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BEHAVIOR OF CONCRETE SLAB AND GIRDER BRIDGES

DETAILED RESULTS OF A RESEARCH PROGRAM TO STUDY THE BEHAVIOR OF 40-FOOT SIMPLE SPAN PAN-FORMED CONCRETE SLAB AND GIRDER BRIDGES ARE PRESENTED. THE INVESTIGATION WAS CARRIED OUT USING APPROXIMATELY 1/6-SCALE DIRECT MODELS OF THE BRIDGES (INCLUDING SUBSTRUCTURE); THESE MODEL TESTS WERE SUPPLEMENTED BY ANALYSIS AND FULL-SIZE FIELD TESTING. FOUR ACCURATE MODELS WERE TESTED AT SERVICE LOADS, MODERATE OVERLOADS, AND ULTIMATE LOAD LEVELS IN ORDER TO FULLLY DOCUMENT THE BEHAVIOR OF THE STRUCTURES FOR THE FULL RANGE OF LOAD CONDITIONS. PATTERNS OF LOAD DISTRIBUTION WERE OBTAINED USING BOTH STRAIN GAGES AND DEFLECTION MEASUREMENTS. THE MAIN VARIABLES IN THE INVESTIGATION WERE ANGLE OF SKEW, LOAD LEVEL, AND GRADE AND QUANTITY OF REINFORCEMENT. COMPARISONS ARE MADE WITH THE SERVICE LOAD AASHO LOAD DISTRIBUTION FACTORS FOR DESIGN OF SLAB AND STRINGER BRIDGES, AND WITH DISTRIBUTION FACTORS COMPUTED FROM AN ORTHOTROPIC PLATE SOLUTION USING A DISCRETE ELEMENT MATHEMATICAL MODEL. DESIGN RECOMMENDATIONS ARE MADE FOR COMPUTATION OF ULTIMATE LOAD CAPACITY. AMONG THE CONCLUSIONS ARE THE FOLLOWING: (1) THE AASHO SERVICE LOAD DISTRIBUTION FACTORS FOR SINGLE-WHEEL, SINGLE-TRUCK, AND MULTIPLE-TRUCK LOADS ARE OVERCONSERVATIVE WHEN COMPARED TO THE SERVICE LOAD TEST RESULTS. (2) ULTIMATE LOAD DISTRIBUTION FACTORS SHOULD BE BASED ON THE YIELD ZONE AND THE TRANSFERRED LOAD. HOWEVER, THE LATTER IS DIFFICULT TO EVALUATE GENERALLY, SINCE IT IS DEPENDENT ON LOAD POSITION AND LOADED LENGTH. FOR SIMPLICITY, CONSERVATIVE ULTIMATE LOAD DISTRIBUTION FACTORS MAY BE BASED ON THE GIRDERS WITHIN THE YIELD ZONE AFETER NEGLECTING ANY TRANSFERRED LOAD. (3) TRANSVERSE STEEL RARELY EXCEEDED THE DESIGN STRESS UNTIL FAILURE OCCURRED. AT FAILURE THE STEEL USUALLY YIELDED AS A SECONDARY EFFECT. (4) UNDER BOTH MAXIMUM MOMENT AND MAXIMUM SHEAR LOADINGS THE BRIDGES EXHIBITED A PRIMARY MODE OF FAILURE BY YIELDING OF TENSION STEEL IN THE MOST HEAVILY LOADED GIRDERS. THESE GIRDERS ARE DEFINED BY A DISTRIBUTION ZONE BOUNDARY EXTENDING FROM THE EDGE OF THE LOADED SURFACE AND INCLINED 30 DEGREES FROM THE HORIZONTAL. THE MAIN LONGITUDINAL STEEL WILL YIELD OR BE VERY CLOSE TO YIELD IN ALL GIRDERS IN WHICH THE TENSILE STEEL LAYERS ARE ENCLOSED WITHIN SUCH A 30 DEGREE ZONE. THIS IS REFERRED TO AS THE YIELD ZONE. INCREASED LOAD WILL BE TRANSFERRED TO THE REMAINING GIRDERS. THE TRANSFERRED LOAD IS LIMITED BY THE SLAB SHEAR CAPACITY IN THE TRANSVERSE DIRECTION, UNLESS THE REMAINING GIRDERS YIELD BEFORE THE SHEAR CAPACITY IS REACHED. /AUTHOR/

  • Supplemental Notes:
    • 94-3f, 214 PP, 114 FIG, 8 TAB, 46 REF, 1 APP
  • Corporate Authors:

    University of Texas, Austin

    Center for Highway Research, 200 West 21st Street
    Austin, TX  United States  78712
  • Authors:
    • Leyendecker, E V
    • Breen, J E
  • Publication Date: 1969-5

Subject/Index Terms

Filing Info

  • Accession Number: 00209389
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 18 1971 12:00AM