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Takanobu Sasaki

Research Faculty of Agriculture　Fundamental AgriScience Research　Forest ScienceProfessor
Center for Natural Hazards ResearchProfessor

Researcher basic information

■ Degree
  • 博士（工学）, 秋田大学
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Keyword
  • CLT deck
  • wooden check dam
  • wood pile
  • wood durabirity
  • CLT: Cross Laminated Timber
  • 木橋
  • クリープ
  • プレストレス木床版橋
  • スギLVL
  • モニタリング
  • エポキシ樹脂
  • 挿入鋼板
  • 集成材
  • 木ダボ
  • 振動実験
Research Field
  • Life Science, Wood science, Timber Engineering
  • Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention), Civil engineering material, execution and construction management
■ Educational Organization

Career

■ Career
Career
  • Apr. 2024 - Present
    Hokkaido University, Center for Natural Hazards Research, Director
  • Apr. 2021 - Present
    Hokkaido University, 広域複合災害研究センター, 兼務教員
  • Apr. 2019 - Present
    北海道大学大学院, 農学研究院・基盤研究部門森林科学分野, 教授, Japan
  • Apr. 2012 - Mar. 2019
    Akita Prefectural University, Institute of Wood Technology, 教授
  • Apr. 2006 - Mar. 2011
    Akita Prefectural University, Institute of Wood Technology, 准教授
  • 2001 - 2005
    Akita Prefectural University, Institute of Wood Technology, 講師
  • Apr. 1995 - Mar. 2001
    秋田県立農業短期大学, 附属木材高度加工研究所, 助手
Position History
  • 広域複合災害研究センター長, 2024年4月1日 - 2026年3月31日

Research activity information

■ Papers
  • RENOVATION WORK ON THE TSURU-NO-MAI BRIDGE AND DETERIONRATION EVALUATIONS OF THE DEMOLISHED GIRDER
    Takanobu SASAKI; Hideyuki HIRASAWA; Humihiko GOTOU; Tatsuro HAMANO; Hisashi SHIBUTANI; Yoshinori JIN
    Japanese Journal of JSCE, 82, 28, n/a, n/a, Japan Society of Civil Engineers, Mar. 2026, [Peer-reviewed], [Lead author]
    Japanese, Scientific journal
  • Proposal for the structure and management method of a rapid-erectable emergency temporary bridge
    Tsutomu Hiraike; Takanobu Sasaki; Yoshikazu Tomioka; Shuichi Honda; Yuki Chikahiro; Shinya Watanabe; Hiroshi Watanabe; Hideyuki Hirasawa; Chihiro Morita
    Journal of Structural Engineering, A, 72, A, 818, 830, Mar. 2026, [Peer-reviewed]
    Japanese, Scientific journal
  • 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, Mar. 2026, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal
  • EVALUATION OF BUILDING DESIGN PROCESS USING SAKHALIN FIR PRODUCTED IN NAKAGAWA EXPERIMENTAL FOREST, HOKKAIDO UNIVERSITY– Case of Nitobe Enyu Living Laboratory building from logging plan to lumber manufacturing –
    OZAWA Takeo; NAITO Tomohito; SASAKI Takanobu; TAKAHASHI Riku; UEDA Rintaro; OHASHI Yoshinori; TANICHI Daisuke
    AIJ Journal of Technology and Design, 32, 80, 374, 379, Architectural Institute of Japan, 20 Feb. 2026
    Japanese, This paper evaluates and reports on the timber procurement and architectural design process for the new construction of Nitobe Enyu Living Laboratory, in which Sakhalin Fir from the Nakagawa Experimental Forest of Hokkaido University is used for the wooden frame. Rationality of the methods are confirmed in the process of adopting a wooden structural system that combines flat square timber by taking the characteristics of tree species into consideration, and of drawing timber cutting diagrams according to the size of felled logs before sawing up. This report provides basic knowledge for developing systematic methods of utilizing Sakhalin Fir.
  • Investigation of post-fabrication treatment of CLT using creosote oil and copper naphthenate
    Teruhisa MIYAUCHI; Shinichi ISAJI; Junko MIYAZAKI; Ryuya TAKANASHI; Yoshinori OHASHI; Takanobu SASAKI
    MOKUZAI HOZON (Wood Protection), 51, 3, 103, 115, Japan Wood Preserving Association, 2025, [Peer-reviewed]
    Scientific journal
  • MEASUREMENT OF YOUNG’S MODULUS AND SHEAR MODULUS OF PLYWOOD BY FLEXURAL VIBRATION TEST AND INFLUENCE OF SPECIMEN SHAPE
    小川智之; 佐々木貴信; 高梨隆也; 澤田圭
    土木学会論文集(Web), 81, 4, 2025, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal
  • Timber Bridges in Modern Japan
    Humihiko Gotou; Yukari Aoki; Daisuke Oikawa; Hideyuki Hirasawa; Takanobu Sasaki
    Structural Engineering International, 35, 1, 118, 124, 2025, [Peer-reviewed]
    English, Scientific journal
  • Effects of Steam-bending on Deformation Properties of Wood
    Yuki Okuda; Takanobu Sasaki; Kei Sawata; Yoshihisa Sasaki; Koji Adachi
    Mokuzai Gakkaishi, 70, 4, 125, 133, Japan Wood Society, 25 Oct. 2024, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal
  • Collapse behavior of steel railing post considering installation and replacement on CLT deck
    Koki Ogawa; Humihiko Gotou; Takanobu Sasaki; Shogo Araki; Makoto Imai
    Journal of Structural Engineering, 70A, 885, 893, Mar. 2024, [Peer-reviewed]
    Japanese, Scientific journal, 45248337
  • INVESTIGATION OF THE MANUFACTURING METHOD OF CROSS-LAMINATED TIMBER (CLT) USING VACUUM PRESS
    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, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal
  • STRENGTH PROPERTIY OF CURVED LAMINATED VENEER LUMBER
    Kentaro HORIKOSHI; Takanobu SASAKI; Kei SAWATA; Yoshihisa SASAKI
    Japanese Journal of JSCE, 80, 28, n/a, n/a, Japan Society of Civil Engineers, 2024, [Peer-reviewed], [Corresponding author]
    Japanese, 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], [International Magazine]
    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.
  • Relationship between the Ratio of Width to Thickness and Rolling Shear Strength of Japanese Larch Lamina
    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]
    Japanese, 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], [International Magazine]
    English, 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.
  • REPAIR DESIGN AND ANALYSIS OF THE FOREST ROADWAY BRIDGE USING CLT FLOOR SLABS
    Ryotaro OKAMOTO; Takanobu SASAKI; Kei SAWATA; Yoshinori OHASHI; Teruhisa MIYAUCHI; Takahiro KATO
    Japanese Journal of JSCE, 79, 28, n/a, n/a, Japan Society of Civil Engineers, 2023, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal
  • Issues in design and design criteria of emergency temporary bridges for disaster prevention and mitigation
    渡邊学歩; 佐々木貴信; 森田千尋; 小林博之; 勝呂翔平; 松田伊佐雄; 木下幸治
    Journal of Structural Engineering, 69A, 1258, 1268, 2023, [Peer-reviewed]
    Japanese
  • Recommendations on the required performance of emergency temporary bridges learned from heavy rain disasters
    平池勉; 有尾一郎; 近広雄希; 森本真一; 佐々木貴信
    Journal of Structural Engineering, 69A, 1227, 1236, 2023, [Peer-reviewed]
  • 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
  • Life Cycle Regional Economic Impacts of Bridge Repair Using Cross-Laminated Timber Floor Slabs: A Case Study in Akita Prefecture, Japan
    Tomohumi Huzita; Takanobu Sasaki; Shogo Araki; Chihiro Kayo
    Buildings, 12, 2, 158, 158, MDPI AG, 02 Feb. 2022, [Peer-reviewed], [International Magazine]
    Scientific journal, Recently, cross-laminated timber (CLT) has attracted attention as a civil engineering material in Japan. In particular, the use of CLT floor slabs for bridge repair is expected to have regional economic impacts throughout their life cycle, but their economic impacts have not been evaluated. In this study, the life cycle regional economic impacts of using non-waterproofed CLT, waterproofed CLT, and reinforced concrete (RC) floor slabs for bridge repair in Akita Prefecture, Japan, were compared. Using past-to-present input–output tables, we quantitatively evaluated the economic impacts over the life cycle of floor slabs by estimating the future input–output tables for construction, maintenance, and disposal. The results showed that the construction and maintenance costs (final demand increase) of CLT floor slabs are higher than those of RC slabs, but the regional economic impact is larger. In addition, the non-waterproofed CLT must be renewed every time it is maintained. Therefore, the demand for CLT production in the prefecture will increase, and the economic impact will be larger than that of the other two floor slabs. This demand for CLT production will not only redound to the benefit of the forestry and wood industry but also the revitalization of regional economies.
  • 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], [International Magazine]
    English, 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.
  • CLT同士のスカーフジョイントによる二次接合の曲げ性能
    小林玲陽; 佐々木貴信; 澤田 圭; 佐々木義久; 山内秀文
    木材工学論文報告集, 19, 52, 59, Feb. 2021, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal, 45123324
  • 含水率変化に伴うCLTの寸法変化と被覆処理
    本宮由美子; 佐々木貴信; 澤田 圭; 佐々木義久; 山内秀文
    木材工学論文報告集, 19, 45, 51, Feb. 2021, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal
  • 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, [Corresponding author]
    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.
  • COLLAPSE BEHAVIOR OF CLT DECK WITH STEEL RAILING POST
    OGAWA Kouki; GOTOU Humihiko; SASAKI Takanobu; ARAKI Shogo; AOKI Yukari
    Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 77, 5, I_55, I_63, Japan Society of Civil Engineers, 2021, [Peer-reviewed]
    Japanese, 45248337
  • 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], [International Magazine]
    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.
  • Environmental and Economic Evaluation of Small-Scale Bridge Repair Using Cross-Laminated Timber Floor Slabs
    Tetsuya Iwase; Takanobu Sasaki; Shogo Araki; Tomohumi Huzita; Chihiro Kayo
    Sustainability, 12, 8, 3424, 3424, MDPI AG, 22 Apr. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Cross-laminated timber (CLT) has gained popularity worldwide in recent years, and its use in buildings and civil engineering structures has attracted attention in Japan. In this study, the life-cycle greenhouse gas (GHG) balance and costs associated with CLT floor slabs were evaluated with respect to small-scale bridge repair as the first instance of the use of CLT in civil engineering projects in Japan. Additionally, waterproofing treatment was applied to CLT slabs, and the potential GHG and cost reduction of CLT in comparison with reinforced concrete (RC) slabs were examined. GHG emissions were the smallest for non-waterproofed CLT slabs and the greatest for RC slabs. When replacing RC slabs with CLT slabs without waterproofing, fossil-derived GHG emissions can be reduced by 73 kg-CO2eq/m2 per slab, and fossil/wood-derived GHG emissions can be reduced by 67 kg-CO2eq/m2; however, the use of disposed CLT as fuel is essential. Moreover, a reduction in GHG emissions can be expected if RC slabs are replaced with CLT slabs that are waterproofed only once every 20 years. Further, the cost associated with RC slabs is 20% of that attributable to CLT slabs. Hence, measures need to be taken to reduce the cost of CLT and waterproofing materials.
  • 直交集成板を床版に用いた橋梁の ライフサイクル温室効果ガス排出量
    岩瀬 鉄也; 佐々木 貴信; 橋本 征二; 荒木 昇吾; 加用 千裕
    木材工学論文報告集, 18, 40, 46, Dec. 2019, [Peer-reviewed]
    Scientific journal
  • 木材腐朽がビス接合部のせん断性能と変形挙動におよぼす変化
    上田麟太郎; 澤田 圭; 高梨隆也; 佐々木貴信
    木材工学論文報告集, 18, 62, 69, Dec. 2019, [Peer-reviewed]
    Scientific journal
  • Design and repairing of short span bridge using cross laminated timber slabs
    豊田淳; 佐々木貴信; 荒木昇吾; 林知行; 有山裕亮; 後藤文彦
    Journal of Structural Engineering, 65A, 799, 806, Mar. 2019, [Peer-reviewed], [Corresponding author]
    Japanese, Scientific journal, 45079309
  • 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, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • CLT床版の耐久性付与技術の開発
    佐々木 貴信; 有山 裕亮; 荒木 昇吾; 豊田 淳; 山内 秀文; 林 知行
    木材工学論文報告集, 16, 39, 44, Dec. 2017, [Peer-reviewed], [Lead author, Corresponding author]
    Scientific journal, 45079309
  • トルクレンチを用いたプレストレス木箱桁橋の緊張力制御
    後藤文彦; 河原萌; 石坂晃太郎; 佐々木貴信; 野田龍
    構造工学論文集 A(CD-ROM), 62, ROMBUNNO.16‐3, 1306, 土木学会 ; 2007-, 15 Mar. 2016, [Peer-reviewed]
    Japanese, In on-site construction of timber stress-laminated box-beam bridges, use of torque wrenches can make the on-site prestressing easy. In the case of prestressing for longer bars such as PC bars than high strength bolts, the torque introduced by the torque wrench may be consumed not only by friction but also by torsional deformation and possibly by torsional buckling. In this study we investigate how the torsional deformation and the torsional buckling influence the prestress control. According to experimental and numerical considerations, we conclude that the torque introduced by the torque wrench is consumed by friction and torsional deformation.
  • 災害時の応急構造物としての木製治山ダムの可能性
    野田龍; 佐々木貴信; 千田知弘; 中田裕治; 後藤文彦
    構造工学論文集 A(CD-ROM), 62, ROMBUNNO.16‐1, 1289, 土木学会 ; 2007-, 15 Mar. 2016, [Peer-reviewed]
    Japanese, With the improvement of forest resource, we developed timber check dam which used the large-diameter timbers that supply increased. The construction of timber check dam becomes the structure that construction is possible after not needing a high technique without asking a short term and in all season. In addition, we performed horizontal load test it for timber check dam where approximately 13 years passed from actual construction. The results, we found it satisfying demand performance at the same level at first. From these results, short -term construction is possible, and construction is easy and, in timber check dam which the service of the fixed period of time can expect, the use as the temporary structure between one of the introduction of a concrete check dam is expected.
  • Life cycle greenhouse gas emissions of woodchip-paved walkways using tsunami salt-damaged wood - Examination in Otsuchi, Iwate Prefecture
    Chihiro Kayo; Chiaki Watanabe; Takanobu Sasaki; Seiki Kumagai; Ryu Noda; Seiji Hashimoto
    Journal of Wood Science, 61, 6, 620, 629, Dec. 2015, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • The optimum design used FEM analyses and the development of wooden check dam: Part 2, Failure tests and the performance assessment of cost reduction type all wood type wooden check dam
    千田知弘; 佐々木貴信; 野田龍; 野田龍; 井上孝人; 原田利正; 三浦靖浩
    砂防学会誌, 68, 3, 3, 10, 砂防学会, 15 Sep. 2015, [Peer-reviewed]
    Japanese
  • 岩手県大槌町における津波塩害木を活用したウッドチップ舗装歩道のライフサイクルアセスメント
    加用千裕; 渡辺千明; 佐々木貴信; 熊谷誠喜; 野田龍; 橋本征二
    木材利用研究発表論文集, 14, 57, 62, Aug. 2015, [Peer-reviewed]
    Japanese
  • Carbon balance in the life cycle of wood -Targeting a timber check dam-
    Chihiro Kayo; Ryu Noda; Takanobu Sasaki; Shinya Takaoku
    Journal of Wood Science, 61, 1, 70, 80, Feb. 2015, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Numerical modeling and stiffness estimation for timber stress-laminated box-beam bridges
    Gotou Humihiko; Oyama Ryunosuke; Saito Hikaru; Sasaki Takanobu
    Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), 61, 570, 577, Japan Society of Civil Engineers, 2015
    Japanese, While FEM is needed to evaluate the behavior of the on-site timber stress-laminated box-beam bridges, whose shear deformation can be significantly large, it is very difficult to model the detail parts such as prestressed connection, holes in plates, diaphragms and so on. Firstly, we compare the exact FEM calculations considering the influence of the prestress by the contact problem to the simpler FEM calculations neglecting the prestress by the shared nodes at the adjacent planes between members. Secondly, we compare the simpler FEM calculations and Timoshenko's beam theory with some trial shear coefficients to the experimental results. As a result we conclude that Timoshenko's beam theory can be good approximation within possible cross-section range for the types of timber box-beam bridges.
  • Evaluation of CO2 emissions reductions by timber check dams and their economic effectiveness
    Ryu Noda; Chihiro Kayo; Takanobu Sasaki; Shinya Takaoku
    JOURNAL OF WOOD SCIENCE, 60, 6, 461, 472, Dec. 2014, [Peer-reviewed]
    English, Scientific journal
  • 木杭基礎と自然石を用いた用水路護岸工の試験施工
    佐々木 貴信; 永吉 武志; 荻野 俊寛; 後藤 文彦
    木材利用研究論文報告集, 13, 22, 27, 2014
    Scientific journal
  • 秋田スギの木杭による水路護岸基礎工および地盤補強工法の開発
    佐々木 貴信; 永吉 武志; 荻野 俊寛; 後藤 文彦
    秋田県立大学ウェブジャーナルＡ, 2, 1, 9, 2014
    Scientific journal
  • The load bearing capacity of wooden check dam utilizing deformed steel bar as connector
    Chida Tomohiro; Sasaki Takanobu; Noda Ryu; Watanabe Hiroshi; Harata Toshimasa; Miura Yasuhiro
    Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), 60, 0, 715, 722, Japan Society of Civil Engineers, 2014, [Peer-reviewed]
    Japanese, Recently, it has been shown the pull-out strength of deformed steel bar whose pilot hole diameater was 14mm was as strong as the pull-out strength of lag screw whose poilot hole diameater was 15mm. From this result, general purpose utilization of deformed steel bar to wooden civil engineering structures is considered. Therefore, in this study, in order to confirm wheather it is possible to use deformed steel bar for actual civil engineering structures, we made the real-size specimen of all wood type wooden check dam utilizing only deformed steel bar whose pilot hole diameater was 14mm, and conducted horizontal load test. We also compared the performance of the specimen utilized lag screw whose pilot hole diameater 15mm.
  • Estimation of Shear Strength and Pull-out Strength of Timber Joints Using Deformed Steel Bars for Civil Engineering Construction with Large Cross Sections. Performance comparison of specimens utilizing lag screws and deformed steel bars of .PHI.16mm and
    野田龍; 佐々木貴信; 千田知弘
    木材学会誌, 60, 5, 249-260 (J-STAGE), 260, 日本木材学会, 2014, [Peer-reviewed]
    Japanese
  • Development of original wooden check dam in Akita Prefecture
    NODA Ryu; SASAKI Takanobu; CHIDA Tomohiro; INOUE Takato; HARATA Toshimasa; MIURA Yasuhiro
    Journal of the Japan Society of Erosion Control Engineering, 65, 1, 39, 46, Japan Society of Erosion Control Engineering, 15 May 2012, [Peer-reviewed]
    Japanese, In Akita Prefecture, to promote the demand expansion of the Japanese cedar produced in Akita Prefecture and to activate the local areas by centering timber industry, various civil engineering structures used timber have been proposed and developed, and have been actually constructed. Wooden check dam is one of these, there are two kinds of wooden check dams called "Akita standard". One of which is "all wood type" dam composed only wood members and lag screws, and usage rate of timber is up to 90%. Another is "hybrid dam" packed the thinned wood and gravels in the steel flexible frame, and usage rate of timber is about 80%. In this study, we presented the details of all wood type wooden check dam and hybrid type. In all wood type wooden check dam, we reported results of the strength test of joint used lag screw and failure test of real-size dam specimen, which were conducted before construction, and monitoring study at construction site. In addition, we accessed the strength property, usage rate and cost performance of each Akita standard dam by comparing the crib dam which ever have spread in the whole country. In the failure test, it was shown that the specimen have safety rate 10 for the design load. With regard to monitoring study, from actual water level inside dams, it found that phreatic line was lower than design position. In comparison with the crib dam, although for used amount of timber Akita standard dam was very effective, for cost there was no difference.
  • 木質土木構造物の接合具としてのラグスクリューと異形棒鋼の引抜性能
    千田知弘; 佐々木貴信; 野田龍; 三浦靖浩
    構造工学論文集 A(CD-ROM), 58, 0, ROMBUNNO.11-2, 792, 公益社団法人 土木学会, 31 Mar. 2012, [Peer-reviewed]
    Japanese, In all-wood-type wooden check dam in Akita Prefecture, lag screws and deformed steel bar are utilized as the connectors. From many failure tests of wooden check dams, it was confirmed that the structures with these connectors have very high strength for pull -out and shear behavior. Recently, general purpose utilization of lag screw and deformed steel bar to other wooden civil engineering structures is considered. However there are few examples reviewed pull-out strength of lag screws and deformed steel bar. Therefore, in this study, we conducted many pull-out test of lag screw and deformed steel bar with different pre-drilled hole diameter, and we tried formulization of each pull-out strength.
  • The optimum design used FEM analyses and the development of wooden check dam : Part 1, The optimum design of all wood type wooden check dam
    CHIDA Tomohiro; SASAKI Takanobu; NODA Ryu; INOUE Takato; MIURA Yasuhiro
    砂防学会誌 : 新砂防 = Journal of the Japan Society of Erosion Control Engineering, 64, 5, 14, 23, 砂防学会, 15 Jan. 2012, [Peer-reviewed]
    Japanese
  • The fundamental study of the proposal of shear failure standard test method and estimation of pure shear strength of japanese cedar
    Tomohiro Chida; Humihiko Gotou; Hidefumi Yamauchi; Takanobu Sasaki; Yasuo Okazaki; Yasuo Kawai; Yasuo Iijima
    World Conference on Timber Engineering 2012, WCTE 2012, 5, 173, 178, 2012
    International conference proceedings
  • A Proposed Standard Test Method for Shear Failure and Estimation of Shear Strength of Japanese Cedar I. Shear failure test of Japanese cedar laminates using wood material as stiffener and finite element analysis, and estimation of shear modulus
    Tomohiro Chida; Takanobu Sasaki; Hidefumi Yamauchi; Yasuo Okazaki; Yasuo Kawai; Yasuo Iijima
    MOKUZAI GAKKAISHI, 58, 5, 260, 270, 2012, [Peer-reviewed]
    Japanese, Scientific journal
  • Experiment and elasto-plastic FEM analyses of shear stress of steel-plate-inserted glulam-beams
    Chida Tomohiro; Sasaki Takanobu; Gotou Humihiko; Usuki Seizo; Iijima Yasuo
    Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), 55, 932, 942, Japan Society of Civil Engineers, 2009
    In the beam theory the shear stress becomes maximum value on the neutral axis, which is also adopted for hybrid structures as to steel-plate-inserted glulam beams. However, in previous its shear failure test, every specimen did not break on the neutral axis but on stress concentration zone which was observed in FEM analysis. In this study we try to experimentally and numerically investigate three types of steel-glulam hybrid beams and evaluate stress transfer mechanism between steel and glulam. In FEM analysis we search the shear stress distribution on xy cross section and compare to experiment, discuss the influence of stress transfer between different materials on failure condition.
  • Shear performance of steel-plate-inserted glulam beams
    Daikokuya Masahide; Gotou Humihiko; Sasaki Takanobu; Hasebe Kaoru
    Kozo Kogaku Ronbunshu. A (Journal of Structural Engineering. A), 55, 925, 931, Japan Society of Civil Engineers, 2009
    Shear stiffness of glulam beams is very small compared with it's bending stiffness. While hybridization of glulam beams with inserted steel plates improves the bending stiffness, it does not so improve the shear stiffness. As a result, ratio of shear deformation to bending deformation is greater in the steel-plate-inserted glulam beams than even in glulam-only beams. Since wood members, whose toughness is very small compared with those of steel members, have tendency to drastically lose strength after fracture, it is important to investigate fracture modes and toughness of wood-steel hybrid beams like steel-plate-inserted glulam beams. The fracture modes and toughness depend on ratio of Young's modulus of wood parts to steel parts and on ratio of shear strength to bending strength. In this study we perform three-point bending tests to experimentally estimate the shear elasticity and perform asymmetric four-point-bending tests to consider shear performance and toughness of the steel-plate-inserted glulam beams for both cedar and larch.
  • 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
  • 集成材―複数挿入鋼板型ハイブリッド梁の曲げ弾塑性挙動に関する実験と解析
    薄木 征三; 千田 知弘; 佐々木 貴信; 後藤 文彦
    構造工学論文集, Vol. 53A, 2007, [Peer-reviewed]
  • 鋼板挿入集成材梁の有限要素弾塑性解析
    千田 知弘; 後藤 文彦; 薄木 征三; 佐々木 貴信
    構造工学論文集(CD-ROM), Vol. 53A, 2007, [Peer-reviewed]
  • 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, [Peer-reviewed]
    Japanese, 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
  • Effects of cure time and humidity cycles on withdrawal strength of hardwood dowel joints
    A Koizumi; T Sasaki; Y Matsuki
    MOKUZAI GAKKAISHI, 50, 4, 248, 254, 2004, [Peer-reviewed]
    Japanese, Scientific journal
  • End joint with glued-in hardwood dowels in timber construction II - Bending properties of beams jointed with multiple rows of dowels
    T Sasaki; A Koizumi; JL Jensen; Y Iijima; K Komatsu
    MOKUZAI GAKKAISHI, 48, 1, 23, 31, 2002, [Peer-reviewed]
    Japanese, Scientific journal
  • Axially loaded glued-in hardwood dowels
    JL Jensen; A Koizumi; T Sasaki; Y Tamura; Y Iijima
    WOOD SCIENCE AND TECHNOLOGY, 35, 1-2, 73, 83, Apr. 2001, [Peer-reviewed]
    English, Scientific journal
  • Effect of external pressure on the strength of hollow cylindrical wood columns
    Hidefumi Yamauchi; Takanobu Sasaki; Ling Fei Ma; Orlando R. Pulido; Hikaru Sasaki
    Proceedings of the Fourth International Conference on Materials Engineering for Resources, 1, 100, 103, 2001
    English, International conference proceedings
  • Moment-resisting properties of post-to-sill joints connected with hardwood dowels
    A Koizumi; T Sasaki; JL Jensen; Y Iijima; K Komatsu
    MOKUZAI GAKKAISHI, 47, 1, 14, 21, 2001, [Peer-reviewed]
    Japanese, Scientific journal
  • End joint with glued-in hardwood dowels in timber construction I. Bending properties of beams jointed with single row of dowels
    T Sasaki; A Koizumi; JL Jensen; Y Iijima; Y Tamura; K Komatsu
    MOKUZAI GAKKAISHI, 45, 1, 17, 24, 1999, [Peer-reviewed], [Corresponding author]
    English, Scientific journal
  • Withdrawal properties of hardwood dowels glued perpendicular to the grain
    A Koizumi; JL Jensen; T Sasaki; Y Iijima; Y Matsuki; K Komatsu
    MOKUZAI GAKKAISHI, 45, 3, 230, 236, 1999, [Peer-reviewed]
    Japanese, Scientific journal
  • Strength properties of sugi (Cryptomeria japonica) grown in Akita Prefecture V. Production and performance evaluation of the glulam
    Y Iijima; N Itagaki; Y Okazaki; T Esashi; A Koizumi; T Sasaki; H Mihashi
    MOKUZAI GAKKAISHI, 45, 4, 313, 323, 1999, [Peer-reviewed]
    Japanese, Scientific journal
  • Withdrawal properties of hardwood dowels in end joints I. Evaluation of shear performance of adhesives
    A Koizumi; JL Jensen; T Sasaki; Y Iijima; Y Tamura
    MOKUZAI GAKKAISHI, 44, 1, 41, 48, 1998, [Peer-reviewed]
    Japanese, Scientific journal
  • Withdrawal properties of hardwood dowels in end joints II. Effects of dowel diameters, Young's moduli of adherends, dowel spacings and numbers of dowels
    A Koizumi; JL Jensen; T Sasaki; Y Iijima; Y Tamura
    MOKUZAI GAKKAISHI, 44, 2, 109, 115, 1998, [Peer-reviewed]
    Japanese, Scientific journal
  • Manufacturing condition and mechanical properties of cylindrical LVL manufactured by spiral-winding method
    Hidefumi Yamauchi; Izumi Miura; Takanobu Sasaki; Akio Koizumi; Shuichi Kawai; Hikaru Sasaki
    Zairyo/Journal of the Society of Materials Science, Japan, 47, 4, 350, 355, Soc Mater Sci, Japan, 1998
    Japanese, Scientific journal
  • Strength properties of sugi (Cryptomeria japonica) grown in Akita Prefecture .1. Young's moduli of logs
    A Koizumi; Y Iijima; T Sasaki; Y Kawai; Y Okazaki; H Nakatani
    MOKUZAI GAKKAISHI, 43, 1, 46, 51, 1997, [Peer-reviewed]
    Japanese, Scientific journal
  • Strength properties of sugi (Cryptomeria japonica) grown in Akita prefecture .3. Some relationships between logs and sawn lumber
    Y Iijima; A Koizumi; Y Okazaki; T Sasaki; H Nakatani
    MOKUZAI GAKKAISHI, 43, 2, 159, 164, 1997, [Peer-reviewed]
    Japanese, Scientific journal
  • Strength properties of sugi (Cryptomeria japonica) grown in Akita prefecture .4. Reasonable lamination method and estimation of moduli of elasticity of glulam
    Y Iijima; A Koizumi; Y Okazaki; T Sasaki; K Horie
    MOKUZAI GAKKAISHI, 43, 2, 165, 170, 1997, [Peer-reviewed]
    Japanese, Scientific journal
  • Strength properties of sugi (Cryptomeria japonica) grown in Akita prefecture .2. Mechanical properties of lumber
    A Koizumi; Y Iijima; T Sasaki; Y Okazaki
    MOKUZAI GAKKAISHI, 43, 2, 210, 214, 1997, [Peer-reviewed]
    Japanese, Scientific journal
■ Other Activities and Achievements
■ Syllabus
  • 林産学特論Ⅱ, 2024年, 修士課程, 農学院
  • 森林資源科学特論, 2024年, 修士課程, 農学院
  • 森林資源科学特論演習, 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
  • 林産学実習, 2024年, 学士課程, 農学部
  • 木材理学Ⅱ, 2024年, 学士課程, 農学部
  • 木質材料学, 2024年, 学士課程, 農学部
  • 構造力学演習Ⅱ, 2024年, 学士課程, 農学部
  • 構造力学Ⅱ, 2024年, 学士課程, 農学部
  • 英語演習, 2024年, 学士課程, 全学教育
  • 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
  • 森林科学総合実習Ⅰ, 2024年, 学士課程, 農学部
  • 卒業論文, 2024年, 学士課程, 農学部
  • 森林科学演習Ⅰ, 2024年, 学士課程, 農学部
  • 森林科学演習Ⅱ, 2024年, 学士課程, 農学部
  • 構造力学, 2024年, 学士課程, 農学部
■ Research Themes
  • 大型木質材料（CLT、LVL、MPP）を用いた橋梁用床版の開発
    科学研究費助成事業
    01 Apr. 2026 - 31 Mar. 2030
    佐々木 貴信
    日本学術振興会, 基盤研究(B), 北海道大学, 26K01029
  • Developments of waterproofing system and guardrail system of cross laminated timber for the bridge deck application.
    Grants-in-Aid for Scientific Research
    01 Apr. 2021 - 31 Mar. 2025
    佐々木 貴信; 後藤 文彦; 宮内 輝久
    本研究では、小規模な既設鋼橋の床版取替工事におけるCLT床版の実用化を目的として、①防腐処理方法の開発、②防護柵設置方法の検討、③橋梁の補修設計の提案を主たるテーマに研究を進めている。当該年度の主な研究成果を以下に示す。
    ①防腐処理方法の開発では、R4年度までに行った小型試験体を用いたプレインサイジング処理したCLTへの油性薬剤の浸潤度を評価結果に基づき、R5年度には加圧注入処理を行った実大レベルのCLT試験体（スギ，5層5プライ，150×1000×2000㎜）について検討した。加圧注入試験ではクレオソート油では表層10mmの範囲でほぼ100％の薬剤浸潤度、ナフテン酸銅では断面のほぼ100％の高い浸潤度が確認された。
    ②防護柵設置方法の検討では、経済性や橋梁の規模を考慮して、より簡便なガードレールを防護柵として設置する方法を検討し、R3年度に防護柵支柱の水平載荷試験を実施している。
    この水平載荷試験結果をFEM（有限要素法）解析の結果と比較して実用化に向けて改良案の検討を研究分担者の後藤が中心に行い、その検証としてR5年度に同様の水平載荷試験を行った。これらのその成果は査読着き論文として投稿し掲載された。
    ③橋梁の補修設計の提案では、床版取替の対象となる既設の橋梁を想定し、補修設計を行うための設計資料の整備を目指し、２級林道用のCLT床版の試設計を行い、CLT床版用の設計式を導く方法を提案している。これらの設計法の検証として、R4年度に架設工事が行われたCLT床版を用いた林道橋（北海道赤平市）を対象に車両載荷試験を行った。設計荷重相当のダンプトラックを橋梁上に載荷してCLT床版や橋梁全体の変形やひずみを測定した。これらの実験結果は土木学会等で発表する予定である。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23K20963
  • Developments of waterproofing system and guardrail system of cross laminated timber for the bridge deck application.
    Grants-in-Aid for Scientific Research
    01 Apr. 2021 - 31 Mar. 2025
    佐々木 貴信; 後藤 文彦; 宮内 輝久
    本研究では、小規模な既設鋼橋の床版取替工事におけるCLT床版の実用化を目的として、CLT（直交集成板）の防水・防腐処理技術の開発と、CLT床版への防護柵の設置方法の検討を行うものである。
    2021年度には、CLTのインサイジング処理技術と油性防腐剤を用いた防腐処理方法の検討を行った。最外層のラミナの表面をインサイジング処理したカラマツおよびトドマツラミナを用いて製造したCLTから切り出した試験体（5層5プライ、厚さ150×幅420×長さ800㎜）に対し、クレオソート油およびナフテン酸銅を用いた加圧注入処理を行った。その結果、カラマツに対する注入量はトドマツよりも低く、また、いずれも、スギCLTを用いて行った場合よりも低かった。また、同様にクレオソート油またはナフテン酸銅で加圧注入処理されたスギCLT試験体（90×280×280㎜）を用いて吸水性を調べたところ、処理により吸水が抑えられ、寸法変化もある程度抑えられることが確認された。
    CLT床版への防護柵の設置方法の検討では、防護柵支柱をCLTに固定する方法として、LSB（ラグスクルーボルト）の可能性を検討した。仕様の異なるLSBについて引抜試験を行い、最適な直径と長さを見いだした。次に、設計荷重40kN程度の防護柵を想定した鋼製支柱をスギCLT（5層5プライ、厚さ150×幅950×長さ980㎜）にLSBおよびボルトで固定した試験体を製作し水平載荷試験を行った。防護柵支柱に設計荷重相当の荷重を作用させ、十分に変形してもボルト接合と比較してもLSBの引抜変位は大差なく、十分な耐荷力を示した。LSB接合では、LSBの打込み後にCLTの被覆防水処理を行うことができ、処理を傷めない接合が可能となり防水効果の向上が期待できる。これを検証するために、今後、各種の材料で被覆処理したCLTの耐水性試験を行い、実用化の検討を進める計画である。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21H01412
  • 安全性・メンテナンス性に考慮したオンサイト木橋の改良
    科学研究費助成事業
    01 Apr. 2020 - 31 Mar. 2023
    後藤 文彦; 佐々木 貴信; 野田 龍
    2021年度は、PC鋼棒による横締めを行わないオンサイト木橋の新しい形式についての検討を行った。これまで、角材の横締めにより構成されていたボックス桁の上下フランジ部を、CLTパネルで代替する構造についてFEMモデルによる検討を行った。これは上下に配置したCLTパネルを２つの鋼I桁にボルトで接合し、ボックス桁を構成する新しいモデルである。CLTパネルは、強軸、弱軸2方向の曲げに対してそれぞれある程度の剛性を有するものの、仮に強軸方向を通常 床版として使用される際の幅員方向ではなく、橋軸方向の剛性を高めるように橋軸方向に向けたとしても、角材の軸方向の剛性の半分程度の剛性しか有さない。このため、CLTパネルを用いたモデルをボックス桁として構成した場合に、従来型の角材を横締めするタイプのオンサイト木橋と同程度の断面性能を有するかどうかについて、３次元有限要素モデルにより検討を行った。その結果、従来の角材を横締めするタイプと同程度の大きさの断面で構成した場合、CLTパネルを用いたモデルでは、剛性はわずかに低下するものの、CLTパネルの強軸方向を橋軸方向に配置するならば、従来タイプと比較してそれほど遜色のない結果が得られた。このことから、今回のCLTパネルを用いたモデルは、オンサイト木橋を構成する木・鋼ハイブリッド断面によるボックス桁構造として、PC鋼棒による横締めを用いない有力な代替候補となる可能性が示された。
    日本学術振興会, 基盤研究(C), 秋田大学, 20K04658
  • Evaluation and optimization of joint performance of the cross laminated timber (CLT) with bricks-joint
    Grants-in-Aid for Scientific Research
    01 Apr. 2018 - 31 Mar. 2022
    Yamauchi Hidefumi
    The study aimed to evaluate and optimize the joint performance of bricks-joint CLTs, which give uneven joint structure reminiscent of toy blocks at the end of the CLTs.
    As a result of various studies, it was clarified that by changing the end joint structure from butt-joint to scarf-joint, it is clarify the conditions for improving the joining performance to the extent that there is no practical problem, and it could be greatly reduced the labor at the time of jointing, too. Furthermore, the effect of shifting the joint position of the lamina in the plane direction of CLT was evaluated. As a result that by optimizing the combined use of scarf-joint and the shifting, it was cleared that there was conditions under which joined CLTs perform as well as CLT without joint.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Akita Prefectural University, 18K05769
  • Development of repairing system of short span bridge using cross laminated timber slabs
    Grants-in-Aid for Scientific Research
    01 Apr. 2017 - 31 Mar. 2020
    Sasaki Takanobu
    Cross laminated timber (CLT) is a new type of engineered wood panel consist of several layers of structural lumber boards stacked crosswise at 90° angles and glued together on their faces. It is possible to produce CLT panels of 3 m wide, 12 m long, and 270 mm thick. CLT is light-weight material which the unit weight of CLT made of Japanese cedar is about 1/6 of reinforced concrete, therefore it's has advantage in terms of the transport and construction works. The authors consider using CLT elements for bridge deck replacement instead of a concrete deck slab.
    In this study, we developed the structure of the gird rail to use for CLT deck and the new physical preservative treatment system. For the latter, rather than using conventional chemical treatments to prevent decay, we developed methods such as covering the entire CLT with an FPR sheet or embedding it in polymer cement to physically gain waterproofing and preservative effects.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), 17K06514
  • Development of general-purpose emergency bridges adapted for diverse nature and climate environment
    Grants-in-Aid for Scientific Research
    21 Oct. 2016 - 31 Mar. 2019
    GOTOU Humihiko
    Extending the concept of the on-site timber bridge, which has been in practical use, we proposed a new type bridge with flanges in joint parts, which enable spans longer than 10m.
    It is important to clarify the local buckling behavior, which can occur in longer and slender members under snow load height over 3m.
    We made 3D models for the bridges and analyzed local bucking behavior under the snow load. We proposed the diagrams, which help to check the risk of buckling and showed that local buckling does not occur for the span length of 21m (longest case).
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Akita University, 16K01324
  • Development of canal walls using timber pile foundations and fieldstones
    Grants-in-Aid for Scientific Research
    01 Apr. 2014 - 31 Mar. 2017
    SASAKI Takanobu
    Nature-friendly canal walls that combine a timber pile foundation with fieldstone walls were built in Ogata-village, Akita. The timber piles, which provide a foundation, were 4 m long and 160 mm in diameter. First, the piles were driven into the bottom of the canal at intervals of 800 to 1000 mm, after which horizontal members were connected to the top of the timber piles using steel pins. This nature-friendly canal wall construction method, combining timber pile foundations and fieldstone walls is economical in comparison with the conventional method using steel sheet piles and concrete blocks. Furthermore, this method produces an attractive result. The safety of the canal wall construction method proposed in this study was demonstrated by a loading test after construction, as well as the results of monitoring of the behavior of the timber piles and fieldstone.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Akita Prefectural University, 26450346
  • Development of upgrade timber emergency bridge kits corresponding to reconstruction road map
    Grants-in-Aid for Scientific Research
    01 Apr. 2013 - 31 Mar. 2016
    GOTOU Humihiko; SASAKI Takanobu; WATANABE Chiaki; HORIE Yasushi
    We installed two timber stress-laminated box-beam bridges ordered by Akita Prefecture in 2013 and 2015 so that the dilapidated existing bridges in heavy snowfall mountains were upgraded.
    Since the restrained deflection due to heavy snowfall was recognized from the fixed point camera images, we improved the fixing and setting methods of the stiffeners and confirmed the practicality of the bridges which are applicable to unforgiving environments like heavy snowfall mountains.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Akita University, 25350502
  • A delaying and neutralizing procedure of bending brittle fracture of glulam beam with inserted steel plates
    Grants-in-Aid for Scientific Research
    2003 - 2005
    USUKI Seizo; GOTOU Fumihiko; SASAKI Takanobu
    The glulam beams having a cross section of 120mm × 60mm and a span of 216cm (the span by beam height equals 18) are arranged and the steel plates having a section of 40mm × 9mm are inserted to upper slits of beams and are glued with epoxy resin. On the other hand, one steel plate having the same section as upper steel plate is inserted and glued to lower slits of beams (Type-A), two steel plates having a section of 40mm × 4.5mm are inserted and glued to those (Type-B) and finally, three steel plates having a section of 40mm × 3mm are inserted and glued to those (Type-C). As a results, three types of glulam beams having different inserted steel plate layout in tension sides of beams are provided and tested under consentrated load at mid span.
    Then, these have same bending rigidity, as they have same cross sectional area of steel plates in tension sides of beams. The average ultimate load of three Type-A beams is 25.9kN, that of Type-B is 27.1kN and that of Type-C is 30.7kN, respectively. The different of these ultimate loads are depending to yield points of steel plates. This is no doubt, as the load-srain curves of Type-A, B, C reveal non-linearity at different loading points of the curves. The ductile capacity is also follow the order of Type-C, Type-B and Type-A.
    As a conclusion, if the glulam beams have same bending rigidity, the type having multiple inserted steel plates in tension side are superior in engineering ability.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Akita University, 15560392
  • Full-Scale Dynamic Experimental Inspection of Fundamental Techniques Creating Near Future Type of Traditional Wooden Construction Sustainable to Earthquakes.
    Grants-in-Aid for Scientific Research
    2001 - 2003
    SUZUKI Tamotsu; IIJIMA Yasuo; SASAKI Takanobu; GOTO Masami; MURAKAMI Masahide; KITAHARA Akio
    (1)The following fundamental principle was set up for creating a near future type of traditional wooden construction sustainable to any earthquake: 1) to utilize the vibration absorbing, isolating, and controlling mechanisms which exist originally in wooden structures, 2) to apply some kinds of modern simple technique to the construction, and thus, 3) to produce high efficient function of those resistant mechanisms.
    (2)Several elementary basic techniques to build structures, suitable to the above-mentioned principle, were devised and realized as for materials and constructions of wall, connection, frame, and foundation.
    (3)The representatives of such basic techniques are cylindrical Laminated Veneer Lumber, improved soil wall with wood lattice, wooden wall made of thick Sugi plates, wooden tenon joint using adhesive, skeleton frame with improved wooden connections, and stone and buried girder foundation system supporting upper-structure without connecting. All of them are resulted from Japanese traditional construction skills and wisdoms. And their validity and usefulness were examined through static tests of componential specimens and a full-scale model house, both of which included each or couple of those techniques.
    (4)Based on the various results of the previous study, two types of three dimensional unit frame, designated as 'soil wall and Sugi wood plate wall systems', were built and tested on the shaking table in the Institute. The fundamental dynamic characteristics of these wall systems were finally investigated. Thus, the validity and usefulness for the effects of accumulating the devised elementary techniques were satisfactorily confirmed through both tests of three dimensional frames and a full-scale building
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Akita Prefectural University, 13450225
  • Bending Capacity of Timber Beam Stiffened with Orthotropic Sieel Deck
    Grants-in-Aid for Scientific Research
    2000 - 2002
    USUKI Seizo; SASAKI Takanobu
    The bending capacity of a doubly symmetric composite timber beam is invesligated. The composite beam consists of giued-laminated timber with a rectangular cross section and two robbed steel plates inserted vertically at the top and bottom surfaces of timber, the ribbed plates and timber being joined together with epoxy resin. The yield moment, as well as the moment at which the cross section of ribbed steel plates are wholly plastic and the moment at which the edge stress of timber reaches bending strength are presented. The deflection corresponding to these moments at mid-span of a simple beam are also presented and copmpared with the experimental ones.
    The bending capacity of a composite bridge consisting of glued-laminated double timber beams and orthotropic steel deck is also investigated. The ribbed plates welded to steel deck are inserted to upper slits of beams and the ribbed plates are also inserted to lower slits of beams and these are joined together with epoxy resin. The yield moment, She lower rib wholly plastic moment and the brittle failure moment of beam are calculated by using the composite beam theory considering effects of shear deformation. The 1/3 reduced models having the span length of 5m and the roadway width of 1.67m were built up and tested under one point loading at mid span. The results were compared with predicted values. The decomposition of timber beam and ribbed steel plates were observed just before final state.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Akita University, 12650469
  • Structural joints with glued-in hardwad dowels
    Grants-in-Aid for Scientific Research
    1999 - 2000
    KOIZUMI Akio; HIRAI Takuro; JENSEN J.l.; SASAKI Takanobu
    Moment-resisting properties of post-to-sill joints made with glued-in hard-wood dowels were studied. Dowels of 12 mm in diameter made of hard maple are glued into post and sill members of sugi glulam with polyurethane adhesives to make joint specimens. Assuming that joints fail by withdrawal of dowels, moment-resisting strength and stiffness of joints were predicted by considering withdrawal force of dowels and compressive stress perpendicular to the grain in a sill members. Withdrawal strength and stiffness of single dowels were derived from previous experiments. Tests of joint specimens showed the possibility of controlling moment-resisting strength and stiffness by choosing proper arrangements of dowels in the joint area. The greatest strength was obtained by arranging dowels in the outer section of the joint area. In this case, predictions of strength and stiffness agreed well with experimental results. Strength and stiffness for joints with dowels in the inner section were overestimated by the calculations. The reason may be explained as follows : The compressive stress at the edge of the joint area exceeded the elastic limit and the neutral axis moved toward the tension side, which caused a larger pull-out force for the dowels than calculated assuming elastic behavior on the compression side. Furthermore, bending forces would act on dowels when a joint rotated significantly. Racking tests of dowelconnected frames were conducted to verify their performance as shear walls. The test results of frame specimens without braces showed good agreement between experimental strengths and calculated estimations based on moment distribution among joints assuming rigid-joint frames. Test specimens with braces failed by duckling of the braces, which showed sufficient withdrawal strength of the dowels comparable to metal fastners for post-to-sill joints.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), 11660170
  • Development of the remote monitoring system for timber bridges using a internet.
    Grants-in-Aid for Scientific Research
    1998 - 1999
    SASAKI Takanobu; KOIZUMI Akio; IIJIMA Yasuo; USAKI Seizo; KOMATSU Kohei; OKAZAKI Yasuo
    The glued laminated timber (glulam) tied arch bridge "Hyakume-ishi" located on a forest roadway in Akita Prefecture, Japan was completed in March 1999. The bridge also used using Japanese cedar grown in the prefecture. The bridge length is 20.9m with span length is 20.0m. The clear roadway width is 5m. In this study, a remote monitoring system for the long term measurement of the stress losses under environmental changes of the bridge in service was developed. The data from the measuring device that consists of six load-cells, a thermometer and a hygrometer are sent to a central station about 100 kilometers away automatically using a telephone line and modem at constant time intervals. These measured data were corrected using the remote monitoring control program. Temperature and humidity of the backside of the bridge are simultaneously monitored. The data are analyzed to determine the characteristics of this type of bridge during actual service. Results showed that the bar force loss already reached almost the maximum 60% level within less than a year. One possible reason is the use of a water-borne preservative for the preliminary pressure treatment of the glulam members. Changes in humidity, either increase or decrease, cause creep in wood and wood products. This effect is known as mechano-sorptive creep.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), 10556041
  • 木造車道橋の静的および動的挙動特性に関する実験的研究
    科学研究費助成事業
    1997 - 1998
    佐々木 貴信
    本研究では、「木橋の静的および動的挙動特性」に主眼をおき、これまで皆無に近かった、たわみ特性、振動特性等に関する諸データを収集することを目的とし、ダンプトラックを用いての車両走行試験を、既存のまたは今後架設される他の木橋について実施することを計画した。9年度までに、長野県内の木橋2橋について、20tfのダンプトラック2台を使用して、車両走行試験を行い静的および動的挙動特性に関する各種のデータを得た。
    10年度にはこれらの実験データや、既に報告されている木橋の振動特性に関するデータをもとに、木橋の動的特性について鋼橋やコンクリート橋との比較を行った。その結果、近代の木橋は道路橋として十分な剛性や強度を有していることが明らかになった。減衰定数に関しては鋼橋やコンクリート橋に比べて若干大きな値を示しており、木橋が高い減衰性能を有していることが確認された。
    衝撃係数に関しては、木橋の設計衝撃係数0.25を下回るような結果が得られた木橋もあった。鋼橋やコンクリート橋では、橋長によって衝撃係数が決定されるが、木橋の場合には一律に0.25とされている。これに対し、カナダやヨーロッパの木橋の基準では、橋長によって設計衝撃係数が決定されている。一般に、橋長が長くなると、衝撃係数は小さくなるため、長スパンの木橋の場合には、現行の設計では過剰な安全率を有する結果になってしまう。近年、ますます長スパンかする傾向にある近代木橋に対応した設計衝撃係数の提案というものはなされておらず、また、本研究においても基準案を提案するまでには至っていない。したがって、今後さらに多くの実測データを蓄積する必要がある。10年度中に秋田県内に完成する、現在架設中の木橋についても本研究と同種の車両走行試験を行う計画である。
    日本学術振興会, 奨励研究(A), 秋田県立農業短期大学, 09760164
  • Development of Machines for Simultaneous Lumbering and Flaking and for OSB Manufacture
    Grants-in-Aid for Scientific Research
    1997 - 1998
    SASAKI Hikaru; IIJIMA Yasuo; YAMAUCHI Hidefumi; TAMURA Yasuo; KOIZUMI Akio; SAITOH Katumi
    1) Although ordinary lumbering is conducted along the longitudinal axis of a log with saws, this machine was able to process logs in the lateral direction, therefore, lumbering rate increased considerably. Since drum flakers were used for the saws, a lot of strand-type wood flakes (strands) for OSB were produced simultaneously with the lumbering.
    2) Although, the machine could press logs of only 300 mm in length and less than 300 mm in diameter, it is still good enough to provide every information useful to design a full-scale machine for industrial practice.
    3) The cutting time for this machine is proportional to the speed of rotation and the diameter of the drums. This was verified in an experiment conducted at full capacity which showed that the cutting time was only 3 sec for a log with 300 mm in diameter.
    4) In this case, the average moisture content of the flakes at the collection chamber was about 150%. At this condition the power requirement per unit weight of flake production was estimated at 2 kWh/ton (wet) or 5 kWh/ton (dry). The variation in the thickness of the resulting planks after one-pass cutting was less than 0.5mm or less than 0.5%. This shows that lumbers with smooth surface and uniform thickness can be produced with this Flaking Mill.
    5) The Flaking Mill developed was highly efficient and extremely fast for the processing of sugi plantation thinnings into dimension lumber and strands for OSB production. OSBs manufactured from the strands had very good properties even at low density. These could be used as alternatives to structural plywoods.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), 09556040
  • Strength Effects of Connecting Methods and the Reinforcements between Cylindrical LVL Posts and Horizontal Members
    Grants-in-Aid for Scientific Research
    1996 - 1998
    SASAKI Hikaru; IIJIMA Yasuo; YAMAUCHI Hidefumi; TAMURA Yasuo; KOIZUMI Akio; SUZUKI Tamotsu
    1) The most reasonable method of manufacturing cylindrical LVL was determined. After many trials, a method to produce high quality products with high productivity and low production costs was found.
    2) A number of 300mm-diameter Cylindrical LVLs were manufactured from 26mm-thick pine veneers and resorcinol resin adhesive using this method. These products were used as structural columns to test joints with beams. The test results showed that joints with special metal connectors have enough strength for practical application.
    3) Cylindrical LVL products with reinforcements of glulam cores at both ends for the traditional tongue-and-groove connections performed excellently in the earthquake resistance tests conducted on an actual size house.
    4) The stresses at the interface between the inner surface of the cylindrical LVL and the glulam core were analyzed using the Finite Element Method.
    5)The industrial application of the technology developed was investigated.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), 08456091
  • プレストレスLVL床版橋の長期雪荷重によるクリープ変形
    科学研究費助成事業
    1996 - 1996
    佐々木 貴信
    目的
    スギLVLを用いたプレストレス床版橋について、死荷重及び雪荷重による長期的な変位挙動を確認することを目的として、実橋の1/2スケールの床版橋についてアスファルト舗装と雪を想定した荷重を載荷しクリープ試験を行った。プレストレス床版橋の構造は幅員方向に並べたラミナ(製材、集成材、LVL)を、床版厚の中心で貫通した複数のプレストレス鋼棒(PS鋼棒)によって緊張することで、ラミナ全体を一体化させトラック等の重荷重に耐えるものである。
    実験
    実験はPS鋼棒の緊張力の低下が落ち着いてから行った。クリープの対象とした荷重は舗装厚7cmのアスファルト(161kgf/m^2)と設計雪荷重(100kgf/m^2)で、実橋と作用応力が等しくなるように2.87tfのおもりを床版全体に分布するように載荷した。測定は、支間中央の鉛直変位、PS鋼棒の緊張力、温湿度のそれぞれの経時変化を定期的に測定した。
    結果及び考察
    鉛直変位の変動は短期間内では、温湿度の変動と定性的に類似の傾向を示すmechano-sorptive変形挙動を示した。また、長期的にみた場合、室温の変化に伴い、冬期間では変位は徐々に減少し、逆に夏期間には変位増加が認められた。これらの温湿度との関係をさらに明らかにするために、今後は恒温恒湿状態での、モデル実験が必要であると思われる。また、PS鋼棒のプレストレス力の経時変化に伴う、床版面内のクリープ現象については、部分モデルを作製しその変動挙動を確認したところ、四要素の粘弾性モデルを用いることで定量的に説明できることが明らかになった。
    日本学術振興会, 奨励研究(A), 秋田県立農業短期大学, 08760170
■ Industrial Property Rights
  • シート被覆木材
    Patent right, 佐々木 貴信
    特願2016-008591, 20 Jan. 2016
    特開2017-128025, 27 Jul. 2017
  • ＣＬＴ同士を接続可能としたＣＬＴ
    Patent right, 佐々木 貴信
    特願2016-254513, 27 Dec. 2016
    特開2017-119436, 06 Jul. 2017
  • プレストレス木床版を用いた木橋
    Patent right, 佐々木 貴信
    特願2010-047202, 03 Mar. 2010
    特許5464350
    09 Apr. 2014