Study On The Key Technologies Of Incremental Launching Construction Of Through Steel Three-Arch-Rib Bridge

Incremental launching method was first carried out half a century ago. It has advantages of not affecting traffic, reliable and shortening the construction period etc. Although the skills got mature by now, it was mostly employed in construction of concrete beam bridges. Because of the application of steel arch bridges, incremental launching method is likely to be widely used in the construction of steel arch bridge. Based on the the project of Hongguo Bridge, some key technologies in the incremental launching construction are discussed and studied. The main work accomplished in this thesis is as follows:1. The thesis describes the developing of steel arch bridge and incremental launching construction and introduces the research situation of pushing method in domestic and abroad. The author summarizes the principles, characteristics, technology, classification and frequently encountered problems of the incremental launching construction.2. The stress of the main girder during the incremental launching construction is very complex. The thesis adopts software MIDAS CIVIL to establish a full-bridge model and analyzes the whole process of steel box girder incremental launching, investigates the variation trend of the deformation, internal force and reaction force of the bridge during the incremental launching process, and identifies the most unfavorable loading state.3. Design of the guide girder of steel arch bridge is studied by taking length, stiffness and weight into consideration. Through changing the guide girder design parameters and optimizing in the construction process, it takes the comparison and selection study for structure form of temporary braces in the process of incremental launching, which provides a reference for the design and construction of similar bridge type.4. Through software MIDAS FEA using plate and shell elements to build local finite element model and carry out a precise analysis of the most unfavorable loading state of the steel box girder, the stress distribution of each panel near the supporting point is obtained. The thesis analyzes how the parameter changes of each components (bottom, webs, diaphragms and longitudinal ribs etc) affect the performance of local stability of steel box girder. The thickness of the steel box girder which has great influences on its local stress state is discussed and several improving suggestions are put forward, which will become a reference for similar project construction.