Analysis On Mechanical Characteristics And Study On Practical Calculation Method Of Skew Box-Girder Bridge

With the rapid development of transport and gradually increasing of cities, a large number of interchange, highways and flyovers have emerged. In order to achieve the purpose of crossing barriers and lines, while meeting the economic and aesthetic requirements, more skew bridges are needed. Skew bridges are different from orthogonal bridges, and its force status, structural design and construction are complex than orthogonal bridges. Early stages of development, the structural form of skew bridge was simple-span, and common types of cross-section such as T-shape, I-shape, hollow and small box girder, are always suitable for small and medium span; in recent years, along with the increasing of the span and the width of the deck, multi-span continuous skew box-girder bridges have appeared. However, current researchs on its mechanical characteristics and calculation methods of skew box-girder bridge are not enough,and they still have some questions. In order to solve them, study about skew box-girder bridge is launched in this thesis.1, For a three-span continuous skew box-girder bridge project of1#bridge, the elastic theory and finite element method are used to analyze it. By using the space grillage modeling method, the internal force (including shear, bending moments and twisting moments), pressure and deformation characteristics are analyzed; and stress analysis is achieved with using finite element method for solid model. On this basis, mechanical characteristics of skew box-girder bridge are analyzed.2, With the engineering example, the thesis uses grillage method to discuss the impacts of the structure behavior owing to skew angle. It ensures other influencing parameters such as supporting stiffness, bending and torsion stiffness ratio and wide-cross ratio unchanged, takes different skew angle from0°to60°, and analyzes the impact of different structural internal force and displacement due to skew angle.3, According to different skew angles, the plane beam element model and a number of spatial beam lattice models are established. By comparing computational models to analyze the regular pattern about moment of critical sections such as midspan and support section under live load, and generalizes a simplified practical calculation method of moment.4, Based on the project example of five-span continuous skew box-girder bridge-Hui Longhe Bridge in Guangyuan of Sihuan Province, control sections’theoretical values of internal forces and displacement are calculated by using finite element software to establish a single beam model and simplified practical calculation method of moment, and validated by the loading test results of the project. Then skew box-girder bridge structure response characteristics are analyzed, some summary on loading test methods are done, and it can provide recommendations about loading test for skew box-girder bridges in the future.