The purpose of this study is to give the cause of cracking at the middle part of steel piers with a circular cross section damaged by the 1995 Kobe Earthquake. We investigate the residual strains, hardness and Charpy absorbed energy of the steel plate with a local buckling deformation in the pier that was hit by the Earthquake. The synthetic consideration for the obtained results and the features of the fracture toughness of the steel plates at the period when the piers were fabricated, concludes that it would be one of the causes of cracking that the fracture toughness in the pier direction was originally small.
