Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jcsr.2023.108172

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.1080/15732479.2023.2218354

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.2208/jscejj.22-14003

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

DOI： 10.11532/structcivil.69A.202

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

Cantilever-suspended girder bridges are provided with intermediate hinges to reduce the effects of support settlement, including damage to hinge bearings caused by corrosion. To inspect, repair, and efficiently maintain these bridges, it is necessary to develop a monitoring technology. Accordingly, research have been conducted on a bridge response health-monitoring technology. In particular, the properties of bearings significantly influence the vibration characteristics of bridges. However, previous studies are yet to examine changes in bridge response due to the corrosion of hinge bearings. Using finite element analysis (FEA), this study aimed to investigate changes in the bridge response and modal parameters of cantilever-suspended girder bridges due to the corrosion damage levels of the hinge bearings. In the FEA, model-installed elastic spring was used shell elements. Furthermore, static and eigenvalue analyses were conducted. Static analysis demonstrated that the target bridge type exhibited more minor changes in its girder deflection due to bearing corrosion. In addition, the effects were quantitatively determined by altering the corrosion position of the hinge bearing in the bridge.

DOI： 10.1007/978-3-031-07258-1_75

Publishing type：Research paper (scientific journal)  

This study is intended to examine changes in modal parameters PC box girders due to defective grouting and failures in PC tendons through a laboratory experiment. In the laboratory experiment, three PC box girders, which have different damage scenarios, are examined. Both static loading and vibration experiments were conducted. The static loading experiment was performed with 4-point bending loading, and as vibration experiment, the impact hammer test was applied. This study investigates the relationship between the energy-based bending performance adopted as a load carrying capacity, and frequencies of the PC box girders. The static loading test showed that local cracks were dominated around the location of defective grouting and failure of PC tendons, and energy-based bending performance evaluated from load–displacement curve, decreased according to loading process. Frequencies of bending modes showed a decreasing tendency but showed fluctuations as loading progresses. A moderate correlation was observed between the energy-based bending performance and the natural frequency of 1st and 2nd bending modes.

DOI： 10.1007/978-3-030-93236-7_51

Publishing type：Research paper (scientific journal)  

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

The cast iron deck modules is a lightweight deck slab with excellent fatigue resistance. Friction joint are used to join the cast iron deck modules and the main girder. In this study, the effect of the structural type of the support member between the deck and the girder on the slip behavior and composite effect are investigated by FE analysis. As a result, the reduction rate of the slip coefficient due to the difference in shape of the support member between the cast iron deck module and the main girder was evaluated from the coefficient calculated by multiplying the friction coefficient by the correction coefficient of slip coefficient.

DOI： 10.11273/jssc.29.114_37

Publishing type：Research paper (scientific journal)  

Currently, the remaining riveted bridges are almost over 60 years old. Therefore, the rivets are corroded and loosen over time, deteriorated the condition of the bridges further. Previous studies have shown that replacing the riveted joints with a high-strength bolt for friction is considered the best approach to repairing the riveted joint in steel bridges. However, the current state is that the load transfer mechanism of the rivet and high-strength bolt friction joints is still unknown, and the load capacity of the combined joint has not been sufficiently discussed. Technical standards and design methods for repair have not been established. This study examined the load transfer mechanism and repair application range of the combined joint using the tensile test and FEM analysis.

DOI： 10.11273/jssc.29.113_1

J-GLOBAL

Publishing type：Research paper (scientific journal)  

DOI： 10.11532/structcivil.68A.505

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)  

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.

Publishing type：Research paper (scientific journal)  

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.

Publishing type：Research paper (scientific journal)  

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.

Publishing type：Research paper (scientific journal)  

FRP is a composite material made by mixing fiber such as glass with resin plastic to increase its strength. In this study, focusing on the temperature application time when performing the thermal cycle application test and the dry treatment before tensile and bending tests, the temperature cycle application test was conducted in which the time of one cycle was changed for GFRP using unsaturated polyester resin. After that, a tensile test and a flexural test are performed, and the purpose is to clarify the change in mechanical properties of the target material depending on the temperature application time and water content. As a result, it was found that tensile and bending properties were not affected much by the temperature application time in the case of non-drying treatment before the cyclic test, and that strength were affected by the thermal cycle in the case of drying treatment.

DOI： 10.2208/jscejseee.78.5_ii_42

J-GLOBAL

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.istruc.2020.12.003

Publishing type：Research paper (scientific journal)  

DOI： 10.2208/jscejseee.77.1_13

Publishing type：Research paper (scientific journal)  

J-GLOBAL

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

<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

Publishing type：Research paper (scientific journal)  

<p> Fiber Reinforced Polymer, FRP provides unique mechanical properties like high strength, high corrosion resistance, light weight and so on. FRP is a composite material composed of fiber/resin material, and it is possible to make versatile material design. Therefore, material properties like strength, elastic modulus may diverse. Statistical evaluation on material properties is needed to understand the response of FRP composites. This study aims to investigate compressive and bending properties of Glass Fiber Reinforced Polymer, GFRP manufactured as channel cross section by hand lay-up molding. Coupon test specimens which was cut from several locations of the GFRP channel members, are used in tensile and compressive test. Then, influences of changing the sampling positions of the specimens on the channel section against compressive and bending characteristics of them are discussed. In addition, Monte Carlo simulation is performed by using the tested data to evaluate compressive and bending statistically behavior of such a cross sections of the member.</p>

DOI： 10.2208/jscejseee.76.1_110

CiNii Article

Publishing type：Research paper (scientific journal)  

<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

Publishing type：Research paper (scientific journal)  

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

Publishing type：Research paper (scientific journal)  

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

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

<p>This study aims to examine how changes in load resistance capacity of a prestressed concrete bridge (PC bridge) influence on their modal properties. Static loading test was carried out under step-by-step loading until failure. In addition, forced vibration tests were carried out along the static loading test in order to assess the changes in the modal properties of the PC bridge with different health conditions. Energy performance calculated by load-displacement relation is used in order to estimate the structural performance of the PC bridge. Observations showed strong relationships between 2nd bending modal frequency and the level of structural performance. This indicates the usefulness of the 2nd bending mode in vibration-based bridge health monitoring for PC bridges.</p>

DOI： 10.2208/jscejam.75.2_I_51

CiNii Article

Publishing type：Research paper (scientific journal)  

<p> Fiber Reinforced Polymer (FRP) provides superior mechanical properties such high strength, high corrosion resistance, light weight etc.. As a volume fraction of fibers of FRP members influences significantly on the mechanical properties, that also depends on manufacturing process, therefore it is necessary to assess the material properties of different volume fraction of fibers to make sure the sectional capability enough with respect to the construction requirement.</p><p> This study aims to investigate tensile properties of Glass Fiber Reinforced Polymer (GFRP) manufactured as channel cross section by hand lay-up molding method and pultrusion molding method. Coupon test specimens which was cut from several locations of the GFRP channel members, are used in tensile test. Then, influences of changing the sampling positions of the specimens on the channel section against tensile strength, elastic modulus are discussed. In addition, Monte Carlo simulation is performed by using the statistical model of tested data to evaluate tensile properties in the entire cross sections of FRP member.</p>

DOI： 10.2208/jscejseee.75.293

CiNii Article

Publishing type：Research paper (scientific journal)  

© 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.

Publishing type：Research paper (scientific journal)  

<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

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

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

Publishing type：Research paper (scientific journal)  

This paper investigates changes in modal properties of a steel plate gider bridge due to artificial damages at the girder end. The modal properties are identified from vehicle-induced vibration data measured during the damage experiment on the bridge. Stochastic subsupace identification (SSI) is adopted to identify modal properties of the bridge, and dominant modes are extracted by means of stabilization diagram (SD). Observation demonstrates feasibility of damage detection from changes in modal properties. In order to examine the mechanism of the change, eigenvalue analysis utilizing finite element model with artificial damages is carried out. The mechanism of increasing frequency for the first bending mode is discussed by means of sesnsitivity analysis. Observations showed that the first bending mode is more greatly affected by changes in boundary condition due to damage than those changes in stiffness due to the damage. It is noted that in vibration-based bridge health monitoring it needs to consider the influence of change in boundary conditions at the supports.

DOI： 10.2208/jscejam.74.I_513

CiNii Article

Publishing type：Research paper (scientific journal)  

This paper discusses about on-site long term monitoring static and moving vehicle experiments on a composite twin girder bridge, and also investigates validity of an FE model constructed utilizing assumed structural properties from existing inspection documents as well as a visual inspection. The feasibility of a particle filter aided FE mode updating was also examined. In the model updating, the frequencies for the first and second bending modes were considered as design variables in the cost function.Those identified parameters from the model updating were compared with those from material experiments of which specimen were obtained formt the observation bridge. Observations showed that the roller support was not functioning due to deterioration. The updated FE model led to comparable results with those from field experiments.

DOI： 10.2208/jscejam.74.I_705

CiNii Article

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (scientific journal)  

© 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.

Publishing type：Research paper (scientific journal)  

This paper aims to investigate dynamic characteristics of an FRP truss pedestrian bridge in service by means of field vibration test and eigenvalue analysis. Pedestrian-induced vibrations are also measured and utilized to identify dynamic parameters of the bridge. A multivariate autoregressive model combined with stabilization diagram was utilized to identify modal properties of the bridge. Every node of the bridge is reinforced by stainless steel plate, and FE models considering the reinforcement by increasing Youg's modulus led to comparable frequencies and mode shapes to those from observed in the test. Moreover as a boundary condition at both ends fix model resulted in a comparable modal properties to experimental ones. This study also demonstrated that the effect of reinforcement and boundary conditions have to be properly considered in an FE model to analyaze real behaviour of the FRP bridge.

DOI： 10.2208/jscejam.71.I_841

CiNii Article

Authorship：Corresponding author  

DOI： 10.1201/9781003323020-67

DOI： 10.1201/9781003323020-63

DOI： 10.1201/9781003322641-206

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