In the past 10 years many welded steel bridges, most of them relatively new, have cracked. Cause is lateral deflection of main-girder webs, caused by lateral loads imposed by connecting lateral beams and diaphragms or cross-bracing. Most such cracks have been found in the negative moment area of continuous-girder bridges (that is, over the piers) and only near the tension flange. That flange is constrained by the bridge deck above, and the same girder's web immediately below is freer to move laterally. Relatively simple corrective steps appear to cure the problems. And new steel bridges are being designed to preclude repetition of the problems. Bolted and riveted connections are less susceptible to such cracks than are welded ones. This article discusses the causes of the problem, and the two methods of dealing with it, minimizing the movement or accommodating it. Three techniques are used: Drill a hole at each end of the crack. Or remove a segment of the connection plate near the crack to lengthen the web gap. Or bolt the connection plate to the tension flange in the bridge's negative moment areas.

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  • Accession Number: 00450171
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: Aug 27 2004 9:55PM