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Hiroaki Kubotera, Toshiaki Sato, Yohei Aioi,Kazuo Niikuma, Development of Temporary Structure Using CLT Panel -Invention of Construction and Verification by Construction Experiment-, 2023 World Conference on Timber Engineering, WCTE 2023, 2023.06, Temporary buildings have the advantage of being able to meet sudden demand. In recent years, the demand has been affected not only in the event of a disaster but also due to COVID-19 infection. This paper shows a temporary structure that can be used repeatedly for the purpose of constructing a temporary building using Cross Laminated Timber (CLT), and confirmed its practicality through construction experiments.. |
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Toshiaki Sato, Yasuhiro Nambu, Yuji Miyazu and Masayuki Nagano, Seismic Performance Evaluation of Reinforced Wooden Temple Based on Long Term Earthquake Observations, 2023 World Conference on Timber Engineering, WCTE 2023, 2023.06, The seismic performance of structures is known to change over time, and the causes are affected by the surrounding environment such as temperature and humidity as well as damage caused by disturbances such as earthquakes. In terms of structure, seismic performance has been evaluated based on the construction age, mainly the transition of related laws and regulations, but the seismic performance changes over time, considering the material properties that swell and shrink sensitively due to temperature and humidity. the purpose of this study is to quantitatively evaluate the effects of various influential factors using earthquake observation records which are measured over a long period of time at the main hall of wooden temple. The subspace method was applied to the observation record of target temple, and the transition of the natural frequency due to aging was verified as the environment was changed. As a result of the investigation, the natural frequency changed as the temperature up and down, suggesting the effect of swell and shrink of the joint. Further, in the deformation range about less 3 mm, the variation in the natural frequency may have the same effect as the nonlinearity due to the large and small response.. |
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Toshiaki Sato, Recent research for constructing middle-rise wooden building - joint development using GIR technology and related basic research -, The 4th Japan-Taiwan International Engineering Forum, 2023.03, Recently the applicability of timber structure has been expanded, and we also try to support these activities in the research field. One of the important features of timber structure is not able to make a rigid frame, because the flexibility of wood is affected. However, high stiffness joint is necessary to construct middle-rise or more high-rise building, and we need to develop it. This presentation shows the joint which currently being developed. The joint is developed with the goal of ensuring high rigidity by using Glued In Rod (GIR) Technology. Furthermore this presentation also shows the related research, which is the basic research for evaluating the characteristics of GIR components, such as the boundary condition between glue and steal, mechanical property of glue, and friction of wood surface.. |
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Yasuhiro Nambu, Hiroki Tabata, Toshiaki Sato and Toshihiko Ninakawa, Vibration Investigation and Eigenvalue Analysis of The Traditional Wooden House with Thatched Roof in Japan, 17th World Conference on Earthquake Engineering, WCEE, 2021.10. |
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Ryota Tobari, Masato Ishii, Toshiaki Sato, Haruyuki Kitamura, Keisuke Yoshie, Mitsuru Miyazaki, Kazuhiko Sasaki and Yuichi Iwasaki, Proposal for Response Control Structure using Viscous Wall Dampers with Deformation Amplification Mechanism, 17th World Conference on Earthquake Engineering, WCEE, 2021.10. |
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Toyohide Yamauchi, Haruyuki Kitamura, Masayuki Nagano, Toshiaki Sato, Kento Suzuki, Yoriyuki Matsuda and Yoshinori Tobita, Dynamic Characteristics of Pile Top Seismic Isolation Buildings Considering Variable Axial Load, 17th World Conference on Earthquake Engineering, WCEE, 2021.10. |
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Ryo Inoue, Takuro Mori, Kotaro Sumida, Hiroshi Isoda, Kei Tanaka and Toshiaki Sato, Status of Wooden Houses in Mashiki Town Two Years after The 2016 Kumamoto Earthquakes, 17th World Conference on Earthquake Engineering, WCEE, 2021.10. |
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Kaori Fujita, Jiro Kajihama, Kanto Minamitani, Yoshihiro Fukushima, Toshiaki Sato, Masahiro Watabe, Hiromi Sato, Masao Koizumi and Tsuyoshi Seike, Seismic Reinforcement of Existing Timber Architecture Using Permeable Structural Wall -Result of Horizontal Loading Test of Timber and Polycarbonate Resin-, 2021 World Conference on Timber Engineering, WCTE 2021, 2021.08, This paper aims to evaluate seismic performance of wooden houses with friction dampers through full-scale shaking table tests of two-story wooden frames. First, we conduct cyclic loading tests of a friction damper and some wooden walls used in the shaking table test, and make their analytical models to use in time-history response analyses. Next, we conduct the full-scale shaking table test of the two-story wooden frames with/without friction dampers. It is found that the friction damper is effective to reduce the story drift under strong seismic ground motions, and the seismic responses obtained by the time-history analyses agree well with those obtained by the shaking table tests.. |
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Yuji Miyazu, Masayuki Nagano, Toshiaki Sato, Michio Iguchi, Tadashi Mikoshiba, Takahiko Katada and Kazumasa Sugawara, Evaluation of seismic performance of wooden houses with friction dampers by full-scale shaking table tests, 2021 World Conference on Timber Engineering, WCTE 2021, 2021.08, This paper aims to evaluate seismic performance of wooden houses with friction dampers through fullscale shaking table tests of two-story wooden frames. First, we conduct cyclic loading tests of a friction damper and some wooden walls used in the shaking table test, and make their analytical models to use in time-history response analyses. Next, we conduct the full-scale shaking table test of the two-story wooden frames with/without friction dampers. It is found that the friction damper is effective to reduce the story drift under strong seismic ground motions, and the seismic responses obtained by the time-history analyses agree well with those obtained by the shaking table tests.. |
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Kohta Kawashima, Kaori Fujita, Hiromi Sato, Masahiro Watabe, Toshiaki Sato, Tsuyoshi Seike, and Masao Koizumi, Seismic reinforcement of existing timber architecture using permeable structural wall part 2 Modeling and result of analysis of timber-acrylic wall, 12th ISAIA, 2018.10, Seismic reinforcement of existing buildings have been strongly promoted in Japan since the hazardous damage by the 1995 Kobe Earthquake. This paper introduce the results of the reinforcement of existing timber structures which the authors have been conducting since 2003.
This paper follows “Seismic reinforcement of existing timber architecture using permeable structural wall, Part 1 Outline of Research” by the authors. In Part2, the results of the experiments on the proposed reinforcement wall consisting of timber lattice and acrylic membrane is discussed in detail. The structural elements of the proposed permeable wall are: acrylic membrane, shear strength of screw nail connection between acrylic and timber lattice, timber lattice, and shear strength of nail joint between timber lattice and timber post/beam. The results of the element tests and FEM analysis based on element tests are discussed in comparison with those of the static lateral loading test of the reinforcement wall. The distribution of the strength between the hybrid members are revealed, and the methodology to construct an effective analytical model is proposed.. |
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Kaori Fujita, Kohta Kawashima, Hiromi Sato, Masahiro Watabe, Toshiaki Sato, Tsuyoshi Seike, and Masao Koizumi, Seismic reinforcement of existing timber architecture using permeable structural wall part 1 outline of research, 12th ISAIA, 2018.10, Seismic reinforcement of existing buildings have been strongly promoted in Japan since the hazardous damage by the 1995 Kobe Earthquake. This paper introduce the results of the reinforcement of existing timber structures which the authors have been conducting since 2003. In the preceding research, on-site investigation, questionnaire to the residents, microtremor measurement, and seismic diagnosis on thirteen existing timber houses were operated. Based on these results reinforcement device: permeable structural walls, to reinforce the opening was proposed and the validity was evaluated by applying the device for structural strengthening repair work on existing timber architecture (Fujita et.al. 2007).
In this paper the outline of the research including the above mentioned background, the structural characteristic of the proposed permeable structural wall consisting of timber lattice and acrylic membrane is introduced. The results of horizontal loading test of the wall is introduced together with the results of element tests. The structural performance of the proposed wall is discussed together with the validity of its application.. |
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Makoto Tanoue, Toshiaki Sato, Akane Taguchi, Toshihiko Ninakawa, Experimental study on bending performance of two layers glued build-up member made of cedar, 2018 World Conference on Timber Engineering, WCTE 2018, 2018.01, Glued build-up members (GBMs) are structural building members that are developed as an application to effectively utilize Japanese domestic box-heart timber. The purpose of this study is to establish a method to evaluate the bending performance of a GBM. In this study, we describe the results of a full-scale bending test of the GBM specimen to characterize its bending performance. Further, a structural model to evaluate the experimental results has been proposed and validated. The results exhibit that the evaluation that considers a GBM as a uniform elastic body is almost as effective as the simple method. In addition, the results obtained on the GBM cross-section model, which accounts for the differences between the elastic bending moduli of different pieces of the timber, are compared with those obtained using the uniform member cross-section model. The data reveal that the experimental results can be evaluated more accurately using the proposed GBM cross-section model than with the uniform member cross-section model.. |
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Toyohide Yamauchi, Haruyuki Kitamura, Masayuki Nagano, Toshiaki Sato, Kento Suzuki, Dyanamic characteristics of buildings constructed by pile top seismic isolation system considering nonlinearity of laminated rubber bearing, World Conference on Earthquake Engineering, 2017.01, A pile top seismic isolation system is used for constructing base-isolated buildings. In this system, seismic isolators are set on the pile’s top directly, and piles are connected with thin foundation girders or a mat slab. In recent years, many logistics centers in Japan have been constructed using this system because it enables significant cost reductions in underground construction. However, this system does have some problems. For example, the laminated rubber bearing’s bottom part easily undergoes bending rotation because the thin foundation girders have low stiffness. This tendency becomes more pronounced in the case of soft ground. If bending rotation occurs, the laminated rubber bearing’s horizontal stiffness reduces under the influence of the horizontal component of the axial load, and its inflection point moves downward from the center height of the device (usually, the point does not move). This, in turn, significantly affects the structural characteristics of the pile top seismic isolation building. In addition, it has been noted that the horizontal stiffness and rotational stiffness of the laminated rubber bearing show deformation-dependent nonlinearity. . |
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Takenori Hida, Toshiaki Sato, Masayuki Nagano, Study on structural health monitoring method by recursive subspace identification based on shaking table tests of wooden structure, World Conference on Earthquake Engineering, 2017.01, The Structural Hearth Monitoring (SHM) methods attracting attention again since the 2011 off the Pacific Coast of Tohoku Earthquake occurred in Japan. There are a great number of studies those investigating the seismic safety of structures based on system identification approach. Therefore, the diagnostic accuracy of these approach was not investigated enough. Thus, the system identification accuracy must be validated to consolidate the methodology of SHM. For this purpose, the SHM methods based on the Recursive Subspace State Space System IDentification (4SID) and non-recursive 4SID approach were applied to the data which observed from full-scaled shaking table tests on wooden post and beam structure. Thereby, the temporal variation of natural frequencies, damping factor and story stiffness of the specimens were evaluated by each approaches. Then, the difference of identification accuracy between recursive and non-recursive 4SID was investigated. As a result, it is clarified that the recursive 4SID approach is suitable for structural health monitoring when a structure shows highly non-linear behavior during an earthquake.. |
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Masayuki Komiyama, Toshiaki Sato, Toichiro Watanabe, Takenori Hida, Kento Suzuki, Yuichi Masaki, Michio Iguchi, Masayuki Nagano, Experimental Study on Structural Response of Two Story Houses Focusing On Dynamic Characteristics of Each Story, World Conference on Timber Engineering, 2016.08, Specimen is a two story wooden house which has equivalent aseismic performance on the structural calculation about 1st and 2nd layer. When seismic waves were input in a shaking table, response of this building was concentrated to 2nd layer, though each layer has equivalent aseismic performance. This phenomenon is examined from proof stress based on skeleton curve and changes in vibration mode, in this report.. |
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Ryoma Tanaka, Toichiro Watanabe, Toshiaki Sato, Kento Suzuki, Masayuki Nagano, Fundamental Study on Simple Compression Test and Stress Relaxation Characteristics of Wood, World Conference on Timber Engineering, 2016.08, In recent years, as the service lives of timber structures have increased, there has arisen a need for better comprehension of how the seismic performance of such structures can be changed via wood stress relaxation. Herein, the authors report on their study of wood-bolted joints, and describe the effects of imposition time on wood stress relaxation. More specifically, imposition times of 1, 3, 5, and 10 s. were set and imposed via a precision universal / tensile tester (PUTT), after which 100 s simple stress relaxation tests were conducted. The results were then compared to wood-bolted stress relaxation tests previously conducted by the authors. The results suggest that the wood stress relaxation is only slightly affected by imposition speeds and that wood-bolted joint stress relaxation can be reproduced via simple stress relaxation testing.. |
