In response to the reexamination of the upper limit of minor additional constituents in Portland cement, the effect of the amount of minor additional constituents in Portland cement on the activity index test results of micro powder for ultra-high strength concrete was examined. As a result, it was confirmed that even if the mixing ratio of the minor additional constituents was increased from the current JIS upper limit of 5% to twice that amount (10%), the activity index test results did not change significantly.

An experimental study was conducted using 2 types of rebound hammers for high-strength concrete ranging 49 to 150 MPa as design strength. Based on rebound numbers and rebound speed ratios obtained by hitting concrete specimens, compressive strength in structure, that is core strength, was estimated. As a result, rebound numbers and rebound speed ratios were independent of loading stress to concrete and addition of polypropylene short fiber. Based on these results, strength-estimating equations of high-strength concrete were suggested using rebound numbers and rebound speed ratios. These equations have more than 85% precision of compressive strength in structure.

This study extended previous research by predicting the slump flow and time to 500 mm flow using various factors of high-fluidity concrete with multiple machine learners. The prediction results for unknown data showed a coefficient of determination R² of 0.73 for slump flow and 0.71 for 500 mm flow arrival time, both with high accuracy over 70%. Permutation Feature Importance and Partial Dependence Plot visualized and evaluated the feature importance and influence of various factors on flow characteristics through machine learning.

New admixtures have been developed for high-fluidity, super-low shrinkage concretes. The properties of fresh and hardened high-fluidity, super-low shrinkage concretes using these admixtures were examined in laboratory experiments. It was found that the concretes using these admixtures have the effect of improving carbonation resistance by the experiments. Furthermore, the cause or mechanism was examined, and it was found that the amount of pores larger than 400 or 500 Å was reduced. It is expected that the concretes will have high durability not only in terms of improving crack resistance by reducing shrinkage, but also in terms of improving carbonation resistance.

This study investigates the corrosion behavior of various rebar types embedded in mortar under chloride-rich conditions using electrochemical noise methods and polarization curve measurements. Results show that surface films, including passive, black oxide, zinc layers, and protective rust, significantly affect corrosion resistance. Oxidation and reduction reactions vary with surface film conditions, influencing corrosion progression. Notably, black oxide films inhibit corrosion, while layers on weathering steel act as insulative barriers. Conversely, galvanized steel shows more active ionic reactions in chloride environments. The research emphasizes surface films' critical role and diverse performance on rebar under corrosive conditions.

The purpose of this study is clarified to the actual use status of preceding lubricant by questionnaire survey for general contractors. The main points of the results are as follows. Only 18% of respondents answered they had used preceding lubricant, which was significantly lower than the 80% of pumping constructors who answered they had used them. Preceding lubricant have the advantages of reducing waste and costs, but many respondents answered concern about the decrease in concrete strength and blockages. Many contractors are open to using preceding lubricant going forward.

In this report, a method for restoring existing plaster reliefs using a 3D scanner and 3D printer was proposed. In Chapter 2, the material properties of gypsum such as strength, surface hardness and fluidity were investigated experimentally. Chapter 3 reports the results of trial restoration of gypsum relief installed in the trial interior by using a 3D scanner and 3D printer, and in Chapter 4 the process for restoring existing gypsum reliefs using a 3D scanner and 3D printer was proposed.

Numerous practical wind tunnel test reports for high-rise buildings has been compiled. Galloping onset determination was conducted for 160 cases of wind force characteristics. If the judgment is met, the critical wind speed was calculated. For many buildings, the critical wind speed was found to be outside the design wind speed range; however, in some cases, the critical wind speed was within the range. Due to the diversity in the shapes of actual building, predicting the critical wind speed is challenging. Therefore, in wind tunnel tests of buildings undergoing structural performance evaluation, it is essential to galloping onset determination.

This study conducted an analysis to differentiate target performance levels for seismic design based on the intended use of buildings. The seismic hazard assessment of spectral accelerations, published by the Headquarters for Earthquake Research Promotion, was utilized to calibrate the current practices of seismic design in Japan, including the importance factors used for governmental facilities.

A simple experimental method is investigated to evaluate the drag force acting on a building structure by controlling the Froude number in an open channel flow hydraulic test. A weir model is installed upstream of the building model, and the overflowing flow interacts with the building structure. This experimental method, which generates a critical flow by overflowing a weir model, is commonly used in civil engineering. By adjusting the overflow rate, the Froude number of the flow reaching the downstream building structure can be varied, enabling the evaluation of the corresponding drag force.

The annual accident probabilities of building structures due to external explosions are assessed using a tree model approach. This study focuses on the effect of accidental explosions within hazardous facilities on the surrounding environment. Branch probabilities in the event trees are heuristically determined. The major factors influencing branch events are identified by fault trees. Domestic accident databases are utilized to calculate the annual occurrence probabilities of accidental explosions. Furthermore, past explosions are reevaluated using the present approach, considering their annual accident probabilities.

In a high-rise building with a large bending deformation, the damping performance of middle to upper dampers may be deteriorated. To improve the deterioration of damping performance, a “combination-system” (High-rise building with hysteretic dampers and viscous dampers) is proposed. However, there is very little research on a response prediction method for “combination-system”. This paper presents a response prediction method and performance evaluation for “combination-system”. Accuracy of this prediction method is validated by comparing the predicted values with the time history analysis results. The performance curve is derived through the calculation process of the prediction method.

The Recommendation for Loads on Building (RLB) of AIJ allows for a simple calculation of wind response parameters without using time history analysis. The RLB also considers the simultaneity of wind forces and stipulates a method for combined of wind loads. However, there are a few cases in which the wind force of a seismic isolation layer under combined loads has been evaluated. Therefore, this study evaluates the combined wind loads based on the RLB for high-rise seismically isolated buildings with elastic sliding bearings.

Creep characteristic of the thick laminated rubber bearing made of natural rubber installed in the actual vibration isolation building for 55.2 years could be estimated by using existing measurement data and newly measurement data. Creep measurement data sets were examined by simple regression equation of recommended by JIS K6410-2. Regression analysis showed that the average creep displacement characteristics could be described by a power law. Average creep displacement of the thick laminated rubber bearings installed the building for 60 years was estimated 3.4 mm by the regression equation. The method of JIS K6410-2 is useful for forecasting creep displacement.

Ambient vibration measurements on a historical brick building with RC floors determined its primary natural frequency and vibration modes. Comparing a simple multi-degree-of-freedom model with measurements revealed: 1) Unlike masonry buildings with wooden floors, which show significant out-of-plane displacement of central walls, this building exhibits translational vibration in both directions, indicating rigid floor behavior due to RC floors and tie beams. 2) The vertical mode shape is linear from basement to rooftop; a four-degree-of-freedom model matches measurements better than a three-degree one. Thus, when evaluating seismic performance of buildings with elevated first floors, basements should be treated like above-ground floors.

This paper proposes a hybrid method for topology optimization of frame structures, combining a mathematical programming with the ESO (Evolutionary Structural Optimization) method. In this method, ineffective elements are deleted from the initial ground structure using the ESO method as the first process until the target total mass ratio is satisfied. The following process uses a mathematical programming method to derive the optimal solution from the initial solution solved by the ESO method. The effectiveness of the proposed method is shown by comparing it with the conventional methods (the CONLIN method and the IESO method) on the basic examples.

Based on results of a shaking table test to verify the effect of TMDs for a gable roof using a scaled-down specimen, we studied the robust design of TMDs against variation in both the natural frequency of the specimen and damping values of TMDs through analysis. Our findings indicate that the method of installing multiple TMDs with different natural frequencies is effective. Especially against decrease in the natural frequency, the method of installing two TMDs, one tuned to the natural frequency of control mode and the other to 30% smaller frequency, can be highly robust.

The cantilever roof of the stadium generally adopt a lightweight structure. Therefore, the wind load is more dominant than the seismic load in the structural planning of the stadium’s cantilever roof. As an example of an attempt to reduce wind load, there is a construction example in which an eave called a stabilizer is installed at the tip of a roof, but there is no quantitative evaluation of the wind load reduction effect associated with the installation of stabilizers. In this paper quantitatively evaluates the wind load reduction effect due to installing stabilizers on the stadium’s cantilever roof.

CLT walls-steel beams hybrid structural system with steel plates and large-diameter bolts for the joints was proposed to accelerate promotion of mid-rise timber buildings. A full-scale static loading test was conducted on a partial frame consists of a steel beam and a CLT wall derived from targeted four-story building designed using the proposed hybrid structural system. From experiment, high average shear stress of 1.5 N/mm² in CLT panel and ductile deformation capacity until story drift angle of 3% were observed.

NLT sheathed with structural plywood was tested for its in-plane shear properties. Plywood sheathed NLT showed higher yield strength and initial stiffness than NLT with no sheathing. Load deformation curve of the plywood sheathed NLT was derived by applying theories proposed by Kamiya and Sha. The calculated result well traced the load deformation curve of the test result at the relatively small deformation level but underestimated the load at relatively large deformation level. Embedment of the lumbers composing NLT was not modeled and this incomplete modeling may have caused the difference between the test result and the calculated result.

To develop an appropriate experimental method for a mud-wall element without the influence of moment resistance at column joints, cyclic shear loading tests were conducted on two types of mud-wall specimens with pin-connected column joints. One type used steel tenons instead of traditional wooden Hozo joints, while the other employed clevis joints. These modifications aimed to remove the influence of column joints of the mud-wall elements. The restoring force characteristics and failure process were observed and compared with previous mud-wall tests. Test results indicate that both types of specimens effectively eliminate the influence of column joints.

In this study, a flexural loading test of a wooden panel with CFRP rods embedded in the longitudinal members of the frame was performed and an experimental investigation was conducted regarding a flexural reinforcing effect of the CFRP rod. As a result, it was shown that the flexural rigidity and failure load of the panel reinforced with CFRP rods were significantly increased compared to the unreinforced panel, and a reasonable correspondence was seen between the calculated value by the equivalent cross-sectional analysis and the experimental result.

Seismic walls with bearing pressure joints between the steel frame and CLT panels are modelled as compression braces, as compression forces are transmitted in the diagonal direction of the seismic wall during horizontal loading. Generally, the brace replacement of a seismic wall is evaluated as a series spring of axial stiffness and joint spring stiffness, but a method has not yet been established for CLT panel seismic walls. To solve this problem, an elemental experimental method is proposed and a correction method for each stiffness is investigated in order to apply the results to CLT panel seismic walls.

Timber joints using tensile bolts with distantly spaced sets of nuts and washers are studied in this paper. Firstly, static loading tests are conducted to grasp the overall behavior. Then 2-D FEM analyses are performed to understand the stress distribution in the timber. Based on the results of the above, a new 1-D model is proposed that well represents the stiffness and the stress distribution of the joint.

In the previous research, buckling restrained braces (BRBs) were developed using round steel bars, steel tubes, and steel material for core members, buckling-restraining members, and spacers. But changing the length of these BRBs is difficult. Therefore, in this study, we developed a connection of BRBs using Pipe-LSB and round steel bar cores by a wooden frame construction which can easily change the length of BRBs. We examined the connection and the result showed that it achieved its target value.

In this study, four-point bending loading tests were conducted on RC floor slab specimens to verify the effects of crack control joints and deformed bars as crack inducers on the flexural performance. The experimental results confirmed that the load-deflection curves of the specimens with joints were almost equivalent to those of the normal specimens. It was also confirmed that the existence of joints had no effect on the crack distribution below the deflection at which the ultimate state of bending was reached. Further performance improvement was confirmed by applying resin sand with porosity to the joints.

Although the seismic design of power transmission towers in Japan is not stipulated by law, the design standards on structures for transmissions JEC-5101 published at the end of December 2023 requires seismic design based on the story shear force method. It requires estimation of the natural period to calculate equivalent static seismic load, but the current estimation formula calculates it only from the tower height, and there is a need to improve its accuracy. In this study, the natural period estimation formula that can be applied to steel lattice tower for power transmission is proposed.

Steel bars with selectable strengths in the longitudinal direction were realized by partial induction hardening. The strength difference in one steel bar can induce damage to the target lower-strength region without affecting the higher-strength region, which economizes the steel consumption compared to the traditional cross-sectional difference. This study introduced the specimen with the target yield strengths of 600 and 1200 MPa (600-1200 specimen), and of 800 and 1200 MPa (800-1200 specimen) from the viewpoint of heat treatments. All the single regions satisfied the target yield strengths with great ductility. However, unexpectedly, the 600-1200 specimen’s strength transition region became a weakness.

This paper proposes a guideline for design, fabrication, and quality control of buckling-restrained braces using steel mortar planks (BRBSM). Important items are extracted from design, fabrication, and quality control based on constructed buildings and previous studies, and are organized accordingly. Based on the results of tests using specimens fabricated in accordance with the proposed guideline and meeting the recommended design values, the structural performance of BRBSM can be evaluated as safe.

Since the 1990s, several studies have examined CFT columns, thus accumulating a large amount of experimental data. A previous study collected experimental data on CFT columns from existing research and reported the results of a comparison of the design standards at that time. Subsequently, the AIJ published “Recommendations for Design and Construction of Concrete Filled Steel Tubular Structures.” Therefore, the present study adds new test data derived from recent years to the database and examines current design recommendations. Based on the results, we demonstrate the characteristics of the structural performance of CFT columns in relation to current design recommendations.

In this study, CFRP repair method using VaRTM technique is proposed for angle steel with the simulated corrosion. Full-scale cyclic horizontal loading tests were conducted to evaluate the effectiveness of the repair method in restoring the structural performance of the member. The results show that the proposed CFRP repair method using VaRTM technique effectively restored the structural performance of perforated angle steel with simulated corrosion. Furthermore, the design approach mitigates early debonding by ensuring that the plastic hinge position is avoided from the CFRP adhesive zone.

Experimental investigations were conducted on flexural performance of reinforced concrete (RC) beams with tension sides strengthened with slurry infiltrated fiber concrete (SIFCON) plate. As a result, we reached the following conclusions: (1) Ultimate load of RC beams can be raised nearly twice as large as that of un-strengthened RC beams by this strengthening method. (2) Peeling of SIFCON plate can be prevented up to ultimate load only by adhesive bonding. (3) There is a problem that RC beams strengthened with carbon fiber reinforced plastic plate fail brittlely due to plate-peeling. However, this technique has a possibility of solving the problem.

Glass itself is a flat plate and it is difficult to make H-shaped like steel beam. Therefore, there is a potential risk of deformation exceeding permissible limits. To address this issue, the authors have developed a solution to reduce glass deformation by using slender tempered glass stiffeners. This paper reports the structural behavior of T-shaped glass screens in a series of full-scale experiments under negative pressure considering sealants’ behaviors. These results are compared with the results of finite element analysis applying sealants’ properties from these experiments. This comparison shows the reliability of the proposed system.

In this study, we focus on the observation characteristics of 3DCAD and VR during the experiment. Based on eye data collected during the experiment, we grasped the observation characteristics such as the observation time, the distance moved through the design plan, the direction of the gaze when the subjects were searching for incorrect conditions. In addition, we analyzed the differences in observation characteristics between 3DCAD and VR tools, and the relationship between the observation characteristics and the situations in which incorrect conditions were found.

This paper proposes prediction method for vibration propagation to structures by subway railcars running. Applicability of previously method by dynamic analysis using voxel finite element method is confirmed. Simulation is carried out for evaluation of vibration by using three-dimensional soil-structure model. Assuming that a pulse occurs at the wheel position of cars, excitation force is made and set to node of train running position in consideration of a time gap for train speed. Good agreement between records and simulation results is shown and effectiveness of proposal method is validated.

This paper proposes a method to evaluate excitation force considering the planar spread of multiple people on the ground. The excitation force is divided into before and after ground input, and each reduction rate is evaluated using a simple envelope. The reduction rate before ground input is calculated by comparing cases with/without considering the sound arrival time difference. The reduction rate after ground input is calculated for receiving points by comparing planar excitation and point excitation. Using a finite element analysis of a two-layered ground model, it is shown that the reduction rates can be evaluated with a simple envelope.

It is well known that the thermal conductivity of an insulation foam increases due to the emission of the blowing agents from the insulation foams and the transfer of the air into them. In this study, numerical simulation based on three-dimensional finite difference method is conducted to study the distribution of thermal conductivity within an insulation foam for a long-term. The influence of surface gas barrier and side seals on thermal conductivity change was examined. In addition, the time variation of thermal conductivity distribution for various types of plastic insulation foams are compared.

District heat supply to residences is effective for the use of woody biomass for local production for local consumption. Therefore, we conducted a survey on the actual conditions and factors affecting supply efficiency. The average supply efficiency was 69.7%. In the investigation of factors influencing supply efficiency, it was confirmed that the effect of the amount of heat received was the largest, with a partial correlation coefficient of 0.64. When the effect of heat quantity received was excluded, the partial correlation coefficient of supply temperature was -0.31, indicating that supply efficiency tends to be higher at lower supply temperatures.

In this study, annual primary energy consumption intensity and annual average hourly primary energy consumption before and after the COVID-19 are compared for elementary and junior high schools affiliated with Niigata University. Furthermore, based on the event calendar of elementary and junior high schools, the correlation between energy consumption and outside temperature is shown by dividing into three categories: school days, days when teachers work without classes, and holidays.

This paper aims to provide information to support discussions on setting targets for the introduction of photovoltaic (PV) systems in non-residential buildings. By analyzing application data from building energy standards, the study investigates three aspects for non-residential buildings newly constructed between FY2018 and FY2022: 1) the introduction rate of PV systems, 2) the distribution of design specifications such as system generation capacity and tilt and azimuth angle, and 3) their impact on the Building Energy Index (BEI).

This paper presents indoor fungal contamination and countermeasures taken to restore indoor environment in 28 detached houses after flooding occurred on August, 2021 in Saga prefecture. Two field surveys, after three months and eleven months, were conducted. Almost houses were not restored even three months after the disaster. The concentration of airborne fungi in a crawl space tended to increase after flooding and could become a source of contamination in indoors. Since there are few survey reports of indoor environment after flooding in Japan, it is important to continue filed surveys and compile information that will contribute to rapid restoration.

In recent years, there have been movements to consider traditional houses as local resources which are used for revitalizing the region. Under the movements, we aim to establish a renovation method of traditional houses with friendliness to design and environment factors. In this paper, at Maezawa magariya village in Fukushima prefecture, we conducted a survey of winter living conditions of the residents and measured winter indoor thermal environment of traditional houses. In addition, we simulated the thermal environment with modeled traditional houses and compared them with simulation results in our previously published report.

This study investigates the life cycle CO₂ (LCCO₂) reduction potential of high-thermal performance curtain walls (CW) made of wood and recycled aluminum for a medium-scale office building. By calculating embodied carbon and operational carbon in detail, the authors demonstrate that optimizing material selection, such as wood and recycled aluminum, and thermal performance can significantly lower the environmental impact of building envelopes. The findings highlight the importance of addressing both manufacturing and operational stages. This integrated approach to CW design provides insights that may contribute to the decarbonization of the built environment.

The purpose of this report is to organize and analyze the current status of vacant rooms in detached single family houses and related factors in a suburban detached housing complex that has been in development for about 50 years, to understand the actual situation. The survey methods used were questionnaires and face-to-face surveys. The survey revealed that the current status of vacant rooms in suburban detached housing complexes, as well as the patterns and processes of their occurrence, have certain architectural and social universality.

The purpose of this study is to indicate the conditions for a library to be a sound library. The survey was conducted from the viewpoints of library operators, users, and noise levels, and the spatial configuration of public libraries can be classified into four types based on the level of sound tolerance: “separate quiet and dynamic,” “mixed quiet and dominant,” “mixed dynamic and dominant,” and “specific quiet and dynamic. For libraries to be sound tolerant, it is necessary to create a sound environment with “buzz” in order to create a cycle in which sound attracts people and creates new sounds.

Against the backdrop of a very low birthrate, an aging population, a shift of population to urban areas, and a shift to nuclear families, local communities are becoming increasingly diluted. The need for a different kind of community formation has been pointed out, and “local places to stay” are attracting attention as a social resource in many areas. This report focuses on Fujisawa City’s “Chiiki-no-Engawa” project, a community-based “place for the community” in which the city is involved, and clarifies the characteristics of the case study and the actual conditions of the users.

In Japan, a few public libraries have been renewed recently, and some of them have relocated their sites. This study investigates their relocation motivations through a questionnaire survey of 217 libraries relocated between 2010 and 2020, with 143 valid responses collected. Key motivations include urban planning, narrow space in old buildings, and the need to compound with other facilities. Text mining and correspondence analysis of free-text responses reveal correlations among motivations, and the relationships between motivations, library types, and land use changes. This research enhances the understanding of library relocations and provides insights for future public library planning.

COVID-19 pandemic had a major impact and in Japan there were concerns about a crisis of medical service collapse due to the shortage of hospital beds caused by the securing of beds for the COVID-19 patients. In this study we examine the actual status of numbers of hospital beds for COVID-19 patients in Japan. We also clarify regional characteristics by converting each secondary medical service area into an index of 100,000 population. We then attempted to analyze the medical service delivery system for the COVID-19 pandemic in terms of the number of hospital beds.

The purpose of this report is to demonstrate the potential of university facilities as venues for international conferences, based on JNTO data, which is an international conference indicator. The survey revealed that approximately 30% of international conferences were held at university facilities. While the number of university facilities used as venues is smaller compared with conference centers, they were frequently utilized for hosting small-scale international conferences. Further, a small number of international conferences were organized in collaboration with facilities near the universities or historical buildings, indicating the potential for expanded utilization through regional partnerships.

This study aimed to understand the relationship between nursing care delivery systems and floor plans of patient-room layouts in hospital wards. The results of the survey of five hospital wards are shown below: 1) We have examined and categorized the various nursing care delivery systems currently being implemented. 2) When a nurse-assigned-to-patients system is employed, in cases where patients (beds and rooms) are dispersed in a ward, the nurses cannot attend to them in one area. 3) When a nurse-assigned-to-room system is employed, it becomes difficult for nurses to continue attending to the same patients. The above facts were obtained.