The fluidity and compressive strength of mortar using five types of slag fine aggregate for concrete, including coal gasification slag aggregate, were investigated. As a result, the following conclusions were obtained. Even if the particle size distribution of the fine aggregate was made the same, the effect of the fine aggregate volume fraction on the J14 funnel flow test results differed due to differences in the particle shape of the fine aggregate. Furthermore, in this experiment, the change in the compressive strength of the mortar due to adjusting the particle size distribution of the fine aggregate was not large.

A literature survey was conducted on the influence of various factors on test results of rebar corrosion caused by sea sand. The rust area ratio was mainly adopted for evaluation methods of rebar corrosion. As a main result of the investigation, the NaCl content is more dominant than the carbonation on corrosion of rebar. For vertical rebars, the influence of cover thickness is dominant, but for horizontal rebars, the influence of the height from the bottom of the specimen is large. It was also found that when the NaCl content increases, the effect of cover thickness may become less dominant.

Gas pressure welding using acetylene gas is a widely used method for rebar jointing in modern construction. However, the increasing production and transportation costs of acetylene gas have made its use less favorable, particularly in remote areas. To address these challenges, a novel gas pressure welding method has been developed, utilizing the readily available and cost-effective propane gas, commonly used in households. This study conducted tensile and bending tests to elucidate the mechanical properties of the welded steel bar joints using propane gas. The results demonstrated the new method meets the performance regulations for gas pressure welding Class A joints.

This study aims to investigate the impact of the raw material total moisture content during the manufacturing process on the performance of volcanic glass powder (VGP) in order to reduce the environmental impact. The results showed that when the raw material was sorted in a total moist state of around 6%, the recovery rate of volcanic glass remained unchanged compared to the dry state. Although the possibility of weathering material contamination was confirmed, the analysis of chemical composition, specific surface area, and the activity index test of VGP all met the requirements of JIS standards.

UHPFRC has high potential for various kinds of structural application including repair and reinforcement of existing RC structures. This study is an experimental investigation that aims at providing UHPFRC with anti-washout properties for under-water use. Results showed the modified UHPFRC with 2% of cellulose ether properly satisfied the standard quality values for anti-washout materials (pH value and turbidity). This new material has a compressive strength of above 100 N/mm² and a tensile strength of 7.69 N/mm² as well as high flexural toughness (provisionally at 7 weeks age). Both the compressive and tensile constitutive-laws are also presented for structural design.

With Japan’s infrastructure aging, non-destructive diagnosis of RC structures is crucial. This study investigates the impact of cracks within cement paste on voltage fluctuation. Cement paste specimens with/without stone undergo cyclic loading with voltage and Digital Image Correlation measurements to clarify the correlation with crack initiation or strain change. Results reveal a correlation between voltage and strain, with distinct periodicity in specimens with each stone shape. The findings indicate characteristic voltage patterns when visible cracks form, though the correlation with DIC-measured displacement was unclear. Understanding voltage variations offers a potential method for assessing crack conditions, which is vital for infrastructure maintenance.

A 99-year-old reinforced concrete building, formerly serving as the Ogimi Village Office and constructed with concrete equivalent to blast furnace cement Class C, was investigated. Despite being located in a salt-affected environment with high levels of airborne salt, EMPA analysis confirmed that the permeation of chloride ions into the building was suppressed.

Assuming reflection in design, the quantitative evaluation of tensile ductility of steel fiber reinforced concrete (design strength 30-60 MPa) containing 1.0% steel fiber with hooks at the ends was investigated. The method for evaluating the lower limit management value of tensile ductility of concrete in structure was proposed by setting the reduction factor based on the results of investigation of quality variation during actual manufacturing at a precast factory and the distribution of steel fibers within structure member. The tensile ductility evaluated by the proposed method was on the safe side compared to test results during actual manufacturing.

The characteristics of the fired bricks change as the firing temperature changes, and this tendency is specific to each clay. In order to understand this trend for clays from the Bhaktapur area of Nepal, test specimens were prepared at different firing temperatures and various properties were measured. The results showed a relationship between firing temperature and density, strength, water absorption, and color, and the possibility that color measurement could be useful in diagnosing brick quality.

In this study, we surveyed the actual conditions of adjustment and management of curing temperature and heating equipment in heat curing for 33 cold weather concrete works. As a result, the difference between the planned and actual values of curing temperature was 5°C or more and less than 10°C in 39% of the works, and heating adjustment was assumed to have been performed in 64% of the works. In addition, the curing temperature management could have been optimized by reviewing the predicted average temperature immediately before construction in 64% of the works.

For some overseas concrete, there is a possibility of large variations in concrete strength due to large fluctuations in unit water content because aggregate is stored in the open air. In addition, the quality control level of engineers varies widely. In this paper, we propose a method to quickly estimate the strength of concrete by measuring the electrical conductivity of concrete at the time of the acceptance inspection of concrete at the site. From the trial results, it is considered that this method is suitable for use in screening concrete whose strength deviates significantly from the formulation control strength.

This report presents findings from a questionnaire survey aimed at clarifying the actual state of wall formwork construction using plywood sideways. It covers various factors, including the percentage of plywood sideways use, structural calculations, and composition of wall formwork. The survey revealed that in wall formwork using plywood sideways, the formwork composition is often specified by the designer. Therefore, design considerations are given priority over the rigidity of the formwork, and it is possible that sufficient attention has not been given to the rigidity of the formwork.

In Japan, there is Article 73 of the Building Standards act enforcement order and Article 4 of the Ministry of Land, Infrastructure, Transport and Tourism Notification No. 594, which stipulates that the reinforcement of the column heads on the top floor must be secured with column main reinforcement hooks or mechanically fixed. Therefore, this report summarized the results of a questionnaire survey of reinforcement contractors to clarify the actual state of reinforcement arrangement in capital in top floor.

The stock ofexternal wall tiling is enormous. However, falling-off of the wall tiling due to degradation poses a considerable danger to pedestrians. Therefore, the new method for refurbishment of external walls with stone-like decorative fabric that can prevent falling-off of wall tiling is developed for long-term maintenance and preservation. This stone-like decorative fabric is tightly installed with adhesive polymer cement mortar and mechanical anchor pins. Furthermore, it contributes to the reduction of the construction process. This paper presents the outline of the new method, evaluation of the performance and the application to exterior wall refurbishment work.

Autoclaved lightweight concrete (ALC) panel exterior walls are widely used in Japan, because they are expected to have high deformation capacity. However, during an earthquake, not only the in-plane deformation but also the out-of-plane inertial force are likely to act on the exterior walls. In this paper, combined in-plane and out-of-plane loading tests were conducted on ALC panel exterior walls. It was found that the deflection due to the out-of-plane load resulted in the earlier bearing state when the wall deform in the in-plane direction and the damage to the ALC panel exterior wall depends on the mounting hardware.

In recent years, to achieve carbon neutrality in housing, there is a need to expand the number of long-life quality housing that has a long-life and has low life-cycle CO₂ emissions. For this reason, high durability of concrete for housing base is needed. In this study, we focused on curing sheets used in concrete for the housing bases to improve durability and investigated the effect of difference in retention period of curing sheets on carbonation. We also investigated the effect of curing sheets on the length change of concrete in comparison with elastic paint.

In this study, as a new functional addition to building materials using GFP genes was investigated. It was confirmed that the mixture of GFP did not affect the strength of plaster and gypsum within the range of this experiment. On the other hand, the fluorescent function was affected by the amount of GFP in the mixture, and the higher the amount of GFP in the mixture, the greater the intensity of fluorescence. It was also reconfirmed that the active pH range of GFP itself affected the fluorescent function.

The results of the mechanical properties and aesthetics of rigid PVC products for window with high thermal insulation performance are reported after five years of outdoor exposure test. By the fifth year of exposure, the tensile modulus had increased and a change in color difference due to staining was observed. However, there was no difference in mechanical and aesthetic properties between the lead-based stabilizers used so far and the recently switched calcium-zinc stabilizers.

In this study, Electrochemical Noise (EN) was measured to understand the electrochemical behavior of galvanized and weathering steels in mortar. The relationships between the corrosion form based on wavelet analysis of EN and the observation of the surface film failure and corrosion product formation were investigated. Every steel showed a localized corrosion tendency in the EN analysis. This is due to the corrosion concentration at the film loss locations. Although the rate of film loss varies among the steels, clarifying the conditions that lead to film breakage, which in turn initiates corrosion, is necessary.

Buildings must be assessed over their lifecycles considering the environmental impact. Building demolition work differs drastically from other types of work as it lacks deliverables such as buildings or structures. Hence, it is necessary to establish evaluation methods according to the performance requirements to accurately conduct demolition work. This review proposes evaluation indexes based on three factors (economy, safety, and environment) and total to understand the conditions of demolition methods. These evaluation indexes were used to simulate the demolition of actual buildings. Results showed that overall demolition performance can be quantified based on these three factors.

One of the advantages of implementing limit state design for buildings is the increased accountability regarding building performance against external load. This is achieved by differentiating target performance levels according to the use of the building and associated potential risk. This study examines current national practice of wind resistant design to calibrate the return period of design wind speed and target performance level, thereby enhancing the clarity of the design criteria.

Wind pressure measurements and scattering experiments were conducted using a full-scale severe storm generator (FSSG). First, scaled experiments were performed using a turbulent boundary layer wind tunnel to confirm the similarity of the wind pressure distributions on a full-scale model using the FSSG. Subsequently, J-shaped tiles that can measure surface wind pressures were fabricated using a 3D printer, revealing the wind pressure characteristics acting on roof tiles. Finally, scattering experiments were conducted using J-shaped and flat-shaped tiles for representative wind directions, and the results were presented.

Annual probabilities of blast loads acting on building structures due to internal explosions are calculated by event and fault tree analyses. Influence factors in the internal explosions are identified from past accident experiences and used to create branched tree models by considering their causal relationships and correlations. Branching probabilities are determined from past accident data. A local database is built based on domestic public sources. The calculated values are found to be comparable to those of ISO 10252. Moreover, the paper provides the reassessment of past two accident examples from the point of view of accident probabilities.

Measuring the displacement on seismic observation of buildings is important, especially for structural health monitoring. However, there is still no standard method for measuring seismic displacement. Therefore, we studied the applicability of kinematic GNSS positioning to measure the displacement. As a result, we saw that the seismic displacement measured by GNSS positioning agrees with the seismic displacement measured by displacement meter in two examples of seismic records. Furthermore, we also saw that kinematic GNSS positioning can have higher accuracy than what is generally said when used for seismic observation.

A structural monitoring system with one sensor installed on the upper floor of a building was developed in previous paper. In this paper, this system was partially improved and verified using seismic response simulation results and observation records. In the simulation above, the seismic response of multi-mass models ranging from 3 to 15 stories was analyzed and the proposed method was applied. In the verification with observation records, the proposed method was applied to the buildings where the system is installed.　Both results showed that the proposed method can estimate the building’s story-drift-angle with sufficient accuracy.

In this paper, a method to prevent the collapse of specific stories and improve safety by incorporating steel rocking pillars (RP) into wooden house is proposed. By redistributing the excess or deficiency of seismic performance on each floor by means of rigid RP, a response suppression effect can be expected. At the same time, it enables a highly flexible design that is not bound by the wall quantity balance between the upper and lower floors. Using collapse analysis, the effectiveness of RP and relationship between stiffness of RP and the response suppression effect.

Japanese wooden houses often collapse due to the collapse of the first layer by major earthquakes. One method to prevent the collapse of a specific layer is to place rocking pillars in the building. In this study, the effect of response reduction by inserting rocking pillars was confirmed through vibration experiments using a shaking table. When a 2-story model without rocking pillars was subjected to repetitive vibration, the response gradually increased and eventually collapsed, but when rocking pillars were inserted, the response was greatly reduced, which was found to be effective in greatly reducing the likelihood of collapse.

To make a specific ceiling earthquake resistant, we isolate the ceiling and wall surfaces to ensure the original acoustic performance of the design, place anti-vibration rubber bearings at the collision points between the ceiling and wall and analyzed the collision phenomenon between the anti-vibration rubber and the wall. We modified the Hertzdamp model, which can appropriately evaluate the current state of collisions, and used a method applied to a structural analysis model that takes dissipated energy into account, to rationally set the design seismic intensity of the ceiling surface and apply it to the renovation of an actual project.

A soil investigation was conducted to determine the extent and degree of loosening of the surrounding ground due to removal of existing piles and backfilling of the area. The area affected by ground loosening was approximately 2 to 3m from the edge of the casing, and the decrease in N-value etc., was more pronounced closer to the edge of the casing. The tendency of decrease by soil type was more pronounced for sandy soil. Based on the investigation results, we proposed a soil investigation plan to determine the effects of ground loosening caused by the removal of the existing piles.

This paper compares the long-term settlements of a low-rise parking structure on piled raft foundations in reclaimed ground obtained by conventional leveling measurements with those obtained by multi-temporal InSAR analysis. The vertical displacements obtained from the InSAR analysis are found to be generally in good agreement with those from the leveling measurements. The study demonstrates the usefulness of SAR analysis for monitoring vertical displacements of buildings on soft ground. Moreover, these results indicate the potential of SAR technology to contribute to the establishment of more effective assessment techniques for infrastructure maintenance.

Membrane-tensegrity composite structures have outstanding characteristics such as lightweight, easy assembly, and compact storage for transportation. However, it is not easy to accurately determine the overall equilibrium shape and evaluate its stiffness. Moreover, while there are many previous studies on form-finding and stability, only a few methods exist that can accurately predict their stiffness. Our research goal is to establish a computational model in which membrane materials are replaced with truss elements, allowing simple and accurate evaluation of stiffness. In this study, we propose an analysis method for form-finding and stiffness evaluation and offer preliminary discussions about its architectural applications.

This article reports on the structural design and construction involved in renovating the “Former Hidaka-Town-Office” into a theater, as well as on the micro-vibration characteristics associated with this transformation. To convert the ground-floor hall into a theater and ensure the required floor height, the second floor was raised and reinforced to accommodate the increased load. Additionally, seismic reinforcement was conducted primarily around the building’s perimeter walls, significantly enhancing both stiffness and load-bearing capacity. The comparison of vibration characteristics before and after the renovation revealed increases in the frequencies of the primary vibration modes, confirming an increase in initial stiffness.

In this paper, we present the experimental results of traditional mud walls subjected to constant amplitude multi-cycle loading. In this study, specimens with wall length in 1,820 mm was adopted. The number of the lording times were considered the earthquake response analysis results of the models. From the experimental results, I examined the strength deterioration and the change of the hysteresis loop. I discussed the strength deterioration factor, which is considered the multi-cycle loading or earthquake motions.

This study proposes a structural system of passive controlled shear wall for mid-rise wooden construction consist of high damping rubber, cross laminated timber and drift-pin joint. In this paper, to verify the effectiveness of proposed shear wall, cyclic loading tests of high damping rubber damper and full scaled shear wall specimens were conducted. As a result, it was confirmed that the proposed shear wall demonstrated its target performance of 150kN horizontal strength. And it was also confirmed that no degradation occurred in proposed shear wall in the range of 1/50rad.

In this paper, the hysteretic behavior of two high-capacity slotted-in steel plate CLT-bolt connections is investigated. Hysteresis models are developed based on test results of single-bolt connections with varying grain direction and bolt diameter. The damping ratio for small-bolt connections is found to be three times larger than for large-bolt connections. The hysteretic behavior remains similar after the development of the distinct structural phenomena in the connections. The developed hysteresis models account for strength and stiffness degradation, unloading strength, and pinching path stiffness, allowing for accurate dynamic analysis of the proposed connections.

To understand the vibration characteristics of traditional wooden houses in Okinawa Prefecture, ambient vibration measurements were conducted to determine their natural frequencies. Six traditional wooden houses, designated as cultural properties, were selected for the study. The results showed that the natural frequencies of Okinawan traditional wooden houses were around 2.5 Hz. In houses showing deterioration, the frequencies were about 30% lower than the average. Compared to houses in other prefectures, Okinawa’s traditional wooden houses were found to have lower frequency ranges.

Experiments were conducted to evaluate the withdrawal performance of screwed joints for diagonal beam fastening structures at the joints between diagonal beams and beams, which serve as tensile members in truss structures used in wooden buildings with large spaces. In the experiment, the angle of the diagonal beam, the angle of the screw, the length of the screw, and the direction of the screw were used as parameters. The experimental results were in general agreement with the calculation results using the proposed formula for inclined screw withdrawal strength.

NLT is composed of layers of lumbers jointed with steel nails. As steel cannot be cut by saws for lumbers, it is difficult to cut NLT with saws normally used for lumber processing. To make it possible to process NLT by the lumber saws, NLT composed of nails made of aluminum was produced and tested for its out-plane bending properties. The bending strength and stiffness of the NLT composed of aluminum nails were almost equivalent to that of NLT composed of steel nails. NLT was modeled to verify the ratio of bending and rotation of the butt jointed lumbers.

In this paper, parameter identification using interpretable machine learning and quality engineering is applied to a shaking table test data of a full-scale 5-story wooden structure. The following results are shown; 1) By the parameter identification for detailed analysis model, good agreement with experimental result is obtained. 2) It was confirmed that the difference between the analytical results and the experimental results becomes smaller when the capacity of some walls and other elements was increased.

The authors have previously proposed a calculation method to reproduce the mechanical behavior of the joints in CLT rocking frames as a damage control technology for mid- to high-rise wooden buildings. However, there are issues such as the model used for the evaluation may differ from the actual behavior, and the embedded stiffness at the contact area between the column and beam was calculated based on predictions from other literature. Therefore, the goal of this research is to understand the mechanical behavior of the column-beam joints of CLT rocking structures and repropose an evaluation method.

To understand the structural behavior of RC beams made of concrete, where part of the cement is replaced with ground-granulated blast-furnace slag, shear-bending tests were conducted on RC beams using the replacement ratio of ground-granulated blast-furnace slag as the experimental variable. The results showed that even for a 70% replacement ratio of the ground-granulated blast-furnace slag, the beam exhibited hysteresis characteristics and damage properties equivalent to those of a normal RC beam without ground-granulated blast-furnace slag.

Japan is prone to large earthquakes. Therefore, buildings may be subjected to multiple seismic loads. In this study, the RC cantilever specimens were subjected to shear loads three times. As the results of the test, as the number of loads increased, the crack width opened; and the stiffness decreased without repair. However, with crack repair, the crack width became small; and the stiffness recovered slightly. In addition, the machine learning model were constructed; and then it could reasonably estimate the envelope curves.

In recent years, there has been a growing demand for seismic resilient buildings that not only have the ability to prevent collapse in the event of a severe earthquake, but also have the ability to reduce or control damage and repair quickly. Therefore, it is necessary to establish an index to evaluate the damage and repair performance of components in order to assess their post-earthquake functional use. In this paper, we present a method to evaluate the damage and repair performance of full-scale beam specimens with　high seismic resilience technology by conducting experiments.

In this study, the joint shear strength is discussed on reinforced concrete column-beam joints with different floor levels on beams (stepped beam joint). 1) Compared to a normal interior joint, the stress transfer in the stepped beam joint is more complicated, making it difficult to properly evaluate the shear strength of the joint using the AIJ toughness guideline formula. 2) The shear strength of stepped beam joints can be reasonably evaluated based on a split strut mechanism that takes into account the presence of steps and the effect of the anchorage type of the beam reinforcement.

Unbonded PCaPC walls with great potentiality for damage reduction will be a promising option for more flexible responses to earthquakes. Therefore, in this study, the structural performance of unbonded PCaPC walls was experimentally investigated. RC wall specimen was also designed for structural performance comparisons, and the variables for unbonded PCaPC wall specimens were the methods of tendon arrangement. From the experiments, the unbonded PCaPC walls exhibited excellent damage control performance and origin-oriented historical properties even after large deformation. The maximum strength evaluation method was also proposed based on a macro model, and the calculations showed reasonable agreement with the experiments.

This paper reports an outline of reconnaissance results of 74 steel school buildings including 50 gymnasiums damaged by the 2024 Noto Peninsula Earthquake. The structural, non-structural, and overall damage have been ranked based on “Standard for Post-earthquake Damage Evaluation of Damaged Buildings”. Structural damage similar to that reported in previous earthquakes was observed. On the other hand, some buildings were found to be rotated due to foundation damage. As for non-structural damage, severe damage caused by inappropriate connections was observed. However, the removal of ceilings in large spaces was indicated to be effective in reducing damage.

One method of connecting steel members is by using mechanical fastenings such as bolts and self-drilling screws, which are commonly used in cold-formed steel structures. The AIJ revised the “Recommendations for Design and Fabrication of Light Weight Steel Structures” this year, specifying the use of these mechanical fastenings. However, it is not permitted to combine different components in one joint. This study conducted real-scale tests to evaluate the ultimate strength of combined joints, and the results showed that it might be possible to sum the strength delivered from each component.

Faster R-CNN is used to detect vertical braces, column bases and horizontal roof braces, and the objects are correctly detected in many cases. Accuracy for the damage classification of vertical braces using deep learning is about 72%, accuracy for column bases is about 81%, and accuracy for horizontal roof braces is about 85%. An application software is developed for assessing post-earthquake damage by taking photographs of gymnasium.

Although slender steel braces are widely used, they buckle prematurely in compression load, and several damages will occur by the deformation. Therefore, the authors have been researching and developing bracing materials in which lightweight, high-strength CFRP materials are anchored to standard pipe-type turnbuckle bodies. Previous studies showed that the material can be easily joined to existing turnbuckle-type braces and can significantly reduce out-of-plane deformation during compressive deformation. This paper shows the impact loading method and conducts to confirm the structural performance under impact loads.

This research discusses a smoke control method for temporary refuge spaces in small-scale buildings with a single staircase, aimed at ensuring fire evacuation safety when a fire occurs near the staircase. Closing the door to the temporary refuge space can prevent smoke from entering in the early stages of the fire. However, over time, smoke can enter through gaps in doors and ceilings. Smoke vents in fire rooms can reduce the pressure. In contrast, the impact of openings in temporary refuge spaces can be either positive or negative, depending on the openings around the fire room.