This is because, in tip resistance, the variation of designed values is small and the variation of soil has an impact on resistance factors. In the case, in which soil profile is not uniform, it is important to consider the spatial distribution of soil.

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It is very important to understand the seismic performance to improve the seismic safety of traditional wooden houses in Kyoto, and to understand the repair effects of damaged houses will relieve the structural anxiety of the owners and reduce their financial burden. In this study, static horizontal load experiments were conducted on a two-story traditional wooden house in Kyoto and the repair effect was confirmed. The results showed that even if damaged by an earthquake, repair and restoration would result in some loss of bearing capacity, but no significant change in deformation performance.

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This study proposed a new structural system for mid-rise wooden building to enhances the strength and ductility using a new steel rod insertion and adhesive bonding joint construction and CLT panel shear walls. To verify the effectiveness of proposed structural system, cyclic loading tests of full scaled specimens were conducted and also conducted lateral load-carrying capacity calculation and time history response analysis. This paper firstly presents the relationship of the strength and ductility of structural system, and then studies the seismic resistance design of the new structural system, introducing an actual project.

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This paper discusses structural design using a case study of a real six-story hybrid structure project that incorporates a bidirectional timber rigid structure with glued-in rod (GIR) joints. We will calculate the horizontal load-carrying capacity of Timber structures, which has not yet been systematically developed. We also conducted a tri-directional loading test on a full-scale specimen and found that the calculated values corresponded well with the experimental values. Furthermore, a time history response analysis was performed to verify that the design values for the structural coefficient were appropriate.

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NLTs (Nail Laminated Timbers) reinforced with wood blockings were tested for their in-plane shear properties and to verify the effect of reinforcement. The test results indicated that the in-plane shear properties particularly the ultimate strength and maximum strength of NLT can be improved by installing wood blockings. The effect of reinforcement was governed by the accuracy of the installation works and the size and species of the wood blocking. The load deformation relationship of NLT subjected to in-plane shear was calculated using the test results of the nail joints. The calculated results under estimated the load carrying capacity.

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The development of timber tensile joints with high strength is expected, and it is necessary to prevent brittle fractures of wood. Therefore, we conducted experiments on tensile-bolt glulam joints with wide range of shear length, which had not been verified so far. The tendency of strength, failure modes and stiffness on the shear length is discussed. Finally, evaluation method of the strength considering the failure modes is proposed.

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Sao-shachi joint is used for the joint at column-to-beam connections with large cross-sectional areas, providing relatively high resistance and exerting a significant impact on the overall building load-bearing capacity. Therefore, the seismic performance evaluation method for column-to-beam connections with Sao-shachi is important in designing traditional wooden buildings. This study aims to develop a formula for evaluating the bending performance of such joints based on full-scale experiments. The comparison of estimated values obtained from the proposed method with experimental results generally revealed accurate predictions of failure modes and moment and rotation angle relationships.

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Strain ageing of reinforcement is one factor that can affect the future seismic performance of damaged RC buildings. In this paper, tensile tests were conducted on 84 steel reinforcement specimens and it was found that the factors that control the reduction in ductility and increase in strength of reinforcement due to strain ageing are vanadium content, ageing period, and pre-strain. Equations were proposed to predict the change in reinforcement properties due to strain ageing. Verification of the proposed models against previous studies showed that ductility was reasonably predicted while strength increase could be predicted to within a 10% error margin.

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Research on seismic damage estimation is underway for the purpose of estimating the repairing cost after earthquakes. To accurately calculate the amount of damage in the spalling area of RC members, it is desirable to evaluate the damage based on the three-dimensional geometry. This study proposes a method to calculate the volume of the spalling area from 3D point cloud data of RC column members reconstructed by SfM. In this method, the spalling area is extracted from the point cloud data based on the positional relationship with the surface of the member, and it is modeled as alpha shape.

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Seeking to suppress the damage of RC beams, structural experiments were carried out on RC beams with partially debonded longitudinal rebars in which a vertical prestress force was applied at the beam ends. The experiments showed that RC beams in which longitudinal rebars were partially debonded and prestress force was applied to the beam ends exhibited less damage at the beam ends and in debonded zones compared to conventional RC beam specimen. In addition, we confirmed that partial debonding longitudinal rebars significantly reduce repair material used, thereby reparability of RC beams could be improved.

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In this study, a measurement of strain distributions of rebars in the shear-dominant reinforced concrete beam specimens via fiber optic sensors is discussed. After shear cracking, it was observed that the strain in longitudinal reinforcement was greater than calculated value based on Euler Bernoulli Beam Theory, indicating an effect of the bond stress of the longitudinal reinforcements, which is a component of the truss mechanism. The distribution of bond stress, which was calculated on the strain distribution of the longitudinal reinforcements, reached calculated bond strength, and this was consistent with the failure mode observed in the experiment.

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In the half-pre-cast column, the conjunction with the joint surface between the pre-cast and post-cast sections should be needed, and it is consequence to grasp the mechanical characteristics of the joint surface. We developed an alternative process using the form sheet, tests and FE analysis were conducted on the mechanical characteristics of concrete joint surfaces. Our developed construction method showed good enough integrity of the joint surfaces. The shear force was assumed to be transmitted at the joint surfaces by cohesion, coulomb friction, and shear resistance of roughness. Modeling method was proposed to evaluate the shear transmission mechanism.

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The transfer length and prestressing effective ratio were reported when prestress was introduced at the center of the cross section of the member using pre-tension method using steel strand for prestressed concrete. The transfer length of the indented steel strand for prestressed concrete was about 50 to 60% of that of the normal one. The transfer length was generally constant after 1 to 2 years after prestressing. It was possible to roughly estimate the prestressing effective ratio using existing calculation methods. The prestressing effective ratio fell slightly below the calculated value after about three years from prestressing.

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A survey was conducted among practitioners and educators regarding AIJ design standards and recommendations for steel structures and their internationalization. From a total of 640 responses, the frequency of use of current design code provisions, correspondence with Japan’s current building standard laws, and awareness of internationalization were analyzed.

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The use of buckling-restrained brace in frames shortens the natural period and possibly increases the seismic input. To overcome this issue, this paper proposes a displacement-restraint buckling-restrained brace in which no axial force occurs initially and the axial force occurs with a delay. Thereby, the natural period can maintain the same level as the moment frame without bracing and the concentration of the deformation into the local stories can be avoided. In this study, a trial design and seismic response analyses of a high-rise building model are conducted to reveal the effectiveness of the proposed braces.

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It is necessary to consider providing damping performance only for the effective deformation when modeling passive control devices in a multi-degree-of-freedom model. In this study, we proposed a method to replace the dashpot with a spring of appropriate stiffness. As a result, the responses of the multi-degree-of-freedom model and the three-dimensional frame model exactly matched. Furthermore, we investigated the effective stiffness that maximizes the cost-effectiveness of a passive controlled building. It was shown that the structure can be economically designed by not exceeding a certain stiffness.

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Whitworth screws have customarily been used for hanging bolts used for seismic support of suspended lightweight equipment such as air conditioners. However, the material properties and cross-sectional characteristics against bending of Whitworth screws are not clear because they are not described as current JIS standards. This study systematically clarifies the material properties and cross-sectional characteristics against bending of Whitworth screws, and examines the effect of mounting hardware used in the connection between hanging bolts and braces on the stiffness of units consisting of suspended lightweight equipment and other support members.

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Loading tests and FEM analysis were conducted to investigate the ultimate shear strength of beam-column joints of a cover plate type consisting of a reinforced concrete column and steel beams. Based on these results, a design formula for ultimate shear strength was proposed, considering the effects of the width-thickness ratio of the cover plate, the concrete strength of the column-beam joint, and the cross-sectional shapes of the column and beam. Furthermore, the proposed design formula was verified using existing experimental data, and it was shown to have good accuracy.

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Hydraulic model experiments using a scaled model were conducted to verify the validity of author’s previous analytical studies for seismically isolated building against tsunami. The scale of the model was 1/150. The experimental parameters included the installation angle of the model. The results showed followings: (1) The maximum hydrodynamic force is roughly proportional to the width of model across the tsunami flow, (2) The hydrodynamic force doesn’t increase sharply when the installation angle is 45 degrees, (3) The experimental results show the similar trends to previous studies. A 3-D fluid analysis was also conducted to reproduce the experimental conditions.

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We conducted an experiment using a small water tank in order to confirm the inflow characteristics of water from the small openings of a wooden house when the site is flooded. The results can be summarized as follows.

1) By measuring the outflow of water, the inflow velocity into the room during flooding is investigated.

2) The characteristics of the water inflow rate can be almost expressed using Torricelli’s theorem, and the flow rate coefficient C, which corrects the flow rate due to opening resistance, is approximately 0.7 for steel plates with small depth and for the packing construction used for ventilations.

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The development of Carbon Fiber Thermoplastics (CFRTP) stranded wire has been underway since 2007. Eight years later, CFRTP wire was first used as an additional element for seismic reinforcement in a building in Ishikawa. Later, it was standardized under Japanese Industrial Standards (JIS A 5571) in 2019. The purpose of this paper is to clarify the basic physical properties and particularly tensile strength of CFRTP wire. This study aims to specify its tensile strength as stranded wire, considering the effect of twist, based on the effective cross-sectional area of the wire, which is not clearly defined in the JIS.

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In this article, as one of the basic studies to promote the use of GLB(Glued Laminated Bamboo), we report on the examination of material strength using the GLB. Recently, it is concerned about wood shortage to increase the wooden, sustainable resources, construction. To satisfy those requirements, bamboo which is left and not managed, was adopted as structural materials, were verified characteristic value; bending, compression (parallel or vertical to fiber), and shearing strength (small or real scale), by experiments.

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A flat plate specimen is used in the coupon tensile test in case when a round bar specimen cannot be manufactured for thin steel plates. However, effects of the specimen shapes on the mechanical properties of steels at elevated temperatures were not clarified. The coupon tensile tests at elevated temperatures were conducted with various specimen shapes, and it was clarified that the full-thickness flat plate specimens possessed the low effective strength, however that effect was very smaller than that of the variation among the steel lots.

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In this report, an experimental study was conducted on floor impact sound insulation performance when tatami with anti-vibration proposed in the previous reports was constructed on floating floor system. As a result, from the results of the car-tire source, when tatami mats with anti-vibration are installed, reduction of transmitted impact sound is 2 to 4 dB for the 63 Hz band in some specifications, and floor impact sound insulation performance using the car-tire source is better than that of the bare surface.

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We conducted a questionnaire survey on residential buildings for elderly in Hokkaido district. The survey revealed features of building structure, number of floors, heating and hot water equipment, and so on, by type of the buildings. And using the data obtained from the survey, carbon dioxide emission and primary energy consumption of the buildings were estimated.

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There has been an increase in the number of passive houses with large windows to acquire solar heat. This study aims to evaluate window treatments such as roller screens based on thermal environment, and to make it possible to select them appropriately. The characteristics of the treatments are analyzed through experiments, and the necessity of thermal environment evaluation in consideration of solar radiation is demonstrated. Combining solar radiation analysis and CFD analysis, we developed the thermal environment simulation method considering BSDFs and solar radiation. Through case studies using this method, basic findings for the selection of treatments were summarized.

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In this study, underfloor ducted heating houses with roof-air-based PVT was investigated to verify the insulation specifications that achieve both energy efficiency and thermal comfort. Simulation model was constructed to simulate the behavior of the system, and multiple patterns of insulation specifications were analyzed for the standard detached house in region 5-6 defined in energy-saving standard, and the heat load during heating, system power consumption, and indoor comfort were evaluated. Furthermore, the amount of heat loss under the floor was determined, and cost-effective insulation specifications of the foundation were clarified.

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In recent years, there has been a demand for energy conservation in housing. The authors study PVT/heat pump heating/cooling/ventilation/water heating system to improve the energy independence rate in winter. They conducted case studies to verify the results of the analysis, which suggested that the energy independence rate can be improved by raising the temperature setting during the daytime and using PV power generation to store heat under the floor. The analysis results showed that appropriate heat pump heating operation and under-floor heat storage design tended to improve the energy independence rate and realize a comfortable thermal environment.

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“Tenant Mix” is a project that aims to increase visitors and sales by change the composition of stores business types in the shopping arcade. However, it has not been clarified how the change the composition of stores business types, will affect the willingness to visit, Satisfaction and so on. In this research, we will focus on existing shopping arcades in regional cities, use the diversity index and the abundance index to clarifying the influence of different stores business types composition in the shopping arcade.

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Using the school accident data and outdoor weather data, the relationship between the incidence of heatstroke in school buildings and the environment around the school buildings before/during the new coronavirus pandemic was determined. Comparing the occurrence of heatstroke in high school classrooms before/during the coronavirus pandemic, it was found that the outdoor WBGT where the peak incidence of heatstroke was gained during the coronavirus pandemic, was lower than that before the coronavirus. One of the reasons was thought to be a decrease in cooling efficiency due to the combination of opening windows and using air conditioners.

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When a sudden power outage occurs at night, people must rely on emergency power sources or flashlights. In this experiment, emergency lights were placed in 157 rooms across 76 houses, and specific behaviors were evaluated after spending two hours there. In darkness ranging from 0.1 lux to 1 lux, tasks requiring detailed visual work or searching the surroundings became challenging. In some cases, these difficulties were alleviated by proper light placement and diffusion. Additionally, there was a tendency for people to gather closer together in dark environments.

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This report is focused on considering about transition of the land plots in aged development site of the suburban housing. The target of this report is a suburban area in Osaka, developed about 90 years ago. In this case, half of land plots are keeping original state in area and frontage. The spec is similar as standards in original plan. On the other hands, large plots that were rearranged, has been subdivided. The factor of subdivision is seemed to concern to terraced house. The result shows a sample of exitance of sustainable scale and housing type for long time.

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Temporary housing prepared for natural disaster is determined by law to be demolished two years later in the Japanese present system. However, for the 2016 Kumamoto Earthquake 683 out of 4,303 temporary housings were made of timber and some of them was diverted to permanent housings. In the previous report, we analyzed whether timber temporary housings were diverted or not according to former land use. In this study, we researched process of residents moving after diversion and details of renovation for diversion. Accordingly, we considered the roles fulfilled by diverted timber temporary housings every municipality.

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