Research On Stability Of Steel-Concrete Composite Girder Bridge By Incremental Launching Construction

The composite beam structure has been widely used in bridge engineering for the advantage of good mechanical properties.The steel sections of composite bridge is often designed to be thin-walled shape.When the Incremental launching method is used for construction,stress concentration and local stability problems often become quite serious,so it is of great practical significance to study the stability problem of composite bridges in the process of Incremental launching construction.The development and advantages of the Incremental launching method about composite bridge are introduced in the thesis firstly,and the analysis methods of two types of stability problems are summarized.Subsequently,the Baojiazhuang Bridge in the Jianshui(Gejiu)to Yuanyang Expressway in Hong He Prefecture is used as the engineering background.The beam elements is used to establish the finite element model of the full bridge during the entire process of the Incremental launching construction.The stress,deformation and overall stability of the three different construction schemes during the process of construction are analyzed,and an optimized scheme is proposed for the overall stability of the split double-box composite beam at the maximum cantilever.On the basis of above analysis,two most unfavorable working conditions in the process of construction are determined.The large-scale finite element software ABAQUS is used to establish a full-bridge shell element model.The influence of longitudinal stiffener rib height and thickness,web thickness,and template beam stiffness to local bucking are analyzed.The relationship between the stability coefficient and the normative local stability formula is discussed.The stability problems of dangerous working conditions are evaluated on the basis of considering nonlinearity.Finally,in view of the unsynchronized Incremental launching construction in the project,the stress state and stability of the super-high pier under the unsynchronized Incremental launching construction are analyzed.