Influences Of Lateral Multi-Trace Loading On Fatigue Behavior Of Orthotropic Steel Deck

The fatigue of the orthotropic steel deck is prominent, and fatigue failure has become one of the main damage-patterns of steel bridge structure. Accurate calculation of fatigue stress spectrum is one of the vital issues of anti-fatigue design due to the extremely important of effective and reliable anti-fatigue design. As the fatigue stress spectrums of vulnerable fatigue details were calculated, the means of single trace loading was adopted currently without considering the influences of wheel trace transverse distribution, hence there exist differences between the calculation of stress spectrums and the real stress spectrums. Three typical vulnerable fatigue details of the orthotropic steel deck of Hong Kong-Zhuhai-Macao Bridge were cited and were studied in this thesis. Based on the comparative analysis of foreign and domestic research findings of wheel trace transverse distribution, the influences of three types of models of the typical wheel trace transverse distribution on the stress ranges of vulnerable fatigue details were studied. This thesis mainly accomplished five aspects as following:Several fundamental concepts which were needed in the research of steel bridge fatigue were introduced briefly and systematically, as following: definition of fatigue, the causes and the research status of fatigue problems of steel deck, foreign and domestic application and development of orthotropic steel deck, several important fundamental concepts related with steel bridge fatigue, three typical cumulative theory of fatigue damage and their derivation processes, equivalent conversion between capricious fatigue ranges and constant fatigue ranges, several anti-fatigue design methods.The comparative analysis was carried out based on the sort out of the foreign and domestic research findings of the wheel trace transverse distribution. The results indicate that wheel trace transverse distributions of foreign and domestic different from each other, and the degrees of dispersion of transverse distribution of domestic vehicle centerline traces were relatively large.The vulnerable fatigue details were chosen based on the overall fatigue studies of Hong Kong-Zhuhai-Macao Bridge. Three typical models of the wheel trace transverse distribution were cited depend on the comparative analysis of foreign and domestic research findings of the wheel trace transverse distribution. The standard fatigue vehicle model was determined referring to the results of three means of calculation. The three-dimensional simulation analysis model for the fatigue control girder segment of the actual bridge was built up by the finite element software ANSYS. The locations of the vulnerable fatigue details were located by the systematical analysis of lateral multi-trace loading.Stress processes of three types of vulnerable fatigue details were calculated according to the means of lateral multi-trace loading, followed by the comparative and systematical analysis of stress processes. The contributions of each lateral trace loading were calculated and were analyzed systematically as the equivalent fatigue stress ranges was calculated. The reduction factors of equivalent stress ranges of single trace loading were calculated and were analyzed systematically.The main conclusions of this thesis were obtained in the last section, therefore, prospection and advices for future research were discussed.