Research On The Key Technologies Of Incremental Launching Of Long-Span Cable-Stayed Bridge With Steel Box Girder

Incremental launching method is increasingly used in the constrution of steel box girder bridge, whereas there are several pressing issues. Fuming bridge, a cable-stayed bridge with steel box girder in Ningbo City, is taken as an example in this thesis. Some key technologies in the incremental lauching construction of it are discussed and studied, which provides a reference for the design and construction of similar bridge type.Firstly, this thesis describes the technologies of incremental launching construction. The reasons of the cumulative manufacturing errors of steel box girder are analyzed, and then the caculation method of secondary interal force caused by manufacturing errors is proposed. On this basis, the location of the temporary pier is optimized in a simplimied model to reduce the cumulative manufacturing errors.Secondly, a bar system FEM model is established to investigate the variation trend of the reaction force, internal force and deformation of the steel box girder during the incremental launching process, and the mose unfavorable loading state is identified. Based on the same model, the reaction force, internal force and deformation of the steel box girder caused by its cross-section temperature difference are studied.Finally, based on the mixed beam and shell elements method of ANSYS software, a precise analysis of the most unfavourable loading state of the steel box girder is carried out, and the stress distribution of each panel near the supporting point is obtained. Furthmore, the thickness of bottom, webs, diaphragms, transverse ribs and longitudinal ribs of the steel box girder which have great influences on its local stress state are discussed and several improving suggestions are put forwad.