Research On Steel-Concrete Composite Segment Fatigue Behavior Of Hybrid Girder Bridge

Hybrid girder, which plays the role of the concrete beam weights and the spanning capacity of steel box girder, has a strong competitive power in the large spa-n bridge design. Steel-concrete composite segment which exists between steel girder and concrete beam is an important component structure of hybrid Girder Bridge. Because the stiffness of steel girder and concrete beam has significant difference, the Force transmission from steel girder to concrete beam and the effects of Shear connector have big effect on connection performance of steel-concrete composite segment. The structure and stress distribution of steel-concrete composite segment are very complex, fatigue problems may arise under the influence of live load. So the experimental and theoretical research on steel-concrete composite segment has very important practical significance.Yongjiang railway extra long-span cable-stayed bridge employs structural style of hybrid girder, with its steel-concrete composite segment locating in the midspan,24.5meters away from the bridge tower. Fatigue property of the steel-concrete co mposite segment has significant effects on reliability and durability for the bridge structure, So a detailed study on fatigue mechanical properties under railway load requires. This thesis is based on the Yongjiang rail-way extra long-span cable-staye d bridge, through the finite element, and studies the method for calculating the val ve of fatigue test load of the steel-concrete composite segment. Then stress distrib ution of the fatigue model is analyzed in detail. Therefore, this thesis has great re ference value. The main wok has been done as follow:1. The development of hybrid girder bridge, the research on fatigue of steel-c oncrete composite segment and the method for fatigue problems have been summar ized.2. Through the three-dimensional finite element MIDAS/CIVIL model of the whole bridge, the internal force influence line can be concluded. Then the equivale nt fatigue of internal force amplitude can be gained by using the fatigue accumula ting damage principle.3. After establishing the ANSYS finite element model for the fatigue test, the stress distribution and influence on fatigue performance can be obtained.4. The process of selecting the fatigue test model and testing scheme is intro duced in detail at last.