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  4. Vol.45 No.136 2021.3


Vol.45 No.136 2021.3


* By clicking ▸ on the title of Technical Reports, abstract will be indicated.

【巻頭言】Prefatory note

  • 技術者としての技術力向上を考える

    Improvement of technical capabilities of bridge engineers


    Shinichi Oe

【技術論文】Technical report

  • 明石海峡大橋主ケーブルの開放調査

    Internal inspection of main cable of the Akashi Kaikyo Bridge


    Shigeyuki Nagase, Naoaki Sugimachi, Yukihiro Fujisawa


    In the Akashi Kaikyo Bridge, the dry air injection system has been introduced since the the bridge was opened to protect the main cable wire from corrosion. In 2018, after 20 years of service, the exhaust cover and rubber wrapping were partitially removed to observe the current status of the cable wire and to confirm the effect of the system. In addition, information on the maintenance and management of wrapping was obtained by investigating the amount of consumption of cable coating. In this paper, the results of each survey and the necessary investigation that should be continued for maintain the cable wrapping and the dry air injection system for a long time in the future are reported.

  • 明石海峡大橋主塔外面作業車の開発

    Development of maintenance vehicle to improve accessibility to outside of main towers of Akashi Kaikyo Bridge


    Hidefumi Okamura, Akira Kagawa, Hideki Higashi


    To maintain long-span bridges, we are required to approach heights with safeness and efficiency. However, to approach Akashi tower (Akashi Kaikyo Bridge main towers), which is about 300 meter high and sectional area decrease toward top of tower, we need to solve many problems. Therefore, we develop maintenance vehicle to approach outside of Akashi tower based on previous experience. In this paper, we report some of consideration (for example: vehicle type, to reduce vibration of wire rope, how to get over difference in level, weight saving) and results of experiment at Akashi tower.

  • 瀬戸大橋桁橋部の耐震補強工事

    Seismic retrofit of girder bridges in Seto-Ohashi Bridges


    Hiroki Murakami, Yasuyuki Hirayama


    Seismic retrofit work of the Seto-Ohashi Bridges and approach viaducts started in 2014, and completed in the end of FY2020. This paper describes the seismic retrofit work of the girder bridges, excluding suspension bridges, cable-styaed bridges, truss bridges in the Seto-Ohashi Bridges. The girder bridge were verified and retrofitted to meet the design requirement, Seismic Performance Level-2, specified in “the Design Specifications for Highway Bridges.” According to the result, it was found that shear capacity of bridge piers and strength for bearings were not sufficient against large-scale seismic motions. Fiber sheet lining around the piers and reinforcement of the bearings were done as seismic countermeasures.

  • 非破壊検査手法を活用した鋼床版舗装の劣化度評価

    Deterioration evaluation of steel plate pavement using non-destructive inspection method


    Kajio Mitsukuni, Morita Hideaki, Ota Masahiko



    Goose asphalt on the steel plate plays an important role in protecting the upper surface of the steel plate from external deterioration factors such as water. In recent cases, it has been confirmed that damage has progressed to goose asphalt during cutting due to the improvement of the pavement surface layer, and the evaluation of the degree of deterioration is important in the maintenance of steel deck pavement. In this paper, a non-destructive inspection vehicle equipped with a microwave radar is used to scan at a speed of 80km/h to acquire pavement internal data from the road surface, and image diagnosis and time-frequency analysis of reflected waveforms are performed based on the three-dimensional processing data. We report the effectiveness of the deterioration evaluation method for steel deck pavement.

【技術開発報告】Report of technology development

  • TRSを用いたUリブ鋼床版ビード貫通亀裂の下面補修工法の施工マニュアル

    Manual for repair method for bead-penetrating crack using Thread Rolling Screw from the underside of the orthotropic steel deck


    Noriyasu Arima, Masahiro Nishitani

【海外報告】Overseas report

  • 海外の橋梁技術者を対象に研修を実施

    Technical training program for bridge engineers from developing countries


    Naoki Toyama, Hidetsugu Ikeda

【技術ニュース】Technical news

  • 岩城橋の工事現況

    Iwagi Bridge Construction Progress


    Naoki Toyama