Density and absorption of aggregate are important to secure the quality of aggregate and to calculate the mix proportion of concrete. In this report, the history of test methods for them was investigated and the various terms relating to density in ASTM and in Japan were set in order. In addition, the history of standards for density and absorption in Japan were investigated and it became clear that the kind of density for standards changed from oven-dry density to saturated surface-dry density, and again to oven-dry density.　

Percentage of gravel and sand to all aggregates for concrete is decreasing, but yet large amount of them has been used in Japan. In this report, the history of test methods for fines, organic impurities, lightweight particles, clay lumps and soft pebbles as deleterious substances in gravel and sand was investigated. As the result of survey, it was confirmed that above test methods of Japan were established on the basis of ASTM test methods and then they developed in their own way in detail. The test methods for lightweight particles and soft pebbles in JIS were discontinued in 2015.

In this study, compressive strength of high strength mortar using cement-based powder extracted from sludge separated from ready-mixed concrete was examined for the purpose of assisting effective treatment of returned concrete. As far as the mortar with a W/B of 30% was compared, the mortar with a high recycled cement replacement rate of over 75% took a longer time to flow down and tended to have a higher viscosity than the other mortars. And, it was found that the compressive strength of mortar using 100% recycled cement was about 0.7 to 0.8 that of mortar using ordinary Portland cement.

In this study, the authors investigate various properties of coal gasification slag fine aggregate (CGS) when applied to high-strength concrete. The amount of admixture using CGS concrete is lower than that of ordinary aggregate concrete. The initial compressive strength and the onset of strength up to 91-day of age were smaller than those using ordinary aggregate. Young’s modulus of CGS concrete is approximately 1.1 times of ordinary aggregate concrete. CGS concrete reduced autogenous shrinkage only in the case of ordinary portland cement. In the case of moderate heat portland cement, the autogenous shrinkage of CGS concrete is the same as land sand concrete.

In this study, we constructed a machine learning model to predict the compressive strength of standard cured specimens and core specimens in high-strength concrete from the material quality, material type, mix proportioning, and construction conditions, in addition to a discussion of factors affecting the strength of the model. The results showed that the machine learning model predicted compressive strength with high accuracy. Furthermore, the effects of factors such as air and maximum temperature of core specimens on the strength were consistent with previous studies, confirming that the model could learn the factors affecting the strength appropriately.

In skyscrapers with a height of over 300 m, the pressure required for pumping concrete is expected to reach about 20 MPa. In this study, for the purpose of obtaining basic data for construction, we conducted a long distance pumping experiment in which a high pressure of about 20 MPa was generated for various concretes. From the results, the effect of high pressure pumping on lightweight concrete and high-strength concrete on the fresh properties and compressive strength of concrete was clarified. Also, construction data such as pressure loss in the pipe were obtained.

As the one of the environmental-conscious concrete, equivalent for the type A portland blast-furnace slag cement is due to concomitant use the ordinary portland cement and the type B portland blast-furnace slag cement. In this research, considered about this environmental-conscious concrete which made the accumulation weighing used these cements. As the results, performances of concrete were equally with concrete used ordinary Portland cement. Moreover, influence due to be assumed of the weighing error for the concrete properties such as the compressive strength development and carbonation resistance were small.

New type admixtures were developed for High-fluidity and Super-low shrinkage concretes with water-cement ratio of 40-55%. Properties of fresh and hardened concretes using these admixtures were studied by laboratory test. Properties of these hardened concretes, such as strength and durability were investigated experimentally. Furthermore, effects of reducing and restraining cracks using these admixtures were verified by test on drying shrinkage cracking of restrained concrete. More than 10% drying-shrinkage reduction was obtained for super-low shrinkage concrete using one of these admixtures compared to ordinary concrete. This concrete was applied to a fair-faced wall of a building in Hyogo.

Carbonation of lightweight aerated concrete (AAC) is a reaction in which Tobermorite, a major mineral, decomposes into calcium carbonate and silica gel, causing cracks in the AAC. It is important to understand the progress of carbonation in order to determine the maintenance and replacement time of AAC. In this study, Rietveld analysis was applied to AAC to quantify the major minerals including Tobermorite and to clarify the changes in the content of Tobermorite and calcium carbonate due to carbonation.

In construction practice of reinforced concrete with half-precast concrete members, it is important to inspect a bonding surface between half-precast concrete and cast-in-place concrete. The purpose of this study is to find the non-destructive inspection method that can find an internal defect in a bonding surface. In reference to actual reinforced concrete with half-precast concrete members, several types of concrete specimens which included voids and non-adhesion areas inside were made. The voids and non-adhesion areas inside specimens were explored using ultrasonic waves and electromagnetic waves in the experiment.

In order to determine the shape and size of structure, the formwork must be designed to be strong enough to prevent movement, entanglement when concrete is poured. In the case of concrete with high fluidity, there is no established method for evaluating lateral pressure, so a method of calculating hydraulic pressure is adopted so that the evaluation is on the safe side. In this study, when using high fluidity concrete in the normal strength range, the effect on the lateral pressure of the conventional formwork was confirmed by a full-scale experiment, and the structural calculation of the formwork was examined.

In this study, we surveyed ready-mixed concrete shipped in Okinawa Prefecture from June 2020 to December 2021 to investigate the actual condition of concrete at the time of mixing and unloading using concrete formulation, material temperature, environmental and transportation information. In addition, Random Forest and LightGBM were used to learn to predict the concrete temperature at the time of mixing and unloading from each factor in the collected data. In addition, the effect of features on the prediction accuracy of the learning model was evaluated by Partial Dependence Plot.

In this paper, we describe the spraying method using a fireproof coating spraying robot. We have developed a spraying robot that can perform fireproof coating work on columns, beams, and joints. We taught this robot how to spray columns, beams, and joints, and verified the spraying. As a result, the effectiveness of the proposed spraying method was shown.

To investigate annual fluctuation of internal temperature and humidity of concrete members, we measured and analyzed them in outer wall and balcony slab in a 46-year-old RC building. The results showed that annual average of internal temperature is higher by 1~6 degree C than air temperature mainly because of solar radiation, which leads to decline of water content and average internal humidity. Increase of internal temperature is also responsible for temporary increase of internal humidity. Comparison of the humidity fluctuation at the same range of internal temperature can enable to evaluate fluctuation of water content.

In this report, the effect of shade caused by slits on the surface of cementitious materials on the brightness (L* value) of the surface of the cementitious materials was investigated, and the modeling of the brightness (L* value) based on the irradiation angle and the irradiation area was proposed. Furthermore, the applicability of the above model was confirmed by the trial work of designing and construction.

It is assumed that there is still the possibility of the development of non-glued Massiv Holz construction method which could be considered to improve the yielding percentage of products, mass production at factories and high workability at fields. Including the field of view of the wide spread of Massiv Holz construction method, the authors developed the non-glued laminated panels with wooden screws between columns using fitting-shaped worked timber that is able to combine with conventional post and beam structure method. This research reports the possibility and the issues of the non-glued laminated panels through comparison with other construction methods.

This paper reports on the influence of environmental temperature on pull-out properties of post-installed adhesive anchor. And the follow conclusions were found. There is relationship between the maximum pull-out load of post-installed adhesive anchor and the compressive strength of concrete at temperatures up to 80°C depends on the adhesive type.

In this study, for the purpose of applying air milk as a sound insulation material against rain noise on a wooden roof panel covered with galvalume steel plate, an experimental investigation was conducted regarding an effect of air milk filling on the sound insulation performance of the panel in comparison with the unfilled conventional method, in which performances of flexural loading, air sound insulation and sound insulation against rain noise of the panels were examined.

The problem of inappropriate time-history waveforms due to gaps between wall and fluid particles in the boundary conditions of SPH method was solved by modeling the wall particles shifted by the smoothing length. Based on the verified method, a fluid analysis was performed where cubic buildings were aligned. As a result, the continuity of pilotis space in orthogonal direction to mainstream causes the concentration of the hydraulic force on the wall of the building located downstream direction of the piloti-type buildings. And the continuity of pilotis space in mainstream direction also keeps the level of water pressure over a distance.

The seismic safety of ALC panels was verified by three-dimensional shaking table tests on a full-scale 10-story reinforced concrete building conducted at E-defense in 2018 and 2019. The results suggest that the ALC panel was rocking behavior and followed the story drift angle more than 1/50 rad. Additionally, there was no damage impaired the function of the exterior wall. Therefore, it was shown that the rocking mechanism of the ALC panel functioned normally and the clearance was provided enough between the ALC panel and the building.

This study evaluates action difficulty of residents for three types of high-rise residential buildings, i.e., earthquake-resistant, seismic response controlled, and seismically isolated buildings. The results of questionnaire surveys on action difficulty during earthquakes are reviewed with reference to aseismic types of buildings. A new formula is proposed for action difficulty evaluation using the accumulated values of time history waveforms based on strong-motion records and the questionnaire surveys. It is applied to action difficulty evaluation for three types of building models using seismic records and is validated in comparison with the questionnaire surveys.

In this paper, the applicability of a wireless MEMS accelerometer for a vibration experimental learning material is examined. It was shown that the acceleration record is obtained with sufficient accuracy by shaking table test. Using the accelerometers, the model vibration experiment with quantitative measurement can be conducted. By the survey in the lecture on the vibration theory, the educational effect of quantitative measurement in vibration experiment for students majoring in architecture is shown.

The effectiveness of braces depends on brace placement and stiffness. Therefore, in meeting the design target story stiffness, both of these parameters should be optimized to achieve the highest effective brace deformation. In this paper, a method for this is proposed by presenting a relationship between brace placement, brace stiffness and effective brace deformation ratio. This relationship is derived by using an equivalent spring model that considers the effect of axial deformation of columns and seismic isolation bearings. Through several examples of mid-rise base-isolated building models, it is demonstrated that the effectiveness of various brace placements can be quantitatively evaluated.

The developed oil damper changes the damping force passively and steplessly depended on damper displacement at low speeds of approximately 30 cm/s or less. A prototype damper with a maximum force of about 500 kN was tested and it was confirmed that the damping force changed as expected. Numerical analysis using the damper with the characteristics of the experimental results confirmed that the maximum displacement of the isolation layer was reduced by about 15% during long-period earthquakes, and that the acceleration response during moderate earthquakes was equivalent to that of a conventional seismically isolated building.

In this paper, we measured ground vibrations excited by rhythmic actions of large audience at an outdoor concert. This kind of noticeable ground vibration is excited by large audience at least over 1,000. However, our knowledge of this vibration is based on vibration tests excited by several people. So, we carried out this measurement. As a result, the following conclusions are obtained. 1) The vibrational energy can be concentrated in a narrow band even if the vibration is excited by large audience. 2) The effect of audience size reduces the high frequency components of the exciting force.

It is known that the topology optimization (TopOpt) problem of frame structures can be formulated as a mixed-integer second-order cone programming problem (MISOCP), when the compliance is minimized and the cross-section of each member is selected from a set of predetermined candidates. However, when considering the constructability of real-world building structures, it is insufficient to only minimize compliance. In this paper, in order to control the density of members, the constraints of the number of members connected to each node are additionally considered into TopOpt by MISOCP treated in the previous study.

This paper is a summary of the results of a survey on small building foundations. The aim of the questionnaire is to confirm the discrepancies between “Recommendations for Designing of Small Buildings Foundations” published in 2008 and actual practices, and to provide references for technical guidelines for the next decade. The results of the questionnaire clarified the current state of small building foundation design and important problems to be resolved in the near future.

This study aims to fit an approximate equation to evaluate the global buckling load of single-layer space frames with crossing-grids. Through linear buckling analysis, buckling load factors associated with various geometric parameters in a total of 1470 cases are analyzed, and established a dataset as an input into a statistical software 1stOpt. Accordingly, an approximate equation can be fitted based on the regression analysis aided by the 1stOpt. In addition, the authors examine the overfitting and accuracy of the approximate equation, and consequently propose an applicability range in which the rate of difference concentrates in ± 25%.

In this study, on a premise that super elastic alloy is incorporated into large space frame structures, behavior when compression axial force acts on test pieces with large slenderness ratio assuming braces are analyzed as a beginning of the study. Also, it is demonstrated that the maximum deflection amplitude, maximum strain, and energy absorption due to buckling when the braces using super elastic alloy receives a compressive force can be estimated accurately by evaluation formulas.

Reed is considered　a useful ingredient for structural materials from the viewpoint of sustainability as well as its high tensile strength. In this report, for the aim of verifying the practicality of Reed-made Strand Board (RSB), we produced the small prototypes and discussed the basic performance focusing on the relationship between the parameters related to the manufacture, such as the length and orientation angle of strands, and the out-of-plane bending performance. As a result, RSB has a effective correlation between the manufacturing parameters and the bending properties and satisfies the required performance adequately.

Pull-out fracture of lag-screw bolt is brittle and has a large dispersion in strength. therefore, the bucking of the pipe preceding the pull-out of the lag-screw bolt controls the strength and toughness of the joint. The pipe is sandwiched between the lag-screw bolts fixed to the base plate. The method of bucking the pipe has little dispersion, and the strength and toughness can be controlled by adjusting the thickness and length of the plate. The effect was confirmed by experiments. and it was also confirmed that once the maximum load is reached, it can be restored by exchanging the pipe.

The purpose of this study is to estimate the structural properties and yield capacity of CLT two-sided shear joints with shear plates and drift pins. In order to estimate yield capacity of joints, CLT embedding test and a tensile test of joints were conducted to confirm the adaptability of the proposed equation for yield load based on the yield theory. Specimens consisted of two CLTs, two shear plates, and drift pins. Parameters of the experiment were presence of shear plates and position of joints. Test results were compared with the calculated values.

A new column-base joint system with inclined screws and a steel base-plate were developed to be used in large timber constructions. This method is aimed to use in the column base joint of large timber constructions. Experiments were conducted with various number of screws, screw lengths, and steel plate types. Experimental results and calculated results by proposed formulas of previous research not applicable within this experimental study, clarifying issues in previous studies.

In recent years, the demand for drift pins connection with inserted steel plate has grown due to its high resisting capabilities. The connection is generally used as tensile joints in CLT shear walls for mid-rise building. Moreover, the effect of different steel types of drift pins, usage of bolts instead of drift pins to prevent the opening of slit, drift pin length and its loading history on structural performances are unclear. Therefore, this study reports the results of tensile tests performed on the CLT drift pins joint with inserted steel plate considering the unknown factors mentioned above.

To develop a new brace connector, static incremental analysis of a braced shear wall with a detailed analysis model was conducted. Several kinds of load-displacement relationships, that are necessary for the analysis model, were defined based on elemental tests, such as tensile tests and shear tests of the screws. The shear stiffness of the tensile brace shear wall from the analysis was higher than the one from a shear loading test, while the maximum shear strength from the analysis with the column and the brace of high density was near the one from the shear loading test.

In recent years, there are a lot of wooden houses that is needed seismic retrofitting. We have developed a lattice bearing wall suitable for seismic retrofitting of tenement style wooden house. It is made of 12mm structural plywood laid diagonally for transparency and ventilation. In this study, the performance of lattice bearing wall is clarified and we proposed the simple analysis model of lattice bearing wall as a result. It was clarified that the simple analysis model could accurately estimate the structural performance of lattice bearing wall.

In order to evaluate repairability (i.e., repair time and repair cost, etc.), it is necessary to estimate the amount of labor (person-day) for repair caused by seismic damage. The purpose of this study is to obtain the fundamental information necessary for establishing the relation model between the labor amount L per unit floor area and the inter-story drift angle R (i.e., L-R model). We analyze the effects of the amount of structural and non-structural components and the failure mode of the structural members, on the L-R relation, and discuss the feasibility of establishing a L-R model for repairability evaluation.

This paper presents the simplified approximate equation for the ultimate moment of reinforced concrete interior beam-column joint. The proposed equation is derived by extracting the main terms of the theoretical equation. The convergent calculation is omitted, and the branch conditions are simplified without significant loss of accuracy. The approximate equation is able to calculate not only the ultimate moment at both the beam and column rebar yielding but also that when the stress of the column rebar is given by the critical reinforcement.

In recent years, with the development of high-strength steel materials and improvements in welding technology, high-strength steel has been widely used in steel structure. In the Nagoya Zokei University of Art & Design project, 40m trusses is designed, and 100mm thick TMCP440 was used for the diagonal members. The erection plan required on-site welded joints at the ends of the diagonals, and ensuring the quality of the welds was a major construction management issue. Therefore, additional skill tests were conducted to find appropriate welding conditions and to confirm that the welded joints to be installed would have enough strength.

This paper discusses the effects of rust and paint on the workability of retightening anchor bolts and turnbuckles through the element experiment. The findings obtained from the element experiments are summarized as follows: (1) Required torque to adjust the nuts of the anchor bolts as all the thread painted to the original position by retightening was higher than that as no thread painted. (2) The torque to satisfy the requirement for the axial force of the rusted anchor bolts was higher than that of the anchor bolts with the antirust paint.

The majority of steel factory buildings constructed in 1960-70’s in Japan do not display satisfactory seismic performance due to the lack of strength in the brace-end joints or the foundations. The retrofit works that simply add lateral bracings would be undesirable because it would prevent ordinary factory operations. Then, another retrofit approach could be alternative by enhancing ductility of each structural member. In this study, the practical applications to the existing steel factory buildings are presented and the efficiency of the seismic retrofit with ductility enhancement is discussed.

A finite element model was developed to study the effect of mortar bed thickness in the compressive behavior of masonry prisms. For this, microplane models, calibrated using 10 mm mortar bed prisms, were used to predict the behavior of prisms with 30 mm and 60 mm mortar beds. The results showed the model could replicate the behavior of the experimental data generally. The models whose components differed significantly in compressive strength were affected by a variation of mortar thickness. In them, a reduction of the confinement effect of brick units over mortar beds was observed when mortar bed thickness increased.

Adhesive bonding has been increasingly used for seismic retrofit and repair recently. However, the interaction between bolt and bonding joints is not clear in detail. This study focuses on the hybrid joint method using adhesive bonding and high-strength bolts for the single-shear lapped joint to improve joint strength. Three experimental parameters, with or without adhesive, bonding area, and bolt tension, were adopted. The results show that the connection strength can be effectively increased by adhesive. Moreover, the effective adhesive area and strength evaluation formulas are proposed through the cohesion failure behavior.

We surveyed, via questionnaire, local governments and Architects & Building Engineers Associations nationwide regarding the dissemination of earthquake-resistant wooden houses.　We grasped the overall situation and content of the seminars, then further looked at the situation and characteristics of seminars using demonstration models. As a result, it was found that about 30% of all respondents used a demonstration model, and of those about 70% of them owned the model. Furthermore, when we sorted the evaluations by model users of the 10 types of models that were used, the need for scenarios and videos of the demonstration models became clear.

Many buildings have been reported to stop their service due to damage to non-structural members such as equipment piping after large-scale earthquakes. Although data on deformation capacity and strength of carbon steel pipe for ordinary piping is being collected, few studies are conducted on polyvinyl chloride pipes (PVC pipes) for drainage. Cyclic bending tests are conducted of PVC pipes with nominal diameters of 40A, 50A and 75A to evaluate their deformation capacity and strength. The result is that the deformation of PVC pipes is larger than that of steel pipes, and shows brittle failure.

The aim of this study is to quantitatively grasp the effect of excess fuel gas on the temperature distribution and heat flux rate of the fire plume ejected from an horizontal opening when the amount of combustible gas generated in the compartment was changed. In this study, a series of medium-scale fire experiments were carried out. Compared with the former research, the effect of excess fuel gas on the temperature distribution and the behavior between fire plume ejected from gas burner and fire plume ejected from opening is elucidated.

In recent years, the need for accessibility for people with impairments has been growing. This trend requires event halls, such as arenas and multi-purpose venues, to install an increased number of wheelchair-user seats at various places. However, evacuation of wheelchair users is a difficult problem, especially while the crowd of healthy people also evacuate simultaneously. This paper presents the essence of a fire evacuation design and guidance program for wheelchair users in event halls by analyzing the decision process of an actual design example of a multi-purpose venue.

Conventional metal curtain walls have used aluminum frames to support the fireproof boards of the spandrels. Since aluminum melts at about 660°C, the fireproof board may fall off in the event of a fire, causing the fire to spread to the upper floors. Therefore, we have developed a curtain wall fireproof board supported by the frame, and confirmed its fireproof performance (prevention of falling off) for 2 hours in fireproof experiments. We have also developed composite insulated steel beams and columns using these fireproof boards, and have achieved rationalization of construction.

Fires involving a large number of casualties in elderly nursing homes in China in recent years are described. The fire safety codes and standards for elderly nursing homes in China and Japan are overviewed, and comparisons were made for specific model buildings. According to the comparative analysis, understanding of the differences between the two countries was possible. In China, codes for fire protection of buildings, such as fire compartments can meet the codes and standards in Japan. But the codes and standards for fire report apparatus, smoke exhaust systems, stairwells, and evacuation equipment were found not to be as well organized as in Japan.

The shielding performance of a magnetically shielded room (MSR) for bio-magnetic measurement was evaluated using JEITA standard (EM-4502 and EM-4503). In the process of evaluation, some problems were extracted, such as the fact that the MSR shape was not covered by the standard. Therefore, the authors revised EM-4502 and EM-4503. The main points of revision are the expansion of the target MSR shape and the reexamination of the placement conditions and accuracy of the exciting coils. Finally, EM-4502A and EM-4503A formulated as JEITA revised standards were used to reevaluate the shielding performance of the aforementioned MSR.