This paper presents the acoustic design of halls and galleries in the TODA BUILDING, which was completed in October 2024, as well as the acoustic measurements taken upon completion. To achieve good indoor acoustics in the halls, acoustic panels with a Penrose tile pattern were installed on the walls to mitigate acoustic problems, including flutter echoes. The finished halls provide good acoustic environments with flat frequency responses in reverberation time and no particular acoustic anomalies. Various measures were implemented in the galleries to reduce noise transmission from the machine rooms on the upper floor and the halls on the lower floor. The machine room floors are floating floors to block airborne sound, while each piece of equipment is supported by vibration isolators to block solid-borne sound. Furthermore, each of the halls employs a floating structure, which helps reduce airborne sound generated when sound is produced inside. Measurements taken upon completion confirmed that the intended sound insulation performance was achieved.

The building surveyed in this study is a 165-m-high, 28-story skyscraper with a core wall structure. We predicted the settlement behavior of its spread foundation at the design stage and later measured the actual settlement to verify the accuracy of the prediction. With a footprint of 68 m × 65 m, the building is supported by a spread foundation on the Tokyo Gravel Stratum at a depth of -25.6 m relative to the first-floor level. This paper reports the results of field measurements of ground heave and settlement in the bearing stratum during construction and compares them with the predicted settlement values. This analysis used Young’s modulus evaluated based on the strain and confining-pressure dependence of the shear wave velocity, assuming the soil to be elastic. The following conclusions were drawn.
The measured maximum settlement of the foundation was 32 mm, which is in good agreement with the predictions. The accuracy of the settlement prediction improved when the confining pressure dependence of the soil stiffness was considered. The results suggest that the prediction method is applicable to heavy buildings on spread foundations that have a mean contact pressure of 600 KN/m².

This study examined the effects on the physiological and psychological responses of office workers when a small number of desk planters were introduced into an office environment that previously lacked plants. In the experiment, physical environmental factors such as temperature, humidity, and lighting were kept constant across all experimental conditions. The results indicated that, under the condition with plants in place, subjective evaluations of the spatial environment , such as “vividness” and “calmness,” improved. Under the condition with real plants, the office environment was rated as “natural,” and the subjects’ heart rates were significantly lower than in all the other conditions. While imitation plants also produced certain positive effects, the impacts were more pronounced when real plants were within the field of view. On the other hand, the presence or absence of plants was found to have a relatively minor effect on seating preferences, which were influenced primarily by interpersonal factors. There were individual differences in perceptions of plant quantity and suitability, and not all office workers responded positively to the introduction of plants. Nevertheless, the findings confirm that even a small-scale introduction of plants may exert beneficial effects on both the psychological and physiological well-being of office workers.

This study aims to assess the actual conditions of office sound environments–an important factor for improving employee well-being in corporations–and to clarify the relationship between these conditions and occupant evaluations of the environments. To this end, physical measurements and questionnaire surveys targeted at users were conducted in workspaces and meeting rooms of multiple offices. It was found that, in workspaces, the higher the 95% time-rate noise level (L_A95), which represents ambient and HVAC noise, the more occupants perceived the environment as “loud.” Regarding room acoustics, spaces with tile carpet floors and mineral wool acoustic ceilings had shorter reverberation times, and few users reported negative evaluations about speech intelligibility. However, no clear correlation was found between physical quantities, such as noise levels or reverberation times, and subjective evaluations, such as perception of others’ sound or speech intelligibility. For meeting rooms, though sound insulation performance ranged from D-20 to D-35, few users gave negative feedback regarding the level of incoming sound. While the physical measurements indicated favorable room acoustics in all the meeting rooms, the questionnaire results showed a higher percentage of negative feedback regarding speech intelligibility than in the workspaces. For both workspaces and meeting rooms, it is concluded that more extensive and detailed research is necessary to establish a clear correlation between survey results and physical measurements.

Recently, the higher bearing capacity of piles has resulted in an increase in the horizontal load on the piles. In response to this issue, constructors are taking measures such as increasing the strength of concrete and using more rebar in cast-in-place concrete piles. These measures, however, pose a concern that construction work may be hindered by insufficient concrete filling and interference between the pile reinforcement and the foundation beam reinforcement, if the reinforcement density is too high.
To address these issues, we developed cast-in-place concrete piles that use high-strength reinforcement (685 N/mm², 590 N/mm²) as the main reinforcement.
This paper reports on experiments conducted to verify the bond and structural performance of cast-in-place concrete piles using high-strength reinforcement. The experiments yielded the following results.
1. Pull-out tests of reinforcement and lap-spliced reinforcement conducted while immersed in drilling slurry showed that even high-strength reinforcement allows for safe settings if conventional development and lap joint lengths are adopted.
2. The behavior after the bending moment peaked varied among the specimens. The results showed that shear reinforcement and axial force influenced the behavior in the large-deformation region.
3. The behavior before the bending moment peaked can be evaluated using general cross-sectional analysis methods, even for high-strength reinforcement. On the other hand, it was found that evaluating deformation regions larger than the maximum bending moment requires clarifying the effects of shear reinforcement quantity and the cyclic performance of the reinforcement on deformation performance.

Recently, the use of precast columns and precast column-beam joints has increased in Reinforced Concrete column and Steel beam (RCS) structures. Precasting contributes to reducing member cross-sectional dimensions, thereby lowering fabrication and transportation costs. However, the upper limits on material strength specified by the Architectural Institute of Japan Standards restrict the feasible cross-sectional size in design. The authors have therefore initiated the development of a beam-penetrating, hoop-type RCS structure using high-strength materials that exceed the limits of current standards. As part of this effort, static loading tests were conducted on seven specimens with different joint configurations and failure modes to examine their ultimate strength and failure behavior. The following findings were obtained.
1. The ultimate shear and bearing capacities of specimen joints with high-strength concrete (F_c80) were found to exceed the values calculated based on the Architectural Institute of Japan guideline formula.
2. In top-floor T-shaped joints with high-strength concrete (F_c60) and rebar (SD490), damage to joint concrete may have caused the critical section to shift slightly from the column end surface towards the joint, potentially altering the effective flexural length of the column.

The purpose of this study is to assess the structural performance of the PC steel bar crimping method and the steel bar anchorage method as the means of attaching braced dampers to RC frames. First, we conducted elemental experiments on the attachment joints, by subjecting 10 specimens to loading. Subsequently, we performed structural experiments on the framework with braced dampers to examine the damage conditions at the attachment joints for the two methods. We then carried out a plane frame analysis to simulate a structural experiment, and compared the experimental and analytical results to investigate the effect of misalignment displacement of the attachment on the behavior of the braced damper. As a result, the following findings were obtained.
1. The elemental experiments found that the shear capacity of the attachment joints exceeded the calculated values.
2. The structural experiments showed stable properties with almost no reduction in bearing capacity up to large deformations.
3. Based on a comparison between the experimental data and the analytical results, it was inferred that the effect of misalignment displacement of the attachment on the behavior of the braced damper was small.

To control inundation of the base-isolation layer through the slit during flooding, we developed a flood protection measure using waterproof rubber, and conducted experiments to verify its waterproofing performance. In this method, the lower part of the rubber is fixed to the side of the rising wall, whereas the upper part is kept in contact with the lower section of the seismic isolation apron, thereby suppressing external water intrusion. To verify the waterproofing performance of the rubber, we conducted experiments using specimens simulating both straight and corner sections of the base-isolation layer.
The experiments yielded the following results:
1. Compared to the estimated leakage in the absence of waterproof rubber, applying it reduced water leakage into the base-isolation layer by more than 99.5%. This demonstrates that the waterproofing performance of the rubber is extremely high.
2. With this method, the total water leakage for the entire building could be handled by a single 100 L/min drainage pump. This suggests that the waterproof rubber, when used with drainage pumps, effectively prevents inundation of the base-isolation layer through the second-stage ditch.

In shield tunneling projects, such as those for road construction, which are subject to the Act on Special Measures concerning the Public Use of Deep Underground (hereinafter referred to as the “Deep Depth Method”), it is necessary to consider (1) loads from large buildings in high-rise building projects in commercial areas, (2) the effects of adjacent construction when parallel tunnels are built, and (3) fire resistance in road tunnels. Conventional RC segments, therefore, cannot provide sufficient structural performance. In these cases, expensive composite segments are used, leading to major increases in construction costs. We have developed RC segments made of ultra-high-strength concrete as a less expensive alternative to composite segments. This contributes to reducing costs and streamlining construction works in shield tunneling projects where the Deep Depth Method is applied.
This report describes the manufacturing and strength testing of ultra-high-strength concrete conducted for the development of ultra-high-strength RC segments, along with evaluations of fire resistance, durability, and crack initiation caused by delayed ettringite formation. It also reports on the verification of structural performance using flat specimens extracted from full-scale ultra-high-strength RC segments.

When wood is used for the exterior of a building, it is prone to deterioration over time due to ultraviolet rays, wind, and rain. Wood plastic composite (WPC), made by mixing and molding wood powder and resin, is a material that provides weather resistance. This paper reports the results of outdoor exposure experiments on WPC up to the fifth year. Changes in color and gloss were measured on vertical louvers, as a vertical component. As a horizontal member, a wooden deck was subjected to surface temperature measurements, analysis of surface deposits, and observation of moisture properties. As a result, the following findings were obtained.
1. When used as a vertical louver, WPC exhibits only minor changes after five years of exposure, though the way it changes varies depending on the type of resin.
2. When used as a wood deck, WPC is highly susceptible to sunlight and ultraviolet rays and deteriorates rapidly. The extent of deterioration depends on the resin and surface conditions, such as roughening.

To reduce environmental impact, laboratory experiments were conducted on a concrete equivalent to type C blast-furnace slag cement, which was produced by mixing type B blast-furnace slag cement with ground granulated blast-furnace slag. The experiments evaluated its fresh properties, strength, and durability. Regarding its fresh properties, type-C equivalent concrete mixes with a low water-to-binder (W/B) ratio exhibited delayed setting and increased water bleeding. In terms of strength, compared with type-B cement-based concrete having the same W/B ratio, the type-C equivalent concrete exhibited lower compressive strength; this difference grew as the curing time increased. With respect to deformation, the autogenous shrinkage strain was equivalent, while the length change ratio was slightly lower. The depth of carbonation increased with increasing W/B ratio. Interestingly, type-B cement-based concrete with a W/B ratio of 45% and type-C equivalent concrete with a W/B ratio of 35% exhibited similar carbonation depths. The results suggested that the freeze-thaw resistance may decrease when the W/B ratio and the content of ground granulated blast-furnace slag are both high.

This study evaluated the effectiveness and practicality of the next-day continuous pouring method that uses ultra-retardant concrete for caisson framework construction in deep underground structures. Concrete containing an ultra-retardant, which can control the setting time, was adopted to reduce the workload and shorten the time associated with conventional joint treatment. This helps ensure the integrity of joints during continuous pouring over two days.
Laboratory and field tests showed that the ultra-retardant concrete had compressive strength and durability equal to or greater than that of regular concrete, as well as excellent resistance to carbonation in the joints. Construction quality was ensured by taking specific measures on-site to address technical issues, such as optimizing the rate of retarder addition according to the concrete temperature, removing bleeding water, controlling the setting process, and applying appropriate compaction methods.
As a result, the structural construction period from the eighth lot onward was successfully shortened by approximately three months. This construction method has proven effective in saving labor, shortening construction time, and ensuring quality.

The authors have developed a three-dimensional (3D) transport simulation system that utilizes point cloud data and BIM/CIM information to improve productivity and quality in transport planning. The system reproduces the time-based movement of transport vehicles along the planned route together with the actual conditions at the scene in three dimensions. This enables users to visually identify potential interference between vehicles and surrounding structures. Applied to various construction sites in residential areas, and wind-power and other facilities, the system has assisted in making decisions on vehicle selection, route feasibility, and safety planning. This report outlines the features of the system and presents use cases in multiple projects.