Keigo Suzuki

• Doctor of Engineering
• University of Fukui

Municipalities manage a lot of social infrastructures, and are facing a difficult situation to maintain them. In particular, deterioration due to chloride attack and alkali silica reaction (ASR) is likely to occur at concrete structures in Hokuriku region, and immediate action is required. Based on above background, this paper reports support for r...

Bolt axial force of high-strength bolted joints decreases due to deterioration. One of the conventional methods to evaluate the bolt axial force is ultrasonic testing. However, quantitative evaluation of the bolt axial force is controversial in terms of accuracy, and some problems remain for practical use. This study attempts the accurate evaluatio...

p>It has been confirmed that bolt axial force of high-strength bolted joints decreases due to various effects. Generally, evaluating the bolt axial force of existing bolts has been an important issue. In a conventional ultrasonic bolt axial force evaluation method, bolt length change due to the change of bolt axial force is evaluated. However, bolt...

Weathering tests using monitored steel plates are a widely applied method for evaluating the atmospheric corrosion rate in Japan. To calculate the regional corrosion rate, the corrosion layer on the surface of the steel plate needs to be removed to determine the thinning. However, the process of removing the corrosion layer is time and labor consum...

Damage of PC tendons in a prestressed concrete structure need to be detected before such damage accumulates to cause a serious failure. That, however, is quite a difficult task because the PC tendons are invisible from outside and the damage location cannot be known beforehand. Phase space analysis based on vibration data is a novel method for dama...

Linearized Inverse Scattering Methods based on Kirchhoff approximation can be applicable to visualize flaw shapes with scattering waves from the flaw. Scattering waves from the flaws are measured by pseudo UT pulse-echo mode that two probes are operated simultaneously. In order to visualize the flaws inside the concrete, Parasitic Discrete Wavelet...

PC tendon is a vital component for strength of prestressed concrete structure. However, there is no warning sign when it is degraded or damaged, because of its invisibility from outside. Vibration-based method is one of the technique for damage detection due to simplicity. However, the extensively used method such as modal-based analysis is still i...

This study develops a method to visualize the state of steel-concrete interface with ultrasonic testing. Scattered waves are obtained by the UT pitch-catch mode from the surface of the concrete. Discrete wavelet transform is applied in order to extract echoes scattered from the steel-concrete interface. Then Linearized Inverse Scattering Methods ar...

This study evaluates the effect of reduction in plate thickness for a steel plate existing in concrete on guided ultrasonic SH (g-SH) waves. It has been found that the time of flight (TOF) increases if the plate thickness is reduced. The parameter investigated in this study is a delay time obtained from a TOF comparison between a healthy and a dama...

This study evaluates internally present flaws in RC deck using Ultrasonic Testing. The ultrasonic waves are input from the surface of the asphalt pavement. Wavelet analysis with original mother wavelets CRMW successfully emphasizes the location of the horizontal cracks in the RC deck. The original wavelets are developed by the reflected waves from...

This study attempts image sharpening of concrete voids with the application of parasitic discrete wavelet transform. For detection of flaws existing inside the concrete, Linearized Inverse Scattering Methods (LISM) based on Born and Kirchhoff approximation can be applicable to reconstruct the shape of flaws with ultrasonic waves. The frequency char...

This study attenpts to visualize state of steel-concrete interface with ultrasonic testing. Scattered waves are obtained by ultrasonic pitch-catch mode from surface of the concrete. Wavelet analysis extracts echoes scattered from the steel-concrete interface. Then linearized inverse scattering methods (LISM) are used for imaging the interface. The...

Application of maintenance to ensure the safety, extend the service life and reduce the life-cycle cost of civil structures is important. In this paper, a new inspection method is proposed using a robot which can effectively approach target sections of structures, such as areas that are either too narrow or too dangerous to approach and perform bot...

Corrosive sources, such as water and chrorides, for infractrucrtures are influenced by wind direction, wind velocity, temperature, humidity, rainfall, sea waves and so on. This study discusses relations on corrosive damage on bridges between meteorological data and corrosive responses. With the multiple regression model, the seasonal tendency of co...

The research studies applicability of an Eddy Current NDT inspection method for detection of corrosion in steel structural members including at locations where direct access to the steel element surface is not possible. The method is evaluated by 3D numerical analysis. Parametric study is conducted for selection of appropriate inspection probe para...

In this research, additional welding with low temperature transformation welding material and improvement method which combined cleaning treatment with a grinder and hammer peening treatment have been investigated. The improvement effect is clarified from the fatigue test of girder specimen with the out-of-plane gusset plate. Although the improveme...

Fatigue strength improvement method which combined a cleaning treatment with a grinder and a peening treatment is investigated. Although a stress concentration at a weld toe is reduced by the cleaning treatment, the peening treatment does not change the stress concentration. The reduction of stress concentration at the weld toe greatly improves a c...

This paper proposes a method to achieve Weigh-In-Motion during traffic congestion. By analyzing strain data, the characteristics of strain during traffic congestion are acquired. This system judges traffic condition on the bridge from the time history of the minimum strain and the picture information. The picture information provides location of th...

単弦ローゼ桁橋の鉛直材が鋼床版に貫通する溶接部位において，疲労損傷の疑いを持つき裂が発見された．これらのき裂は溶接割れか疲労を原因とする可能性が高く，特に後者の場合は適切な対策が必要となる．本研究は，き裂の原因を特定し，そのメカニズムを明らかにすることを目的として，コア抜き調査と応力測定を行った．コア抜き調査の結果，ルート部に未溶着部の存在が確認され，また破面観察からは疲労き裂の疑いのある破面が見られた．応力測定では，活荷重のレベルとその作用位置に対する応答に着目し，活荷重が損傷部位に及ぼす影響を明らかにした．

Recently, the maintenance of the road structures such as bridges has been important both in the developed countries and in the developing countries. For the maintenance of road structures, it is important to investigate on the service conditions including the weights of vehicles and the number of vehicles. For that purpose, Weigh-in-Motion is one o...

Bridge monitoring system is required to grasp structural deterioration and damage modes accurately. In order to achieve structural health monitoring, it is important to utilize the effective information given from the obtained in-situ data of the acting external disturbance and the responses. This study fully analyzes monitoring data acquired over...

Composite orthotropic steel deck systems with SFRC pavement was proposed as an effective preventive work for fatigue damage based on the investigations on the effects on the stresses on the deck systems. The systems were applied to the actual structure for the first time, to the lower deck of Yokohama Bay Bridge. The effect of stress reduction by S...