Durability of Steel-concrete composite Hybrid members in marine environments is investigated. In order to gather data on corrosion characteristics of steel plates, exposure tests of elemental Hybrid beam specimens in marine environments and field corrosion survey of actural structure are carried out. From these studies, the following results are obtained;
(1) The main cause of the deterionation of Hybrid members is corrosion of steel plates. This corrosion of plates causes cracks in concrete occasionally.
(2) The typical corrosion rates of steel plates of Hybrid members are nearly equal to them of steel pipe piles or sheet piles investigated formerly.
(3) The cathodic protection is effective for the members in the submerged zone.
(4) Anti-corrosive paintings are effective, however the effectiveness varies depending on the kinds of painting matrials.