Steel Framing Strategies for Highly Skewed Bridges to Reduce/Eliminate Distortion near Skewed Supports

Different problems in straight skewed steel I-girder bridges are often associated with the methods used for detailing the cross-frames. Use of theoretical terms to describe these detailing methods and absence of complete and simplified design approach has led to disputes between stakeholders, costly repairs, and delays in construction. The objectives of this research were introduction of simplified terminologies to describe detailing methods, identification of structural responses affected by the detailing methods and recommendation of methods of analysis to evaluate these responses, development of methods to estimate fit-up forces and practices to reduce them, and finally development of design provisions for the skewed bridges. Two terminologies, erected fit and final fit, are introduced to describe the detailing methods in order to be consistent with field practice. The components of the structural responses affected by the detailing method are identified and are referred to as lack-of-fit effects. It has been shown that lack-of-fit effects for the final fit detailing method at steel dead load stage are equal and opposite to the lack-of-fit effect for the erected fit detailing method at total dead load stage. It is recommended to use improved 2D grid analysis to calculate the lack-of-fit effects for the erected fit and final fit detailing methods. The fit-up forces required to attach the cross-frames during the erection can be estimated from improved 2D grid analysis. 3D erection simulation has shown that erecting the cross-frames starting from the middle of a bay and going toward the ends reduces the maximum fit-up force. Finally, recommendations were made on the method of calculating the cambers, and a flow chart was developed for each detailing method to facilitate the selection of the detailing method and carrying out the necessary design checks.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 172p

Subject/Index Terms

Filing Info

  • Accession Number: 01532587
  • Record Type: Publication
  • Contract Numbers: BDK80 977-21
  • Files: TRIS
  • Created Date: Jul 25 2014 12:55PM