Assessment of fatigue reliability of steel girder bridges

HP Hong, K Goda, C Lam, A Au

Research output: Contribution to conferenceConference Paperpeer-review


The study is focused on the evaluation of fatigue reliability, and calibration of the required fatigue design factor. A literature review shows that the target reliability index employed for the bridge design code varies, and the target reliability index employed for the calibration of the current CHBDC is set equal to 3.5 for a design life of 75 years, which is adopted in the present study. For calibrating the required fatigue design factor to achieve a target reliability level, firstly, a simple equation relating the reliability index to the fatigue design factor is developed. Also, a program is implemented and used to carry out dynamic analysis considering the bridge-pavement-vehicle interactions and to assess the statistics of the stress cycle and stress range. For the analysis, bridge with span ranging from 12 to 36 (m) are considered. Several categories of pavement roughness and different truck speeds are employed as well. The analysis results show that for bridges with pavement roughness classified as good and average categories, the use of the fatigue load factor of 0.52 implemented in the current design code is not conservative, in almost all case, except for the cases of the bridge with a span of 35.36 (m) and truck speed less than or equal to 100 km/hr. This observation is based on the consideration that the traffic volume used for the design represents the actual traffic volume. However, the required fatigue load design factor is significantly decreased if the pavement roughness is ignored or the number of girders of the bridge participating in the dynamic response is increased. The findings of this study indicate that a detailed review or perhaps a recalibration of fatigue design factor is needed for the next edition of the Canadian bridge design code considering possible assessment of the pavement roughness, statistics of traffic volumes, and validation of numerical model with in situ stress measurements.
Translated title of the contributionAssessment of fatigue reliability of steel girder bridges
Original languageEnglish
Pages298-1 - 298-11
Number of pages11
Publication statusPublished - Aug 2010

Bibliographical note

Name and Venue of Event: Niagara Falls, Canada
Conference Organiser: Canadian Society for Civil Engineering


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