| The birth of the orthotropic steel bridge deck structure is considered to be the landmark innovation achievement of modern bridges.Due to its advantages of light weight,large bearing capacity,good wind resistance and good economic benefits,it has been widely used in the field of bridges.The orthotropic steel bridge deck of large cantilevered steel box girder is a kind of bridge structure form emerging in recent years.The wide deck formed by the hollow diaphragm system makes it different from the general flat steel box girder deck.Based on the engineering background of the newly built Fuchimen Road-rail Cable-stayed Bridge on the Ningbo-Zhoushan railway.The main research contents and results are as follows:(1)The overall finite element segmental model of the cantilevered steel bridge deck is established by the large-scale general finite software ANSYS,and the standard fatigue car loading is carried out considering the lateral distribution of the wheel traces;the most unfavorable position of similar fatigue details is found out for structural details such as the ribto-deck joints,rib-to-diaphragm joints,deck-to-longitudinal beam joints and arc-shaped notch of diaphragm;From the perspective of stress and deformation,the fatigue stress characteristics and behavior mechanism are analyzed,and the fatigue stress behavior of orthotropic steel bridge deck of cantilevered steel box girder is summarized.(2)A solid finite element model including the welding details of the deck-to-longitudinal beam joints is established,and its fatigue performance are studied with the use of the hot spot stress method.It is found that there is a risk of fatigue cracking in the welding toe of the panel;on this basis,the control variable method is used to analyze how the structural parameters(plate thickness,welding leg size,the distance between the longitudinal beam web and the adjacent longitudinal ribs,the distance between the diaphragms and the thickness of the bridge deck)influence the characteristics of the force mode and the stress distribution law,and the influence mechanism is analyzed.(3)Mainly based on the Chinese specifications for design of highway steel bridge,fatigue life evaluation is carried out on the welding details of the deck-to-longitudinal beam joints in combination with the British BS5400 specification and the European Eurocode3 specification.The results show that the fatigue damage caused by Chinese standard fatigue car is bigger than other specifications,which to a certain extent accords with the characteristics of high proportion of heavy vehicles and large traffic flow in China.(4)Considering the probability of lateral distribution of wheel tracks has a significant impact on the calculation results of fatigue life of structural details,and the influence of lateral distribution of wheel tracks should be reasonably considered when designing steel bridges. |
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