Design Guide for Bridges for Service Life (2013) / Chapter Skim
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Pages 604-612
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From page 604... ...
602 G.1 introduction This appendix provides a procedure for designing sliding surfaces for service life that is applicable to various bearing devices that allow rotation and use sliding surfaces to allow horizontal movements. A key factor in the process is being able to predict the service life of sliding surfaces, which is based on the following essential parameters: 1.
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From page 605... ...
603 Appendix G DESiGN pROviSiON FOR SLiDiNG SURFACES USED iN BEARiNG DEviCES FOR SERviCE LiFE G.2 eLementS oF deSign ProviSionS G.2.1 Wear Rate Tests have shown that plain polytetrafluorethylene (PTFE)
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From page 606... ...
604 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE carried out to develop final PV versus wear rate curves that can be reliably used for actual service life design. Figure G.1 shows wear rate versus PV data for plain PTFE sliding surfaces.
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From page 607... ...
605 Appendix G DESiGN pROviSiON FOR SLiDiNG SURFACES USED iN BEARiNG DEviCES FOR SERviCE LiFE NCHRP 432 Tests SHRP 2 Tests Dimpled unlubricated SHRP 2 Tests Plain ♦ NCHRP 432 Tests Glass Filled SHRP 2 Tests Fluorogold Wear Rate – Reinforced PTFE Figure G.1.
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From page 608... ...
606 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE G.2.2 Estimating total Accumulated movements The total travel demand is the total accumulated distance that the sliding surface will be traveling throughout the service life of the bridge system. This total travel demand can be estimated using (1)
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From page 609... ...
607 Appendix G DESiGN pROviSiON FOR SLiDiNG SURFACES USED iN BEARiNG DEviCES FOR SERviCE LiFE In Equation G.2, A is a parameter that accounts for boundary conditions at both ends of the span.
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From page 610... ...
608 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE G.2.2.4 Total Induced Horizontal Movement, (TD) Demand Finally, Equation G.5 estimates the total bridge movement at the bearing: (TD)
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From page 611... ...
609 Appendix G DESiGN pROviSiON FOR SLiDiNG SURFACES USED iN BEARiNG DEviCES FOR SERviCE LiFE G.2.3.2 Speed of Movement per Temperature Variation The speed of travel (V)
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From page 612... ...
610 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE where (TD) Demand = total induced horizontal movement (see Equation G.4)
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