Based on the actual state of corrosion of steel structures obtained by the suggested corrosion survey method, corrosion tendencies of steel structures, occurrence mechanisms and conditions of corrosion tendencies, and measures against concentrated corrosion resulting from the corrosion tendencies were contemplated, and the following results were obtained.
　1) According to the condition of occurrence of concentrated corrosion, tendencies of steel sheet piles could be divided into five types, (a) to (e), while steel pipe piles into three types, (a) to (c).
　2) It was considered that existence of tidal range, depths of water, presence of fresh water, depths of coping concrete, shapes of steel, kinds of backfilling materials,fluctuations in residual water level, etc. were factors influencing corrosion tendency.
　3) It was found that it became possible to estimate corosion tendencied (a), (b) and (c) for steel sheet piles by using component analysis results.
　4) As one mesure against concentrated corrosion, a method was indicated of changing the conditions for occurrence of concentrated corrosion of steel stuctures into conditions making it difficult for concentrated corrosion to generated.