Fatigue And Reliability Evaluation Of Welded Structure For Orthotropic Steel Bridge Deck

Orthotropic bridge deck is one of the most common structure forms in large or medium span bridges. Under the action of moving vehicle load, the orthotropic bridge deck will be easy to appear fatigue with increasing in working time. Some studies show that the stress concentration is much serious in connection joint of orthotropic bridges because of welding defects and construction quality factors. And some orthotropic bridge decks appear fatigue cracks in short working time, which influence badly the security and durability of bridge. Choosing Guangya Bridge as the engineering background, the orthotropic bridge deck is simulated to evaluate its fatigue life.Firstly, the history of studying fatigue and basic analysis theory of weld fatigue are introduced. Advantages and disadvantages are illustrated by comparing some analysis methods of fatigue life. Some fatigue design thoughts of steel bridges are summarized.Secondly, provisions about fatigue, such as fatigue loads, in existing national highway bridge specification are systematically summarized and reorganized. Besides, by comparing difference in national standard specification vehicles fatigue, a concept called as Equivalent wheelbase load is proposed in order to facilitate designers, whose accuracy has been proved by the cases. Furthermore, the standard fatigue car is used in the present model.Finally, choosing orthotropic bridge deck of Guangya Bridge as the engineering background, and respectively selecting British standard statistical fatigue cars and China general fatigue cars obtained by statistics as fatigue loads, the moving processes of fatigue cars on orthotropic deck are simulated based on transient analysis of finite element software ANSYS. And the dynamical responses of orthotropic deck are obtained to comparative analysis and discussion. Fatigue life and safety factor of the orthotropic deck are also calculated by fatigue analysis software FE-SAFE. The computational results show that the safety factor of orthotropic bridge deck is large enough and the design is conservative in safety.