Study on mechanics behavior and fatigue performance of steel-concrete composite joints of railway hybrid girder cable-stayed bridges

A partial full-scale model is designed and manufactured by the principle of equivalent stress to investigate the mechanics and fatigue performance of steel-concrete composite joints of long-span railway hybrid girder cable-stayed bridges. Both verification fatigue load and destruction fatigue load are applied to the test model, where the variations of stress on the steel beam and shear stud with loading history are obtained. Meanwhile, the influence of friction force in shear force transmit on the joint section is investigated by considering different friction coefficients. The test results indicate that the friction has little contribution to the transmitting shear force under the fatigue load when the structure is in elastic state. The calculation value difference of the longitudinal stress using contact analysis is less than 0.5% when the friction coefficient is 0.1 and 0.6, respectively. Moreover, the stress of the composite structure is low and the stress of each measure points is stable for the 2 million times verification fatigue test, which demonstrates the reliability and good fatigue performance of structure force transmitting. The stress of steel beam and shear stud increases obviously due to the separation between steel and concrete, especially on the top position after 1million times destruction fatigue loading, but the steel-concrete composite structure still works well with fatigue safety reserves to some extent. ©, 2015, Editorial Office of China Civil Engineering Journal. All right reserved.