Localized Stresses in a Post-Tensioned Steel Girder Web-Field Verification. Part 2. Appendices

摘要

A steel plate girder and concrete deck slab bridge (Yuba Pass Bridge and Overhead) has been rehabilitated by placement of a concrete deck overlay, addition of lower steel flanges and post-tensioning of girder webs. A previous Caltrans report and TRB article discussed purely theoretical, pre-construction analyses with FINPLA and STRUDL made because of concern over potential large web stresses due to post-tensioning forces. A second phase study has been performed to modify previous analyses for assumed full clamping of post-tensioning brackets to webs and to verify analytical procedures by installation of SR-4 rosettes in the vicinity of a bracket on one girder web and monitoring during post-tensioning. Assumptions included full composite and non-composite deck contributions, and uniform and non-uniform bracket loadings. Theoretical/experimental correlations were good for longitudinal strains and minor principal stresses, less encouraging for vertical strains and major principal stresses. Correlations were improved when some composite action by the physically non-composite deck and for non-uniform bracket loading was assumed. Theoretical stresses were significantly reduced by assumption of full bracket clamping.