Shirasu is a name of pyroclastic flow deposits called in the southern part of Kyushu. This paper presents a production method of wet consistency concrete using Shirasu as fine aggregate (Shirasu concrete) and its properties. It was necessary for producing Shirasu concrete to add a lot of amount of air-entraining high-range water reducing admixture and reduce sand-total aggregate ratio. On the other hand, the compressive strength of Shirasu concrete was larger than that of concrete using land sand as fine aggregate. In addition, Shirasu concrete demonstrated superior performance on resistance against neutralization and development of strength of concrete in structure.
To validate criteria of JIS A 1160, experimental data for certifications and technical proofs were collected and examined by evaluation criteria specified by JIS A 1160. The evaluation yielded the following findings: 1) All data using standard J-ring met the specification, the validity of JIS A 1160 was proved, 2) In case of using Narrow gap type J-ring, some experimental data deviated from the specification, and 3) The specification can also be applied to concrete using superplasticizer containing viscosity modifying agent.
Investigate the influence of changes in unit volume of water and sand-total aggregate ratio in high-strength concrete, results of pumping experiments by actual concrete pumps, finishing experiments by plaster craftsman and compressive strength tests by imitated concrete column are described.
In order to clarify influence of difference of concrete transportation equipment in construction site and placing site of concrete on working time of concrete construction, Survey was carried out for working time of transport vehicles of ready-mixed concrete. As a result, Concrete transportation equipment in construction site had a large influence on unloading speed of ready-mixed concrete.
There have been formwork methods which make it possible to remove the bottom forms for slabs and beams before the strength of concrete reaches design strength. In order to collect information of those methods in real site, we carried out some questionnaires targeting the engineers involved in selecting methods. In this report, firstly we classified formwork methods and wrapped up the questionnaire results about removal methods of shoring under slabs and beams in the conventional formwork.
A problem using trailer house as immovable property is a secure fixing method with the ground. Examining through real construction projects of both Ogatsukan and Hotel El faro, this report aims to develop a knowledge of rational construction method of fixing a trailer house-chassis to foundation on the ground. As trailer houses can expect various ways of using themselves in the normal times, immediately after disasters, and during recovery period, accumulation of technical knowledge in the trailer houses as in this report is thought to lead to optimization of operation methods.
We aim to incorporate sensor-monitoring technology into housing so that residents can use it to maintain their buildings and improve living conditions. In this study, we propose a diagnostic technology that prevents the early deterioration of structural members of buildings by monitoring moisture movement inside them. Those experiments were conducted to test a diagnostic technology that can detect the physical deterioration of building components early on by using a wetting monitoring system installed on the reinforced concrete external wall. As a result, we could construct a wetting monitoring system in the building．
The purpose of this study is to evaluate the impact for human of falling glass debris. In this study, we measured the depth of the skin damaged by falling glass debris using a pig skin instead of human skin. The experimental results were evaluated with the weight and the falling velocity of glass debris, the depth and length of wounds, and the incidence of wounds. The depth and length of wounds are proportional to the weight of glass debris, and the depth of the wounds is inversely proportional to the length.
In this study, an evaluation method based on box shear tests is developed to estimate the mechanical characteristics, such as the cohesion or angle of internal friction, of wall clay used for mud walls in the existing houses. The core samples of wall clay extracted from the existing houses in Marugame City are used for the box shear tests as a specimen. The wall clay is also extracted and mixed with water used for unconfined compression tests. The results of the box shear tests and unconfined compression tests are presented and discussed. The results of box shear tests is similar to that of unconfined compression tests, although they show a little variations.
The relationship between crack width of concrete and retention ratio of ultimate load for cast-in-place anchor and inorganic type post-installed anchor was confirmed by introducing cracks after the construction anchor construction. The retention ratio of ultimate load was 40 to 80% at crack width of 0.3 to 0.5 mm, and the retention rate in the confined test was equal to or greater than that of the unconfined test.
When buildings are seismically retrofitted, new members are connected to existing members by roughened concrete surface. However, there are few studies on roughened concrete. To evaluate the shear strength of the roughened concrete, the shapes of roughened concrete were measured using 3D scanner, then we conducted the shear loading tests. As a result, failure modes were supported failure and shear failure when rcr were respectively 0.1 to 0.3 and 0.5 to 1.0. This paper focused on supported failure, a shear strength formula constructed considering the concrete compressive and the vertical projection area. The proposed formula could estimate the test results.
We investigated structural characteristics of the base isolated buildings designed by the time history response analysis. The investigation period is from November 2014 to March 2017, it is just before long-period ground motion is legally required. Main investigation items are type of input ground motion, combination of base isolation devices, response characteristics and energy absorption amount of the base isolated buildings. As a result of the survey, in many cases, the large deformation’s natural period is about 5 seconds, the yield shear strength coefficient of the base-isolation story was about 2%, and oil dampers were used in combination.
Recently, the shock-resident design for buildings became important. Therefore, a first book concerning to the problem was published by AIJ in 2015. In the book, the response analysis was shown using simple SDOF (single degree of freedom) model. However, the boundary condition of the explained models was only both-ends fixed type, so it is demanded to show more types. In this paper, two other boundary condition types were added and the applicability of them were explained. Moreover, the accuracy of the borders among 3 loading regions, which are important characteristics for the impulse analysis, were studied.
Dynamic behaviors of building 30 severely deteriorated and damaged are investigated by processing acceleration data acquired by the vibration sensor network in Gunkanjima. Long-term and short-term variations of the vibrational characteristics of building 30 have been evaluated by singular value decomposition and spectrogram, respectively. It is observed that predominant frequencies change unsteadily as a time-variant system depending on damage evolution and external environment during long-term and short-term monitoring even in normal time.
This paper induces the reduction factor of the total input energy for long-period ground motions due to the damping in the elastic single-mass system. The paper investigates the evaluation formula by response analysis using same method applied in the previous research. The analysis uses long period ground motions on the free surface of engineering bed rock for four districts of Kanto, Shizuoka, Chukyo, and Osaka announced by the MLIT, considering ground amplification of soil. Finally, this paper proposes formula as a function of damping factor and building period. The formula shows excellent suitability with analytical results.
The simple evaluation method of stud type vibration control structure with nonlinear viscoelastic damper was shown. In this method, loss displacement of stud type damper can be appropriately considered by replacing the damper with an elasto-plastic spring and performing pushover analysis. By reflecting the loss displacement in the multi degree of freedom system model, simple and accurate dynamic analysis is made possible. The accuracy of this method was proved by a case study in a real building.
We have already proposed generic shear multi-mass models (S models) for vibration analysis models of the super high-rise RC buildings. In this study, the bending deformation component of the vibration analysis models are analyzed and then we propose the generic bending shear multi-mass models (BS models). Natural periods and modal shapes of higher modes of the BS models are consistent with those of the moment-resisting frame models. Proposed generic BS models are validated by the nonlinear earthquake response analysis for pulse type input wave with short period, where the higher modes are stimulated.
In this paper, time history response analysis considering the multi-cyclic characteristics of the isolation devices by the simplified method is performed using the long period ground motion for each target area due to Nankai Trough Earthquake. Moreover, time history response analysis of changing the arrangement of the isolation devices is performed in order to investigate the differences in the response characteristics of the base-isolated buildings, and attention points for aseismic design are indicated. In addition, the behavior of the collision to retaining wall is confirmed in the case where large deformation occurs in an isolation story.
Experiments were conducted to evaluate the floor vibration characteristics by human walking on actual floors of over-track buildings (two railway stations). The following conclusions were obtained. (1) It is confirmed that the resonance vibration occurs when the frequency of response acceleration is almost same to integer multiples of the up-down frequency of the floor. (2) The floor vibration by five walkers is almost same as the characteristics of the floor vibration caused by the crowd and (3) It is not uncomfortable under V-90 of evaluation curves provided in the guideline of A.I.J..
In case of reusing only existing piles other than foundation, it is necessary to select a demolition method of the foundation that doesn’t damage the piles. There is no study to examine the relation between the extent of the pile damage and the working efficiency in the demolition method. This paper describes the experiments of the relation using the foundations and the piles of building under demolition. The method with cutter is the most reasonable because its working efficiency is equivalent to the method with crusher and its effect on the pile soundness is equivalent to the method with wire-saw.
This paper describes simplified theoretical equations to estimate stresses in piles subjected to ground deformations. The proposed equations are derived with approximated ground displacement by polynomial function. The approximation is effective to solve the differential equation of deflection of piles considering ground displacement. These equations are very simple and efficient to estimate pile stresses at preliminary seismic design of pile foundation.
The shear wave velocity is necessary for modeling the ground so as to calculate the amplification characteristics and the deformation of the ground by seismic response analysis. Basically, the PS logging is performed to obtain the shear wave velocity, but it is rare to perform the PS logging unless it is an important building of the design. Therefore, an expression for estimating the shear wave velocity from the N value of the standard penetration test has been proposed. In this report, we verified the relationship between the estimated value by Ohta and Goto or Imai et. al and measured value. Using actual measurement data conducted after 2000, review the correction factor of the estimation formula of the original, we propose equations to estimate the measured value slightly smaller.
Deployable structures are presented using regular 2N-gonal frames, which have 2N bars connected with two types of inclined revolute joints. Series expansion method shows that the frames satisfy a necessary condition for finite mechanism. The frame can be folded to a state where all bars are aligned to a rod, if the cross-section of all bars is an isosceles triangle whose vertex angle is π/N and the axes of the revolute joints are directed to the intersection of lateral faces of two adjacent bars. As an application, a dome-shaped structure that can be folded into a rod is proposed.
An approximate design system is developed to design a free-form surface combining developable surfaces. The cost of construction may be reduced using developable surfaces, while maintaining the architectural characteristics as well as the mechanical performance. The proposed system is composed of a series of operations: (1) forming an initial shape and determining a target free-form surface, (2) geometric approximation of the free-form surface based on the combined developable surfaces, and (3) minimizing of the strain energy of the combined developable surfaces. The performance of the system is demonstrated through examples of a roof shell and a free-form facade.
In the last few years, Kochi Prefecture has been rapidly increasing its efforts to retrofit old wooden houses. Through a listening survey, this study aimed to clarify the reasons behind this spike in seismic retrofitting work. We found that the primary reasons could be traced to newly available and reasonably priced seismic retrofitting methods for older wooden houses that have recently become popular in the prefecture. These new methods have made it possible for house owners to feel much more confident that their homes and families would be able to endure earthquakes without suffering physically or incurring severe economic liabilities.
Regarding to the in-plane shear strength of CLT the authors proposed an equation for the in-plane shear strength in the width direction of CLT beams proposed by M. Flaig et al., and verified the validity of the proposed equation for Japanese cedar. On the other hand it has not been confirmed whether the proposed equation is applicable to other wood species. In the past research the in-plane shear strength of CLT tested by one-way monotonic loading with no vertical load was only verified. The aim of this study is to confirm the applicability of the proposed equation to Japanese cypress and for the testing condition that vertical load or repeated load is applied.
As an alternative idea of ordinary seismic retrofit method, seismic shelter is sometimes utilized. It is a device to protect human life from house collapse. In this paper, a seismic retrofitting method making use of seismic shelter is proposed. The shelter is inserted inside the existing wooden houses and connected with oil dampers. The response control effect was confirmed by time history analysis. It was revealed that the response of the existing house could be reduced effectively.
Small clear test specimens with different width to pin-diameter ratio (l/d) were loaded for creep rapture and time to failure was discussed in terms of the effect of length to pin-diameter ratio. The time to failure of the test specimens with l/d from 6.7 to 10 was longer and that of the test specimens with l/d from 4.3 to 6 was shorter than the time to failure estimated by the Madison Curve. The test results indicated that the duration of load factor for the tested joints should be evaluated with consideration of the effect of the width to pin-diameter ratio.
Various shapes of joints are used for members of traditional wooden buildings. Since these have complex stress distributions in the joints and large dispersion in the characteristics of wood, these have been used with unclear strength characteristics. In this study, tensile tests were conducted to evaluate the tensile strength characteristics of Koshikake-kama-tsugi. As a result, since it had been observed that latewood crushes earlywood in the compression surface of the joint, the compression strength of earlywood had been quantified. It was verified that the compression strength of the joint was evaluated with the compression strength of earlywood.
This report proposed a method to estimate the degree of earthquake damage of wooden buildings. We conducted a static loading experiment to understand the relation between the damage situation and the displacement of the finishing material. Focusing on the cracks generated around the opening, a figure and equation showing the relationship between cracks and maximum displacement was prepared.
Recently, flattening beam cross sections is getting popular to create open living space in RC residential buildings, resulting in flat beam-column joints. However, the structural performance of T-shaped flat beam-column joints has not been clarified. Therefore, in this study, static loading tests were conducted on three T-shaped flat beam-column partial moment-resisting frame specimens to investigate the structural performance. As a result, the beam-to-column flexural strength ratio significantly affected the structural performance of the specimens, showing that the experimental lateral resistance of the specimen with the ratio of approximately 1.0 didn’t exhibit the design strength assuming yielding of member longitudinal rebar.
Finite element analysis was conducted on a R/C residential building with soft first story which was built in 1992 and heavily damaged in the 2016 Kumamoto Earthquake. Structural damage observed on first story column and second story beam members of the soft first story could be predicted in good accuracy. By carrying out a parametric study, it was found that the detail of second floor beam and wall above the soft first story affect to the horizontal load carrying capacity and deformation capacity of whole building.
Corrugated fold roof deck plates are used for roofs in steel buildings and are cost effective without concrete slab. In addition to their strength and stiffness against loads in out-of-plane vertical directions, they have certain capability to resist loads in the in-plane horizontal directions providing the diaphragms of roofs. The roof deck plates are typically connected to the beams with puddle welding. They can rapture under excessive shear force experiencing large inelastic strain around the connections. The material properties of the plates are firstly investigated including their large strain region. Simplified material properties for FEM simulation is secondly proposed and are varied with the test data of the connections with puddle welding.
In a steel building with concrete slabs, it is common to break concrete slabs when attaching reinforcing members and join the floor beams to the reinforcing material. However, since the destruction work of the concrete slab generates noise and vibration, it is often difficult to perform reinforcement work while using the building. Therefore, without breaking the concrete slab, we developed a method to attach reinforcing members to steel beam columns, and carried out reinforcement work. As a result, we were able to achieve results such as reduction of construction scope, cost reduction of temporary expenses, shortening of construction period, etc.
In recent years, steel structural members have been corroded and thinned with aging, and deterioration in structural performance has been reported. As a countermeasure for that, research and development of adhesive bonding method using CFRP are carried out. However, it has a problem unstable adhesive strength. This problem is caused by brittle failure occurs at the interface of the adhesive layer, and it is considered the adhesive strength is stabilized by maintaining the sufficient adhesive layer and improving adhesiveness at the construction. Based on these backgrounds, recently developed vacuum assisted resin transfer molding (VaRTM) was adopted in order to apply to repairing and strengthening of steel structures, a double strap tensile shear tests were carried out to analyze the fundamental adhesive strength in this study.
Many steel structural members have been corroded and thinned with aging lately. Hence, the structural performance has been deteriorated. This is one of the problems the Japanese construction industry has, and various countermeasures are being researched and developed continuously. Among them, the repair and reinforcement method using a CFRP attracts attention because repair and reinforcement effect can be obtained with little weight increase of the structure after construction. Repair and reinforcement by CFRP is mainly performed by adhesive bonding; however, instability due to debonding at the adhesive layer interface is concerned. Therefore, in this study, the relationship between fracture modes and strength was analyzed and evaluated by changing the number of laminated CFRPs and the bonding length for the purpose of increasing the bending stiffness of steel plate. In the test, a three-point bending test was conducted on a specimen which was molded and bonded at the same time by VaRTM technology.
A series of pullout tests was conducted to evaluate the tensile capacity of single post-installed anchors in low strength concrete. This study focused on application of bonded anchors which were installed on a half-scale RC slab made using low strength concrete with brick chips for coarse aggregate representing Bangladeshi concrete. This paper reports the pullout test results of five types of anchor specimens with different diameters and embedment lengths. The experimental tensile capacity of all specimens was higher than calculation using equations in Japanese guidelines, indicating that Japanese guidelines conservatively estimate the tensile capacity of bonded anchors in Bangladeshi concrete.
The research identified issues in communication in the customized house planning process: while professionals ensure that client’s needs are incorporated into the plan, customers felt that needs and tastes were not sufficiently reflected. Factors that affect customer’s general satisfaction are final building, entire process, the interaction with the sales representative, and how the building is placed, as well as the precision of the design drawings/plans. In addition to the tools to share images that reflect needs and taste, an involvement of an interior decorator is found to improve customer satisfaction and reduce the burden of professional in meeting client’s needs.
Presently, in the Tokyo metropolitan area mainly in Tokyo, there are many problems of waiting children. For that reason, in the center of the city, nursery schools are being built one after the other in severe environments from the sound and vibration under the elevated railway. In this report, as a basic study, we first conducted a questionnaire survey targeting childcare workers at the elevated nursery school. The contents of the questionnaire survey consists of 17 items. Next, at the elevated nursery school, we measured the noise and vibration at the time of passing through the train.
Vibration measurement has been performed in a full-scale field test of 6 story wood framework wall system. 6 microtremor sensors and 20 MEMS acceleration sensors were installed to understand the dynamic behaviors of the target building considering soil-structure interaction, and to estimate modal properties of the superstructure in translational and torsional vibrations. It is concluded that the overall behaviors of the target building are governed by rocking motion of the foundation subsystem rather than dynamic characteristics of the superstructure subsystem.
Vibration measurement has been performed for a full-scale field test of 6 story wood framework wall system under external excitation. A vibration generator was placed on the ground near the target building. 20 MEMS acceleration sensors were installed inside and outside of the building to monitor the propagation characteristics of vibration in the superstructure and foundation. It is concluded that the rocking motion of foundation becomes predominant rather than the deformation of superstructure when the height/width ratio is large.
The purpose of this research is proposing relevant conditions for the heat specific measurement of Phase Change Materials (PCM) by calculating thermal conductivity. It was found that the accuracy of the measurement was low when the thermal resistance of PCM was high. On this condition, the temperature change should be slow for higher accuracy.
In order to evaluate the performance of the central air-conditioning house using geothermal heat, field survey in the model house equipped with the earth tube and thermal storage concrete mat foundation was carried out in Maebashi city for three years. In this paper, measurement results of indoor thermal environment, amount of heat exchange by the earth tube, condensation in the earth tube, and indoor temperature stabilization effect by the thermal storage concrete mat foundation were described.
Three types of humidity-variable vapor retarder were focused and their water vapor transmission properties in the directions from hydrophilic layer to hydrophobic layer and vice versa were measured by cup method. Eight different relative humidity conditions in test cup were controlled by desiccants, aqueous solutions, or water. In the high relative humidity range, the vapor transmission resistances were positively small for all three films and in both directions. In the low relative humidity range, however, the resistances were enough high in one direction but mildly low in the other direction. Furthermore, the resistances measured by desiccants and those by aqueous solutions had an opposite trend, that indicated that the dry cup method with desiccants should not be used for humidity-variable film with hydrophilic layer.
Saving energy in the residential is required under the influence of global warming and electricity shortage caused by natural disaster in Japan. For the purpose of promoting zero energy house, “ENEMANE HOUSE 2017”, a competition of Zero-Energy House was held. This paper shows the overview of the building and equipment planning, and also the evaluation of thermal environment and energy in the zero energy house which the consortium of Waseda University and Shibaura Institute of Technology proposed in the competition. This zero energy house demonstrates a method of renovation of housing using low-insulated outer wall of an existing industrialized house. The aim of the facility planning was not only the compatibility of energy-saving and comfort but also the increase in self-consumption of surplus power.
The study aims to experimentally examine how the drainage performance of an apartment house drainage stack system is affected by installing a pumping toilet system for nursing care at a selectable location. This report evaluates the drainage performance of a high-rise building drainage stack system, when the toilet and other fixtures are connected through horizontal branch pipes to the drainage system and a load is applied from each fixture, and provides basic data for establishing a planning and design method of such a drainage system.
The purpose of this study is to examine the effects of a seismic retrofit and renovation on the sprinkler piping of existing buildings. In a full-scale experiment, it is difficult to model a sprinkler piping system deployed in a wide area. Therefore, we created a model of a sprinkler system installed in an evaluation building, and conducted numerical analysis. It was demonstrated through numerical analysis that the horizontal sprinkler piping was vulnerable. In contrast, the installation of braces on the horizontal sprinkler piping was demonstrated to contribute to improved aseismic performance.
In recent years, as the need for development of low-carbon architecture increases, practical use of the natural energy that surrounds buildings is attracting attention. Heat/cool trench systems make use of one such natural energy, subterranean heat. These systems reduce the fresh air load by introducing outside air through trench that pass beneath the bottom floor-slab before blowing the air indoors. This study involves a year-round measurement survey of outside air and indoor outlet temperature of indirect and direct subterranean heat use systems. The thermal effect of an indirect subterranean heat use system is evaluated through comparison between both.
In recent years, R&D work has focused on radiant air-conditioning systems that use groundwater as a heat source/sink for realizing net zero-energy buildings (nZEBs). In a previous report, we described summer target figure for PMV of a ceiling radiation cooling system using groundwater including the power consumption of the electric fan and air-conditioner based on thermoregulatory behaviors. This paper presents the results of research about a cool spot installation in the radiation cooling/heating office. The effectiveness evaluation was carried out considering the number of time until thermal sensation is restored to a comfortable state after a subject’s going-out action.
Home energy saving is essential to prevent global warming, and it is not exception in the local city. Akita prefecture has drawn up ‘Regional Promotion Plans for Combating Global Warming in Akita’ in 2017, and declared the CO2 reduction of 26.0% from 2013 levels by 2030 in the residential sector. The development of scenarios for energy saving should be useful to implement the new scheme of low carbon society. Authors have already built the simulation method to forecast home energy consumption in the future. This paper describes the prediction accuracy of our methodology and the possibility of CO2 reduction level with the penetration of several energy saving technologies.