In this report, the history of JIS on crushed stone and crushed sand for concrete was investigated. In the course of survey, ASTM standards, standards of crushed stone for road, provisions of academic organizations and research papers on crushed stone/sand which affected on JIS above were investigated. It was found that some items were newly stipulated or changed in JIS, which referred ASTM, based on the circumstance of aggregates in Japan. These findings will provide informative materials for revision of JIS in the future.
Influence of consolidation method for test specimen on activity index test results of micro-powder for ultra-high strength concrete based on mortar was investigated. This investigation led to the following conclusions. 1) Density and compressive strength of standard mortar and test mortar using volcanic glass powder were increased using a vibrator. 2) Coefficient of variation of the compressive strength was not changed by consolidation method. 3) As a result of the 1), consolidation method for test specimen influenced activity index test results.
In this report, the history of stipulations relating to grading of fine aggregates was investigated. In the course of survey, great influence of ASTM standards on the stipulations in Japan was verified. But some cases different from ASTM standards were recognized. And it was found that the history of revision was a little different among the organizations preparing the stipulations or the kinds of fine aggregate. As for the present stipulations, it is thought to be established not only on the ideal grading curve theory, but also on the actual state of grading of fine aggregates.
In this study, an experimental study is carried out to confirm time dependent change of fresh concrete, setting time and compressive strength of ultra-high strength concrete exceeding 35℃. As the result, it is confirmed that the fresh properties of concrete using chemical admixture properly was stability. And, it is confirmed that concrete could secure the prescribed compressive strength. Additionally, it is suggested that the time to reach the respective penetration resistance value could be estimated from concrete temperature and chemical admixture usage.
Aiming to make defect-free reinforced concrete buildings, high-fluidity technology and non-drying shrinkage type concrete technology, using a new admixture, were combined to develop a suitable concrete for applications. This concrete was applied to a wall that embodied a refined design whereas it could not contain crack-inducing joints. 18 months after its construction, an investigation confirmed that no cracks were observed on the wall. Furthermore, based on research results on the effect of member thickness on drying shrinkage strain, a prediction of long-term strains in this wall was made showing the concrete expansive behavior that would be exhibited in the future.
The phenomenon that letters and symbols by markers on concrete slab seep on the surface of polymer based flooring materials after several years of completion becomes a problem.
In this report, for the purpose of reproducing the stain experimentally and for the marker which is relatively widely used in the field, typical polymer based flooring materials and organic adhesives were combined, and accelerated curing test and thin-layer chromatography test were carried out.
As a result of the test, there was a correlation between Rf value of the marker ink with respect to the degree of seepage of the ink.
Tensile test was conducted after water immersion to clarify the influence of moisture on structural silicone performance. As a result, it was found that modulus of structural sealant decreased and elongation increased due to absorbed water. On the other hand, it was also found that elastomer performance was restored to near initial value by drying process. It was considered that the change of elastomer performance was caused by change in the intermolecular forces and cohesive force acting between the inorganic fine particles in structural sealant due to adsorption of water on surface of the particles.
In this report, we analyzed the concrete pump operation records for accumulating data that can be used for pumping planning and construction management from now on. As a result, it was possible to easily collect the data that could not be obtained without conducting actual measurement surveys and field experiments by analyzing the data recorded in the IoT system. And it was suggested that the IoT system could be used for pumping planning and construction management from now on.
It was shown that the color of materials in a closed space can be measured from the outside of space under diffuse illuminations by using a concave glass as a partition. The measurement accuracy is ΔE*ab = 0.9 in average for 24 colors of the standard color chart, where ΔE*ab is the color difference in L*a*b* (D65/ 2-deg.) color space of JIS Z8781-4. It is lower than that of the conventional colorimetry without a glass partition, in which the measurement accuracy is ΔE*ab = 0.7 in average; it is, however, high enough compared to that of visual colorimetry.
The present paper proposes the external wind pressure coefficients for designing the main wind force resisting systems of low-rise gable-roofed steel structures in the framework of gust-effect-factor approach, based on a wind tunnel experiment and a two-dimensional frame analysis. For evaluating the wind pressure coefficients focus is on the bending moments induced in the members as the most important load effect. The equivalent static wind pressure coefficients generating the maximum load effect is evaluated by the LRC method. The gust effect factor considers the resonance magnification factor for the first vibration mode.
Photovoltaic (PV) panels are seldom installed in the edge zones along the eaves and ridges of roof, because very large suctions are induced in such zones. The present paper investigates the wind loads on PV panels installed over the whole roof, including the edge zones, of a square roof in a wind tunnel. In the present study, we propose to install PV panels with small gaps between them, which may reduce the net wind forces on the PV panels due to pressure equalization. The external pressures on the roofing may also be reduced significantly.
A large-amplitude oil damper system with twice the stroke and velocity of a normal oil damper has been developed. The damper system consists normal oil dampers connected in series. In order to make the displacement of dampers in the system same, “displacement adjustment mechanism” is connected in parallel. The mechanism consists of right-hand threads and left-hand threads with same pitch. We made a full-scale prototype of the system and conducted loading tests. As a result, it is confirmed that the displacements of each damper are same, and the stroke and velocity are twice that of a normal oil damper.
In the Great East Japan Earthquake 2011, a number of automated warehouse’s functions were suspended for a long time because stacker cranes were prevented from working by loads fallen into the aisles. Authors have developed a new structural control system for automated warehouse utilizing the loads themselves as weights of the TMD. This paper first presents the outline of the system. After examining the target specifications, the developed control slider is reported. Finally, the results of a shaking table test are presented.
To use tuned mass damper (TMD) for structures with period fluctuation, the authors proposed a newly developed semi-actively controlled TMD. Its resonance frequency is controlled by changing the damping coefficient of the variable dampers. This paper reports on its shaking table tests. First, the configuration and control method of the proposed TMD are described. Second, the design concept and specification of the specimen are presented. Finally, the results of the shaking table tests are shown. They are compared with that of simulation analyses, and the accurate operation of the control system and expected behavior of the specimen are confirmed.
In seismic response analysis of buildings against strong earthquakes, it is very important to appropriately set the model parameters of the building. Numerous methods have been proposed to identify these parameters. However, most are based on only linear analysis; some studies using nonlinear analysis noted difficulty in practical applications. In the present study, the Modal Iterative Error Correction method (MIEC method) is proposed to identify the nonlinear seismic parameters of buildings. The accuracy of this technique for RC structure is evaluated on the basis of shaking table test results.
In recent years, although many researchers have focused on the damage to buildings subjected to fault displacement and methods for preventing this, a design method has not been established. Therefore, we propose a design method for pile foundation buildings, considering fault displacement, and we conducted a trial design. We developed a realistic design for a high-rise building located near faults. In addition, we showed the mechanism of moment generation by fault displacement, and the effect of distance between faults and buildings on the inclination angle of the ground by fault displacement.
We have developed a static analysis program for pile foundation by “pile group frame model”. “Recommendations for Design of Building Foundations” (AIJ) was revised, and pile foundation is now required to be designed for loads during large earthquakes with this model. This paper describes the analysis theory and calculation example of the program. These show the basic characteristics of this model and show that this model can evaluate the collapse mechanism of pile group. These are the basic knowledge for the rational “Limit States Design” of pile foundations.
Multi-belled cast-in-place concrete piling method has been developed, which use mechanical belling bucket without hydraulic drive. The buckets are designed for several size applicable from medium-rise to super high-rise buildings. Hydraulic belling buckets are also provided as a compatible device for mechanical ones. Field trials were carried out in order to verify the performance of the proposed buckets and the quality of the constructed piles. From the results, it was confirmed that the piles satisfied the required shape and quality by both mechanical and hydraulic belling excavation ways, and that mechanical one could shorten the construction period for compact piles.
We carried out microtremor measurements of wooden framed houses constructed in the Bingo region, Hiroshima. The microtremor measurement of the house was carried out considering the construction stage. We tried to identify the structural characteristics which are vibration period, damping factor, mass and stiffness. We compared the obtained data of the measurements with the structural calculation documents by the allowable stress concept.
This research focuses on the layered timber beam used in the “Odaka Community Center” constructed in Minamisoma City, Fukushima Prefecture. Shearing experiments of the inclined screw joints connecting the timber layers and a bending experiments of the full-scale layered beam are conducted. A comparison between the initial stiffness of the layered beam and a non-layered beam show an increase, confirming the layering effect. The results from the full-scale layered beam are compared and verified with numerical simulations from an analytical elastic model, displaying similar trends.
The purpose is to develop floor CLT having smaller thickness and higher bending performance with two-by-four timber and stud timber than conventional CLT floor. This study reveals that the optimal CLT floor consists of two-by-four timber and stud timber as outermost layers and cross layers, respectively, on condition that each layer consists of at most 2-ply. The calculation of CLT bending performance leads to estimation results with precision. The required thickness of optimal CLT floor is about 31mm thinner than conventional CLT in average.
In this paper, the structural system using continuous walls which prevents soft-story mechanism of a wooden house is proposed and its mechanical properties are investigated through experimental and numerical studies. The static loading test on a scaled two-story wooden wall and the shaking table test on a two-story wooden frame show that the proposed structural system works to reduce the damage concentration to a specific story and prevent soft-story collapse. Time-history seismic response analysis shows that the effect of the continuous wall is represented by the beam element located along the height of a main frame.
In this paper, we report the results of static loading tests on traditional wooden two-storied frames with through columns. The tests target a frame with column reinforced with a stainless steel plate and a frame reinforced with an FMS alloy damper for the purpose of reinforcing the joints against fracture caused by the axial force and bending moment of beams “Sashigamoi”. We also propose a practical 2-dimensional FEM model that evaluates the behavior of the joint and the frame of the traditional wooden two-storied frames, and compare the analysis results with the experimental results.
We developed a one-way slab system composed with cross laminated timber (CLT) and glulam coupled by lag-screws. Firstly, we conducted element test for the single lag-screwed joint of glulam and CLT to grasp the joint properties as composite beam and cyclic loading test for the lag-screwed joint of glulam-to-CLT panel and CLT panel seams for horizontal diaphragm. Secondly, we conducted the bending tests for CLT slab with glulam ribs to confirm the characteristics of the failure behaviors, the coupling efficacy by the lag-screwed joint and the estimability of their mechanical behaviors from single lag-screwed joint properties.
In horizontal hybrid wooden structures with RC core, the wooden diaphragm is not enough stiff, so the seismic response of wooden parts is dynamically amplified. In this paper, the effects of the axial rigidity of wooden girders and their joints on the wooden diaphragm are shown by comparing the results of modal analysis of shear model and bending shear model. Finally, criteria for seismic force distribution and displacement of wooden diaphragm on dynamic properties, that can be applied to practical structural design, are proposed.
Finite element analysis was performed to replicate the test conditions of a reinforced concrete beam with a guaranteed hinge position having de-bonding of longitudinal rebars. From the analysis, it was found that the existence or nonexistence of longitudinal rebar bonding in the section from the beam end to the assumed hinge position did not affect the shear force-member drift ratio relationship or the damage conditions. In addition, the crack range could be suppressed with almost no decrease in stiffness through de-bonding of only the longitudinal rebars at the four corners instead of all the first layer rebars.
Cyclic loading tests were conducted using damaged R/C soft-first story columns retrofitted by sandwiching and bonding UFC panels. The specimen which was loaded to 0.5% in the first stage of loading, the maximum strength in the second stage was greater than that in the first stage by 14%. However, the retrofit method was not effective for the specimen which was loaded to 3% in the first stage in terms of strength and deformation capacities. The ultimate strength calculated by the proposed method with consideration of the damage in the first stage of loading shows good agreement with the experimental one.
In recent years, many seismic retrofits have been performed. In case of steel structures, the seismic brace connections are often strengthened to resist the full plastic axial load of braces for the plastic deformation performance. This paper investigates the applicability of CFRP strengthening to the connection between brace and gusset plate with stepped surface using VaRTM technique. We demonstrate the elimination of step and strengthening methods by CFRP layers to transfer the axial stress effectively. Eventually, it is clarified that the CFRP strengthening can improve the connection strength and plastic deformation even if it is molded onto stepped surface.
In this study, uniaxial compressive test of ultra-high strength square CFT stub columns was carried out to clarify the effect of column size and steel contribution ratio to its structural performance. The results of experiments were analyzed to clarify differences between structural behavior of CFT stub columns and that of individual steel tubes or concrete. In addition, the applicability of the simple cumulative strength formula is verified.
The Japanese government is promoting use of wood in recent years, because of the environmental provision of carbon dioxide fixation. The authors developed “FR wood”. “FR wood” is the only technique with simply use one tree species in Japan. When considering actual application, it is necessary to verify the fire-safety of joint parts in addition to the development of member. In particular, verification of the joint with the steel frame member is important. So, the specimens of the join part were constructed and fire resistance test was conducted. The resistance performance of steel members and wood members was confirmed.
Cross Laminated Timber (CLT) is an emerging global trend in the field of wood architecture. Particularly in Europe, various types of wood buildings have been built using CLT and the field of CLT construction is growing rapidly. However, in Japan, CLT is still considered to be a new material and there are many barriers that need to be overcome. This study investigates the technical and psychological barriers that different companies in the construction sector might have in order to find solutions to how to overcome them and increase of the use of CLT in Japan.
To prevent COVID-19, the apartment housing was filled with more people for a longer time while at home in Japan. These conditions are thought to have produced something close to the maximum noise load of the apartment housing. In order to better understand the reaction of the residents to this situation, we decided to conduct a questionnaire and collect data. As a result, compared to before stay home, the number of sounds that were heard and worrisome during stay home increased to 1.3 times. In addition, about 10% of the residents were involved in noise problems during stay home.
It is speculated that countermeasures against floor impact sound will become a very important issue in small-scale nursery schools in buildings and apartment houses. In this report, an experimental study was conducted with the aim of proposing a high sound insulation specification using storage furniture with tatami mats for the purpose of preventing heavy-weight floor impact sound. As a result, by properly taking anti-vibration and sound insulation measures for the furniture with tatami mats, performance improvement of 18 to 22 dB was achieved in the 63 Hz band compared to the bare surface.
We have proposed a method for estimating the vibration acceleration level of the floor structure with high accuracy by preventing the mounted resonance of the carpet floor. In this report, we conducted an experimental study using a vibration generator for the horizontal vibration of thick tatami floors, unlike carpets. As a result, good response was obtained by the estimation method of this study for the horizontal vibration of a tatami with polystyrene foam as the core material. In addition, the validity of the proposed method was suggested for at atami with polystyrene foam as the core material with vertical vibration.
This paper describes exciting force models about jumping up and down, which has the biggest exciting force among human motions. First part describes a large floating floor which can be regarded as a SDOF and its transfer characteristics. Second part describes experiments of jumping up and down with from one to sixteen people on the floating floor and how to analyze the experiment results. Final part proposes dynamic load coefficients α1 ～ α6 in consideration of relations between the number of excitations and exciting forces of jumping up and down.
A general hospital examination room with the same ventilation method as a patient cluster occurrence of COVID-19 was measured to clarify its ventilation performance. The only ventilation to the room was the air from the corridor through the undercut of the door. It was found that, for each measurement point, the highest indoor carbon dioxide concentration was approximately 1200 ppm, which was 400 ppm higher than the air supply. If the number of people in the room is large, it is possible that the ventilation is insufficient. It is recommended to increase the ventilation volume and install a high-performance filter.
The Combined Convection-Radiation air conditioning system using building structure is a system that combines the strengths of the TABS and convection systems. The purpose of this study was to investigate the specification of this system and determine its thermal performance. For the experiment, two concrete test specimens were prepared assuming this system and general TABS. The placement method for the pipes and the airflow conditions around the test specimens were varied, and a comparison of the changes in the thermal performance. This paper indicates the strengths and weaknesses of this system compared with general TABS.
This research mainly focuses on 4 large-scale housing complexes in Fukuoka City, using space syntax theory to analyze the characteristics and structural attributes of public space. We mainly used the Axial analysis and chose the integration value and intelligibility to quantify the spatial structure. The results show that the accessibility of the Yanaga complexes is relatively high but the public space inside the group is extremely lacking. Besides, place in Fukuhama and Shirohama are both marginal and decentralized. While in Shimoyamato is widely distributed and the accessibility and activity are very high.
In this study, we will quantitatively clarify the actual condition of straying behavior in multiple facilities with different plans using three-dimensional laser sensor, verify the hypothesis, and clarify the environmental factors of straying behavior. Expressway rest area Ebina SA(up/down) and Fujieda PA(up) are selected as research object having two types of plans. As the result, Spatial range of visual perception of restrooms and its signage are important factor for confirmation and distinction.
This paper aims to raise the issue to consider, that is the architectural planning and living environment of after-school childcare center that higher grade elementary school children feel comfortable. The authors conducted survey at a certain institution. The result shows that those children tend to choose spaces they can stay away from others. Also, they tend to concern about the glances or noises of others in their free activities rather than stated program such as homework. It seems to be the reason of this tendencies that those children are in transition period of the stage of psychological development.
This study aims to clarify how to decide the unit indicator based on the facilities capability. 1) To determine the unit indicator for nursing unit, we verify the correlation of specifications including the number of beds and nursing units and the floor space of nursing unit. 2) To examine the characteristics of the distribution, we accumulate various data as a database based on the unit indicator. As a result of examination, some departments are positively correlated with factors. Others which have no or poor correlation to factors could be regarded these parameters as a distribution.
This study aims to record COVID-19 infection control in detail and to evaluate this in one library. Caption evaluation method was carried out in late June 2020. The evaluation near the counter was generally good in terms of measures to avoid gathering and information presentation. However, in terms of contact, there were many bad evaluations such as handicapped items, copiers, leaflets, etc. Prioritizing the development of user areas, the area where staffs work was not developed. It is significant that the evaluation was carried out because a third party pointed out that the staffs alone had overlooked them.
Assuming the introduction of the departmentalized classroom system to conduct by the grade unit, the school building of M municipality M Junior High School was planned and was built. Features of the building are that departmentalized classrooms, multi-purpose space and teacher station for exclusive use of the grade unit are installed. We analyzed various effects and problems in school management and the school life through the inventory survey for teachers and students. As the result, the purpose-built school building for the special system inspected that it functioned effectively.
In this study, we collected case studies of area hospitality initiatives in Japan that make use of existing buildings and local resources and summarized the actual situation. The results showed that the management style of lodging centers is changing and expanding in various ways, influenced by the location and region, with a focus on the connection with the local resources. It was found that there is an increase in the number of people using the lodging function as a temporary residence. Additionally, we found that the consumers are also seeking experiences unique to the area.
We conducted an observation survey at JR Osaka Station Atrium Square and a quantitative analysis of “securing physical distance” to clarify the effect of “new lifestyle” due to the COVID-19 infection in public spaces. As a result, we found the following. Three months after the state of emergency was lifted, the number of people stopped/stayed increased slightly compared to immediately after the state of emergency was lifted, but their locations tend to be more uniform. This is thought to be the result of the establishment of a “new lifestyle” due to the COVID-19 epidemic.
The Design architect participated in the Nihonbashi Mitsui Tower Project. When the design architect participates in a large-scale project, we report on its design team organization, cooperation and actions.
This report summarized the knowledge gained about the details of changes in team organization, cooperation and action in schematic design and construction document phase.
The purpose is to clarify the position of Nagasaki Yojosho in Japan. The drawings were restored using previous research, old photographs, and excavated materials. It was revealed that Pompe, who came to teach medicine to Japanese people at the end of the Tokugawa Shogunate, used system of measurement in Rheinland and created his concept under the influence of Dutch architectural manuals and Nightingale’s reports. In addition to them, he revised a “plan” that considered the on-site and economic conditions. He built a state-of-the-art hospital at the time, but it had little impact on Japanese hospital construction.
Two subjects lifted 45.0 kg (measuring equipment and humanoid dummy) upstairs on the slope installed on the U-Shaped staircase which includes a landing at the switchback. The pulling force and the required time were measured. The experiment was repeated 3 times on each pair. A large amount of pulling force is continuously required on the slope. A large momentary pulling force is required at the landing. Female-female pairs with a small sum of back muscle strength takes a long time. It became clear that the evacuation time can be greatly shortened if there is at least one male caregiver.
Ohira village devised the extension of life plan of the public housing in 2014 and started the Gotanda public housing’s long-life repair work includes roof waterproofing, outer wall insulation, window insulation in 2017-2020.
Because the building before was easy to be affected by outside temperature, there were various troubles inside. This study clarifies the influence that the repair work gave for the improvement of the room environment of the dwelling-units by analyzing the temperature-humidity data.
In conclusion, the room environment was improved after the repair work that inside temperature rises and the risk of the dew condensation was decreased.