Stability Analysis And Control Technic On High Piers Of Highway Bridge At Construction Stage

With the rapid development of transportation enterprise in our country, highway construction is gradually extended to mountain and hilly areas. Due to restrict of the landform, bridges with high piers are widely used in these areas to cross deep gorges. High bridge piers usually have large slenderness ratio and hollow thin-wall section form, whose stiffness is greatly weakened and flexibility is increased, so that the stability analysis is very important. In the process of high pier construction, structure has not yet formed integral, so the partial load due to asymmetric construction and the wind load will make the high pier produced large bending moment and deformation, that the stability problem tends to be the control factor in the construction.By taking some single hollow thin-wall high pier of Xiongdu power station bridge in Hubei as the research object which is in construction in Hubei Province, this paper developed the analysis of stability and the research of construction control. The main works and results of the study are as follows:1. Introduces the application and research status of high pier at home and abroad, discusses the stability theory and temperature effect about high pier structure, and determines the high pier stability evaluation index and temperature effect on the pier top displacement.2. Establishes the beam element and solid element high pier models using finite element analysis software ANSYS, and analyzes the linear elastic stability in different load conditions. Through analysis, the pier construction load is the control load impact of the high pier linear elastic stability. And the stability safety coefficient using solid element model is smaller than it using beam element model, which can better reflect the real bucking load of high pier.3. Analyzes the geometry nonlinear stability using two models under the ideal condition, the initial defect condition, the wind load condition, and both initial defect and wind load condition. Through analysis, it is the worst condition under initial defect and wind load. And on this condition, the top displacement of high pier is maximum, so that the large deformation effect can not be ignored. 4. Establishes the finite element model of the single hollow thin-wall high pier using reinforced SOLID65element, and analyzes the double nonlinear stability under the ideal condition, the initial defect condition, the wind load condition, and both initial defect and wind load condition. Through analysis, the stability safety coefficient in double nonlinear case is obviously reduced than linear elastic, geometry nonlinear case, which illustrates that the material nonlinear stability plays a dominant position in the high pier stability.5. Introduces the basic content on high piers construction monitoring and control, and combined with the actual project, gives a verticality control method of the thin-wall high pier. The results show that the method for uprightness control by total station and laser vertical instrument can guarantee high efficiency and accuracy in the process of high pier construction.