Research On Construction Control And Health Monitoring Of Prestressed Concrete Cable-stayed Bridge

Span cable-stayed bridge has become the fastest growing and most competitive bridge type of the modern bridges due to its superior spanning capabilities, reasonable stress system and beautiful appearance. With increasing span length and structure complexity, the research of cable-stayed bridge’s construction control system and health monitoring system is becoming more and more important. On one hand, construction monitoring and control is an important measure to ensure the quality of construction of large bridges, through strict control of key technologies, timely identification, and error correction in the construction process to ensure that the internal forces and linear match the bridge design well. On the other hand, the overload of vehicles and environmental factors will cause a variety of injuries and diseases to the bridge. The use of real-time online monitoring inclinometers of the bridge to monitor the dynamic deflection is conducive to detect localized damage and the decreasing carrying capacity of the bridge and take measures to effectively prevent sudden disasters of the structure at a low cost. Combining with the practice of construction control on Xiao Gan Bridge in Zhou Shan, this paper has done the following work:1) Make the computational model of the bridge with Finite element software, analysis the internal forces and linear of the bridge in the construction and determine the control parameters; Meanwhile obtain reasonable and ideal bridge construction structural parameters:the camber of the bridge, the elevation of each segment, the reasonable cable force and the unstressed length of cable;2) Use a numerical method to determine interim cable forces according to the forces limitations of traveler and main girder. A space beam elements model is established to analyze the stress and deformation of the form traveler during different conditions. And a shell elements model is established to solve the problem of the stress concentration around the hook;3) Review the bridge deflection measurement of the study’s situation and the latest progress and introduce the common methods of bridge deflection today. My paper makes use of the QY inclinometer to measure the bridge deflection, build up a mathematic model of spline function to calculate the cable-stayed bridge’s deflection. Then building up the cable-stayed bridge by software to verify the feasibility of this mathematic model to calculate deflection and research how to optimize slope sensors installation when measure such bridges. The results of analyze show that it is feasible using this model to calculate the deflection of cable-stayed bridges with few number slope sensors;4) The effectiveness of the Practical formulas was verified by the numerical analysis and the field cable force measurement. This paper considers the influences of two factors as the lanyard extension rod and shock absorbers and determines the sampling frequency range of the cables based on the sampling theory and engineering practice.