DYNAMIC STUDIES OF BRIDGES ON THE AASHO ROAD TEST

THE PROGRAM OF DYNAMIC TESTS CONDUCTED ON THE BRIDGES OF THE AASHO ROAD TEST AT OTTAWA, ILLINOIS STUDIED THE DYNAMIC EFFECTS PRODUCED IN TEST BRIDGES UNDER MOVING VEHICLES AND RELATED THE OBSERVED BEHAVIOR TO THE RESULTS PREDICTED BY THEORY. THE EXPERIMENTAL SETUP CONSISTED OF ACTUAL HEAVY VEHICLES AND FULL-SCALE BRIDGES, ALTHOUGH THE BRIDGES WERE TO AN EXTENT SIMPLIFIED MODELS. LOADING TESTS WERE MADE ON BRIDGES BOTH WITH STATIONARY AND SLOWLY MOVING VEHICLES, TO DETERMINE THE STIFFNESS OF THE BRIDGES AT VARIOUS STAGES, AND STUDY THE LATERAL DISTRIBUTION OF EFFECTS IN ORDER TO DETERMINE TO WHAT EXTENT THE TEST BRIDGES BEHAVED AS A BEAM, WHICH WAS AN ASSUMPTION INVOLVED IN THE THEORETICAL SOLUTIONS USED TO PREDICT THE DYNAMIC BEHAVIOR. RESULTS ARE PRESENTED OF APPROXIMATELY 1900 DYNAMIC TESTS. PRIMARY EMPHASIS WAS PLACED ON DETERMINING ACCURATELY THE PERTINENT PROPERTIES OF THE BRIDGES AND VEHICLES, UNDERSTANDING THE DYNAMIC BEHAVIOR OF THE BRIDGES UNDER THE PASSAGE OF VEHICLES, AND OF THE VEHICLES THEMSELVES. FOR CONCENTRIC LOADS, EACH TEST BRIDGE ACTED ESSENTIALLY AS A SINGLE SIMPLY SUPPORTED BEAM. FOR THE NONCOMPOSITE STEEL, PRESTRESSED CONCRETE, AND REINFORCED CONCRETE BRIDGES, THE FREQUENCIES DETERMINED FROM THE FREE-VIBRATION ERA, AFTER THE VEHICLE HAD LEFT THE SPAN, WERE NOT REPRESENTATIVE OF THE STIFFNESS OF THE BRIDGES WHILE THE VEHICLE WAS ON THE SPAN. THIS DIFFERENCE IS DUE TO THE DIFFERENT DEGREES OF COMPOSITE ACTION OR EXTENT OF OPENINGS OF CRACKS UNDER THE TWO CONDITIONS. THE FREQUENCIES OF THE VEHICLES UNDER DYNAMIC CONDITIONS APPEARED TO BE LOWER THAN PREDICTED BY THE STATIC MEASUREMENTS, REFLECTING THE FLEXIBILITY PROVIDED BY THE VEHICLE FRAME. HISTORY CURVES OF DYNAMIC INCREMENTS PROVIDED THE BEST MEASURE OF THE DYNAMIC BEHAVIOR OF THE BRIDGES. THE PEAK DYNAMIC INCREMENTS GENERALLY INCREASED WITH INCREASED SPEED. UNDER SEEMINGLY IDENTICAL CONDITIONS, THE SCATTER IN MEASURED AMPLIFICATION FACTORS WAS OF THE ORDER OF 20 PERCENT FOR DEFLECTIONS AND 10 PERCENT FOR STRAINS. WHERE THE EFFECTS OF THE INDIVIDUAL BRIDGE-VEHICLE PARAMETERS COULD BE ISOLATED, THEY WERE IN GENERAL AGREEMENT WITH THEORETICAL PREDICTIONS. IN TESTS WITH INDUCED VEHICLE OSCILLATIONS, THE VEHICLE BEHAVIOR ON THE BRIDGE WAS FOUND TO BE ESSENTIALLY THE SAME AS ON A RIGID PAVEMENT. COMPARISONS ARE PRESENTED BETWEEN EXPERIMENTAL AND THEORETICAL RESULTS.

  • Record URL:
  • Supplemental Notes:
    • 358 PP, 83 FIG, 19 TAB, 8 PHOT, 22 REF Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
  • Publication Date: 1962-6

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00209069
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Sep 29 1994 12:00AM