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Ōsaka, Japan

Imagawa Y.,Fuji Engineering Co. | Ohyama O.,Osaka Institute of Technology | Kurita A.,Osaka Institute of Technology
Structural Engineering International: Journal of the International Association for Bridge and Structural Engineering (IABSE) | Year: 2012

Many examples of a bridge damaged due to accidental or incendiary fire heating up the bridge from below have been reported. When steel and concrete composite girder bridges are exposed to fire, it is important to understand the progression of damage to the shear connections. However, determination of the level of damage to the shear connection in experimental tests is a challenge. Furthermore, the post fire performance of the shear connection is not clear yet. To better understand the mechanical properties of the shear stud during and after fire, the authors conducted three different push-out tests of heated studs, in which the fire temperature varied from 300 to 700°C over a period of 90 min. From the results of the static push-out tests conducted after heating, it was found that the maximum shear resistance of shear studs is marginally affected by the heating, but the slip constant was decreased remarkably in proportion to the heating temperature. Furthermore, the fatigue strength of shear studs showed remarkable decrease due to the undesirable slip behavior. Source

Fukada S.,Kanazawa University | Matsumoto T.,West Nippon Expressway Engineering Kansai Co. | Okada H.,Fuji Engineering Co. | Momiyama Y.,West Nippon Expressway Engineering Kansai Co.
Journal of Civil Structural Health Monitoring | Year: 2014

An object prestressed concrete bridge with a 37.47 m span that vibrated greatly upon a truck running on it was investigated through examination and monitoring to clarify the cause of the vibrations. The results of running examinations showed that the bridge vibrated greatly only when the test truck ran in the 2nd slow lane, and the bridge resonated with the truck suspension's spring vibration that was caused by the road roughness with a certain spatial wavelength in that lane. Then, monitoring was conducted in a 2.5 year period before and after the repair of the periodic roughness to detect the abnormal stress due to large dynamic amplification and to confirm the effect of reduction and validation of the repair under the movement of ordinary trucks. The monitoring results showed that the diurnal maximums of the dynamic stress after repair decreased by 40 %, and the diurnal maximum dynamic increment factor DIF-1 after repair decreased to approximately one-third. Moreover, dynamic response analysis was performed to investigate the relation among the bridge dynamic amplification and various periodic roughnesses with long spatial wavelengths at the expansion joint. The simulation results showed that a periodic roughness with a spatial wavelength of 10 m affected the dynamic amplification of the bridge when the truck model runs over it at a speed of 80 km/h. © 2014 Springer-Verlag Berlin Heidelberg. Source

Fukada S.,Kanazawa University | Hama H.,Fuji Engineering Co. | Usui K.,West Nippon Expressway Co. | Agawa K.,West Nippon Expressway Co.
Advances in Environmental Vibration - Proceedings of the 5th International Symposium on Environmental Vibration, ISEV 2011 | Year: 2011

At the houses near-the bridge, there have been complaints aborit a rattling soimd and /or complaints about, mental and physical discomfort caused by the infrasound, which is radiated from the highway bridge under moving vehicles. General truck in Japan with rear leaf suspension have frecruencies of about 3Hz. Also, the frequencies of the tire spring vibration are about 10-20Hz. The steel continuous bridges with middle span length have the vibration modes with the same phase in each span and with the secondary mode shape. These bridge vibration modes are related to the suspension spring vibration and/or the tire spring vibration of the trucks. This study clarifies the relation of the infrasound, the vibration of the trucks, and the bridge vibration by using several experimental results. Source

Fujigiken Co., WEST NIPPON EXPRESSWAY COMPANY Ltd and Fuji Engineering Co. | Date: 2012-12-17

A method of carrying out post-treatment to a sprayed coating includes spraying aluminum-containing material onto a surface of a steel for forming a sprayed coating on the steel, and coating electrolytic aqueous solution or water base paint containing electrolytic aqueous solution therein onto the sprayed coating.

Fuji Engineering Co., WEST NIPPON EXPRESSWAY COMPANY Ltd and Fujigiken Co. | Date: 2012-12-17

The plasma spraying apparatus includes a cathode, a first gas nozzle defining a first gas path between the cathode and itself, a second gas nozzle defining a second gas path between the first gas nozzle and itself, and a third gas nozzle disposed between the first and second gas nozzles to define a third gas path between the first and second gas paths. A wire is disposed at a distal end thereof in front of a nozzle opening of the second gas nozzle. A first gas sprayed through the first gas nozzle is turned into plasma flame, which melts the wire into droplets, and the droplets are sprayed onto a target by a second gas sprayed through the second gas nozzle. The third gas absorbs heat from the plasma flame to thereby turn into a high-temperature gas flow externally of the plasma flame.

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