A GENERALIZED DEFLECTION THEORY FOR SUSPENSION BRIDGES

AN IMPROVED AND EXTENDED DEFLECTION THEORY FOR SUSPENSION BRIDGES IS PRESENTED IN THIS PAPER. THE THEORY IS GENERALIZED TO INCLUDE STRUCTURES OF ANY NUMBER OF SPANS, CONTINUOUS OR NON-CONTINUOUS, SYMMETRICAL OR UNSYMMETRICAL, AND WITH OR WITHOUT TIE CABLES. THE MORE GENERAL ADOPTION OF THE CONTINUOUS TYPE OF SUSPENSION BRIDGE, OFFERING ADVANTAGES OF ECONOMY AND RIGIDITY HAS BEEN RETARDED BY THE LACK OF AN ACCURATE THEORY FOR ITS ANALYSIS. THE DEFLECTION THEORY FOR SIMPLE SPAN SUSPENSION BRIDGES HAS BEEN AVAILABLE TO THE ENGINEERING PROFESSION FOR MORE THAN 45 YEARS, BUT THUS FAR, THE CORRESPONDING THEORY FOR THE SUSPENSION BRIDGE WITH CONTINUOUS STIFFENING TRUSS HAS BEEN LACKING. IN ORDER TO ELIMINATE THIS DEFICIENCY, THE AUTHOR HAS UNDERTAKEN TO DEVELOP A GENERALIZED DEFLECTION THEORY, APPLICABLE TO BOTH CONTINUOUS AND NON-CONTINUOUS, 3-SPAN, AND MULTIPLE-SPAN STRUCTURES. BY SIMPLY DROPPING THE RECOGNIZABLE TERMS DUE TO CONTINUITY, THE FORMULAS ARE REDUCED TO THOSE FOR THE SIMPLER CASE OF STIFFENING TRUSSES HINGED AT THE TOWERS. IN THE DEVELOPMENT OF THE ANALYSIS HEREIN PRESENTED, MAXIMUM SIMPLICITY OF FORMULAS AND EASE OF PRACTICAL APPLICATION HAVE BEEN GOVERNING CONSIDERATIONS. USE OF SIMPLIFICATIONS ARE DEVELOPED AND INTRODUCED IN THE WORKING FORMULAS. TO SHOW THE PRACTICAL WORKABILITY OF THE GENERALIZED THEORY, THE PAPER INCLUDES A NUMERICAL EXAMPLE OF THE APPLICATION OF THE FORMULAS TO THE CALCULATION OF THE STRESSES AND DEFLECTIONS IN A CONTINUOUS SUSPENSION BRIDGE HAVING AN 800- FOOT MAIN SPAN. /ASCE/