著者

荒木 康弘 腰原 幹雄 大橋 好光 坂本 功

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.69, no.579, pp.79-85, 2004-05-30 (Released:2017-02-08)

参考文献数

32

被引用文献数

12 13

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This paper attempts to build the parameters of hysterisis models for resisting shear walls of timber structures. These parameters enables engineers to make models easily by summation of the parameters. In order to establish these parameters, this paper focuses on the following three subjects. First : Proposition of a hysterisis model fit for timber structures. Second : Proposition of parameters of the resisting shear walls, based on about 100 tests. Third : Prediction of shaking table tests from the models of summation of the walls. In the first part, the combination model of bilinear model and slip model is adopted for its simple mechanism. In the second part, the database serves for determining parameters of five different types of walls. In the third part, three models of one full-scale wooden house are proposed. The earthquake responses obtained by the models correspond to the shaking table tests, and this result confirms the accuracy of the parameters.

著者

東舟道 裕亮 山田 義智

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.86, no.784, pp.860-870, 2021

被引用文献数

3

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<p>With the improvement of earthquake resistance and large scale of buildings, the number of cases where it is difficult to fill the form work with conventional slump-managed concrete is increasing. In addition, slump flows 45 cm, 50 cm, 55 cm, and 60 cm have been added due to the JIS (Japanese industrial standard) revision made in March 2019. In the future, it is estimated that the use of slump flow managed concrete will increase. Furthermore, in recent years, new admixtures have been actively developed, and it is necessary to correctly grasp the flow characteristics of concrete using these admixtures from a rheological point of view. It is the cement paste in concrete that is most affected by the flow properties of the admixture. Therefore, it is useful to be able to grasp the flow characteristics of cement paste. </p><p>We have already examined the relationship between the rheology constants obtained from the rheology test and the flow characteristics obtained from the paste flow test, and we proposed a rheology constant estimation method. In this study, we reexamined the rheological constant estimation method based on the correlation analysis findings using the visco-plastic finite element method (FEM). </p><p>First, flow analysis was performed by FEM using any combination of rheological constant and paste density (yield stress: 10 patterns, plastic viscosity: 7 patterns, paste density: 3 patterns, total 210 patterns) as input values. Next, based on the analysis results, the relationship between the paste flow characteristics (flow value, each flow arrival time, flow stop time) and the rheology constant and paste density was examined by correlation analysis. </p><p>As a result, it was found that the yield stress can be estimated by the flow value, and the plastic viscosity can be estimated by the multiple regression equation of the paste density and the 150 mm flow arrival time. </p><p>Furthermore, we proposed a new rheological constant estimation equation using the actual test results of the cement paste for the relationship obtained from the correlation analysis. After that, the rheology constant was estimated from the actual paste flow test results using the rheology constant estimation equation. Finally, a paste flow simulation was performed using the MPS method, which can consider the influence of the flow cone, and it was compared and examined: the actual paste flow test results and MPS analysis results. </p><p>As a result, the actual paste flow test results could be reproduced by MPS analysis, and the validity of the rheological constant equation was confirmed. </p><p></p>

著者

石井 友 松岡 昌志 牧 紀男 堀江 啓 田中 聡

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

no.751, pp.1391-1400, 2018-09

被引用文献数

9

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&nbsp;If a disaster such as an earthquake occurs, buildings will suffer damages, including residential houses and public facilities. An investigation of damaged buildings is very important in disaster areas because we use such data to make decisions for the implementation of disaster management and restoration plans. However, in the event of a large-scale disaster, conducting a detailed survey has several problems. The number of buildings to be covered will increase, manpower will be insuffficient, the burden on workers will increase, restoration will take time and will be delayed. Therefore, there is a need for a quick and accurate method of investigating building damages.<br><br>&nbsp;In this study, we allowed a CNN (convolutional neural network) to learn the local and aerial photographs of the 1995 Kobe earthquake and verified the possibility of assessing building damages in the CNN based on the learning curve and discrimination accuracy. The Nishinomiya Built Environment Database, which contained damage certificate data, aerial and field photographs, and their shooting points, was used for analysis. In the Nishinomiya city's damage certificate data, the damaged buildings were classified into four classes: &ldquo;severe,&rdquo; &ldquo;moderate,&rdquo; &ldquo;slight,&rdquo; and &ldquo;undamaged.&rdquo; However, in the present study, three classes&mdash;moderate, slight, and undamaged&mdash;were merged into a single class for simplicity, such that we had a two class classification problem, that is, &ldquo;severe&rdquo; and &ldquo;others.&rdquo;<br><br>&nbsp;First, when we created a data set using the damage certificate data, and aerial and field photographs, and allowed the CNN to learn them, a state called over-fitting was created, which made normal learning more difficult. However, as a result of countermeasures called data incrimination, we were able to obtain a estimation accuracy of approximately 63.6% in the aerial photographs and 73.6% in the field photographs. Since the decrease in the accuracy is due to building internal damages, we should also include the possibility of such damages that could not be assessed from the appearance alone, and of the images of damaged buildings from outside the target building; therefore, we investigated and verified the damaged buildings again based on the &ldquo;images of damaged buildings evaluated by visual interpretation.&rdquo; Then, it became clear that the damaged buildings can be identified with an accuracy of 86.0% in the aerial photographs and 83.0% in the field photographs. Furthermore, in the field photographs, it became clear that collapsed buildings can be distinguished with a high accuracy of 98.5%.<br><br>&nbsp;From the above results, it was found that it is possible to assess the condition of damaged buildings by deep learning using field and aerial photographs taken in the affected area after the earthquake; however, the damage that can be identified with the highest accuracy is limited to the photographs of collapsed buildings. In our future research, we plan to correctly identify the difference between &ldquo;moderate&rdquo; and &ldquo;slight&rdquo; damaged buildings.

著者

楠 浩一

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.84, no.761, pp.961-971, 2019 (Released:2019-07-30)

参考文献数

13

被引用文献数

1 2

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Sigmund A. Freeman proposed the capacity spectrum method in 1987, which simplifies down the responses to a single-degree-of-freedom system (referred to as the capacity curve, hereafter) and compare it with the relationship between the response acceleration and displacement spectra (referred to as the demand curve, hereafter). Recently, some researches have been conducted in developing a method to calculate the capacity curve with measured accelerations during an earthquake to evaluate the building damage. Authors had proposed a method to predict the maximum response for the possible maximum aftershock to predict the building damage during the aftershock. In order to evaluate the damage due to an aftershock, safety limit deformation on the performance curve needs to be predicted. Although the safety limit deformation of each story can be estimated from a structural calculation or seismic evaluation, the safety limit deformation cannot be predicted with only them because it depends on the equivalent vibration mode shape at/to the safety limit state. The vibration mode shape may change according to the damage. Therefore, a new method to evaluate the safety limit deformation with considering the vibration mode shape after yielding is proposed. First, a method to model the performance curve to tri-linear model with a simple error function is proposed. Second, a method to predict the safety limit deformation with an assumption that the incremental deformation mode shape from the second corner point to the maximum response point of the tri-linear model is constant. Mode adaptive pushover analysis results with 4-story, 6-story (soft-first-story), and 12-story buildings conducted by Dr. Matsumoto et. Al., which considered the change of vibration mode shape due to damage, and E-Defense shaking table test with 3-story R/C frame structure with pile foundation were used to verify the validity of the proposed modeling and prediction methods. The results were discussed with the relationship between error functions according to the assumed displacement at the second corner point and accuracy of the predicted safety limit deformation. With the pushover analysis results, the accuracy of the predicted safety limit deformation with pushover results that were intentionally stopped before the safety limit state was also discussed. As the results, the following findings were obtained; 1) A modeling method for the performance curve to tri-linear model is modified and proposed. 2) It is confirmed by the pushover analysis results and shaking table test results that the proposed method can find an appropriate second corner point with a proposed error function. 3) A prediction method of the safety limit deformation on the performance curve with the tri-linear model from measured responses is proposed. 4) It was found that the safety limit deformation can be predicted within 10% error when the maximum response is around the second corner point of the tri-linear model, and within the few percent error when the maximum response exceeds the second corner point. 5) The error of the prediction converges faster for a story failure mechanism than for a total yielding mechanism.

著者

早川 崇 片岡 俊一 宮腰 淳一 佐藤 俊明 横田 治彦

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

no.650, 2010-04

---

We estimated the fault of the 1924 Tanzawa earthquake (<i>M</i>j7.3), which was the largest aftershock of the 1923 Kanto earthquake (<i>M</i>s8.2). We could successfully reproduce the observed waveforms in central of Tokyo based on the estimated fault model. This is very important to investigate the characteristics of ground motions by M7 events occurring in the Tokyo Metropolitan area because we only have a few observed waveforms of such events in central Tokyo. Finally, we calculated ground motions around Tokyo metropolitan area by the estimated fault model. The simulated ground motions do not exceed the design spectra around the area but in west of Kanagawa Pref.

著者

中田 善久 斉藤 丈士 梶田 秀幸 大塚 秀三 春山 信人

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.82, no.738, pp.1145-1154, 2017 (Released:2017-08-30)

参考文献数

17

被引用文献数

3 4

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The authors have carried out the experiments to identify the effects on fluidity, resistance to segregation, strength, Young's modulus, dry shrinkage and durability of high-strength concrete when unit water content was varied in high-strength concrete while unit bulk volume of coarse aggregate was fixed, or the volumetric ratios of cement paste and fine aggregate were varied. Three types of cement, ordinary Portland cement, moderate-heat Portland cement and low-heat Portland cement, were used. Limestones were adopted as coarse aggregate. Water-cement ratio was varied with 45, 35 and 25%. Analysis were carried out in concern with properties of fresh concrete, properties of concrete hardening, and properties of hardened concrete where unit water content was varied. When water-cement ratio was 35%, changes in the properties of high-strength concrete with hard sandstones used as coarse aggregate owing to the increase of unit water content were also examined. As a result of the experiments, it was found that increasing of the water content caused no segregation of materials, facilitation of handling, reducing of changes in the retention of slump and slump flow, increasing of flow velocity in L-box tests and increasing of bleeding only slightly. Few effects were observed on the initial properties and on the properties of hardened concrete. Based on the above, it is assumed that slightly increased unit water content in the range between 5 to 10 kg/m3 in high-strength concrete with fixed unit bulk volume of coarse aggregate will improve construction performance without great affection of the quality parameters while the deterioration of the parameters has been afraid when unit water content was increased.

著者

中田 善久 斉藤 丈士 西 祐宜

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.84, no.762, pp.1021-1031, 2019 (Released:2019-08-30)

参考文献数

23

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Experimental research was conducted to clarify fundamental characters of high-strength concrete plasticized by air-entraining and high-range water-reducing admixture. Plasticized high-strength concrete was water cement ratio of 28 to 48%, and target slump-flow was fluidized to 50cm using air-entraining and high-range water-reducing admixture. Investigated items are adsorption characteristics of air-entraining and high-range water-reducing admixture and influence of the difference of various conditions of water cement ratio, unit water amount, slump before plasticization, environmental temperature, fluidization time on properties of plasticized high-strength concrete. As a result, air-entraining and high-range water-reducing admixture showed different adsorption characteristics during mixing and plasticization, and at plasticization, fluidity could be increased with less use than at mixing. Considering the adsorption characteristics of air-entraining and high-range water-reducing admixture, the agglomeration characteristics of cement is thought to change markedly within 180 minutes from 120 minutes after mixing. The decrease in slump-flow amount after plasticization of plasticized high-strength concrete is larger than that of standard high-strength concrete. Also, slower the plasticization time, larger the decrease in slump-flow amount. The setting time of plasticized high-strength concrete tends to be faster than standard high-strength concrete, and the difference increases as environmental temperature to colder. Among properties of hardened concrete, effect of plasticizing by air-entraining and high-range water-reducing admixture on compressive strength, Young's modulus and drying shrinkage ratio was small. From the above results, high-strength concrete plasticized by air-entraining and high-range water-reducing admixture has same points to be noted as conventional plasticized concrete, such as decrease in slump-flow amount after plasticization is larger and setting time faster. However, it is possible to obtain hardened concrete comparable to standard high-strength concrete while reliably obtaining necessary slump-flow.

著者

宮田 敦典 中田 善久 大塚 秀三

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.83, no.751, pp.1217-1227, 2018 (Released:2018-09-30)

参考文献数

38

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It is significant to accurately grasp the pressure loss per unit length of pipeline in calculating total pressure of pipeline. The standard value of pressure loss per unit length of pipeline is shown in recommendation for practice of placing concrete by pumping methods. The standard value of pressure loss per unit length of pipeline were obtained from pumping experiment conducted around 1970. But, mix-proportion and concrete materials has changed compared to the 1970s. Especially, design strength has risen compared to the 1970s, and high-range AE water reducing agent was developed and has spread. Therefore, concrete that has been used recently can't apply the standard value of pressure loss per unit length of pipeline. So this study aimed to reveal influence of mix-proportions on the pressure loss per unit length of pipeline by literature survey and pumping experiment. In the first, we studied the influence of water-cement ratio on the pressure loss per unit length of pipeline. Pressure loss per unit length of a pipe tended to be roughly proportional to the square of cement-water ratio. Next, we examined pressure loss per unit length of pipeline for each slump of concrete that more than W/C 45%, and we examined pressure loss per unit length of pipeline for each unit water content of concrete that less than or equal to W/C 45%. As a result, pressure loss per unit length of pipeline tended to increase when slump decrease and unit water content is low. And we derived the relational expression between pressure loss per unit length of pipeline and true output capacity. In additions, this paper proposed standard value of pressure loss per unit length of pipeline of concrete that more than W/C 45% on the basis of literature survey results. Finally, we confirmed the validity of the relational equation obtained from literature survey by pumping experiment. This paper shows a result of pressure loss per unit length of pipeline of concrete with normal portland cement. Therefore, we should does experiment of test pumping with reference to result of this paper when we use concrete with cement and materials other than normal portland cement.

著者

中田 善久 斉藤 丈士 梶田 秀幸 大塚 秀三 春山 信人

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.83, no.748, pp.751-761, 2018 (Released:2018-06-30)

参考文献数

14

被引用文献数

3

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The authors have carried out experiments to identify the effects on fluidity, separation resistance, strength, Young's modulus, drying shrinkage and durability of high-strength concrete when sand-total aggregate ratio was varied. In high-strength concrete while water-cement ratio and cement-paste volume was fixed, that is, volumetric ratios of coarse aggregate and fine aggregate were varied. Three types of cement, normal portland cement, moderate-heat portland cement and low-heat portland cement, were used. Limestones and sandstones were adopted as coarse aggregate. Water-cement ratio was fixed as 35%. Unit water content was fixed as 170kg/m3. Analysis were carried out in concern with properties of fresh concrete, properties of concrete hardening, and tendency of properties of concrete where sand-total aggregate ratio was varied. As a result of the experiments, If sand-total aggregate ratio is smaller than general range, impression of state of fresh concrete tends to be somewhat impaired, but even if sand-total aggregate ratio is somewhat larger than general range, impression of state of fresh concrete is it was not compromised. However, when sand-total aggregate ratio is large as addition rate of high-performance AE water-reducing agent is significantly large, impression of state is impaired due to separation of fresh concrete in addition to increase in bleeding and delay of settling-time. In hardened concrete, influence of sand-total aggregate ratio on compressive strength is small, As sand-total aggregate ratio is larger, tendency of young's modulus to slightly decrease, tendency of length change by drying to slightly increase, tendency of carbonation depth to slightly increase. Based on the above, high-strength concrete may possibly obtain hardened concrete of required quality even if sand-total aggregate ratio is increased somewhat within range where separation resistance is not impaired in consideration properties of fresh concrete.

著者

梶田 秀幸 中田 善久 桝田 佳寛 笹倉 博行

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.84, no.761, pp.905-915, 2019 (Released:2019-07-30)

参考文献数

19

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In this study, with high strength concrete ranging from slump 21 cm up to slump flow 60 cm as the applicable range; in order to shed light on the steady-state flow of fresh concrete in inclined flow test apparatus, we compared and examined the velocity at the tip of the flow determined the vicinity of the gate and the velocity at the tip of the flow of the inclined portion determined from near the end of the test apparatus. Then, based on the relationship between the apparent shear strain rate and the apparent shear stress determined from the velocity at the tip of the flow of near the end of the test apparatus in the inclined portion, we calculated the apparent yield value and the apparent plastic viscosity, and we examined it appropriateness by comparing with the yield value and the plastic viscosity calculated by Terada et al. In addition, we carried out a pumping experiment with an actual pipe length of about 35m, and in addition to confirming the appropriateness of the apparent yield value and the apparent plastic viscosity from the change in the quality of concrete before and after pumping, with regard to evaluation of pumpability of concrete from the relation of pressure loss inside the pipe, we compared and examined with the outcome of the studies conducted by Wami et al. and Terauchi et al. As a result, the following findings were obtained. (1) By measuring the velocity at the tip of the flow of near the end of the test apparatus in the flow portion of the inclined flow test apparatus, we measure the velocity at the tip of the flow where deformation and flow due to the weight of the concrete is close to the steady-state flow, and we could obtain appropriate apparent yield value and apparent plastic viscosity. (2) We proposed the test method of apparent rheological constants determined from the velocity at the tip of the flow of near the end of the test apparatus in the flow part of the inclined flow test apparatus. (3) As a result of investigating the changes in the quality of concrete before and after pumping, values of the apparent yield value and the apparent plastic viscosity obtained from the inclined flow test were appropriate, and the apparent plastic viscosity may evaluate the viscosity of the concrete. (4) As a result of investigating the relationship with pressure loss inside the pipe, it was found that the apparent plastic viscosity obtained from the inclined flow test shows the plastic viscosity of concrete, and it suggested that it may be possible to evaluate the pressure loss inside the pipe from the product of apparent plastic viscosity and actual discharge amount.

著者

武村 雅之

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.69, no.577, pp.153-159, 2004-03-30 (Released:2017-02-08)

参考文献数

18

被引用文献数

1

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A famous result for the damage in Tokyo Metropolis during the Kanto earthquake was that the damage rate of dozo (Japanese traditional timber storehouse coated with clay and plaster finish) is larger in the Yamanote terrace formed by diluvial deposit than that in the Shitamachi low-land by alluvial deposit, while the damage rate of wooden houses, which determined seismic intensity, was smaller in the Yamanote terrace than that in the Shitamach lowland. We re-examined the original data of dozo on the Kanto earthquake and compared with the damage data from the 1948 Fukui earthquake and the 1855 Ansei-Edo earthquake. It can be found that the original data was strongly contaminated by the damage due to fires during the Kanto earthquake, and that the result of dozo was not trusted. The damages of RC buildings and brick buildings which had almost the same natural period as dozo, were also re-examined. We could correlate weakly the damage rate of them with seismic intensity determined from the damage rate of wooden houses, which was larger on the alluvial deposit than on the diluvial deposit.

著者

中田 幸造 山川 哲雄 金田 一男 黒木 正幸 ヌリ モハンマド ザヒッド ジャバディ パシャ

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.85, no.778, pp.1633-1642, 2020

被引用文献数

1

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<p> An economic and convenient seismic retrofitting technique based on the thick hybrid wall (THW) technique reported by Yamakawa¹⁾ is proposed. In the proposed technique, a cast-in-site partial hybrid wing-wall is built using additional concrete sandwiched by steel plates and high-strength steel bars (PC bars) prestressing. The aim of this technique is to enhance the lateral strength, stiffness, and ductility of soft-first story reinforced concrete (RC) buildings that are vulnerable to large seismic excitations. In the THW technique, the retrofitted section consisting of an additional wing-wall with short depth and the existing RC column are unified together as one unit using channel-shaped steel plates and tightened with PC bars. Since the additional wing-wall is not reinforced by longitudinal or transverse bars, the technique is convenient and cost effective. The important structural aspect of the THW technique is increasing the flexural strength as well as ductility by ensuring that all the longitudinal bars in the existing RC column yield in tension due to the increment of the internal moment lever arm, which results from the increase in the neutral axis depth into the additional wing-wall. To verify the efficiency of the proposed THW technique from the perspective of flexural strength, the equations to evaluate ultimate moment resistance in the retrofitted THW column section was proposed³⁾ based on the ACI stress block parameters, which consider the condition that all longitudinal bars yielded under tension in the existing RC column, and the additional wing-wall was in the compression side. Furthermore, the equation to calculate the minimum additional wing-wall length ratio was also proposed to estimate the affordability of the THW technique in Ref. 3).</p><p> This study aimed to experimentally investigate the shear resistance and shear strength of the arch mechanism of the RC column retrofitted by the THW technique. From the test results of the retrofitted RC column showing a flexural failure mode, the proposed equations of the ultimate moment resistance³⁾ of the THW technique were verified.</p><p> Experimental investigations were conducted on six specimens. In this study, two types of specimens were considered. One was a retrofitted RC column with no bonding force between the concrete and embedded longitudinal bars, thereby generating the arch mechanism. The other was a retrofitted RC column with bonded longitudinal bars to evaluate the flexural strength. In brief, the conclusions are as follows: (1) Bonded specimens for which the THW technique is applied showed flexural behavior with high ductility involving the tension yielding of all longitudinal bars in the existing RC column, and the calculated results of proposed equations are in good agreement with the test results. (2) The application of the THW technique not only creates a connection between the RC column and additional wing-wall, but also increases the shear resistance greatly. (3) In the unbonded specimens, the compression zone of the RC column for the arch mechanism was greater than 0.5D, and the zone was distributed from 0.8D to 1.0D. (4) Based on the test results and observations, an equation was proposed to evaluate the shear strength in the case of the THW technique following the proposed concept of the shear resistance (arch) mechanism with a nonuniform section of compression strut. The calculated results of the proposed equation are in good agreement with the test results showing shear failure mode.</p>

著者

土屋 駿介 田守 伸一郎

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.79, no.697, pp.375-384, 2014-03-30 (Released:2014-07-10)

参考文献数

13

被引用文献数

4

---

This paper proposes a optimal design method of base-isolation device and frame member in a reinforced concrete building. The proposed algorithm called DCMOGA( Distributed Cooperation model of MOGA(Multi Objective Genetic Algorithm) and SGA (Standard Genetic Algorithm) ) and conventional multi objective optimization are applied to design two buildings. Finally, a comparison was made among design solutions. Comparing to the conventional multi objective optimization methods , the proposed model found the widespread Pareto solutions. Consequently, the effectiveness of the proposed model was demonstrated.

著者

木村 衛 楠 寿博 太田 道彦

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.61, no.480, pp.133-140, 1996-02-28 (Released:2017-01-31)

参考文献数

17

被引用文献数

1 1

---

Glulam specimens with a large section were tested to find the effect of the processing accuracy of joints on the strength of bonded joints experimentally, furthermore bending tests were carried out with the full scale glulam specimens in order to investigate the bending strength of bonded joints. As a result, the following conclusions were obtained. Bending strength of the bonded joint is substantially subject to the processing accuracy of the joint part, and full strength connection of glulam with a large section will be feasible by big finger joint or scarf joint made under sufficient accuracy control.

著者

平野 修也 山田 義智 西 祐宜 崎原 康平

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.85, no.774, pp.993-1003, 2020

被引用文献数

4

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<p> In order to conduct flow analysis of cement-based material such as cement paste, mortar and concrete, it is important to more accurately obtain the rheological constants representing the flow characteristics of the material. In this study, the rheological constants of mortar were measured by two rheology tests. The first was sphere pull-up test, the second was the measurement by using rotational vane viscometer. According to previous studies, the former was able to measure the rheological constants of high fluidity mortar, and the latter was able to evaluate the shear stress characteristics of cement-based material containing fine aggregate and coarse aggregate. Furthermore, in this study, the flow constitutive equation of mortar was derived and Moving Particle Semi-implicit (MPS) method was proposed. Using this MPS method, flow simulation of mini slump flow test was attempted.</p><p> The results obtained from the experimental study and analytical study in this paper can be summarized as follows.</p><p> Throughout the sphere pull-up test, the rheological constants (yield value and plastic viscosity) of mortar which was the same mix proportion as mini slump tested mortar were measured. In the test results, the larger mini slump flow value was, the lower yield value was, and the relationship between the two values was able to be approximated by an exponential curve. On the other hand, plastic viscosity and arrival time at mini slump flow of 115mm had positive correlation, and the relationship between the two values was able to be approximated by a linear function.</p><p> Using a rotational vane viscometer, the flow curve of mortar was measured for various shear conditions. It was confirmed that the flow curves of all mortar samples were able to be approximated by the Bingham model under all shear conditions. And the obtained flow curve was approximated by the Bingham model, and the rheological constants of all mortar sample was determined. Thixotropy was confirmed in the flow characteristics of the mortar sample from the obtained flow curves. Also, contrary to the general tendency, the larger mini slump flow value was, the higher plastic viscosity was for water cement ratio of 30%. It was suggested that the rheological constants measured by rotating vane blade were affected by amplified apparent viscosity of mortar. As a result, the sphere pull-up test was more appropriate for the evaluation of rheological properties of mini slump flows.</p><p> Applying the polygon model to the wall boundary as boundary condition of MPS method, a phenomenon that mini slump flow was shielded by mini slump cone was expressed on the flow analysis. Adopting the rheological constants obtained by the sphere pull-up test, it was attempted that mini slump flow spread of mortar sample was reproduced by MPS analysis. The results obtained by the analysis agreed well with the experimental results of mini slump flow. Moreover, in terms of mini slump shape, the analysis by MPS method largely reproduced the actual measured shape. Furthermore, following the analysis condition used in mini slump flow analysis, mortar flow spread with slump cone was predicted by MPS analysis. The results obtained by the analysis reproduced the actual measured value of slump flow. Therefore, the analysis by MPS method and the rheological constants obtained by the sphere pull-up test are effective in mortar flow spread.</p>

著者

伊東 敏幸 苫米地 司 三橋 博三

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.60, no.475, pp.9-16, 1995

被引用文献数

8 1

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We carried out experimental research to clarify the effects of different construction method on snow-sliding properties of sheet-metal roofe. In this experiment, the construction methods of roofing adopted were flat plate, standing-seam roofing, corrugated roofing, flat-seam roofing, diagonal roofing and stepped roofing. Experimental results clarified that the snow-sliding velocity of sheet-metal roofing is greatly influenced by the type of construction method. The sliding velocity of the flat-seam roofing or stepped roofing tends to be greater than that of standing-seam roofing or corrugated roofing. Furthermore, in roofs utilizing the same construction method, the snow-sliding velocity is affected by joint details. It was also confirmed that the interval and form of joints, e.g., flat lock seam and steps joint, influence the snow-sliding direction.

著者

中村 友紀子 壁谷澤 寿海

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.65, no.532, pp.51-56, 2000-06-30 (Released:2017-02-03)

参考文献数

13

被引用文献数

3 3

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Expected value of time-history response can be formulated by assuming the phase differences spectrum in Fourier transform of earthquake waves as a normal probability curve. The effect of damping on the response spectrum can be obtained based on the formula. The ratio of maximum displacement to previous peak displacement during nonlinear response can also be calculated theoretically, which may be used for estimation. Both theoretical values were compared with those calculated from the responses to earthquake motions, from which a fair correlation was observed, especially in relation to the duration of earthquake motions.

著者

山田 義智 上原 義己 崎原 康平 浦野 真次

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.85, no.771, pp.663-672, 2020

被引用文献数

5

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<p> Concrete flow analysis is important, because it is possible to visualize how high fluidity concrete flows in the concrete placing form and in the gap between reinforcing bars.</p><p> In this study, MPS (Moving Particle Semi-implicit) method was used as a concrete flow analysis method. First, the flow of Bingham fluid between parallel plates was analyzed, and the validity of the analysis method was verified. Furthermore, the effectiveness of the proposed method was confirmed by comparing the results of slump flow analysis and test results. The research results of Kokado et al.³⁾ were used for the rheological constants (yield value, plastic viscosity) of concrete used for slump flow analysis.</p><p> The results obtained in this study can be summarized as follows.</p><p> The flow of Bingham fluid between parallel plates was reproduced using the proposed MPS analysis. As the result, when the particle size was 20 mm, it was different from the theoretical value, and when the particle size was 10 mm, 5 mm, 2.5 mm, it agreed with the theoretical value.</p><p> The flow of Bingham fluid between parallel plates was reproduced by changing the value of the stress growth index m of the regularized Bingham model with m = 1 and 10,100. As a result, the theoretical value agreed well with the MPS analysis result in the fast range of flow velocity. In the range of slow flow, the MPS analysis results at the stress growth index m = 1 were faster than the theoretical solutions at the center of the parallel plate. Therefore, in order to represent the Bingham fluid, it is necessary to increase the value of the stress growth index m. In this study, the stress growth index m was set to 100 and used for MPS analysis.</p><p> The slump flow test was reproduced by MPS analysis using a regularized Bingham model with a particle size of 5 mm and a stress growth index of m = 100, assuming that the high fluidity concrete was a Bingham fluid. As the result, it was well reproduced in the range of slump flow value of about 500 mm, however, it tended to flow in the experimental result as the slump flow value increased from 600 mm to 700 mm.</p><p> When the slump flow value is less than 600 mm, the spread curve of the flow can be reproduced within the range of the rheological constant within the 95% upper and lower limit prediction interval. However, at the slump flow value of 700 mm, the experimental value flows more than the analytical result using the yield value of 95% lower limit. According to the results of the finite difference analysis in the literature (4), at a slump flow value of over 600 mm, the measured value tends to flow more than the analytical result. Therefore, if the slump flow value exceeds 600 mm, the yield value by the lifting sphere viscometer test may have been evaluated higher. Furthermore, high fluidity concrete with a slump flow value exceeding 600 mm may exhibit non-Bingham properties in the low shear rate region.</p>

著者

石井 建 菊地 優 北村 佳久 仲村 崇仁

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.75, no.647, pp.87-93, 2010-01

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This paper presents a new analytical model for predicting the behavior of elastomeric seismic isolation bearings subject to combined eccentric bending moments and shear deformation. The mechanical model consists of a series of axial springs at the top, mid-height and bottom of the isolator. The model can account for end rotations of the isolator, and the overall isolator rotational stiffness can include the influence of the variation of vertical load on the isolator and the imposed shear deformation. To identify the mechanical characteristics of isolators, static bending tests under various combinations of vertical load and shear deformation were performed. The results of analyses using the new model show very good agreement with experimental observations.

著者

中田 幸造 山川 哲雄 JAVADI Pasha NOORI Mohammad Zahid 金田 一男

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.85, no.767, pp.97-104, 2020

被引用文献数

2

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<p> A strength–ductility–type seismic retrofit technique for soft first-story reinforced concrete (RC) buildings via addition of wing walls or panel walls was proposed by Yamakawa⁴⁾. This method is called the thick hybrid wall (THW) technique and is performed by jacketing an RC column and an additional wing wall using channel-shaped steel plates connected together by high-strength steel bars (PC bars). The steel plates and PC bars make steel formworks inside the RC frames during the additional concrete casting. Furthermore, they can serve for shear strengthening and confinement of RC columns after hardening of additional concrete. No longitudinal and transverse reinforcements or anchorage systems are provided in the additional wing wall; therefore, the construction is easy and cost-effective. The previous investigation⁶⁾ of the one-bay one-story RC frame retrofitted by the THW technique verified that both lateral strength and ductility are considerably improved compared to those of the non-retrofitted RC frame. This study aims to propose equations that can be used to estimate the ultimate moment resistance and the minimum wing-wall length of RC columns retrofitted by the THW technique.</p><p> The ultimate moment resistance of the RC column with a wing wall (THW technique) is calculated by considering the whole section as a united section. In the proposed method, the strain distribution of the THW column section is divided into three fields, such as field A, B, and C, based on the location of the neutral axis changes according to the axial force levels. The unified THW column section is asymmetric about the centerline of the square column section; hence, the wall side is considered in compression only. The moment capacity equation is derived by considering the equilibrium of internal tension and compression forces with the external vertical axial load. Assuming the location of the neutral axis depth, a generalized equation is obtained based on the equivalent rectangular stress block parameters for concrete in compression that is adopted by the American Concrete Institution (ACI). Practically, the THW technique is applied in the field A, where all the rebars in the tension and compression sides of the existing RC column yield in tension, and the limit axial force ratio of the field A is represented as <i>η</i>₁.</p><p> The ultimate moment resistance of the THW column section is more accurately calculated by the fiber model method. The stress-strain model of concrete in the fiber model analysis is considered as Monder's model¹¹⁾. In Section 4, the calculated results of the proposed equation, fiber model analysis, and simplified equations⁸⁾ are in good agreement with the previous test results of both-sided (R03WC-P200S)⁴⁾ and one-sided wing-wall (R03WO-S)⁵⁾ specimens retrofitted by the THW technique.</p><p> The equation used to calculate the minimum wing-wall length of the THW technique is proposed in Section 5 based on the limit axial force ratio (<i>η</i>₁) in the field A. The calculated results based on the minimum wing-wall length equation show that the additional wing-wall length ratio <i>β</i> increases with increasing the axial force ratio <i>η</i>. Furthermore, <i>β</i> decreases with increasing the ratio of the compressive strength of concrete <i>κ</i> and depends on the tensile rebar ratio <i>q</i>.</p>