APPROXIMATE TORSIONAL ANALYSIS OF CURVED BOX GIRDERS BY THE M/R-METHOD

A SIMPLIFIED METHOD IS PRESENTED FOR THE TORSIONAL ANALYSIS OF SINGLE-SPAN OR CONTINUOUS CURVED BOX GIRDERS, WHICH, BY VIRTUE OF THEIR EXCELLENT STRENGTH IN RESISTING TORSION, ARE GENERALLY RECOGNIZED AS IDEAL SUPPORTING ELEMENTS FOR HORIZONTALLY CURVED STRUCTURES. UNDER MOST CONDITIONS ENCOUNTERED IN PRACTICE, THE BENDING AND TORSIONAL ANALYSIS OF CURVED BOX GIRDERS MAY BE UNCOUPLED AND INVESTIGATED INDEPENDENTLY. BY STRAIGHTENING THE CURVED GIRDER TO ITS FULL DEVELOPED LENGTH, THE BENDING MOMENTS AND VERTICAL SHEAR FORCES CAN BE READILY DETERMINED AS CUSTOMARILY DONE. THE PROPOSED METHOD SUGGESTS THAT THE TORSIONAL ANALYSIS CAN BE CARRIED OUT IN A SIMILAR MANNER, EXCEPT THAT (1) A STRAIGHT CONJUGATE BEAM SUBJECTED TO A DISTRIBUTED LOAD IN THE TORSIONAL MOMENT ANALYSIS, AND (2) A STRAIGHT CONJUGATE BEAM SUBJECTED TO A DISTRIBUTED LOAD FOR THE DETERMINATION OF THE ANGLES OF TWIST ARE TO BE CONSIDERED, WHERE M IS THE BENDING MOMENT OBTAINED IN THE APPROXIMATE FLEXURAL ANALYSIS, R IS THE RADIUS OF CURVATURE. THE APPLIED DISTRIBUTED TORQUE IN THE SPANWISE DIRECTION IS ALSO CONSIDERED. SINCE M/R IS A PARAMETER IN THE FORCING FUNCTION IN THE ANALYSIS, THE APPROXIMATE METHOD IS CALLED THE M/R-METHOD TO DIFFERENTIATE IT FROM THE CLASSICAL CONJUGATE BEAM METHOD FOR THE DETERMINATION OF BEAM DEFLECTIONS. THE ACCURACY AND LIMITATIONS OF THE APPROXIMATE METHOD ARE EXAMINED AS WELL AS SEVERAL OTHER ASPECTS RELATED TO THE PROBLEM IN GENERAL. IT IS FOUND THAT WITHIN THE LIMITS SPECIFIED, THE METHOD WILL GIVE RESULTS WITH SUFFICIENT ACCURACY FOR PRACTICAL PURPOSES.

• Supplemental Notes:
  • Vol 7, No 3, PP 65-74, 9 FIG, 7 TAB, 6 REF
• Authors:
  • Tung, D H
  • Fountain, R S
• Publication Date: 1970-7

Media Info

• Serial:
  • Engineering J, Am Inst Steel Constr

Subject/Index Terms

• TRT Terms: Bending; Bending moments; Box girders; Continuous structures; Curvature; Radius; Shear stress; Structural analysis; Test procedures; Torsion tests
• Old TRIS Terms: Curved profiles; Radius of curvature; Vertical shear
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00209327
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 19 1970 12:00AM