This study is focused on the fatigue reliability and calibration of the required fatigue design factor to achieve a selected target reliability level. A review of the previous bridge design code calibration analyses shows that the target safety level employed for the calibration of several versions of the design codes are inconsistent. However, the target reliability level employed for the calibration of the CHBDC is set equal to 3.5 for a design life of 75 years. This target reliability level and design life period is adopted in this 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, MATLAB scripts were 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. Two categories of pavement roughness and different truck speeds are employed as well. The analysis results show that in almost all cases, 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, the use of the fatigue design factor of 0.52 is not conservative. This conclusion is based on the consideration that the traffic volume used for the design represents the actual traffic volume. Based on the findings of this study, it is suggested that the fatigue design factor is to be recalibrated for the next edition of the Canadian bridge design code. Also it is recommended that the truck survey task should be extended for many locations including the collections of the statistics of traffic volumes, and that comparison of the in situ measurement and numerical analysis of the stress cycle and range to be conducted to assess the modeling error.
|Translated title of the contribution||Fatigue Reliability Analysis of Steel Girder Bridges|
|Publisher||Ministry of Transportation Ontario|
|Number of pages||78|
|Publication status||Published - 2006|