Spatial Stress Test And Analysis Of The0#Block For Extradosed Cable-stayed Bridge

Extradosed cable-stayed bridge is being more and more widely used because of its excellent structure performance and good economic indicator.0#block of extradosed cable-stayed bridge is located at the joint among tower, pier and beam. Its geometry and boundary condition are very complex. As the starting point of cantilever construction, the0#block bears the cantilever weight on both sides during the construction progress, it is usually arranged with a lot of ordinary steel bars and prestressed steel bars and its stress constantly changes along with the construction. On account of complex three-dimensional pressure state, the method of ordinary plane beam-column calculation cannot meet the accuracy requirement. Therefore the method of establishing the0#block three-dimensional space finite element model and making a detailed analysis of the space stress state for0#block are necessary.Changshan bridge(65+108+65m extradosed cable-stayed bridge with double towers and single cable plane) is treated as engineering background in this paper. Firstly, the plane beam-column model is established by finite element software Midas/civil to analyze the static characteristic of Changshan bridge. It focuses on internal force, displacement, stress, cable force of the largest cantilever phase and completed bridge phase. Meanwhile, the data for subsequent0#block is provided. Secondly, the0#block space model is established via software MIDAS/FEA. Based on the theory of box girder space stress analysis, three-dimensional stress and principal stress in the largest cantilever phase and completed bridge phase are analyzed respectively to get stress state and distribution rule on top plate, bottom plate, web plate and diaphragm plate of the0#block. Finally according to the actual situation of the construction site and theoretical result, stress test sections and points are selected. Through embedding sensors to monitor the stress of control section at important construction phase, its stress variation rule during construction is summarized and timely compared with theoretical value to analyze the cause of error and ensure the construction safety.The conclusion of this article can provide data support for related project. Meanwhile, the conclusion can supply reference for0#block optimal design, spatial stress analysis and stress testing. It has important practical significance.