DESIGN GRAPHS FOR HIGHWAY SUSPENSION BRIDGES OF MODERATE SPAN

THE EXACT OR RIGOROUS DETERMINATION OF STRESSES IN SUSPENSION SPANS IS SOMEWHAT TEDIOUS AND INVOLVED. FOR THIS REASON IT HAS BEEN GENERAL PRACTICE TO MAKE CERTAIN APPROXIMATIONS, PARTICULARLY IN THE DESIGN OF STRUCTURES OF COMPARATIVELY SHORT SPAN. SUCH APPROXIMATIONS, IN CERTAIN CASES, INVOLVE ERRORS OF CONSIDERABLE MAGNITUDE, AND ERRORS WHICH AFFECT DIFFERENT PORTIONS OF THE STRUCTURE IN DIFFERENT DEGREE. BECAUSE OF THIS OREGON HIGHWAY DEPARTMENT IN 1937 INITIATED CERTAIN RESEARCHES LOOKING TOWARD THE DERIVATION OF EXACT AND RATIONAL DESIGN METHODS FOR HIGHWAY SUSPENSION BRIDGES AND THE DEVELOPMENT OF DESIGN GRAPHS WHICH WOULD SHORTEN THE TIME AND LESSEN THE LABOR INVOLVED. THE PRESENT PAPER SUMMARIZES THE MATHEMATICAL THEORY UNDERLYING THE EXACT OR RIGOROUS METHOD OF STRESS ANALYSIS, UTILIZING THE FOURIER-SERIES EXPANSION OF THE DEFLECTION TERM PROPOSED AND DEVELOPED BY TIMOSHENKO AND PRIESTER. A COMPARISON OF THE RESULTS OBTAINED BY THIS METHOD WITH THOSE DERIVED BY THE APPROXIMATE METHOD INDICATES A DEGREE OF DIVERGENCE AMOUNTING, IN CERTAIN CASES, TO OVER 250 PER CENT, AS SHOWN BY TABLE I OF THIS ARTICLE, WHICH TABLE IS BASED ON A COMPARISON OF 24 SEPARATE DESIGNS. THE DEGREE OF ERROR INCREASES WITH THE SPAN LENGTH AND DECREASES AS THE RIGIDITY OF THE STIFFENING FRAME IS INCREASED. THE LARGE DEGREE OF MAXIMUM ERROR, TOGETHER WITH THE VARIATION IN PERCENTAGE OF ERROR FOR DIFFERENT PORTIONS OF THE SAME STRUCTURE WARRANTS THE CONCLUSION THAT THE APPROXIMATE OR "ELASTIC-THEORY" METHOD IS OF QUESTIONABLE VALUE IN ANY CASE. A RECOMMENDED DESIGN PROCEDURE BASED UPON THE RESULTS OF THE OREGON STUDIES IS INDICATED AND CERTAIN DESIGN GRAPHS ARE PRESENTED WHICH MAY BE USED WITH REASONABLE ACCURACY FOR TWO-LANE ROADWAY STRUCTURES DESIGNED FOR STANDARD HIGHWAY LOADINGS. /AUTHOR/

  • Supplemental Notes:
    • Vol 20, pp 549-567, 19 FIG, 2 TAB
  • Authors:
    • Mccullough, C B
  • Publication Date: 1941

Media Info

  • Monograph Title: Proceedings of the Twentieth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 3-6, 1940
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00209421
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 23 1971 12:00AM