STRUCTURAL RESPONSE OF PRESTRESSED CONCRETE BOX-BEAM BRIDGES

THE FIELD TESTING IS DESCRIBED OF AN IN-SERVICE BEAM-SLAB HIGHWAY BRIDGE SUPER-STRUCTURE, CONSISTING BASICALLY OF (1) FIVE LONGITUDINAL PRESTRESSED CONCRETE BOX BEAMS, SPREAD APART AS IN TYPICAL I-BEAM CONSTRUCTION, (2) CAST-IN-PLACE SLAB, CURB, AND PARAPET SECTIONS, AND (3) END AND MIDSPAN EXTERIOR DIAPHRAGMS. A TEST LOAD VEHICLE, CLOSELY SIMULATING AN AASHO HS 20-44 DESIGN VEHICLE, WAS USED TO PRODUCE LIVE LOAD EFFECTS IN THE STRUCTURE. THE PRINCIPAL OBJECTIVES WERE TO EXPERIMENTALLY INVESTIGATE THE STRUCTURAL RESPONSE OF THE SUPERSTRUCTURE (1) TO THE TEST VEHICLE TRAVELING AT CONSTANT SPEEDS, IN THE RANGE 2 - 60 MPH, AND (2) TO AN IMPACT TEST IN WHICH THE TEST VEHICLE PASSED OVER A RAMP, TWO INCHES IN HEIGHT, AT A SPEED OF 10 MPH. A THIRD OBJECTIVE WAS TO PROVIDE ADDITIONAL INFORMATION ON THE LATERAL DISTRIBUTION OF STATIC VEHICLE LOADING. FROM THE SPEED RUNS OF THE TEST VEHICLE, IT WAS FOUND THAT THERE WAS A SIGNIFICANT VARIATION IN THE DYNAMIC LOAD FACTORS. MAXIMUM VALUES WERE DEVELOPED AT SPEEDS OF 26 AND 55 MPH, AND AT THESE SPEEDS, THE LOADED FREQUENCIES OF VIBRATION OF THE SUPER-STRUCTURE WERE NARLY EQUAL TO THE UNLOADED NATURAL FREQUENCY. THE FACTORS AT SOME OF THE SPEEDS EXCEEDED THE DESIGN VALUE. HOWEVER, IT IS EMPHASIZED THAT THIS DOES NOT IMPLY INADEQUACY OF THE DESIGN VALUE, SINCE THE MAXIMUM-LOAD DESIGN CONDITIONS MUST INCLUDE MULTILANE LOADING CONDITIONS, AS WELL AS CONSIDERATION OF OCCURRENCE PROBABILITIES. THE IMPACT TESTS REVEALED CONSIDERABLE AMPLIFICATION OF STATIC LOAD EFFECTS, AND INDICATE GENERAL BEHAVIOR CHARACTERISTICS RESULTING FROM IMPACT-TYPE LOADING. THE LATERAL DISTRIBUTION OF THE TEST VEHICLE LOAD WAS MORE UNIFORM IN THE SPEED AND IMPACT RUNS THAN IN THE CRAWL RUNS. /AUTHOR/

• Corporate Authors:

  Lehigh University

  Bethlehem, PA  United States  18015

  Pennsylvania Department of Transportation

  1215 Transportation and Safety Building
  Harrisburg, PA  United States  17120

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Chen, Y L
  • VanHorn, D A
• Publication Date: 0

Subject/Index Terms

• TRT Terms: Box beams; Bridge design; Bridges; Cast in place structures; Diaphragms (Engineering); Dynamic loads; Highway bridges; Live loads; Prestressed concrete; Slabs; Static loads; Structural analysis; Structural design; Structural mechanics; Superstructures
• Uncontrolled Terms: Structural behavior
• Old TRIS Terms: Diaphragms
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00208001
• Record Type: Publication
• Source Agency: Federal Highway Administration
• Report/Paper Numbers: 68-27
• Files: TRIS, USDOT, STATEDOT
• Created Date: Aug 8 1971 12:00AM