NEOPRENE BRIDGE PADS: FATIGUE BEHAVIOR IN COMPRESSION AND SHEAR

NEOPRENE BEARING PADS COMPARABLE IN SIZE AND DUROMETER HARDNESS TO THOSE USED TO SEAT PRESTRESSED CONCRETE GIRDERS IN BRIDGE CONSTRUCTION WERE LABORATORY TESTED TO DETERMINE THEIR FATIGUE BEHAVIOR. PLAIN CUT PADS WERE SUBJECTED TO REPEATED COMPRESSION LOADING IN THE RANGE OF 600 TO 1200 PSI, AT THE RATE OF 100 CYCLES PER MINUTE FOR A TOTAL OF 1 MILLION CYCLES, AT TEMPERATURES OF 120 F, 72 F, AND 0 F. THOUGH PADS TESTED AT 0 F SHOWED A FATIGUE EFFECT AFTER 100,000 LOAD CYCLES, NO PERMANENT DAMAGE WAS OBSERVED FOR COMPRESSION LOADING ALONE. BOTH PLAIN AND LAMINATED PADS WERE SUBJECTED TO REPEATED SHEARING LOADS WITH CONSTANT VERTICAL COMPRESSION, FOR DEFLECTIONS UP TO 50% OF THE UNCOMPRESSED PAD THICKNESS. THE TEST TEMPERATURES WERE AGAIN 120 F, 72 F, AND 0 F, BUT CYCLING RATES AND TOTAL CYCLES VARIED. THOUGH TEARING, CHAFING, RAVELING, AND SEPARATION OF NEOPRENE FROM METAL SHIMS IN LAMINATIONS WERE OBSERVED, THE DAMAGE OCCURRED AT SHEARING DEFLECTIONS HIGHER THAN THE PRESENT DESIGN LIMIT OF PLUS OR MINUS 25%. SHEARING STIFFNESS INCREASED MARKEDLY AT 0 F, INDICATING THAT AT LOW TEMPERATURES BRIDGE SUPPORTS MAY BE SUBJECTED TO APPRECIABLE HORIZONTAL FORCES. TO PREVENT SLIPPAGE AT LOW TEMPERATURES, A MINIMUM VERTICAL PRESSURE OF 250 PSI IS RECOMMENDED FOR A DESIGN SHEARING-DEFLECTION LIMIT OF PLUS OR MINUS 25%. /AUTHOR/

  • Supplemental Notes:
    • No B-97, 80 PP
  • Corporate Authors:

    Pennsylvania State University, University Park

    Pennsylvania Transportation Institute, Transportation Research Building
    University Park, PA  United States  16802
  • Authors:
    • Brielmaier, A A
    • Hoblitzell, J R
    • Borden, G G
  • Publication Date: 1968-1

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  • Accession Number: 00208437
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 6 2003 12:00AM