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Affiliation |
Graduate School of Engineering Science Department of Systems Design Engineering Civil and Environmental Engineering Course |
GOTOU Humihiko
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Graduate School 【 display / non-display 】
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-1994.03
Tohoku University Graduate School, Division of Engineering Doctor's Course Completed
Campus Career 【 display / non-display 】
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2016.04-Now
Akita University Graduate School of Engineering Science Department of Systems Design Engineering Civil and Environmental Engineering Course Professor
Research Areas 【 display / non-display 】
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Social Infrastructure (Civil Engineering, Architecture, Disaster Prevention) / Structure engineering and earthquake engineering
Qualification acquired 【 display / non-display 】
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High School Teacher Specialization License (first and second kind,specialization)
Thesis for a degree 【 display / non-display 】
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A numerical technique for finite displacement problems of spacial frames
後藤文彦
1994.03
Single author
Research Achievements 【 display / non-display 】
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ESTIMATION OF VIBRATION CHARACTERISTICS OF MEOTO BRIDGE USING TABLETS WITH ACCELEROMETER
OIKAWA Daisuke, IWASAKI Keito, GOTOU Humihiko, AOKI Yukari
Japanese Journal of JSCE ( Japan Society of Civil Engineers ) 79 ( 7 ) n/a 2023 [Refereed]
Research paper (journal)
<p> It is important to understand vibration characteristics of bridges for estimation of the stiffness of the entire bridge. Generally equipments for vibration measurement are so expensive that everyone can not easily carry out the measurement using the equipments. In this study, we try vibration measurement with enough accuracy using tablet devices with accelerometer for a timber pedestrian bridge. For the most dominant vertically-antisymmetrical mode, error of measured value by the tablet devices to the numerically calculated value is about −4.0%. It shows the utility of vibration measurement using tablet devices with accelerometer. Besides, we discuss vibration characteristics for the measured timber pedestrian bridge, comparing values of natural frequency and of damping constant with the values obtained by the approximate equation for steel/concrete bridges.</p>
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STRUCTURAL PERFORMANCE AND SOUNDNESS EVALUATION OF AGING TIMBER ARCH HIGHWAY BRIDGE
Daisuke OIKAWA , The Late Genjiro SUGANUMA, Hideyuki HONDA and Humihiko GOTOU
Paper Reports on Wood Engineering ( Japan Society of Civil Engineers ) 19 72 - 79 2021.02 [Refereed]
Research paper (journal) Domestic Co-author
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DEGRADATION EVALUATION FOR MEMBERS OF A TIMBER BRIDGE, WHICH HAS BEEN IN SERVICE FOR 27 YEARS
OIKAWA Daisuke, FUJIWARA Arisa, GOTOU Humihiko, NODA Ryu, ISHIKURO Shun
Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures) ( Japan Society of Civil Engineers ) 77 ( 5 ) I_45 - I_54 2021 [Refereed]
Research paper (journal)
<p> In the history of glued timber bridges in Japan 34 years passed since the first bridge was built in 1987, which is much shorter than that of Europe and the United States. Data about stiffness and strength for glue-laminated timber bridges, which have been in service for more than 20 years and then replaced, have not been enough accumulated. In this study, we measure stiffness and strength for the members of Meoto Bridge replaced in 2020 by static/dynamic methods. As a result, the stiffness of the main structural members, such as arch ribs and stiffeners, was generally reduced by about 10%, while design stresses for the arch members and the floor girders are within the allowable stresses. Thus it is suggested that timber members, which have been in service for more than 20 years, have enough stiffness and strength.</p>
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NUMERICAL MODELIZATION OF TIMBER CONSTRUCTION MATERIALS CONSIDERING EFFECT OF KNOTS
KIMIJIMA Mami, AOKI Yukari, GOTOU Humihiko, VALIPOUR Hamid
Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures) ( Japan Society of Civil Engineers ) 77 ( 5 ) I_1 - I_7 2021 [Refereed]
Research paper (journal)
<p> Recently, "reduction of CO2 emission" has been raised as a most important topic needed to be solved immediately all over the world and each country has declared its reduction target. It is known that construction industry shared the highly CO2 emissions. Thus the new sustainable materials and/or construction methods must be developed as soon as possible. In this research, it is a final target to develop a new timbersteel hybrid beam as a new sustainable material. It is expected to use timbers for the construction site to reduce CO2 emissions than the ordinal materials such as concrete and steel, so that timbers are now one of the most recognized as a sustainable material. In order to replace the concrete to timbers, the timber beam should have the same or even stronger strength than concrete. Thus, in this research timber and steel are combined to improve the beam engineering characteristics.</p><p> In this paper, as a first step to develop such a sustainable beam, knots are presented in the timber beam, because it is found that knots on the beam showed significant reduction of the strength of the beam according to experimental researches. It is shown that knots on the beam have unique material properties and linearly analyzed using FEM. The results of beams are presented in this paper.</p>
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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) ( Japan Society of Civil Engineers ) 77 ( 5 ) I_55 - I_63 2021 [Refereed]
Research paper (journal)
<p> While CLT(Cross-Laminated-Timber), which is lightweight and is resistant to fatigue, is expected to apply to bridge deck, it is needed to joint commercially available railing on it. It is important to confirm the safety and to investigate the load bearing performance of the joint part between the railing post and the CLT deck. We show relatively simple modeling of the joint part using general-purpose 3D FEM tool and illustrate the numerical results. The modeling considering elasto-plasticity for both steel and CLT members seems to well simulate the sink deformation behavior of CLT.</p>
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Construction Examples of On-Site Timber Stress-Laminated Box-Beam Bridges
Tomohumi Huzita, Humihiko Gotou, Takanobu Sasaki, Ryu Noda
World Conference on Timber Engineering 2018.08
Research paper (international conference proceedings) Domestic Co-author
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Spacial Beam Analysis using Rotation Group and Rotational Angles about Three Axes
Humihiko Gotou, Takashi Kuwataka, Tetsuo Iwakuma
Advances in Computational Engineering & Sciences 1 837 - 842 2000.08
Research paper (international conference proceedings) Domestic Co-author
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Effect of repeated freeze-thaw cycles on the bending strength of wood
NODA Ryu, ISHIBASHI Kenya, GOTOU Humihiko
MOKUZAI HOZON (Wood Protection) ( JAPAN WOOD PRESERVING ASSOCIATION ) 46 ( 5 ) 251 - 258 2020 [Refereed]
Research paper (research society, symposium materials, etc.) Domestic Co-author
In civil engineering structures constructed in cold snowy regions such as Hokkaido or Tohoku, repeated freezing and thawing of the wooden materials may occur in winter. To understand how the strength of wood changes because of these freeze-thaw cycles, we evaluated the bending strength of both untreated and preservative-treated Sugi (<i>Cryptomeria japonica</i> D. Don) timber under five regimes of freeze-thaw cycles, while varying moisture content.<br>
Each cycle lasted 24 hours, and freeze-thaw regimes were composed of 0, 15, 45, 75, and 90 consecutive cycles. After each sample was subjected to a freeze-thaw regime, a bending test was carried out. There was almost no difference among the values of modulus of rupture or modulus of elasticity in samples subjected to different regimes. Moreover, as modulus of rupture and modulus of elasticity may increase after repeated freeze-thaw cycles, we concluded that the effect of the freeze-thaw cycles on the bending strength of Sugi timber is small. -
SENSITIVITY OF PARTIAL DECAY COMBINATIONS IN KAJIKA BRIDGE TO THE NATURAL FREQUENCIES
AONO Shion, OIKAWA Daisuke, GOTOU Humihiko, AOKI Yukari
Japanese Journal of JSCE ( Japan Society of Civil Engineers ) 81 ( 28 ) n/a 2025 [Refereed]
<p> In the inspection of existing bridges, the measurement of natural frequencies by vibration testing is relatively safe and easy. The natural frequencies can also be determined from analysis using a numerical model. In this study, the effect of partial decay on the natural frequencies of the deck arch bridge (Kajika Bridge) was investigated by subjecting arches and longitudinal girder joints to partial decay on a wooden upper arch carriageway bridge. As a result, it was confirmed that the natural frequency decreased with a reduction in Young's modulus, such that it could be regressed as a second-order polynomial or logarithm. Sensitivity analysis using the slope of the regression line of the reduction curve revealed that the antinode of the vibration in each vibration mode has high sensitivity, while the nodes have low sensitivity. It was also found that the sensitivity of the combination of decay points is almost equal to the sum of the magnitudes of the sensitivities of the decay at one point.</p>
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STIFFNESS AND VIBRATION SERVICEABILITY OF A MODERN TIMBER BRIDGE IN SERVICE FOR 26 YEARS
OIKAWA Daisuke, GOTOU Humihiko, AOKI Yukari
Japanese Journal of JSCE ( Japan Society of Civil Engineers ) 81 ( 28 ) n/a 2025 [Refereed]
<p> This study aims to clarify the stiffness and serviceability of a large section glued laminated timber girder bridge (Fukazawa Bridge) that has been in service for 26 years, natural frequency were measured using a tablet device. To confirm the reduction in bending stiffness due to aging, the natural frequencies were compared with those of a deemed newly constructed bridge calculated using a numerical analysis model. The vibration serviceability of the bridge was investigated by measuring the vibration response of the bridge during both solo and group walking(five person). The results confirmed that the bending stiffness of the entire bridge, calculated from the natural frequency, was reduced by approximately 10%. While the main girder deflection calculated by numerical analysis met the design specifications. In addition, no vibration response that would be uncomfortable for pedestrians was detected in terms of vibration serviceability. There was therefore confirmed that the modern timber bridge, which has been in service for 26 years, has a certain degree of usability.</p>
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Collapse behavior of steel railing post considering installation and replacement on CLT deck
Ogawa Koki, Gotou Humihiko, Sasaki Takanobu, Araki Shogo, Imai Makoto
Journal of Structural Engineering, A ( Japan Society of Civil Engineers ) 70A ( 0 ) 885 - 893 2024 [Refereed]
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INFLUENCE OF PARTIAL DECAY OF TIMBER BRIDGE MEMBERS ON NATURAL FREQUENCY
Oikawa D.
Journal of Japan Society of Civil Engineers ( Journal of Japan Society of Civil Engineers ) 12 ( 1 ) n/a 2024 [Refereed]
<p> In the inspection of existing bridges, measurement of natural frequency by vibration test is relatively safe and easy. The natural frequency can also be obtained from numerical analysis. In this study, we numerically investigated influence of partial decay of timber members, such as arches and joints between columns and girders, on the natural frequency of deck-type timber arch bridges. Concretely, we estimated sensitivity of the decay parts using the regression plots between natural frequency and magnification to the original Young’s modulus of the decay parts. The results showed that the decay at the part of the vibration antinode was highly sensitive, while the vibration node was low-sensitive. Lastly, we tried to estimate the actual state of decay of the target bridge adjusting parameters, such as Young’s modulus and specific weight, so that the natural frequency could fit the measured value.</p>
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SNOW REDUCTION PERFORMANCE OF DECK-OPENABLE TIMBER BRIDGE TO REDUCE SNOW LOADS
OIKAWA Daisuke, NODA Ryu, GOTOU Humihiko, AOKI Yukari, MORIOKA Yoshimi
Japanese Journal of JSCE ( Japan Society of Civil Engineers ) 80 ( 28 ) n/a 2024 [Refereed]
<p> Pedestrian bridges over mountainous areas in Akita Prefecture are in danger of falling because of heavy snow load during winter. The most trivial approach to prevent such snow trouble is increase stiffness of the bridges, while the approach is not so efficient for season-depending load increase. In this study we propose deck-openable timber bridge, whose deck is openable so that the opening can make snow fall down for winter period. In order to estimate the snow reduction performance of the deck-openable bridge, we carried out outdoor exposure test in one of the heaviest snowfall areas in Akita Prefecture.</p><p> As a result, the snow load was reduced by 50% compared to the case of the deck-closed form of the deck-openable bridge.</p>
◆Original paper【 display / non-display 】
◆International conference proceedings【 display / non-display 】
◆Research society, Symposium materials, etc.【 display / non-display 】
◆Other【 display / non-display 】
Grant-in-Aid for Scientific Research 【 display / non-display 】
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Grant-in-Aid for Scientific Research(C)
Project Year： 2023.04 - 2026.03
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Grant-in-Aid for Scientific Research(B)
Project Year： 2021.04 - 2025.03
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Grant-in-Aid for Scientific Research(C)
Project Year： 2020.04 - 2023.03
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Grant-in-Aid for Young Scientists(B)
Project Year： 2001.04 - 2003.03