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  4. Vol.26 No.99 2002.9

本四技報 HONSHI TECHNICAL REPORT

Vol.26 No.99 2002.9

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【巻頭言】Prefatory note

  • 最適管理水準

    A Proper Management of Bridges

    星野満

    Mitsuru Hosino

【技術論文】Technical report

  • 第3回国際吊橋管理者会議報告

    Report on the 3rd International Suspension Bridge Operators' Conference

    吉川章三・鈴木周一・伊藤豊秋

    Shozo Yoshikawa, Shuichi Suzuki, Toyoaki Ito

    5月16日および17日の両日にわたり、第3回国際吊橋管理者会議が本州四国連絡橋公団とニューヨーク州橋梁公団の共催により、淡路島の兵庫県立淡路島夢舞台国際会議場にて開催された。

    本会議では、アメリカ、デンマーク、ノルウェー、中国など海外からの参加者38名を含む260名の参加者が集まり、吊橋の管理に関して国内外より23編の論文発表がなされ、活発な質疑がなされた。近年、吊橋の維持管理では、吊橋を支えるケーブルの保全が大きな課題となっており、老朽化したケーブルの耐荷力評価の手法、補強の方法、モニタリングの手法、長期の健全性確保の手法などが発表された。その他、各国の事情や吊橋のおかれる環境の違いによる固有の維持管理の状況が紹介された。

    The 3rd International Suspension Bridge Operators' Conference (ISBOC) was held at the Hyogo Prefectural Awaji Yumebutai International Conference Center on May 16 and 17, 2002, organized by the Honshu-Shikoku Bridge Authority (HSBA) and the New York State Bridge Authority (NYSBA) .

    260 bridge engineers including 38 international participants from overseas, such as the United States, Denmark, Norway, China, and so forth, participated the conference. Topics on the maintenance works of suspension bridges were reported by 23 presenters from 6 countries at the conference. Since maintenance of the main cables has been concerned deeply with the operators of suspension bridges, discussion of the meeting was focused on assessing the strength, the rehabilitation and the monitoring method of corroded cable wires, and the long-term corrosion protection of the cables. Also reported were of the original maintenance methods derived from the circumferential peculiarities of the bridges.

  • 門崎高架橋(3径間部)の耐風安定性の再評価

    The Reevaluation of the Aerodynamic Stability of the Tozaki Viaduct (Three Span Continuous Bridge Section)

    楠原栄樹

    Shigeki Kusuhara

    門崎高架橋は、基本風速(V10=50m/s) での設計に加え、急峻な地形を有する岬に並行して建設されることから、建設当初よりその耐風安定性に関する検討が実施されており、耐風安定化部材として、4径間部には下部スカートとダブルフラップが、3径間部にはダブルフラップが設置されている。

    しかし、これらの耐風安定化部材は厳しい腐食環境下において約20年が経過し、補修等が必要な状況となっている。一方、現地観測等の供用後に得られた知見から、これら耐風安定化部材の一部撤去の可能性が見いだせた。そのため、将来の維持管理費の縮減の観点から、3径間部を対象とした風洞試験を実施し耐風安定性の再評価を実施した。その結果、3径間部については岬側のダブルフラップを撤去しても、現状の断面と同等の耐風安定性を有することが明らかとなった。

    The Tozaki Viaduct was constructed in the region of severe wind condition where the design wind velocity was 50 m/s. Therefore, the various investigation on aerodynamic stability were conducted during design and construction stages, and some devices for the aerodynamic stability were worked out. As for the devices to the aerodynamic stability, the lower skirt and the double flap system was installed along with the 4-span continuous bridge section, and the double flap system was installed along with the 3-span continuous bridge section. Because the devices were exposed themselves to the severe corrosive environment for more than 20 years corrosion on the devices gradually became problematic, and thus, the repair work would be considered unavoidable.

    Recently, the reduction of the maintenance cost has been focused on, and the necessity of the devices from the viewpoint of aerodynamic stability should be re-evaluated based on the characteristics of the bridge and the wind condition that was obtained in the field experiment and the accumulated field data observed for years after completion of the bridge. The wind tunnel tests on the 3- span section were also conducted with the data on the ambient conditions newly obtained, and finally, it was confirmed that the double flap on the cape side was no longer needed.

  • 海峡部橋梁箱桁用塗装装置の開発

    Development of Painting Robot for Box Deck of Offshore Bridges

    坂本光重・廣田昭次

    Mitsushige Sakamoto, Shoji Hirota

    海峡部の橋梁は、海塩粒子が飛来する厳しい腐食環境にあるため6層からなる長期防錆型塗装を施しているが紫外線や大気中の有害成分により塗膜が劣化するため、15年程度のサイクルで塗替えが必要となる。塗替え作業は、高所で寒風や酷暑に曝されながら無理な作業姿勢を強いられる苦渋作業となるため機械化が望まれていた。また塗替えを要する塗装面積は400万m2を超えるため塗替え費用の縮減が重要となる。そこで今回、従来から機械化を阻んできた要因を整理し、省力化、低コスト化を実現する箱桁用塗装装置を開発した。

    本論文では、塗替え作業の機械化の方針、素地調整及び塗装における要素技術の開発、実橋実験で得られた機械化施工の効果を述べる。

    The Honshu-Shikoku offshore bridges have been coated with the long-term anti-rusting paint layers, which were composed of 6 layers, since the bridges would be exposed in a severe rusting environment with marine salt particles. The coating needs repainting with an interval of about 15 years because the paint layers are deteriorated by the ultraviolet lay and the other harmful ambient gradient. The repainting operation with mechanical assistance would be desired because of the difficult task under the tight work environment, such as unnatural work position with high latitude, cold wind, and hot temperature. Reduction of painting cost was important as well since the total painting area would be more than 4 million square meters. Therefore, the painting machine was developed aiming at labor and cost saving after extensive feasibility study. This paper introduces basic concept of mechanization of repainting work, development of peripheral technologies in blasting and painting works, and the effectiveness of mechanized operation resulted in experimental works on real bridges.

  • 芸予地震における海峡部橋梁の被災復旧状況及び橋体の挙動

    The report on Disaster Restoration of the Offshore Bridges after and the Reaction of Bridges in the Geiyo Earthquake

    古家和彦・磯江浩・森幸夫

    Kazuhiko Furuya, Hiroshi Isoe, Yukio Mori

    芸予地震により損傷した、西瀬戸自動車道の構造物の損傷状況及び復旧状況を報告する。また、動態観測システムにより観測された地震動について検証するとともに、公団保有の構造解析プログラムを用い、観測した地震動を入力とした動的解析により、来島海峡第一大橋センタースティロッドの破断が設計どおりであったことを確認したので報告する。

    This paper refers the outline of damage and restoration of the structure of Nishiseto expressway, which were damaged by an earthquake. In addition to the verification on the observed earthquake motion by the field observation system, the dynamic analysis that simulated the earthquake motion as the input data was implemented by the structural analysis computer program, which was developed by the HSBA. As a result of the above verification, it was confirmed the breakage of the center-stay rod of First Kurushima Kaikyo Bridge was theoretical along with the design.

【技術ニュース】Technical news