Inelastic rotation requirements of two-span continuous bridge girders

This document presents the results of an analytical study performed to assess the inelastic rotation requirements of two-span continuous bridge girders. Specifically, expressions describing the inelastic rotation requirements at the first plastic hinge, to allow formation of a collapse mechanism in the beam, are developed. The study considers twenty-one individual load cases conforming to the requirements of the current AASHTO LRFD Bridge Design Specifications. For each load case, expressions describing the hinge load, the collapse load, and the required inelastic rotation are presented in terms of beam plastic moment strength Mp, flexural stiffness EI, and span L. The accuracy of the derived expressions is verified using the commercially available structural analysis software packages FOPA and RISA 2-D. Using the expressions developed, values for the required rotation capacity are determined. These values are compared to the long established required minimum rotation capacity of 3.0 referenced in the current AASHTO specifications. The origin of the required minimum rotation capacity of 3.0 is also considered. The results of the analytical study indicate that a rotation capacity of 3.0 is not sufficient to allow formation of a collapse mechanism for several of the load cases considered.

Language

  • English

Media Info

  • Features: Bibliography;
  • Pagination: xiv, 139 p.

Subject/Index Terms

Filing Info

  • Accession Number: 01094521
  • Record Type: Publication
  • Source Agency: Northwestern University, Evanston
  • Report/Paper Numbers: 32-00552 UMI
  • Files: TLIB
  • Created Date: Apr 24 2008 8:21PM