Distortion-Induced Fatigue Investigation of Double Angle Stringer-to-Floorbeam Connections

Open Access
Author:
Guyer, Robert Christopher
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 10, 2010
Committee Members:
  • Jeffrey A Laman, Thesis Advisor
Keywords:
  • moment rotation
  • bridge
  • stringer floorbeam connection
  • double angle connection
  • distortion-induced fatigue
  • fatigue
  • railroad
Abstract:
Past research has shown that double angle stringer-to-floorbeam connections in riveted railway bridges are susceptible to fatigue cracking caused by secondary, distortion induced stress. This stress, caused by stringer end rotation is not easily calculable therefore more detailed analysis techniques are needed to quantify connection behavior. The present study was initiated to determine the effect of connection parameters on moment-rotation behavior and stress concentrations from a standard 286,000 pound railcar load. Seventy-two unique double angle connection configurations were investigated using ABAQUS 3D and SAP2000 2D finite element analysis software. Two double angle connection specimens were evaluated experimentally that provided verification data for finite element model calibration. Parametric study results are presented as moment-rotation curves and compared with three empirical prediction equations. Maximum principal stress is investigated in each analysis case and a stress prediction equation is proposed. This equation provides an easily calculable and effective method to predict the magnitude of stress range in connection angles as a function of study parameters: (1) outstanding gage distance, (2) angle depth, (3) angle thickness, and (4) stringer length. This facilitates fatigue life evaluation without the need for rigorous analysis. Additionally, study parameters are quantified and compared to the current AREMA fatigue design rule.