THERMAL CHARACTERISTICS OF HIGHWAY BRIDGES

RESEARCH WAS CONDUCTED ON TEMPERATURE CHANGES THAT AFFECT HIGHWAY BRIDGES TO: (1) DETERMINE THE MAGNITUDE AND SIGNIFICANCE OF THERMAL GRADIENTS IN GIRDER-SUPPORTED HIGHWAY BRIDGES, (2) DEVELOP AN ANALYTICAL METHOD FOR PREDICTION OF THERMAL STRESSES DUE TO THERMAL GRADIENTS, (3) REVISE PRESENT METHODS FOR PREDICTION OF LONGITUDINAL EXPANSION AND CONTRACTION OF BRIDGES TO REFLECT STRESSES DUE TO THERMAL GRADIENTS, AND (4) VALIDATE THE ANALYTICAL METHOD BY FIELD TESTS. THE THEORETICAL INVESTIGATION CONSISTED OF TWO PARTS: (1) AN ANALYSIS OF THE THERMAL DEFLECTIONS AND STRESSES AS A RESULT OF ARBITRARY TEMPERATURE GRADIENTS IN THE BRIDGE SLAB AND SUPPORTING BEAMS, AND (2) A THEORETICAL ANALYSIS OF THE IN-PLANE DISPLACEMENTS IN THE BEAM-SLAB BRIDGE RESULTING FROM TEMPERATURE CHANGES. THE EXPERIMENTAL PHASE OF THE PROGRAM ATTEMPTED TO: (1) PROVIDE DATA FOR VERIFYING AND/OR MODIFYING THE THEORETICAL ANALYSIS, AND (2) GAIN AN INSIGHT INTO THE MAJOR BEHAVIORAL CHARACTERISTICS OF A BRIDGE UNDER THERMAL GRADIENTS. THE EXPERIMENTAL WORK INVOLVED: (1) TESTING OF A LABORATORY MODEL CONCRETE SLAB, WHICH INCLUDED A SINGLE SYMMETRICALLY LOCATED STEEL BEAM, AND (2) FIELD TESTS ON A MULTIBEAM BRIDGE RECENTLY CONSTRUCTED NEAR SAN ANTONIO, TEXAS, NOT OPENED TO TRAFFIC. THE EXPERIMENTAL PROGRAM FOUND THAT FIELD CONDITIONS INTRODUCED SEVERAL UNCONTROLLABLE VARIABLES SUCH AS WIND AND RAPID CHANGE OF TEMPERATURE. BRIDGES ARE GENERALLY TOO LARGE FOR EFFECTIVE INSTRUMENTATION. CREEP IS A COMPLICATING PROBLEM IN MEASURING STRAINS IN CONCRETE, AND MUST BE ACCOUNTED FOR AT LEAST APPROXIMATELY IN INTERPRETING STRAIN MEASUREMENTS. THERMAL STRESSES APPEAR TO BE SIGNIFICANT ON THE ASSUMPTION THAT CREEP IS NOT A DOMINANT EFFECT. FORMULAS WERE DEVELOPED FOR IN-PLANE THERMAL EXPANSIONS WHICH APPEAR TO BE SUFFICIENTLY SIMPLE AND FLEXIBLE FOR DESIGN OFFICE USE. THE STUDY WAS CONFINED TO SIMPLY-SUPPORTED BEAM-SLAB BRIDGES. THE BEHAVIOR OF CONTINUOUS SPANS UNDER THE INFLUENCE OF THERMAL LOADS CAN NOT BE EXTRAPOLATED FROM THE PRESENT RESULTS.

  • Supplemental Notes:
    • Project 12-4, PP 79-95, FIGS, TABS, REFS
  • Authors:
    • Wah, T
    • Kirksey, R E
  • Publication Date: 1969

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Filing Info

  • Accession Number: 00209157
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 9 1970 12:00AM