Fatigue Performance And Control Measures Of Orthotropic Steel Decks On Highway Bridge

Orthotropic steel bridge deck has the advantages of lighter weight,larger bearing capacity,faster construction speed and so on.It is widely applied to the large-span bridges across the world.However,due to its complex structure and numerous welds,the problem of fatigue crack is very serious.The reduction of welds is one of the ways to improve the fatigue performance of orthotropic steel bridge decks,and the orthotropic steel deck with large longitudinal ribs is a structural form that meets this design philosophy.Therefore,the finite element numerical simulation method is used to study the fatigue performance of such kind of orthotropic steel decks,and the influence of the structural parameters on fatigue performance is also discussed.What’s more,the orthotropic steel bridge deck with ordinary longitudinal ribs is studied.The fatigue performance of the two is compared and analyzed in detail.Finally,the control measures of fatigue crack are summarized and considered,and the significant influence on fatigue crack control of the orthotropic plate-UHPC composite bridge deck reinforcement method is verified.The specific works are as follows:(1)The development history of orthotropic steel bridge decks,the theory and research results of fatigue are described,and the research contents and methods of this paper are proposed.(2)Two kinds of finite element models of orthotropic steel bridge decks with ordinary longitudinal ribs and large longitudinal ribs are built.The equivalent stress amplitudes of the three most common fatigue details are calculated using the four specifications,and the differences in fatigue performance between the two are studied.What’s more,the difference of the equivalent stress amplitude calculated according to the norms of each country is compared and evaluated.(3)The thickness of the deck,U ribs and diaphragm of the orthotropic steel decks with ordinary longitudinal ribs and large longitudinal ribs are changed respectively.The differences of the influence caused by structural parameters on the fatigue performance are studied.(4)Aiming at a given size of orthotropic steel deck with ordinary longitudinal ribs and large longitudinal ribs,the finite element model with paving layer entity is built.At the same time,the elastic modulus of the paving layer is changed.The difference in fatigue performance of the two longitudinal ribs caused by the pavement layer is studied.(5)The measures for repair and reinforcement of fatigue cracks in orthotropic steel bridge decks are introduced,and the significant influence on fatigue crack control of the orthotropic plate-UHPC composite bridge deck reinforcement method is verified.The problems of the research are pointed out,and this will provide reference for later researchers.