Analysis Of Creep Effects On Static And Dynamic Behaviors Of Concrete Filled Steel Tube Arch Bridges Based On Model B3

As one of the properties of concrete, creep will increase the deformation of steel-concrete structures, making internal force and cross-section stress redistributed and reducing the bearing capacity of structures. To arch bridges, creep can also change the shape of arch axes and decrease the stability of arch. In recent years, Concrete Filled Steel Tubular (CFST) arch bridges developed rapidly and got wide application in our country, however, creep influence on CFST arch bridges is not considered comprehensively in design and research on this aspect is not sufficient.Applying the creep calculating method for axial compressed and eccentric compressed CFST members based on the model B3 for concrete creep with Finite Element Method (FEM), This method is convenient for application in the engineering practice with the characters of concision and high efficiency. After calculating a CFST arch bridge, with a span of 360 m, located at the center of Guangzhou City, Guangdong Province, China, it can be concluded that creep influence on CFST arch bridges is considerable and should not be ignored. The calculated results show that the deflection of CFST arch bridges and steel stress increase observably, and the concrete stress decrease markedly, on the other hand, creep have a significant influence on the natural frequency and dynamic response of the bridge with the development of creep (360d). When the moment value of arch rib is large, the moment has great influence on creep of CFST arch bridge.By applying the new model, two parameters influencing the value of creep, ratio(by weight) of water to cement( w/c) and ratio of aggregate to cement(a/c) are analyzed for the first time, moreover the effect of material grade and steel ratio on the creep of CFST arch bridge are discussed further, obtaining some valuable conclusions. The variation of concrete mixtures, however, does not have much influence relatively on the natural vibration frequency and dynamic response on the stage after creep of the bridge; and the steel rate, on the other hand, has considerable influence on the dynamic response of the bridge.