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Sawata Kei

Research Faculty of Agriculture　Fundamental AgriScience Research　Forest ScienceAssociate Professor
Institute for Academic InnovationAssociate Professor

Researcher basic information

■ Degree
  • Dr
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Keyword
  • 最大耐力
  • 荷重-たわみ関係
  • 最大荷重
  • 初期剛性
  • 柱脚接合部
  • 筋違い耐力壁
  • 耐力壁
  • 土台
  • 腐朽
  • 接合具
  • ボルト接合部
  • 劣化測定
  • 構造性能
  • 荷重-変形角関係
  • 平行弦トラス梁
  • 平行弦トラス
  • 緑化木
  • 風害
  • 断面係数
  • 低サイクル曲げ疲労破壊
  • 幹折れ
  • 振動台実験
  • 調和振動
  • ホワイトノイズ
  • 野外試験
  • 周波数特性
  • 抗力係数
  • 釘1面せん断接合
  • 根返り
  • 木材
Research Field
  • Life Science, Wood science
  • Life Science, Forest science
■ Educational Organization

Career

■ Career
Career
  • Jan. 2022 - Present
    Research Faculty of Agriculture, Hokkaido University, Associate Professor, Japan
  • Jul. 2015 - Dec. 2021
    Hokkaido University, Graduate School of Agriculture Research Faculty of Agriculture, 講師
  • Apr. 2007 - Jun. 2015
    北海道大学 大学院・農学研究院, 助教
  • Apr. 2003 - Mar. 2007
    Institute of Wood Technology, Akita Prefectural University, Post Doctoral Fellow

Research activity information

■ Awards
  • 2009, 日本木材学会, 第2回日本木材学会論文賞
    澤田圭
  • 2007, 日本木材学会, 第18回日本木材学会奨励賞
    澤田圭
■ Papers
  • JOINT PERFORMANCE OF BEAM USING LONGITUDINAL DRIFT PINNED JOINT
    Masatake NAGATA; Kei SAWATA; Takanobu SASAKI; Ryuya TAKANASHI
    Japanese Journal of JSCE, 82, 28, Japan Society of Civil Engineers, 2026, [Peer-reviewed]
    Japanese, Scientific journal
  • STUDY ON STIFFNESS AND STRENGTH OF DRIFT-PINNED TIMBER JOINTS WITH SLOTTED-IN TWO STEEL PLATES
    Ryosuke TOMITAKA; Kei SAWATA
    Journal of Structural and Construction Engineering (Transactions of AIJ), 90, 832, 735, 746, Architectural Institute of Japan, 01 Jun. 2025, [Peer-reviewed]
    Japanese, Scientific journal
  • EVALUATION FOR ULTIMATE STRENGTH FOR STEEL-PLATE-INSERTED JOINT WITH DRIFT-PINS AT THE END OF GLULAM BEAMS
    Wataru Kambe; Atsuo Takino; Kento Suzuki; Yo Ochiai; Shoichi Nakashima; Shigefumi Okamoto; Kenji Kobayashi; Kei Sawata; Keita Ogawa; Kei Tanaka
    World Conference on Timber Engineering 2025, 4936, 4943, World Conference On Timber Engineering 2025, 2025
    International conference proceedings
  • A DISCUSSION OF EVALUATION METHODS FOR SPLITTING AND SHEAR FAILURE BY CURRENT STANDARD EQUATIONS FOR DRIFT-PINED JOINT WITH INSERTED PLATE AT THE END OF GLULAM-BEAM
    Wataru KAMBE; Kento SUZUKI; Yo OCHIAI; Atsuo TAKINO; Shigefumi OKAMOTO; Kenji KOBAYASHI; Kei SAWATA; Shoichi NAKASHIMA; Keita OGAWA; Kei TANAKA
    Journal of Structural and Construction Engineering (Transactions of AIJ), 90, 827, 94, 103, Architectural Institute of Japan, 01 Jan. 2025, [Peer-reviewed]
    Japanese, Scientific journal
  • MEASUREMENT OF YOUNG’S MODULUS AND SHEAR MODULUS OF PLYWOOD BY FLEXURAL VIBRATION TEST AND INFLUENCE OF SPECIMEN SHAPE
    Tomoyuki OGAWA; Takanobu SASAKI; Ryuya TAKANASHI; Kei SAWATA
    Japanese Journal of JSCE, 81, 4, n/a, n/a, Japan Society of Civil Engineers, 2025
    Scientific journal
  • Regional variation in branch morphological and physical traits in Abies sachalinensis associated with winter climatic conditions
    Tetsuto Sugai; Keiko Kitamura; Kei Sawata; Yoshihisa Sasaki; Wataru Ishizuka
    Journal of Forest Research, 29, 6, 425, 431, Informa UK Limited, 16 Jul. 2024, [Peer-reviewed]
    English, Scientific journal
  • 真空プレスを用いたCLT製造の検討
    Saya HATANO; Takanobu SASAKI; Kei SAWATA; Junko MIYAZAKI; Kamii NAKAMURA; Ryuya TAKANASHI; Hidefumi YAMAUCHI
    Japanese Journal of JSCE, 80, 28, n/a, n/a, Japan Society of Civil Engineers, 2024
    Scientific journal
  • Out-of-plane shear strength of cross-laminated timber made of Japanese Larch (Larix kaempferi) with various layups and spans
    Yasuhiro Kawaai; Ryuya Takanashi; Wataru Ishihara; Yoshinori Ohashi; Kei Sawata; Takanobu Sasaki
    Journal of Wood Science, 69, 1, Springer Science and Business Media LLC, 19 Sep. 2023, [Peer-reviewed]
    Scientific journal, Abstract

    Cross-laminated timber (CLT) is a promising construction material. When CLT is used for horizontal applications, shear stress occurs in the out-of-plane direction and can fracture the transverse layers owing to the rolling shear. The out-of-plane shear strength of the CLT can be evaluated by an out-of-plane loading test and is affected by the CLT layups and/or span conditions. In this study, we conducted out-of-plane loading tests on 3-layer 4-ply, 5-layer 7-ply, 7-layer 7-ply, and 9-layer 9-ply CLT made of Japanese larch (Larix kaempferi) under various spans and investigated the effect of layups and spans on the out-of-shear strength. The fracture modes of the specimens were classified into three types: shear fracture, shear fracture accompanied by bending fracture, and bending fracture. The out-of-plane shear strength of the specimens except for the 9-layer 9-ply ones decreased as the span increased, and then converged to a constant value (1.0–1.5 kN/mm2). In addition, the shear strength decreased exponentially as the number of laminae in the transverse layers increased and then converged to a constant value (1.0–1.5 kN/mm2). The out-of-plane shear strength of the 9-layer 9-ply specimens decreased as the shear span increased; however, the converged value with a longer span could not be calculated because the tests were conducted under only three-span conditions. The shear strength of 3-layer 4-ply specimens was lower than that of the other layups. The results of the Monte Carlo simulation of the shear strength of the laminae in the transverse layers showed that a model, which assumed that the minimum shear strength of the laminae in the transverse layers determined the shear strength of a specimen, tended to correspond with the decreasing tendency of shear strength with longer spans. The results showed that the weakest link model for the out-of-plane shear fracture of the CLT would relate to a specimen with long span.
  • カラマツラミナの幅厚さ比とローリングシアー強度の関係
    Yasuhiro Kawaai; Wataru Ishihara; Ryuya Takanashi; Yoshinori Ohashi; Kei Sawata; Takanobu Sasaki
    Mokuzai Gakkaishi, 69, 3, 134, 139, Japan Wood Society, 25 Jul. 2023, [Peer-reviewed]
    Scientific journal
  • Experimental Investigation on Bonded and Screwed Carbon Fiber-Reinforced Plastic Plates on Timber Column–Sill Joints
    Rintaro Ueda; Akio Sakamoto; Kei Sawata; Yoshihisa Sasaki; Takanobu Sasaki
    International Journal of Civil Engineering, 21, 8, 1305, 1314, Springer Science and Business Media LLC, 16 Apr. 2023, [Peer-reviewed], [Corresponding author]
    Scientific journal, Abstract

    In this study, timber column–sill joints strengthened with carbon fiber-reinforced plastic (CFRP) plates using bonds and screws were subjected to loading tests. Twelve joint specifications were considered depending on different combinations of the CFRP plate surface finish and thickness and the type of bond, and the corresponding effects on the load–displacement behavior of the joints were investigated. Three failure modes were observed in addition to the peeling of the CFRP plate. The specimens that failed owing to screw tear out and screw head pull-through in the CFRP plate or splitting of the sill showed load–displacement curves of a similar shape. Those that failed owing to buckling of the CFRP plate showed a rapid and substantial load decrease due to failure. This failure mode was only observed in 0.50 mm thick CFRP plate specimens. When a peel-ply CFRP plate was installed in the column–sill joint specimens, similar secant stiffnesses were observed in the silicon and epoxy resin-bonded specimens, both with high shear strength. Although the specimens with bonds with a high shear strength showed lower deformation performance, the specimens' maximum load increased with the bond's shear strength. The maximum load improved for a 0.75 mm thick peel-ply silicon- or epoxy-bonded CFRP plate. The load's maximum value after peeling the CFRP plate was 0.79–1.23 times as large as the maximum load of the no-bond specimens and did not change significantly.
  • A STUDY ON THE FAILURE BEHAVIOR OF LARGE DIMENSIONAL GLULAM BEAM-END JOINT BY DRIFT-PINED JOINT WITH INSERTED STEEL PLATE In case of the circular and rectangular arrangement of drift-pin
    Kento SUZUKI; Wataru KAMBE; Yo OCHIAI; Shigefumi OKAMOTO; Kenji KOBAYASHI; Kei SAWATA; Atsuo TAKINO; Shoichi NAKASHIMA
    Journal of Structural Engineering B, 69B, 85, 98, Architectural Institute of Japan, Apr. 2023, [Peer-reviewed]
    Japanese, Scientific journal
  • Shear Strength of CLT with Japanese Larch or Sakhalin Fir Exposed to Low Humidity Environments
    Wataru Ishihara; Ryuya Takanashi; Yasuhiro Kawaai; Yoshinori Ohashi; Takanobu Sasaki; Kei Sawata
    Mokuzai Gakkaishi, 68, 4, 154, 164, Japan Wood Society, 25 Oct. 2022, [Peer-reviewed]
    Japanese, Scientific journal
  • Evaluation of Out-of-plane Shear Strength of CLT made from Japanese Larch
    Yasuhiro Kawaai; Ryuya Takanashi; Kei Sawata; Yoshihisa Sasaki; Takanobu Sasaki
    Mokuzai Gakkaishi, 68, 4, 179, 187, Japan Wood Society, 25 Oct. 2022, [Peer-reviewed]
    Japanese, Scientific journal
  • Elastoplastic performance of wood under compression load considering cross-grain orientation and moisture content
    Wei-Lian Fu; Hui-Yuan Guan; Wei Li; Kei Sawata; Yao Zhao
    European Journal of Wood and Wood Products, 81, 1, 111, 124, Springer Science and Business Media LLC, 16 Sep. 2022, [Peer-reviewed]
    English, Scientific journal
  • Effects of decay on the shear properties of nailed joints parallel and perpendicular to the grain
    Rintaro Ueda; Kei Sawata; Takanobu Sasaki; Yoshihisa Sasaki
    Journal of Wood Science, 67, 1, Springer Science and Business Media LLC, 15 Dec. 2021, [Peer-reviewed]
    Scientific journal, Abstract

    Information on the properties of nailed joints with decayed member is necessary to evaluate the remaining structural properties of timber constructions. In this study, loading tests were conducted on nailed joints parallel and perpendicular to the grain with decayed members, and the relationship between the decrease in shear properties and the loading direction to the grain was investigated. After the loading tests, the extent of decay of the specimens was evaluated by the penetration depth of Pilodyn and the decay depth, and these were compared with the shear properties of the nailed joints. The nailed joints with decay had a low load at the initial deformation, regardless of the loading direction to the grain. The initial stiffness, yield resistance, and maximum resistance of the nailed joints parallel to the grain were negatively correlated with the Pilodyn penetration depth, and those of the nailed joints perpendicular to the grain showed no significant correlation with the Pilodyn penetration depth at the 5% level. The initial stiffness, yield resistance, and maximum resistance of the nailed joints parallel to the grain tended to decrease with increasing decay depth, and those of the nailed joints perpendicular to the grain did not exhibit this tendency. The shear properties of the nailed joints significantly decreased at small decay depths.
  • BENDING STRENGTH OF HYBRID COMPOSITE BEAM OF TIMBER AND CARBON FIBER REINFORCED PLASTIC SHEET
    SHIMOKAWA Ryota; SASAKI Takanobu; SAWATA Kei; SASAKI Yoshihisa; UEDA Rintaro
    Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 77, 5, I_14, I_21, Japan Society of Civil Engineers, 2021
    Japanese, Nowadays, construction of buildings with wood structure is gaining momentum since the Diet introduced a policy to promote the use of wood for public buildings in 2010, and the demand for long wooden beams with a large cross section is increasing. In this study, we tested hybrid composite beams made up of square timbers of Sakhalin fir that were put together with laterally glued CFRP sheets and their bending performance was evaluated. A series of bending tests on hybrid composite beams is reported, of which the test parameters are arrangement of CFRP sheets, presence of butt joint of composing timbers, and that of lateral adhesion between timbers. For the type in which the CFRP sheet was arranged vertically in the cross section of the beams, absence of lateral adhesion between timbers did not lower the bending strength. The type in which two CFRP sheets were arranged vertically in the cross section and externally glued on the tension side of the beams and composing timbers had butt joints exhibited 95% higher bending strength than that without CFRP sheets. These results exhibited potential of hybrid composite beam of timber and CFRP sheet on the production of wooden beams with a large cross section for lengthening of products and labor saving.
  • Degradation of shear performance of screwed joints caused by wood decay
    Rintaro Ueda; Kei Sawata; Ryuya Takanashi; Yoshihisa Sasaki; Takanobu Sasaki
    Journal of Wood Science, 66, 1, Springer Science and Business Media LLC, Dec. 2020, [Peer-reviewed], [Corresponding author]
    Scientific journal, Abstract

    Shear tests were conducted on screwed joints with decayed main members, and the degradation of shear performance of screwed joints by wood decay was investigated. The differences between decayed and control specimens in yield load (Py), and maximum load (Pmax) were both significant at the 1% level, while the difference in the initial stiffness (Ks) was not significant at the 5% level. The extent of decay was evaluated through Pilodyn penetration depth and the decay depth. Pilodyn penetration depth had no significant relationships with Ks, Py, or Pmax of screwed joints. It is inferred that no significant relationship was found between Pilodyn penetration depth and the strength properties because the range of the measured Pilodyn penetration depth was narrow (16–23.5 mm). The decay depth had a significant inverse correlation with Ks of the decayed specimens. There was no significant relationship between the decay depth and Py, or Pmax. Multiple regression analysis was conducted on Ks, Py, and Pmax using the decay depth and sound wood density (WDh) as 2 explanatory variables. The multiple regression of Ks, Py, and Pmax on the decay depth and WDh were significant at the 1%, 5%, and 1% level, respectively. Ks, Py, and Pmax are inferred to be determined by both the decay depth and WDh. The strength properties of screwed joints with one screw obtained in this study were compared with those of screwed joints with seven screws obtained in a previous study. The difference between Ks, Py, and Pmax of the screwed joints with one screw and those of the screwed joints with seven screws was not significant at the 5% level. It is inferred that shear performance of screw joints with multiple screws are sufficiently estimated from those of screw joints with one screw by simply multiplying the strength properties, even if the main members were decayed.
  • Drying characteristics of log cross sections of Japanese cedar during hybrid kiln drying combined with dielectric heating
    Nam-Ho Lee; Noboru Fujimoto; Jinji Piao; Kei Sawata
    Drying Technology, 39, 7, 925, 931, Informa UK Limited, 02 Mar. 2020, [Peer-reviewed]
    English, Scientific journal
  • Correction to: Effect of decay on shear performance of dowel-type timber joints (Journal of Wood Science, (2008), 54, 5, (356-361), 10.1007/s10086-008-0963-7)
    Kei Sawata; Takanobu Sasaki; Shuichi Doi; Yasuo Iijima
    Journal of Wood Science, 64, 6, 882, Springer Tokyo, 01 Dec. 2018
    English, Scientific journal
  • Lateral strength of nailed timber connections with decay
    Kei Sawata; Yoshihisa Sasaki
    Journal of Wood Science, 64, 5, 601, 611, Oct. 2018, [Peer-reviewed]
    English
  • Withdrawal strength of nailed joints with decay degradation of wood and nail corrosion
    Ryuya Takanashi; Kei Sawata; Yoshihisa Sasaki; Akio Koizumi
    JOURNAL OF WOOD SCIENCE, 63, 2, 192, 198, Apr. 2017, [Peer-reviewed]
    English, Scientific journal
  • Fractography of shear failure surface of softwood decayed by brown-rot fungus
    Ryuya Takanashi; Wataru Ishihara; Kei Sawata; Yuzou Sano; Tomonori Azuma; Mitsunori Mori; Akio Koizumi; Yoshihisa Sasaki; Takuro Hirai
    JOURNAL OF WOOD SCIENCE, 60, 3, 186, 193, Jun. 2014, [Peer-reviewed]
    English, Scientific journal
  • Shear resistance and failure modes of nailed joints loaded perpendicular to the grain
    Kei Sawata; Yosuke Shigemoto; Takuro Hirai; Akio Koizumi; Yoshihisa Sasaki
    Journal of Wood Science, 59, 3, 255, 261, Jun. 2013, [Peer-reviewed]
    English, Scientific journal

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  • Dynamic responsive characteristics of nailed plywood-timber joints under harmonic vibrations
    Takuro Hirai; Takeyoshi Uematsu; Yoshihisa Sasaki; Masahiko Toda; Okumu Gordon Wanyama; Kei Sawata
    JOURNAL OF WOOD SCIENCE, 58, 5, 408, 416, Oct. 2012, [Peer-reviewed]
    English, Scientific journal
  • Effective lateral resistance of timber-plywood-timber joints connected with nails
    Okumu Gordon Wanyama; Kei Sawata; Takuro Hirai; Akio Koizumi; Yoshihisa Sasaki
    JOURNAL OF WOOD SCIENCE, 58, 4, 315, 321, Aug. 2012, [Peer-reviewed]
    English, Scientific journal
  • Dynamic response of wall-floor joints of wooden light-frame constructions under forced harmonic vibrations
    Takuro Hirai; Kei Sawata; Ali Awaludin; Yoshihisa Sasaki; Takeyoshi Uematsu
    JOURNAL OF WOOD SCIENCE, 58, 2, 128, 134, Apr. 2012, [Peer-reviewed]
    English, Scientific journal
  • Effective lateral resistance of combined timber joints with nails and bolts
    Okumu Gordon Wanyama; Kei Sawata; Takuro Hirai; Akio Koizumi; Yoshihisa Sasaki
    JOURNAL OF WOOD SCIENCE, 58, 1, 9, 19, Feb. 2012, [Peer-reviewed]
    English, Scientific journal
  • Bending resistance of repaired column members and shear resistance of opening frames with repaired columns of conventional Japanese wooden houses
    Kei Sawata; Masahiko Toda; Satoru Kanetaka; Yoshihisa Sasaki; Takuro Hirai
    JOURNAL OF WOOD SCIENCE, 57, 6, 536, 541, Dec. 2011, [Peer-reviewed]
    English, Scientific journal
  • Nondestructive measurement of cross-sectional shape of a tree trunk
    Akio Koizumi; Keisuke Ikeda; Kei Sawata; Takuro Hirai
    JOURNAL OF WOOD SCIENCE, 57, 4, 276, 281, Aug. 2011, [Peer-reviewed]
    English, Scientific journal
  • Evaluation of drag coefficients of poplar-tree crowns by a field test method
    Akio Koizumi; Jun-ichi Motoyama; Kei Sawata; Yoshihisa Sasaki; Takuro Hirai
    JOURNAL OF WOOD SCIENCE, 56, 3, 189, 193, Jun. 2010, [Peer-reviewed]
    English, Scientific journal
  • 枠組壁工法における壁－床接合部のせん断耐力に及ぼす摩擦力の影響
    孟慶軍; 平井卓郎; 澤田圭; 佐々木義久; 小泉章夫; 植松武是
    木材学会誌, 56, 1, 48, 54, 2010, [Peer-reviewed]
    Japanese, Scientific journal
  • Effect of Frictional Force on Lateral Resistance of Wall-Floor Joints of Wooden Light Frame Constructions
    Qingjun Meng; Takuro Hirai; Kei Sawata; Yoshihisa Sasaki; Akio Koizumi; Takeyoshi Uematsu
    MOKUZAI GAKKAISHI, 56, 1, 48, 54, 2010
    Japanese, Scientific journal
  • Effect of Member Thickness and Nail Length Projecting from Main Member on Shear Performance of Single Shear Nailed Joints
    Kei Sawata; Kosuke Honda; Takuro Hirai; Akio Koizumi; Yoshihisa Sasaki
    MOKUZAI GAKKAISHI, 56, 5, 317, 325, 2010
    Japanese, Scientific journal
  • Effect of decay on shear performance of dowel-type timber joints
    Kei Sawata; Takanobu Sasaki; Shuichi Doi; Yasuo Iijima
    JOURNAL OF WOOD SCIENCE, 54, 5, 356, 361, Oct. 2008, [Peer-reviewed]
    English, Scientific journal
  • Effect of wood decay on embedding performance of wood and shear performance of dowel-type joints and nailed joints
    Kei Sawata; Hiroshi Takiuchi; Masahiko Toda; Takanobu Sasaki; Mitsunori Mori
    10th World Conference on Timber Engineering 2008, 2, 1078, 1084, 2008
    English, International conference proceedings
  • Effects of density profile of MDF on stiffness and strength of nailed joints
    Kei Sawata; Tatsuya Shibusawa; Kazuo Ohashi; Javier Ramon Sotomayor Castellanos; Yasunori Hatano
    JOURNAL OF WOOD SCIENCE, 54, 1, 45, 53, Jan. 2008, [Peer-reviewed]
    English, Scientific journal
  • PREDICTION AND ITS VERIFICATION OF SHEAR FORCE-DEFORMATION RELATION AND BRACING UNIT MULTIPLIER FOR MUD WALLS BASED ON A PORTION -WALL TEST
    OKAMOTO Shigefumi; SAWATA Kei; MURAKAMI Masahide; SUZUKI Tamotsu; INAYAMA Masahiro
    Journal of structural and construction engineering. Transactions of AIJ, 0, 621, 103, 110, Architectural Institute of Japan, 30 Nov. 2007
    Japanese, A portion-wall test method is presented in this paper to predict the shear performance of Japanese traditional mud walls based on their lateral load carrying mechanism. It was already clarified through our recent research that this mechanism consisted of the four resistant structural components. The three kinds of portion-wall specimen, cut from the mud wall considering the carrying mechanism, were applied to predict the hysteretic envelope of shear force-deformation curve and also the bracing unit multiplier of the original mud wall. The predictions for the four different types of mud wall...
  • ESTIMATION OF STIFFNESS AND BEARING CAPACITY FOR MAD WALLS WITH OPENINGS BASED ON THEIR RESISTANCE MECHANISM
    SAWATA Kei; OKAMOTO Sigehumi; MURAKAMI Masahide; KAWANABE Aiko; SUZUKI Tamotsu
    Journal of structural and construction engineering. Transactions of AIJ, 0, 620, 93, 100, Architectural Institute of Japan, 30 Oct. 2007
    Japanese, The purpose of this paper is to evaluate the shear performance of mud walls with various openings based on their load carrying mechanism. The load-deformation behavior of various 1P and 2P mud walls, calculated by the data on the three kinds of component test, showed good agreement with the experimental result up to its maximum load. Then, the simplified equations were contrived to estimate their stiffness and ultimate strength. The calculated values by these equations agreed well with experimental results, and thus the proposed equations were shown to be useful for estimating the principal...
  • Embedding strength of wood exposed to decay fungi
    Hiroshi Takiuchi; Kei Sawata; Takanobu Sasaki; Yasuo Okazaki; Shuichi Doi; Yasuo Iijima
    MOKUZAI GAKKAISHI, 53, 1, 46, 51, 2007
    Japanese, Scientific journal
  • Embedding Strength of Wood Exposed to Decay Fungi
    Hiroshi Takiuchi; Kei Sawata; Takanobu Sasaki; Yasuo Okazaki; Yasuo Iijima; Shuichi Doi
    Mokuzai Gakkaishi/Journal of the Japan Wood Research Society, 53, 1, 46, 51, 2007, [Peer-reviewed]
    English, Scientific journal
  • Estimation of shear strength of dowel-type timber connections with multiple slotted-in steel plates by European yield theory
    Kei Sawata; Takanobu Sasaki; Satoru Kanetaka
    JOURNAL OF WOOD SCIENCE, 52, 6, 496, 502, 2006, [Peer-reviewed]
    English, Scientific journal
  • STUDY ON REDUCTION OF SEISMIC DAMAGE FOR TRADITIONAL WOODEN HOUSE IN MIE PREFECTURE LOCAL ENVIRONMENT(Disaster)
    KISO Kumiko; SARATANI Akiko; MORII Takeshi; SAWATA Kei; AONO Fumie; WATANABE Chiaki; HAYASHI Yasuhiro
    AIJ Journal of Technology and Design, 12, 24, 471, 476, Architectural Institute of Japan, 2006
    Japanese, The Ise and Owase towns in Mie prefecture, which will be the most heavily damaged area in the next Tonankai earthquake, are selected to consider how to reduce the seismic damage of traditional wooded houses in the rural area facing the problem of depopulation and aging. A questionnaire survey for local residents and evaluation of seismic capacity and durability for existing houses are performed. As a result, the following conclusions are obtained. 1) Seismic retrofit can be carried out when existing houses are extended according to the lifestyle modification. 2) Structural design for extension or seismic retrofit should be carried out appropriately so as not to increase eccentricity or decrease deformation performance. 3) Regular maintenance once every ten years are also effective to reduce damage.
  • ANALYSIS OF FACTORS IN DAMAGE OF COLLAPSED HOUSES CAUSED BY THE 2003 MIYAGIKEN-OKI EARTHQUAKE BASED ON MICROTREMOR MEASUREMENT AND MANPOWERED FORCED VIBRATION TEST(Structures)
    SAWATA Kei; KAWANABE Aiko; SUZUKI Tamotsu
    Journal of architecture and building science, 0, 21, 121, 126, Architectural Institute of Japan, 20 Jun. 2005
    Japanese, The two adjacent houses built by different constructions were only judged as fully-collapsed ones hit by the 2003 Miyagiken-oki Earthquake. The factors in damage of these houses were investigated through micro-tremor and forced vibration measurements. Because those houses were located on a hilly area having shallow soft deposit, the site ground motion might be amplified due to soil and topography interaction effect. The predominant frequencies of damaged houses were so close to those of earhtquake ground motion that the frames should be eggectively shaken. The twisting behavior of the house...
  • Estimation of yield and ultimate strengths of bolted timber joints by nonlinear analysis and yield theory
    K Sawata; M Yasumura
    JOURNAL OF WOOD SCIENCE, 49, 5, 383, 391, 2003, [Peer-reviewed]
    English, Scientific journal
  • Determination of embedding strength of wood for dowel-type fasteners
    K Sawata; M Yasumura
    JOURNAL OF WOOD SCIENCE, 48, 2, 138, 146, 2002, [Peer-reviewed]
    English, Scientific journal
■ Other Activities and Achievements
■ Syllabus
  • 林産学特論Ⅱ, 2024年, 修士課程, 農学院
  • 大学院共通授業科目（一般科目）：自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 木質構造学特論, 2024年, 修士課程, 農学院
  • 林産学特論演習Ⅱ, 2024年, 修士課程, 農学院
  • 高分子学概論, 2024年, 学士課程, 農学部
  • 林産学実習, 2024年, 学士課程, 農学部
  • 一般教育演習(ﾌﾚｯｼｭﾏﾝｾﾐﾅｰ), 2024年, 学士課程, 全学教育
  • 木材理学Ⅱ, 2024年, 学士課程, 農学部
  • 木材理学Ⅰ, 2024年, 学士課程, 農学部
  • 構造力学Ⅰ, 2024年, 学士課程, 農学部
  • 英語演習, 2024年, 学士課程, 全学教育
  • 物理学概論, 2024年, 学士課程, 農学部
  • 木材工学実験, 2024年, 学士課程, 農学部
  • 木材理学実験, 2024年, 学士課程, 農学部
  • 構造力学演習Ⅰ, 2024年, 学士課程, 農学部
■ Affiliated academic society
  • WOOD TECHNOLOGICAL ASSOCIATION OF JAPAN
  • ARCHITECTURAL INSTITUTE OF JAPAN
  • THE JAPAN WOOD RESEARCH SOCIETY
■ Research Themes
  • 中大規模木造建築物におけるモーメント抵抗型接合部の耐荷メカニズムの解明
    科学研究費助成事業
    01 Apr. 2023 - 31 Mar. 2026
    澤田 圭
    木造建築物が中大規模化すると部材断面も大型化し、鋼板を複数枚挿入することでドリフトピン接合の接合耐力は上昇する。この鋼板挿入ドリフトピン接合で柱脚接合部や柱－梁接合部を構成した木質構造物はあるが、初期剛性や降伏モーメントといった構造性能を実験によって確認したデータは極めて限定的である。そこで本研究では、鋼板の枚数や間隔、部材同士の接触条件を変化させた静的水平加力試験を行い、接合部の仕様が耐荷メカニズムをどのように変化させるか調べることを目的とした。令和5年度は鋼板の枚数、鋼板間隔を変化させた単位鋼板複数枚挿入ドリフトピン接合部のせん断試験を行った。
    せん断試験体の寸法は、材長500mm、幅72mm、厚さ150mmとした。集成材に幅10mmのスリットを設け、厚さ9mm、鋼種SS400の鋼板を挿入し、集成材と鋼板をドリフトピン1本で接合した。接合の仕様は、鋼板1枚を中央に挿入する仕様と、鋼板を2枚挿入する仕様が3種類で、鋼板間隔は40mm、80mm、110mmとした。
    鋼板1枚挿入接合は20kN付近で降伏後荷重は漸増し、最大荷重を記録した後に荷重は低下した。鋼板2枚挿入接合は、鋼板間隔40mm の場合、30kN付近で降伏した後、荷重は漸増して最大荷重に達した。最大荷重に達して以降は、2体は荷重が減少し、1体は最大荷重の40%まで低下して荷重は横ばいとなった。鋼板間隔80mmの場合は最も大きな最大荷重を示し、最大荷重に達した後、荷重は急激に低下した。鋼板間隔110mmの場合は、最大荷重に達した後の荷重はほぼ横ばいで、変位10mm程度までは顕著な荷重低下はみられなかった。集成材の断面寸法が同じでも挿入鋼板の枚数や挿入する鋼板の間隔が異なると、荷重－変位曲線の形状は変化することが示された。
    日本学術振興会, 基盤研究(C), 北海道大学, 23K05328
  • 大規模木造接合部のせん断メカニズムと振動特性の解明
    科学研究費助成事業
    01 Apr. 2020 - 31 Mar. 2023
    澤田 圭; 冨高 亮介
    木造建築物が大規模化されると部材の断面は大きなものとなる。部材の大断面化に伴い、その大きさを有効に活かした接合法があれば、建築物に対する木材の活用にもつながると考えられる。そこで本研究では、鋼板の配置と枚数を変化させた鋼板複数枚挿入ドリフトピン接合部に静加力および仮動的試験を行うことで、接合部のせん断挙動および振動特性を解明し、接合性能が最大となる接合寸法を示すことを目的とした。令和3年度は柱－梁接合部の静加力試験および柱脚接合部の仮動的試験を行った。
    柱－梁接合部は、E105-F300カラマツ集成材に9mm厚鋼板を挿入し、直径12mmのドリフトピン8本で接合した。集成材の材厚は150mm、材幅は330mm、材長は1356mmとした。試験は鋼板を1枚挿入と2枚挿入の接合部に対して行い、鋼板2枚挿入の場合、鋼板間隔は40mm、80mm、110mmの3種類とした。ドリフトピンは円形配置とし、回転中心からドリフトピンまでの距離は112mmとした。柱脚接合部の材料、接合寸法、ドリフトピン本数は柱－梁接合部と同じとした。
    柱－梁接合部に対する静加力試験の結果より、鋼板を1枚挿入した接合部より鋼板を2枚挿入した接合部の方が、接合性能は向上することが分かった。鋼板2枚挿入接合部の中では、鋼板間隔を80mmとした接合部が、初期剛性および降伏モーメントともに最も大きな値を示した。降伏後のモーメント－変形角挙動は鋼板間隔によって異なり、ドリフトピン接合部分からの割れも確認されたが、大きなモーメント低下はみられなかった。
    柱脚接合部の仮動的試験に先立ち自由振動試験を行い、対数減衰率は5%程度であることが分かった。振幅を一定として、周波数を変化させた正弦波を柱脚接合部に与えた仮動的試験を行い、柱脚接合部は周波数の変化に応じて異なる応答を示した。
    日本学術振興会, 基盤研究(C), 北海道大学, 20K06157
  • 高強度化された木質構造接合部を対象とした割裂耐力の推定方法の提案
    科学研究費助成事業
    01 Apr. 2020 - 31 Mar. 2023
    神戸 渡; 瀧野 敦夫; 澤田 圭; 岡本 滋史; 鈴木 賢人; 小林 研治; 中島 昌一; 落合 陽
    2021年度は、木質部材に鋼板挿入型接合を適用し、その接合部における割裂強度に関する実験的研究を行った。日本建築学会 木質構造設計規準には、割裂強度を算出するための材料定数として割裂破壊定数が定められており、本試験で用いた材料を用い、割裂破壊定数を求めるための試験を行った。また、同材料を用いた鋼板挿入型接合を適用した接合部の鉛直加力試験を行った。ちなみに、用いた材料は異等級構成集成材、樹種はオウシュウアカマツである。鋼板挿入型接合では、接合具としてφ１６と１８と２０のドリフトピンを用いており、それらを配置する方法を試験パラメータとした。また、部材の梁せいとして４５０ｍｍ、６００ｍｍ、１０００ｍｍ、１５００ｍｍのものを用いており、これらを試験パラメータとした。ドリフトピンの配置は矩形配置のものと、円形配置のものを設けており、この配置計画は既往の研究を参考とし、設定した。以上の試験パラメータのものを各１体ずつ試験体を用意し、全８体を用意した。
    試験の結果、接合部試験体の割裂荷重が学会で提唱されている式よりも小さい値で発生することが確認された。計算結果と試験結果が近い値となるためには、梁せい（h）に対する加力側材縁からの接合部までの距離（he）の比率he/h＝αが0.7程度にすることが適切ではないかということが検討よりわかった。本研究で取り扱った試験体は、これまでにない規模のものであったため、規準に示されている式の適用方法に関して、今後検討する必要があると考えられる。
    また、上記より小規模の試験体を用いた実験を行った。これは、規準の式の適用性を検証するためのものである。ドリフトピンの配置を４つ考えた試験体を用意し、試験を行った。その結果、式が適用できるものとそうでないものがあることが確認された。この要因に関して、今後検討する予定である。
    日本学術振興会, 基盤研究(B), 関東学院大学, 20H02303
  • Mechanical analysis of shear behavior of mechanical joints with decayed wood
    Grants-in-Aid for Scientific Research
    01 Apr. 2017 - 31 Mar. 2020
    Sawata Kei
    Timber joints are important for structural performance of wooden house. Structural performance of wooden house is change by decay. Accordingly, it is important to obtain relations between decay and performance of timber joints. Decay often is not uniform in cross section of wood. Relations between decay distribution of wood and shear behavior of mechanical joints were investigated. When neighborhood of nail head was decayed, the strength of joints was lower than the joints which had decay near nail tip. The yield strength of nailed joints with both of sound and decay parts was calculated based on European yield theory. The calculated values were close to the experimental results. Non-linear analysis was conducted on mechanical joints with slotted-in steel plate. When wood near steel plate was decayed, the joints were showed the small initial stiffness and yield strength.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 17K07870
  • Mechanism of nailed joints with decayed wood under lateral force
    Grants-in-Aid for Scientific Research
    01 Apr. 2014 - 31 Mar. 2017
    Sawata Kei; Sasaki Yoshihisa; Saito Nozomi; Takanashi Ryuya
    This study conducted on the nail withdrawal tests, bearing tests of wood, tests of joints connected with a nail under lateral force, and tests of multiple nailed joints. The nail withdrawal strength could be estimated by using corrosion of nail and decay degree of wood. The decay affected the bearing strength rather than the nail withdrawal strength. The ultimate load of the nailed joints decreased as the sum of the sound regions distance in the main and side members was decreased. The initial stiffness significantly decreased when the main or side member had a decayed region in the boundary between the main and side members. The decrease of ultimate load of multiple nailed joints was noticeable rather than that of initial stiffness. This study could obtain the mechanism of nailed joints under lateral force corresponding to the degree of decay and the displacement level of nailed joints.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 26850107
  • In situ method for tree trunk Young's modulus measurements in young plantations
    Grants-in-Aid for Scientific Research
    01 Apr. 2013 - 31 Mar. 2016
    KOIZUMI Akio; SAWATA Kei; TORITA Hiroyuki
    Nondestructive test method for evaluating tree stem Young's modulus was developed. The stem Young's modulus is calculated considering the elastic relations between applied bending moment and stem deflections, which can be observed on a tablet PC. The stem Young's modulus and stress wave propagation speed measured for karamatsu, todomatsu, and guimatsu hybrid trees planted in Hokkaido and were compared with dymamic Young's modulus tested for the logs harvested after the tree tests, as well as the mechanical properties tested for small clear specimens prepared from the logs. As a result, the Young's modulus of trees can be estimated from the proposed tree bending tests with high accuracy.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 25450234
  • Windthrow risk diagnosis for park trees based on the drag coefficients of tree crowns and the measurement of tree form
    Grants-in-Aid for Scientific Research
    2009 - 2012
    KOIZUMI Akio; SAWATA Kei; HIRAI Takuro
    Methods of quantitative evaluation for windthrow risk of park trees were discussed in order to propose a procedure for windthrow diagnosis. A field test method was developed to evaluate drag coefficients of trees, using measured data of wind speed and stem deflection. The moment acting on stem and root-soil plate can be calculated as a function of wind speed, using the obtained drag coefficients. To evaluate windthrow resistance with respect to stem breakage, a nondestructive method for determining the shape of a trunk cross section was developed. Furthermore, pull-down tests of park trees were conducted
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21580169
  • Estimation of lateral resistance timber joints considering dynamic responsive characteristics
    Grants-in-Aid for Scientific Research
    2009 - 2011
    HIRAI Takuro; SAWATA Kei; UEMATSU Takeyishi; TODA Masahiko
    Dynamic tests of nailed joints are conducted under harmonic and white-noise waves. The principal results are as follows : (1)Dynamic response of nailed timber joints is clearly frequency dependent. (2)Under harmonic waves, nailed timber joints break in failure modes typical under static loading in resonance with the frequencies corresponding to safety limit stiffness. (3)Nailed timber joints once respond sensitively to the frequencies corresponding to damage limit stiffness, however, they do not break immediately in failure modes typical under static loading because of cyclic degradation. On the other hand, nailed timber joints may break in low-cyclic bending fatigue failure when they are subjected to many cycles, even if input accelerations are low. (4)The dynamic behavior above under harmonic waves is observed under white-noise waves consisting of similar frequency components. (5)Dynamic behavior of nailed shear walls, which are a model of multiple joint systems, behave in the same way as predicted from the behavior of single nailed joints. These test results show that the responsive characteristics of timber constructions vary due to change in equivalent stiffness along the static load-slip curves of single joints, structural subassemblies and whole structures. Test results also show that the low-cyclic bending fatigue failure of nails may lead timber constructions to critical collapse when the seismic forces act for many seconds and/or repeatedly, even if the maximum accelerations are below the damage limit.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21380105
  • Study on evaluation of structural performance of timber structureexposed by fungal attack
    Grants-in-Aid for Scientific Research
    2007 - 2009
    SAWATA Kei
    本研究では在来軸組み構法片筋違い耐力壁と平行弦トラス梁を対象として、接合部に生じた腐朽が構造物全体の耐力-変形関係にどのような影響を及ぼすか調べた。筋違い耐力壁の水平加力試験の結果より、柱脚部の接合方法によって腐朽が耐力壁のせん断力-見かけの変形角関係に及ぼす影響に差が見られた。平行弦トラス梁の曲げ試験より、斜材に生じた腐朽がトラス梁の荷重-たわみ関係へ及ぼす影響は小さかっ
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (Start-up), Hokkaido University, 19880001