Many steel bridge members are subjected to minute out-of-plane displacement or distortion of components which could induce fatigue damages. The magnitude of the distortion presently cannot be quantified by simple engineering computation. The evaluation of behavior of structural members and details by the measurement of stresses and displacement in a few details of steel bridges are presented qualitatively in this paper. These structural details include the connection between longitudinal stringers and cross floorbeams in deck girder bridges, the junction of floorbeams at truss panel points, the attachment of interior diaphragms in bridge box girders, the tie plate of cantilever brackets, and other cases. The methods of retrofit are discussed.
