LOAD RATING OF SASKATCHEWANS BRIDGES

ONE OF THE LEAST KNOWN ASPECTS OF A BRIDGE IS THE SIZE OF OVERLOAD IT CAN SUPPORT WITHOUT BEING DAMAGED STRUCTURALLY. ALL EXISTING BRIDGES, IN A 1965 TEST PROGRAM IN SASKATCHEWANS HIGHWAY SYSTEM, WERE ANALYZED WITH RESPECT TO STRUCTURAL DETERIORATION AND LOAD RATING. A BRIDGES ULTIMATE LOAD CAPACITY HAD TO BE DETERMINED AND THE FOLLOWING ASSUMPTIONS AND PROCEDURES WERE EMPLOYED' /1/ A SERIES OF AXLES AND AXLE SPACINGS WERE DEVELOPED AND ADOPTED AS REPRESENTING LIVELOAD, /2/ ASSUMPTIONS WERE MADE AS TO THE LIVELOAD DISTRIBUTION TO THE VARIOUS STRUCTURAL MEMBERS OF THE BRIDGES, /3/ THE CONDITIONS CONSIDERED TO RESULT IN FAILURE WERE ASSUMED, INVESTIGATED AND ALTERED WHEN NECESSARY, AND /4/ THE RESULTS OF THE ANALYSIS WERE THEN PLOTTED IN CHART FORM TO PROVIDE A SIMPLE REPRESENTATION OF THE ULTIMATE AXLE LOADS. SOME GENERAL OBSERVATIONS ON THE LOAD CARRYING CAPACITY RATINGS OF DIFFERENT BRIDGE TYPES ARE GIVEN /TIMBER, STEEL GIRDERS, CONCRETE BEAM, COMPOSITE, BOX GIRDER/. THE AUTHOR SUGGESTS THAT SOME OF THE PRESENT BRIDGE DESIGN PROCEDURES NEED REVISING. DIFFERENT LIVELOAD TO DEADLOAD RATIOS PRODUCE DIFFERENT ULTIMATE CAPACITIES. PLASTIC DESIGN, LIMIT DESIGN AND THE USE OF LOAD FACTORS WILL PROVIDE CONSISTENT CAPACITIES. DISTRIBUTION EFFECTS OF A CONCRETE SLAB ARE UNDERESTIMATED. A GRID ANALYSIS AS USED IN EUROPE WILL PROVIDE FOR A MORE EFFICIENT USE OF THE SLAB. IF THESE REVISIONS ARE MADE, CONSIDERATION WILL HAVE TO BE GIVEN TO REPLACING THE AASHO TRUCK AS THE DESIGN LOAD. /CGRA/

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Filing Info

  • Accession Number: 00208170
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 17 1994 12:00AM