掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者,　責任著者   掲載種別：研究論文（学術雑誌）  

担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

DOI： 10.11273/jssc.29.114_37

掲載種別：研究論文（学術雑誌）  

DOI： 10.11273/jssc.29.113_1

J-GLOBAL

掲載種別：研究論文（学術雑誌）  

DOI： 10.11532/structcivil.68A.505

掲載種別：研究論文（学術雑誌）  

既往の研究では乾燥処理をしたGFRPに，-5~40℃（1サイクル14時間）の熱サイクルを70回以上与えると引張強度および曲げ強度が低下すると示されているが，この熱付与時間に関する規定や乾燥処理の有無による影響はよくわかっていない．そこで本研究では，熱付与時間と含水量に着目し，GFRPの一方向材と二方向材を対象に乾燥処理の有無および1サイクル時間を変化させた熱サイクル付与試験を行う．熱付与後，引張試験と曲げ試験を行い，対象材料の機械的性質の変化とその要因を解明することを目的としている．試験の結果，乾燥処理をしない場合は，試験体の水分量の影響により，引張・曲げともに熱付与時間による機械的性質の明瞭な変化は見られず，乾燥処理をした場合には，熱付与時間が強度に影響を与える可能性があることがわかった．

DOI： 10.2208/jscejseee.78.5_ii_42

J-GLOBAL

担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

This study aimed to clarify the performance of high-strength bolted joints for thin-walled glass-fiber-reinforced polymer (GFRP) members by conducting slip tests and long-term relaxation tests. The parameters of the slip test were the FRP surface treatment, bolt axial force, and bolt hole diameter. Relaxation characteristics might also be affected by variations in fiber content based on differences in production lots. Hence, samples from different production lots were taken. However, in these tests, the influence of all parameters was relatively minimal. One year after tightening, the axial force reduction gradually subsided and tended toward convergence. However, because it is difficult to determine convergence based on temperature changes, long-term measurements will continue. In the slip tests, the highest slip coefficient was obtained when the GFRP was coated with fluoroplastic and the connecting plates were treated with phosphate. This study proposes a design slip coefficient for GFRP high-strength bolted friction joints.

掲載種別：研究論文（学術雑誌）  

High-strength frictional bolted joints in civil engineering structures are corroded due to the thin coating thickness at the corners of the bolts and the nuts. A sandglass-shaped bolt composed of a countersunk head bolt and countersunk sleeve nut is being developed to secure the constant coating thickness and prevent corrosion. As its thread diameter is smaller than the usual one by the mechanism, an ultra-high-strength material must be applied to require the same fastening capacity as conventional bolts while considering stress concentration related to hydrogen embrittlement. This paper proposes a novel thread shape for the prototype of the sandglass-shaped bolt, whose stress concentration factor can be reduced by more than 30% current standard thread in Japan, focused on the magnitude of stress concentration. Moreover, FE analysis reveals the general fastening performance by comparing with or without the proposed thread.

掲載種別：研究論文（学術雑誌）  

Rivet joints are widely applied in the connections of steel bridges prior to 1950 owing to their tightness and strength. Some rivets become loosened or corroded after repeated loading and long-term usage. Previous studies indicate that replacing riveted joints with a high-strength bolt to achieve friction may be the best approach for repairing a riveted joint. However, for a long riveted joint, which has an uneven load distribution, the removal of individual rivets may overload the other rivets. This study focuses on long riveted joints at the bottom flange of an actual riveted bridge. The load redistribution mechanism involved when the rivet is removed under a dead load is investigated by performing a finite element (FE) simulation. The FE analysis results show that when a rivet is replaced by a bolt, the rivet's load transferring ability is affected more by rivets near the bolts, whereas more distant rivets pose almost no effects.

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.istruc.2020.12.003

掲載種別：研究論文（学術雑誌）  

DOI： 10.2208/jscejseee.77.1_13

掲載種別：研究論文（学術雑誌）  

J-GLOBAL

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

<p>This study presents basic data on temperature dependence of mechanical properties of GFRP materials. First, coupon specimens are collected from GFRP plates by hand lay-up molding. Then, material tests are conducted under different temperature environments to clarify the relationship between temperature and tensile properties. In order to receive repeated temperature histories in the actual environment, a tensile test was also performed on the cooled material after heating. As a result, it was found that the tensile performance of GFRP decreases as the temperature of the specimen increases. It was also found that the specimens that had undergone the cooling process after heating had the same tensile performance as the initial state.</p>

DOI： 10.11532/structcivil.66A.886

CiNii Article

掲載種別：研究論文（学術雑誌）  

<p> 繊維強化ポリマー（FRP）は，高強度・高耐食性・軽量といった優れた性能を有しており，施工性や維持管理の観点から土木構造物への適用が進められている．FRPの特徴としては，繊維・樹脂材料からなる複合材料であり，自由度の高い材料設計が可能である．一方で，複数の材料から構成されることから，材料物性値にばらつきを有するため，部材性能を統計的に評価を行う必要がある．本論文では，ガラス繊維強化ポリマー（GFRP）溝形部材からクーポン試験片を採取し，引張・圧縮試験を実施して，GFRP部材の材料特性のばらつきを評価する．また，それらの試験結果を用いてモンテカルロシミュレーションを実施し，FRP構造用溝形部材の圧縮・曲げ性能について統計的に評価する．</p>

DOI： 10.2208/jscejseee.76.1_110

CiNii Article

掲載種別：研究論文（学術雑誌）  

<p>The purpose of this study is to elucidate the effect of variations in material properties of GFRP materials on the response performance of pedestrian bridges. First, the static loading test and the vibration test are performed on the actual GFRP pedestrian girder bridge assembled in the factory before completion, and the response performance of the bridge is evaluated. Then, the response analysis of the actual bridge was performed using the constructed finite element model. In addition, the performance of the bridge is statistically evaluated by conducting Monte Carlo simulation assuming the variation of material properties.</p>

DOI： 10.11532/structcivil.66A.329

CiNii Article

掲載種別：研究論文（学術雑誌）  

This study aims to investigate how local damage and varying temperature affect changes in vibration characteristics and structural behavior of a steel plate girder bridge. A damage experiment on a real bridge was conducted. Artificial cracks were applied to the lower flange and web plate near base plate of shoe. Observations showed that the 1st bending frequency increased due to artificial damage even though the 2nd bending frequency and 3rd bending frequency decreased. Finite element model was constructed and updated to clarify the cause of such frequency changes for each mode. FE analysis demonstrated that the 1st bending mode was more sensitive to changes in the boundary condition than changes in stiffness of the girder. The FE analysis is also showed that structural behaviors of supports were affected by stiffness reduction of the girder due to local damage as well as by thermal expansion due to varying temperature.

DOI： 10.1201/9780429343292-37

掲載種別：研究論文（学術雑誌）  

GFRP is a composite material which has high specific strength, high durability, brittleness and anisotropy. It is adopted to a primary member of civil structures such as water gates and pedestrian bridges. However, a repairing method for damaged GFRP has not been established yet. Therefore, the focus of this study is on GFRP repairing, and bonding repair plates on the both sides of GFRP plate is considered as a repairing method. In a previous study, it was confirmed that stress concentration occurred by bonding repair plate on the GFRP. Therefore, this study aims to investigate the reduction method of stress concentration at the end of repair plates. Firstly, by altering shapes of the end of the repair plates, the reduction of stress concentration was evaluated using FE analysis. Secondly, uniaxial tensile tests were conducted. In the experiment, both Intact and repair plate-bonded specimens were prepared.

DOI： 10.1201/9780429343292-104

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

<p>本研究では，PC 橋梁における橋梁の耐荷性能および振動特性の変化の関係性を明らかにすることを目的として，実際の PC 橋梁を対象として，油圧ジャッキを用いた現地耐荷力実験を行った．さらに，各載荷プロセスにおいて，ハンマーおよび車両走行による振動実験を行い，PC 橋梁の振動特性を明らかにした．各載荷プロセスにおける橋梁性能は，載荷試験から得られた荷重−変位曲線より計算したエネルギー吸収能を用いて評価し，振動実験から得られた振動特性との関係性を考察した．その結果，曲げ 2 次モードの固有振動数がエネルギー吸収能と非常に高い相関を示し，振動ヘルスモニタリングにおける特徴量としての有用性があることがわかった．</p>

DOI： 10.2208/jscejam.75.2_I_51

CiNii Article

掲載種別：研究論文（学術雑誌）  

<p> 本論文では，FRP材料・部材における物性値の評価方法を提示することを目的として，引抜成形法およびハンドレイアップ成形法によって製作されたガラス強化繊維ポリマー（GFRP）部材の引張特性について統計的な評価を試みた．まず，溝形断面を有するGFRP部材の各部位からクーポン試験片を採取して，引張試験により，断面内における積層要素の材料物性値を評価した．また，試験結果に基づきモンテカルロシミュレーションを実施し，部位ごとの材料物性値のばらつきが溝形断面を有する部材の引張性能にどの程度の影響を与えるのかを検証した．その結果，試験結果と比較して，溝形部材の強度は低く評価されるが，弾性係数は同程度であることを示した．</p>

DOI： 10.2208/jscejseee.75.293

CiNii Article

掲載種別：研究論文（学術雑誌）  

© 2019 9th International Conference on Structural Health Monitoring of Intelligent Infrastructure: Transferring Research into Practice, SHMII 2019 - Conference Proceedings. All rights reserved. This paper is intended to discuss changes in modal parameters due to artificial fatigue cracks that propagated from the base plate of bearings to the web plate of a steel plate girder bridge through vibration and damage experiments. During the experiments the bridge was excited by a moving vehicle and the resulting acceleration signals are used to identify modal parameters. First three bending modes and first two torsional modes were successfully identified. It was observed that identified natural frequencies were changed due to artificial fatigue cracks. However, the frequencies for the first bending and first torsional modes were increased due to the cracks, while the frequencies for other three modes were decreased due to the cracks. Observations from the static loading test showed that the longitudinal displacement at a support purely under vehicle loading was decreased as the crack propagates, which demonstrated that changes in boundary condition can be a major reason for the increase of the first bending and torsional modes due to damage. The sensitivity analysis for the change in the natural frequencies under varying spring constants showed that these two modes were more sensitive to the change in boundary condition than stiffness changes. On the other hands frequencies of other three modes were more sensitive to varying stiffness than change in the boundary condition.

掲載種別：研究論文（学術雑誌）  

<p>This paper presents the results of a real bridge field experiment, carried out on a glass fiber reinforced polymer (GFRP) pedestrian truss bridge of which nodes are reinforced with stainless steel plates. The aim of this paper is to identify the modal properties of this bridge by using both conventional techniques and a model updating algorithm. Pedestrian-induced vibrations are also measured and utilized to identify modal properties of the bridge. A stochastic subspace identification combined with stabilization diagram was utilized to identify modal properties of the bridge. Moreover, an FE model capable of reproducing experimental results was constructed using the cross-entropy method.</p>

DOI： 10.11532/structcivil.65A.317

CiNii Article

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

An experimental investigation was conducted to determine the damage and wave propagation characteristics in Glass Fibre Reinforced Polymer (GFRP) panels subjected to impact by steel balls at relatively low-velocities up to 91 ms(-1). While maintaining the same impact energy level, the influence of ball mass on panel response was studied. The effects of composite lay-up sequence and successive impacts were also investigated. The wave propagation characteristics, including wave types, wave velocities, wave attenuations, and strain rates, were extracted from dynamic strain records measured at various locations on the panels. The results showed that, for the same level of impact energy, the small ball mass produced larger deformation and delamination than the large ball mass. Additionally, the resistance to impact was influenced by the composite lay-up sequence of similar fibre weight fraction. Test panels subjected to successive impacts showed an increase in cumulative delamination areas, whereas the tests indicated that successive impacts had a little effect on the perforation limit of the test panels. The impact velocity showed a pronounced influence on the measured peak strains and strain rates. The flexural wave was the predominant wave system, propagating at different velocities in different directions. In proximity to the impact site, both flexural wave and indentation predominated over the transient response. In addition to the flexural wave, impact induced low amplitude tensile longitudinal waves of high velocity. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijimpeng.2017.08.007

掲載種別：研究論文（学術雑誌）  

本研究では鋼鈑桁橋を対象とした走行車両による振動実験を行い，人工損傷前後の橋梁の振動特性の変化について検討を行う．振動特性同定手法には確率部分空間法（SSI）を用いて，Stabilization Diagram（SD）により安定的な振動モードを抽出した．人工損傷として鋼鈑桁橋桁端部の亀裂を摸擬し，振動特性の確率分布の変化により異常検知の可能性が確認された．特に損傷による曲げ１次振動数の増加が観測され，同定される振動特性の変動のメカニズムを解明するために，損傷による境界条件の変化の固有振動数に対する感度解析を行った．損傷による曲げ1次振動数の増加の原因は，損傷による支承部の境界条件の変化である可能性が高いことが確認され，橋梁における疲労亀裂などの損傷を考慮する際には，支承部の機能についても十分把握することが重要であることがわかった．

DOI： 10.2208/jscejam.74.I_513

CiNii Article

掲載種別：研究論文（学術雑誌）  

本研究では，撤去予定の供用終了後の単純鋼鈑2主桁橋に対して，長期振動および支承部変位モニタリングと，橋梁点検作業車による静的載荷ならびに車両による走行実験を行い，既設橋梁の変形応答評価および振動特性を同定し，FEMによる数値解析の結果と比較検討を行う．また，FEモデルの再現性を高めるために，計測結果に基づき，Particle Filterを適用したFEモデルのアップデートを試みる．さらには，対象橋梁の撤去時に主桁およびコンクリート床版から採取したサンプルを用いて材料試験を行い，アップデート結果と比較検討を行う．その結果，長年供用された実橋梁は，長期供用による経年劣化で支承部等に機能低下を示した．また，そのような橋梁に対して，Particle Filterを用いたFEモデルアップデートを行うと，動的応答に対して再現性を高めることができた．

DOI： 10.2208/jscejam.74.I_705

CiNii Article

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

掲載種別：研究論文（学術雑誌）  

© 2017 Taylor & Francis Group, London. This paper presents the results of real bridge field experiment, carried out on a fiber reinforced polymer (FRP) pedestrian truss bridge of which nodes are reinforced with stainless steel plates. The aim of this paper is to identify the dynamic parameters of this bridge by using both conventional techniques and a model updating algorithm. In the field experiment, the bridge was instrumented with accelerometers at a number of locations on the bridge deck, recording both vertical and transverse vibrations. It was excited via jump tests at particular locations along its span and the resulting acceleration signals are used to identify dynamic parameters, such as the bridge mode shape, natural frequency and damping constant. Pedestrianinduced vibrations are also measured and utilized to identify dynamic parameters of the bridge. For a complete analysis of the bridge, a numerical model of the FRP bridge is created whose properties are calibrated utilizing a model updating algorithm. Comparable frequencies and mode shapes to those from the experiment were obtained by the FE models considering the reinforcement by increasing elastic modulus at every node of the bridge by stainless steel plate. Moreover, considering boundary conditions at both ends as fixed in the model resulted in modal properties comparable/similar to those from the experiment. This study also demonstrated that the effect of reinforcement and boundary conditions must be properly considered in an FE model to analyze real behavior of the FRP bridge.

掲載種別：研究論文（学術雑誌）  

本研究では，FRP歩道橋の振動使用性を検証するため，加振実験から得た時系列データをもとに振動特性の推定を行う．また，気温変化が振動特性に及ぼす影響についても検討を行う．得られた加速度データに多次元ARモデルを適用し，推定された固有振動数からStabilization Diagram (SD)やStability Criteria (SC)を用いて，安定度の高い振動特性を抽出し，日常的使用に際しては使用性に問題がないことを確認した．また，気温変化により固有振動数が変化することを確認した．さらに，対象橋梁の固有振動解析の結果から，FRPのような軽量で高い強度を持つ材料を主材料とするトラス歩道橋の格点部補強による全体振動特性への影響が大きいことが分かった．格点部補強したFRP橋梁のFEモデル化には，補強による剛性の変化を正しく考慮する必要があることを示した．

DOI： 10.2208/jscejam.71.I_841

CiNii Article