Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Toshiaki Sato Last modified date:2019.05.29

Associate Professor / Structural Engineering and Disaster Mitigation Section / Department of Architecture and Urban Design / Faculty of Human-Environment Studies


Presentations
1. 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..
2. 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..
3. 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..
4. 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. .
5. 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..
6. 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..
7. 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..