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  4. Vol.22 No.85 1998.1


Vol.22 No.85 1998.1


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

【巻頭言】Prefatory note

  • 外国語の奨め

    Let's Learn Foreign Languages


    Yasuhito Kanisawa

【技術論文】Technical report

  • 鋼床版構造の長寿命域疲労試験結果

    Results of Longlife Fatigue Test for Structures on Orthotropic Steel Deck


    Harukazu Ohashi, Naoki Yanadori


    Orthotropic steel deck of bridges is composed of thin steel plates by welding so that fatigue cracks are occasionally caused by magnitude and the number of loading. Fatigue problem has been considered 2 million times of loading, but it is afraid of fatigue cracks at the loading times more than 2 million though load is lighter than considered before. Therefore the series of fatigue tests have been done such as 10 or 20 million times of loading at lower stress level. Test pieces included bolted joint and welded joint of trough rib and some details of steel deck structure. Investigating cracks in the test made it certain S-N diagram already given through test in the past and gave us knowledge about nature of longlife fatigue problems.

  • 主塔点検補修用ロボットの開発

    Development of Repair Robot for Main Tower


    Masami Tsuchiyama, Mitsushige Sakamoto


    Since the coated surface of steel structure deteriorate as time goes by, periodic repair work is inevitable. Partial rusting on generally wholesome surface is unavoidable, since the degree of deterioration varies with the part of structure and general conditions of blow work. Early repair maneuvering on these partial deterioration is desirable, however, difficult access to high-rise wall surface, up to hundreds of meters high, has prevented it until the time of full scale repair work operation.

    This paper presents a newly developed steel surface repair robot, which can cruise on high-rise vertical wall surface and carries out consecutive repair work, such as finding out deteriorated spots, removing rust, and painting. One-man remote control operation from the ground level reduced the burden of manpower and increased safety.

  • 舞子地区遮光施設等工事の設計・施工

    Design and Construction of Light Control Shelter in Maiko Section


    Kazuhiko Furuya, Norihiro Miyaguchi, Shoji Ogo


    Maiko Viaduct is located on Kobe side of approach highway of Akashi Kaikyo Bridge, having a PC rigid-frame, 8-span continuous box deck. The viaduct is 510 meters long, spanning between the Maiko large section tunnel and the Akashi Kaikyo Bridge. The ambient brightness is changed during this portion of 550 meters from a bright open air on the bridge to the dark inside the tunnel. This abrupt change of brightness would cause an influence on the driver, and eventually speed loss of traffic, and a possibility of accident and congestion of traffic. Therefore, a light control shelter is designed for 220-meter portion, from the Viaduct to the south portal of tunnel, to give a smooth transition of ambient brightness for the highway users. This paper report the design and construction work of the shelter facility.

  • 瀬戸大橋の維持管理、十年(主な損傷とその補修について)

    Ten-Year Maintenance of Seto Ohashi Bridge (Major problems and their repair work)


    Masahiko Yasuda, Tsuyoshi Matsumoto

    瀬戸大橋は平成10年4月10日で、供用開始以来十年を迎えることとなる。この間の十年間に、初期欠陥に起因すると考えられる幾つかの間題が生じた。 それらは吊橋主ケーブルの錆の問題、下津井瀬戸大橋のエンドリンクの騒音問題、リンク式伸縮装置の傾斜事故、同伸縮装置の騒音問題、ローリングリーフ式伸縮装置の騒音問題、同伸縮装置の支持台上フランジの亀裂、鋼床版支承の錆び汁、斜張橋ケーブルの振動とそれに伴うケーブルの損傷、鋼ケーソン表面に腐食による穴があいたこと、ゴム製緩衝工が損傷しやすく維持管理に多額の費用を必要とすること、コンクリート橋脚にアルカリ骨材反応が見つかったこと、などである。ここではこれらの損傷について報告する。

    On April 10, 1998, the Seto Ohashi Bridge will celebrate its tenth anniversary since its opening. During these ten years, some problems which were due to the initial defects were found. These were, the corrosion of main cables of suspension bridges, the noise problem of end links of the Shimotsui-Seto Bridge, the accident of an inclination of a link type expansion joint, the noise problem of the same joints, the noise problem of rolling leaf expansion joints, the cracks of the upper flanges of supporting girder of the same expansion joints, the rust problem of bearings of orthotropic steel decks, the damages of cables of cable-stayed bridges due to vibrations, the corrosion holes on surfaces of steel caissons, damages of rubber buffers of ship collision, alkali-silicate reaction of concrete pier, and so on. In this paper, these problems are reported.

  • 新尾道大橋の橋梁連続化の検討

    Examination of Unified Decks of Shin -Onomichi Bridge


    Shuichi Suzuki, Matsuyoshi Taguchi, Masahiro Otsuka


    The Shin-Onomichi Bridge is designed as a cable-stayed bridge to be located at a distance of 55 meters parallel to the Onomichi Bridge, which has been open to the public. A viaduct is also designed to be adjoined to the Shin-Onomichi Bridge. The initial design was composed of the Shin - Onomichi Bridge as a 3-span continuous deck, and a 2-span continuous viaduct. Thereafter, the design was changed that the decks of the bridge and viaduct were unified to form a continuous deck system in consideration of structural characteristics and maintenance of the bridge. In the redesign, the entire structural system was reviewed including evaluation of support conditions and the decks for bridge and viaduct, which would have different cross sections, were analyzed to be structurally adjoined. This paper introduces a course of redesign as well as an outline of major topics in the design.

  • ケーブル被覆構造の評価とアンカレイジ内防食工法

    Evaluation of Cable Coating System and Corrosion-proofing in Anchorage Chamber


    Kiyomi Ishibashi, Kiichi Sudo, Ryu Hashimoto


    The study on corrosion proofing on the cable of suspension bridges was started as water leakage was found at a cable band of the Innoshima Bridge. As a result of investigation, corrosion was found inside the cable coating system, and ad hoc commttees were setup in Honshu-Shikoku Bridge Authority, to conduct various corrosion proofing tests and relevant studies. In addition, the real bridges were tested and repaired as test cases. On the other hand, in 1988, corrosion proofing study was also started on the cable of Akashi Kaikyo Bridge, reflecting those results given by real bridge repairing work and the other tests at that time. This paper introduces various real repairing works, including knowledge and evaluation on such tests.

  • 来島大橋ハンガー・バンドの設計

    Design of Suspender Rope and Cable Band of Kurushima Bridge


    Shinichi Hirano, Koichiro Fumoto, Toshihiro Usui



    ②①の理由のため、ケーブルバンドには公団では初めて横割りバンド(縦締めボルト)を採用した。 このため、従来のバンドボルト本数決定の際に考慮する必要の無かった、ハンガー張力のボルト付加軸力に対する影響を考慮して設計を行った。

    特に、①については従来の鞍掛けの場合、最低でも1格点あたりロープ2本だったのに比べ、ロープが1本ですむため、経済的となる。 なお、大島大橋も箱桁構造であるが、PWSケーブルは明石海峡大橋で初めて実用化されたものである。

    The Kurushima Bridge employed PWS suspender ropes and a steel pin-connected joint system. The pin-connected joint system was also employed on the Akashi Kaikyo Bridge. However, the Kurushima Bridge has a ligter weight box deck comparing the truss deck of Akashi Kaikyo Bridge, therefore, the support system on the Kurushima Bridge has the following features:

    a. single suspender rope was adopted for one support point as lighter weight deck.

    b. a vertically-divided cable band system was, for the first time as a design of HSBA, employed for a suspender rope. This required a design of band bolts to consider an additional axial force by suspender rope tension, which would have been needless in design of ordinary band system.

    Especially, the feature "a" resulted in a more economical solution than ordinary system. The PWS suspender rope had been for the first time designed for the Akashi Kaikyou Bridge.

【海外報告】Overseas report

  • 4月25日橋の鉄道載荷および車線拡幅に伴う改築工事

    Retrofit Work on the April-25 Bridge for Loading of Railway Track and Widening of Lanes


    Ikuo Harazaki, Harukazu Ohashi

  • 中南米道路調査の旅

    Trip to Mid-South America for Road Research


    Gohei Tokunaga

【技術ニュース】Technical news