| 美原大橋は、全長972mの3径間連続斜張橋および3径間連続鋼床版箱桁で構成される橋梁である。本橋は、H5年度の道示に基づき詳細設計が行われたが、鋼床版のデッキプレートは、現道示が規定する剛性を十分確保していないことが認められた。本橋では、疲労予防対策として最も経済的で施行性が良いと考えられる合成鋼床版化を対策手法として採用した。本合成鋼床版には、上面増厚するコンクリートに繊維補強モルタル（ECC）、新たなジベルとして開発されたFRP製のプレート型のジベルが用いられている。プレートジベルの疲労耐久性は明らかとなっておらず、輪荷重走行試験後にジベルの基本性能確認試験（引抜き試験・せん断試験）を実施し、その破壊性状および残存耐荷力を検討した。[*][*]Recently in Japan、 fatigue-cracking damage in orthotropic steel decks is frequently reported. Fatigue damage had occurred by stress concentration around the welding part between steel elements. The reason is considered to be the remarkable increase of traffic volume and existence of overloaded vehicles. As a permanent measures of reducing fatigue damages of new making steel decks、 it is proposed that a layer of fiber reinforced concrete on the steel deck surface is put to change the whole system into a composite deck.[*] Generally、 SFRC(Steel Fiber Reinforced Concrete) is often used for the concrete on the steel deck surface. In addition、 the studs are often used to transmit the shear force between the steel and concrete. For many reason、 new type of composite steel deck that use ECC(Engineered Cementitious Composite) as additional concrete on the deck surface and plate made of FRP as shear connector was developed[*] To verify the idea was good or not、 fatigue test using a using wheel running machine was carried out. It is established by proof that this composite deck has enough fatigue durability. With the use of specimen after fatigue test using a using wheel running machine、 the element examination of plate shear connector carried out to verify the residual load bearing ability. |
