THE RESONANT VIBRATION RESPONSES OF TWO HORIZONTALLY CURVED STEEL GIRDER BRIDGES

THIS REPORT DESCRIBES WHAT IS BELIEVED TO BE THE FIRST INSTANCE OF SUSTAINED RESONANT EXCITATION OF HORIZONTALLY - CURVED BRIDGES TO DETERMINE THE DYNAMIC RESPONSE CHARACTERISTICS OF THIS RAPIDLY EVOLVING TYPE OF DETERMINE THE RESONANT VIBRATION RESPONSE CHARACTERISTICS OF A SIMPLE-SPAN AND A 2-SPAN CONTINUOUS BRIDGE, BOTH FABRICATED WITH HORIZONTALLY-CURVED GIRDERS. A PAIR OF IDENTICAL VARIABLE-FREQUENCY HARMONIC FORCE GENERATORS WERE INSTALLED ON EACH BRIDGE IN TURN AND EACH BRIDGE WAS EXCITED AT ITS VARIOUS RESONANT FREQUENCIES. ONE VIBRATION GENERATOR WAS LOCATED IN EACH TRAFFIC LANE AND THEY WERE OPERATED EITHER IN-PHASE OR OUT-OF-PHASE AS NECESSARY TO DEVELOP THE NORMAL AND TORSIONAL NATURAL MODES OF THE BRIDGES. THE VARIOUS RESPONSES DURING EXCITATION WERE MONITORED BY ACCELEROMETERS, STRAIN GAGES AND DEFLECTO-METERS AT VARIOUS LOCATIONS ON THE STRUCTURES. BOTH BRIDGES WERE HS20-44 DESIGN HORIZONTALLY-CURVED WELDED STEEL GIRDER BRIDGES WITH A COMPOSITE CONCRETE DECK SLAB. THE MEASURED FUNDAMENTAL VIBRATION RESPONSE FEQUENCY AND MODE SHAPE OF EACH BRIDGE COMPARED FAVORABLY WITH THE RESPONSE PREDICTED ON THE BASIS OF AN ASSUMED SINGLE EQUIVALENT STRAIGHT BEAM. THE SIMPLE-SPAN BRIDGE WAS READILY EXCITED IN THE FUNDAMENTAL MODE AND IN THE FIRST TORSIONAL MODE. THE CONTINUOUS-SPAN BRIDGE WAS EXCITED IN THE FUNDAMENTAL MODE AND IN TWO COUPLED MODES./FHWA/

  • Corporate Authors:

    Federal Highway Administration

    Bridge Structures Group, 1200 New Jersey Avenue, SE
    Washington, DC  USA  20590
  • Authors:
    • Varney, R F
  • Publication Date: 1973-9

Media Info

  • Pagination: 27 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00208117
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-73- 79 Final Rpt., FCP 25G4-072
  • Files: TRIS, USDOT
  • Created Date: Jul 16 1976 12:00AM