Fatigue Evaluation of Steel Bridges (2012) / Chapter Skim
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Pages 100-116
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From page 101... ...
Example 1: Note: The example presented below is a modification of the existing example currently in the Section 7 of the Manual for Bridge Evaluation (2011)
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From page 103... ...
F-4 CALCULATION OF FATIGUE SERVICEABILITY INDEX Fatigue Serviceability Index Y aQ GRI N MBE 7.2.6.1 No. of load paths (in this case, girders)
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From page 104... ...
F-5 Example 2: (Retrofit fatigue evaluation) In order to improve the fatigue life of the detail given in Example 1, a retrofit option would be to modify the welded cover plate detail by adding a slip-critical bolted end plate connection.
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From page 105... ...
F-6 Example 3: (Floorbeam Fatigue) A two-girder bridge with floorbeams and stringers has welded cover plates attached to the floorbeam flanges.
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From page 106... ...
F-7 The AASHTO LRFD design truck as specified in LRFD Article 3.6.1.4 and shown in the figure below shall be used to determine the critical stress range. Assume that the floorbeam spacing is 25.
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From page 107... ...
F-8 1 11 1Stringer S1 Reaction = 4 (12 10)
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From page 108... ...
F-9 Infinite-Life Fatigue Check MBE 7.2.4 Rp = 1.0 for transverse members MBE 7.2.2.1 Rsa = 1.0 MBE Table 7.2.2.1-1 Rst = 1.0 Rs = Rsa x Rst = 1.0 ( f)
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From page 109... ...
F-10 Hence, RR = 1.0 MBE Table 7.2.5.1-1 ( f) eff = 1.5 ksi A = 3.8 x 108 ksi3 LRFD Table 6.6.1.2.5-1 n = 1.0 simple span girders with L > 40 ft.
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From page 110... ...
F-11 Example 4: (Strategy to Increase Fatigue Serviceability Index – Accept Greater Risk) If the bridge owner is willing to accept a greater likelihood of fatigue cracking for statistically more risk, the detail given in Example 3 can be evaluated for Evaluation 2 Life with a higher resistance factor RR of 1.6.
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From page 111... ...
F-12 G = 0.9 MBE Table 7.2.6.1-1 No. of Spans = 1 (Simple Span between floor beam ends)
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From page 112... ...
F-13 Example 5: (Strategy to Increase Fatigue Serviceability Index – More Accurate Data) Field measurement is one of the methods that can be used to improve the accuracy of data.
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From page 113... ...
F-14 Example 6: (Strategy to Increase Fatigue Serviceability Index – Use Inspection Information) Consider a welded plate girder bridge with a welded partial length cover plate detail.
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From page 114... ...
F-15 Assuming that the bridge is on an Interstate Highway, I = 0.9 MBE Table 7.2.6.1-3 Q = 44 45 (1.0)
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From page 116... ...
Abbreviations and acronyms used without definitions in TRB publications: AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998)
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