Concrete with high content of admixture is effective in reducing the stress-strength ratio because of the low heat generation associated with the hydration reaction. However, concrete with high content of admixture is out of the scope of general stress-strength ratio estimation formulas. Therefore, the authors conducted an analytical study and developed a stress-strength ratio estimation formulas for concrete with high content of admixture. Case studies using this estimation formula showed that the estimated values can be evaluated safer than the analytical values, and that concrete with high content of admixture is more applicable to massive concrete.

Grading of aggregates is important to secure the workability of concrete and proper unit water content. Therefore, it has been stipulated in some specifications or standards. In this report, the change of treating method of grading and fineness modulus in aggregate surveys were investigated with existing literature. At the result of study, it was clear that after 1980 most literature expressed grading with only fineness modulus omitting table or figure and it was supposed that fineness modulus varied with time due to the revision of specification or stipulation, the change of construction method and the kind of aggregate.

To assess the durability of concrete structures located at waterfront sites, a long-term test to monitor the physical properties of core specimens sampled from simulated high-strength mass concrete members was carried out. The study focused on changes over time of compressive strength and elastic modulus, the tendency of depth direction from the concrete surface, as well as the tendency of dry mass per unit volume. The test results confirmed the integrity of high-strength mass concrete up to 36 years age.

In order to control drying shrinkage cracks in concrete, it is important to grasp the drying shrinkage rate of the concrete. Since the methods of measurement for length change of concrete takes as long as 6 months, JASS5 provides an early judgment formula. However, no coefficient is given for the case of using expansive additives. In this report, we collect a large amount of drying shrinkage rate data and report on the results of examining the estimated coefficients with the early judgement formula for the drying shrinkage rate of concrete using expansive additives or shrinkage reducing agents.

This paper investigates a production management method to verify thermal performance of ALC panels by measuring thermal conductivity of ALC base material sampled from the same production lot. The thermal performance of ALC panel specimens manufactured with different levels of reinforcement were measured using calibrated heat box method and compared with the thermal conductivity of the non-reinforced ALC specimens of the same production lot. The comparison has suggested that apparent thermal conductivity of ALC panels exhibit 0.02 W/(m・K) increase at maximum in comparison with the thermal conductivity of non-reinforced ALC material of the same lot and moisture content.

In this study, the strength properties of traditional plaster materials were experimentally investigated. Material tests in compression, bending, and shear were conducted to clarify the basic performance. It was shown that the stiffness and strength of the plaster decreased as the amount of sand mixed into the plaster increased. The stiffness and strength of the plaster increased with increasing curing time. Furthermore, a comparison of the average values of compressive, bending and shear strength showed that there was a correlation among those values. These results quantitatively clarified the various properties of plaster materials, although they are limited to certain formulations.

This report summarizes the process, issues, etc. of the efforts of Yamato Town, which dismantled and relocated the temporary wooden housing after Kumamoto Earthquake. The purpose is to consider the specifications of the skeleton structure with the aim of improving the reuse rate and cost cut.

The Former Army Clothing Depot in Hiroshima was built in 1913 for the purpose of manufacturing and storing military uniforms. In this building, the outer walls are made of brick, and the main structural elements of the internal columns, beams and slabs are made of reinforced concrete. It is also an A-bombed building located about 2.7 km from the hypocenter. This building has high academic value, and based on past surveys, a survey will be conducted with the aim of accumulating data for future preservation and renovation. This paper presents reference data for future repair and seismic reinforcement plans.

Organic adhesives used for exterior wall tiling are considered to deteriorate when used outdoors because they are organic materials. Therefore, in this study, we devised the basic performance of the organic adhesive method and a heat and cool cycling test that accelerates the deterioration of the organic adhesive, and verified its long-term durability. Considering the various conditions under which organic adhesives are used, the tests were carried out by combining bases, base treatments, and organic adhesives. In addition, an outdoor exposure test was also conducted to examine the relationship with the heat and cool cycling test.

This paper summarizes the results of a questionnaire survey of interior contractors regarding appearance of cloth for seams of gypsum boards in interior finish. In this paper, measures and occurrence status against appearance of cloth for seams of gypsum boards were investigated by a questionnaire survey of interior contractors. As a result, although the interior contractors have taken some preventive measures against appearance of cloth for seams of gypsum boards, it has become clear that more than not a few appearance of cloth for seams of gypsum boards have occurred.

In this study, aiming at developing anti-washout grout for repairing marine structures, experimental investigations were conducted regarding a mix proportion design of grout with high fluidity, which satisfies specifications for anti-washout admixture applied to concrete. As a result, it was possible to present the mix proportion which almost satisfies the specified values in pH, turbidity and strength ratio of specimens made in water and air by means of repeating the prototype.

The authors conducted a questionnaire survey for the purpose of analyzing how severe the disasters are assumed in BCP and which measures are being taken. We have analyzed priority of risk countermeasures and content of countermeasures. In this paper, ratio of cumulative number of respondents to the questionnaire to the total number of respondents is regarded as subjective probabilities of restoration periods or frequencies of assumed disasters. In this way, we regard the recovery performance of facilities or the frequency of assumed disasters as a subjective probability that quantitatively evaluates how people think, and propose them as assumed curves.

To establish the roof snow control by melting snow using ventilation waste heat on the double-layered membrane roof with gentle slope, the authors conducted the field experiment using the membrane roof prototype and examined the method for estimating the quantities of snow melting. As the results, the snow on the roof melted in case of the supply airflow temperature of approximately 20°C. In addition, the necessity to consider the thermal conductivity of the roof snow, and the setting value of snow density and the melting efficiency was clarified in the estimation of the snow melting quantities.

This study proposed a ground motion prediction model in terms of natural period dependent spectrum intensity by employing an indirect method proposed by Kohranghi et al. (2018). Then, probabilistic seismic hazard analysis was demonstrated at Osaka city using a proposed model. A proposed model can be utilized to develop a probabilistic framework of displacement-based seismic performance assessment by combining with a response prediction method proposed by Furukawa & Mori (2020).

This study reports experimental results on an inerter eddy current damper incorporated into a base-isolated multi-degree-of-freedom structure. The secondary vibratory system comprising a dynamic mass (inerter) produced by the disk type eddy current damper and undesirable flexibility of damper connecting member is considered. The simple formula in the literature to calculate the damping coefficient of an eddy current damper demonstrated its accuracy.

The rapid damage estimation of building group in Gunkanjima is performed through the synchronized monitoring of MEMS acceleration sensor network. The anomalous behavior is detected by tracking the observed acceleration time series of each building. Then, the global damage of each building is investigated by singular value decomposition of the whole frame. Finally, the local damage within each building is scrutinized by evaluating the spectral ratios between observed points of the partial frames. This paper deals with the detection of anomalous behaviors related to structural damage from real sensor network data during two successive typhoons.

Static loading tests of displacement restraint PC steel bar brace, which acts as a central pillar when the displacement reaches a given value, were conducted with and without disc springs at the ends. Then the brace was loaded to the ultimate broken state. The behavior of the brace ends, hysteretic characteristics and axial forces acting on the four PC steel bars were confirmed in these tests. Stress distributions in the gusset plate and rib plates at the brace end were analyzed to determine the end rigid zone length when the brace was replaced with a linear element model.

In order to reduce out of plane deformation of dry wall by lateral force, connecting method of stud end to runner by screw is employed as one of the simple measures. Loading tests are conducted using real size stud-runner systems with/without stiffen measure at stud end. Stiffen effect is quantified through elastic curve equation comparing measured results of with/without stiffen model. Calculated results are obtained as rotational spring which connects deflection angle and fixed end moment at stud end. The stiffening effect is not remarkable large as roughly 10% reduction. If larger effect is required more heavy measures are needed.

This paper describes the development of cast-in-place concrete piles at the dawn of foundation technology in Europe and the United States. The first cast-in-place concrete pile was the compressol pile invented in France around 1897. Around 1900, Raymond piles, simplex piles, and pedestal piles were invented in the U.S. Around 1910, franki piles were invented in Belgium. These piles have been installed not only in their home country but also in other parts of the world; more than 100 years later, they still support many historical buildings.

In this report, the applicability of the proposed method is verified by simulation analysis of in-situ horizontal loading test results of piles with measured shear wave velocity. In addition, a sensitivity analysis of the parameters used for ground spring evaluation was conducted. As a result, it was confirmed that the proposed method can reproduce the horizontal loading test results well. It was also confirmed that the ground spring and the deformation coefficient of the ground were more influential when the pile diameter was large, and the plastic horizontal ground reaction force was more influential when the pile diameter was small.

Column-to-beam connections are important to evaluate the seismic performance of traditional wooden buildings accurately. However, there are many types of traditional joints. Some of them have not been studied for evaluating their seismic performance, such that almost no experimental data and no evaluation methods are available. This study aims to evaluate the tensile performance of column-to-beam connections with Sao-shachi joint based on the full-scale tests. It is shown that the evaluation formula for the column-to-beam connections with Yatoi-sao-shachi joint in the past is applicable to evaluate the tensile performance of these connections.

The number of nails, screws or lag-screw-bolt is fixed in some studies about bearing wall using CLT. Additionally, these studies told about a specific wall magnification. Therefore, in this study, we developed a strength adjustable bearing wall using CLT by changing the number of drift pin. We also developed a design method for the bearing wall. We examined the bearing wall and the result showed that our strength adjustable bearing wall attained its target value.

This paper examines the structural characteristics of the Former Hidaka-Town-Office, located in Toyooka-city, which was constructed in 1935, as well as the corrosion deterioration of its wooden members. A comparison with previous research reveals that the structure aligns well with the advanced design of Western-style wooden buildings from the early Showa era. The construction of the roof trusses is mechanically rational, but the joints connecting beams and braces may be fragile. Most of the corrosion deterioration in the wooden members was found within the outer walls, while other parts of the building remain in good condition without significant deterioration.

This paper proposes a safety performance evaluation method that combines damage probabilities based on the results of collapse analysis and seismic motion exceedance probabilities for each region. This method is a more detailed evaluation method than general seismic diagnosis by taking into account the occurrence of building collapse behavior. The safety performance of buildings can be provided quantitatively and in a form that is easy for occupants to understand. In addition, the results of the application of this method to wooden houses connecting with seismic shelter are presented.

This paper proposes a new type of brace with elastoplasticity in tension. The brace is made of laminated wood with a hole in the center and a steel bar through the hole. Prestress force is applied to the brace. The brace absorbs earthquake energy in tension and maintain rigidity in compression in the case of large earthquake. And, the brace avoids brittle failure against tensile force. We confirmed the hysteresis characteristics of the brace by experiments, decided material, size and detail. And then we discuss the mechanics of buckling and compensating effects.

This paper aims to evaluate the design and bending performance of a wood-only timber frame joint inspired by the growth model in trees. The stem branch junction’s features were explored and approached in a simplified application of glued-laminated column-beam members joined in a conical mortise-tenon with bent laminated veneer plies flowing seamlessly across their interface. The joint was manufactured in Japanese Cedar with Beech bent plies, tested, and compared to glued-in rod (GIR) and lag screw bolt (LSB) joints; it showed comparable efficiency in moment transfer with reasonable failure patterns compared to conventional joint systems with added-steel accessories.^Note1)

Wooden grid walls are primarily used as load-bearing walls for wooden structure. The joints of the traditional grid wall consist of half-lap joints. If the joints are consisted of crosspiece joints, it can exhibit more efficient embedding performance than that of the half-lap joints. Therefore, an experimental study was conducted to investigate the performance of grid walls with crosspiece joints. The yield strength of grid walls was discovered to be influenced by the clearances of crosspiece joints. Furthermore, considering the clearances, the proposed formula showed good accuracy in estimating the overall seismic performance of grid walls with crosspiece joints.

In this study, the static shear experiments were conducted to understand the mechanical behavior of the Shin-Kabe panel shear walls. Then, by applying the 4-Point Concentrated Method (reference 5), we proposed the mechanical model of the Shin-Kabe panel shear walls. The basic concept of the mechanical model is the same as the structural performance evaluation used in references 1) to 3), and we proposed the new concentrated method for the spring that expresses the nail effects. As a result, the new concentrated method was able to reproduce the experimental values well.

This paper reports the results of our research on seismic behavior of traditional wooden houses with L-shaped plan, Magariya, in Fukushima prefecture. First, to figure out the structural characteristics and vibration characteristics, we investigated the seismic elements and current state of the Magariya. We understood that main part and attached part of the building may not move as one structure. In addition, we estimated seismic performance and eccentricity of Magariya by limit strength calculation.

The experiment investigating that the loading direction exerts on ultimate shear strength of beam-column joint with different floor levels was carried out. The experiment was conducted on positive and negative alternating cyclic loading, and two specimens with different loading order were designed. The maximum negative load defined in this experiment was larger than the maximum positive load regardless of the loading order, and the maximum negative load for the specimen to which the negative load was conducted first was larger. The effect of the loading order made relatively less impact on the maximum load compared to the loading direction.

LY225 steel, a low-yield-point steel, has few toughness data at low temperatures. The toughness data of LY225 steel and its weld part at low temperatures are needed to safely use low-yield-point steel dampers in cold climate. This study shows that LY225 steel retains a sufficient toughness at low temperatures by the Charpy impact test. The toughness of the LY225 butt weld was equivalent to that of the base metal above 0°C even with weld defects. Also, the absorbed energy obtained by the test is linear with the lateral expansion quantity. Therefore, the toughness of LY225 steel and the weld part can be evaluated from the lateral expansion quantity.

NC braced frames proposed by the authors are a new structural system that can be reduced seismic responses based on an elastic strain energy accumulation. Although the energy accumulation yields a non-linear elastic hysteresis, this hysteresis rule has not been formulated. This report first describes a non-linear elastic behavior of single-story NC braced frames, and then presents a 1DOF reduced model incorporating the hysteresis rules. Time history analyses of the 1DOF and frame models were carried out to verify the response reproducibility. As a result of the comparison, the 1DOF model reproduced the responses of the frame model.

A new type of steel-concrete (SC) composite column was proposed. The proposed SC column is made by encasing square steel tube into circular concrete column confined by thin steel tube with diameter-to-thickness ratio of about 189. With width-to-thickness ratio of the encased square tubes, axial load ratio, and concrete-filling into encased tubes as main experimental variables, a total of thirteen specimens were made and tested under reversed cyclic loading to investigate the structural performance, ultimate strength, and defamation capacity of the proposed columns. Besides, an analytical method was presented to evaluate the cyclic response of the SC column.

Analytical parametric studies were performed on the vertical mixed structure intended for mid-rise buildings, to investigate the seismic behavior. Based on the results of the analysis, a method for rationalization of seismic design is proposed. Specifically, we focus on the ratio of the inverse of the inter-story deformation angles of the upper and lower part of the mixed structure. It is also confirmed that the load capacity is not required to be increased by the Fs value when the ratio of the inverse of the inter-story deformation angles is 15 or more.

Various verifications are required when applying wooden members to a building. In this study, full-scale fire-resistant laminated timbers for columns and beams were manufactured for the purpose of confirming the effects of fire performance materials on the surface and the effects of heat bridges in which runners and crosspieces were attached to the surface with screws. It was confirmed that fire performance materials and screws have little effect on fireproof performance.

An axial composite fire resistive covering method for steel beams was developed by combining intumescent fireproof coating and other fire resistive covering materials. Four types of fire resistive covering materials to be combined with intumescent coating were selected. Fire resistance tests were conducted on steel beams covered with these fire resistive materials. As the result, 1-hour and 2-hour fire resistance was achieved with a combination of intumescent coating and intumescent coating or calcium silicate board, and 1-hour fire resistance was achieved with a combination of intumescent coating and wrapping type rockwool blanket or sprayed rockwool.

Full scale fire tests on low-rise residential buildings run in Japan during the 20^thC have been surveyed through literature. It is confirmed at least 64 tests were run including 32 pre-WWII ones. Outline of the tests have become clear on 44 tests from test reports in various media, and comprehensive report including precise measurement data have been found on 31 tests. Movies have been discovered on 17 tests run since 1976. All test reports and movies found by the survey have been digitized and become available for research under the copyright restrictions.

In this paper, investigations on the applicability of the 3D pressure-velocity sensor in the sound field for acoustic measurement of building are presented. First, a calibration method for the sensor using an acoustic tube is proposed. Next, the measured values from the sensors installed near field of the boundary in the sound field of the floor impact sound are compared with those from the vibration acceleration pickup installed on the boundary. Finally, measurement results of time response of 3D particle velocity and instantaneous sound intensity in the field in wooden and RC buildings are shown.

When predicting ground environmental vibrations, vibration analysis using the finite element method or the thin layer method is often used, but while these methods are capable of precise vibration prediction, they are computationally expensive. In general, most of ground environmental vibrations are caused by vibrating ground surfaces, and it is well known that surface waves are dominant compared to body waves. In this study, the transfer function obtained by ground shaking experiments was compared with the normal mode solution. Next, the normal mode solution was applied to the prediction of construction-induced vibration.

This paper describes exciting force models about walking up/down stairs for landing toe first. First part describes a experiment system for measuring live load of one step when walking up/down stairs by using a force plate and a model stairs which are capable of being adjusted the rise and tread part. Second part describes characteristics of waveform shape and maximum value of one step waveform. Final part proposes dynamic load coefficients α₁ ～α₆ for walking up/down stairs and describes these coefficients are similar to those of walking motion.

We have conducted various studies on methods to prevent contact resonances. It was suggested that the proposed method of the previous studies could be used to estimate carpets and building material tatami. On the other hand, there was a problem with the straw tatami. Therefore, in this report, we conducted an experimental study on an estimation method that is an extension of the proposed method. As a result, it was shown that by considering the modified estimation method, the error of the contact resonances can be reduced and estimated even with the straw tatami.

“Introduction to Environmental Vibration Design for Ensuring Habitability” published in June 2020 provides example of performance matrix for periods of 1 day, 7 days, 30 days, and 365 days for road traffic vibration. However, there are few reports on vibration measurement for one week inside house. In this report, we made two patterns of vibration measurements for road traffic vibration in a wooden house for one week. The results suggested that traffic volume of heavy truck affected changes in vibration level throughout the day.

Changes in regulations on attic and roof space ventilation in International Residential Code of the USA and National Building Code of Canada were thoroughly surveyed to investigate the recent changes in roof construction and development of building science regarding prevention of moisture related problems. Also, differences in attic and roof space ventilation regulations in both the USA and Canada and in Japan are discussed. Present Japanese regulation mostly has its ground in the USA house construction recommendation in 1950s’, and has not been updated for many years. Issues which should be reconsidered in its future updating are discussed.

Gymnasiums are used as evacuation centers during disasters and are poor environments with deteriorating thermal environments and air quality. Ventilation is necessary to prevent air quality deterioration, and radiant air conditioning has the potential to form a comfortable thermal environment during ventilation. This study examined the impact of partitions used during shelter use on radiant air conditioning by comparing cardboard and cloth partitions. While the cardboard partition blocks the effect of radiation through its insulating effect, the fabric partition has the potential to create a thermal environment by capturing and transferring heat during heating.

Many cities in Japan have connected with old travel roads called Kaidō built in early modern days. Shape of land allotments in the city blocks along with Kaidō has been almost the same as that of early modern days in many areas. In this study, summer thermal environment in Kyomachi district in Kumamoto city, was analyzed, and influence of parking lots on traditional land allotments covered with asphalts upon outdoor summer thermal environment was made sure from the field measurement. And counter measures to improve thermal environment making the most of traditional land allotment were proposed.

This paper describes results of a field measurement in which the feasibility of the external insulated house with air circulation through under-floor space, and attic connecting to ventilation layer in walls were examined in Okinawa. Absolute humidity in walls and under floor in median is 4.0 g/kg (DA) and lower than outside air. The external insulation and the air circulation make attic air temperature lower than 30℃.

The purpose of this paper is to introduce a design method of environment-oriented house to optimize natural energy such as natural ventilation and sun radiation throughout a year, by switching the combinations of several established passive design techniques as ‘Mode’. In this paper, the record of actual operation together with the measurement of temperature is presented and an operation flow is developed as a method of recording the environmental adjustment behavior allowing sensory factors.

The spatial composition and characteristics of plazas in underground shopping malls across Japan were clarified. The spatial composition of squares was clarified in terms of (1) their relationship with walking spaces such as passageways and stairways, (2) the installation of interior materials, (3) space staging methods, and (4) diversification of maintenance details. It was found that the plaza has diversified in terms of maintenance methods and uses compared to when it was first established. In addition, the relationship between the plaza and the pedestrian space confirmed its function and characteristics.

Efforts to integrated elementary and junior high schools are being encouraged nationwide to eliminate the “junior high school first grade gap” and to prevent school closures in communities amidst declining birthrates. Integrated facilities are considered to allow for better mobility, facilitate interaction between pupils in different school levels, and enable collaboration between teachers. In this study, after organizing the history of the establishment of three schools and the contents of their respective facility development, we considered the situation regarding school management, facility usage, and response to educational system revisions and then clarified the effects and issues facing each facility type.

This study conducted a hearing investigation on the process from the evacuation situation at the time to the resumption of welfare services, targeting 6 facilities that were flooded by large-scale disasters that occurred after 2018. Of the six flood-damaged facilities, five were located in flood risk zones. Facilities where evacuation to the upper floors had been completed before the flooding had no human damage. After that, residents and staff evacuated to other facilities. In many facilities, changes were seen in disaster prevention after the disaster.