Fatigue Reliability Indices for Steel Railway Bridges

Railway bridges are exposed to repetitive high stress due to the live load and constant, relatively low stress due to dead load. Cyclic live load may lead to failure even when the stress level is lower than the allowable stresses. Therefore, components and connections need to be analyzed for possible damage caused by fatigue. The basic approach for estimating the remaining fatigue life of a structure element is to use S-N curves. However, those laboratory specimens tested with a constant-amplitude stress range show variability in the results. This means that fatigue resistance is a random variable. Moreover, railway bridges are subjected to variable-amplitude stress ranges during their service life. The axle load depends on many factors, not only capacity of the car but also dynamic behavior of the car and dynamic response of the bridge. If load and resistance parameters are random variables, structural performance should be measured in terms of reliability. The objective of this study is to present a reliability model for the fatigue limit states demonstrated on the typical steel railway bridge. The research involves development of 3D finite element model of the bridge, calculation of moment history, effective moment and number of load cycles, as well as presentation of resulting reliability indices corresponding to various considered conditions.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AFF20 Steel Bridges.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Rakoczy, A M
  • Nowak, A S
  • Dick, Stephen
• Conference:
  • Transportation Research Board 93rd Annual Meeting
  • Location: Washington DC
  • Date: 2014-1-12 to 2014-1-16
• Date: 2014

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 15p
• Monograph Title: TRB 93rd Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Axle loads; Engineering moments; Fatigue (Mechanics); Finite element method; Live loads; Railroad bridges; Repeated loads; Service life
• Subject Areas: Bridges and other structures; Railroads; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 01514928
• Record Type: Publication
• Report/Paper Numbers: 14-3185
• Files: TRIS, TRB, ATRI
• Created Date: Feb 21 2014 3:16PM