Retrofit Engineering for Steel Bridge Structures in Japan

The cases of fatigue damage, repair and retrofit applied are presented. The causes of fatigue damage are categorized as follows. (a) welding defects were remained during fabrication, (b) inappropriate structural details of low fatigue strength were adopted, (c) stresses and deformations unforeseen in design occurred at joints of members (d) structures behavior in a manner not expected, such as vibration due to wind. Case studies include girder bridges, orthotropic steel bridge decks, steel bridge pier structures and others.