The Definition Of Mid-cable Force And Effects In Construction Of Cable Stayed Bridge

Cable stayed bridge is usually used in long-span bridges, especially concrete one is more widely used in China, and its spaning ability is second to suspension cable. But compared to suspension bridge, the construction of the cable stayed bridge is a continually changing process of its structure system. So in order to achieve rational complete bridge state and to ensure the safety of constructing bridge, it must be strict with the construct process, which is the central task of the cable stayed bridge construction control.Through a case study on the construction control of Hongfenghu Bridge, which is the first cable stayed bridge in Guizhou Province, this paper discusses one of the main parts, which is about control and detection of the cable force in the process of the cable stayed bridge construction control. In order to ensure the safety in the process of the bridge structure and the large working tools, such as the form traveler , it is very important for the bridge construction to research the mid cable force of the cable, and this paper gives the range of admissible cable force in all kinds of working situations. It is the main factor that the temperature affects the cable force and the elevation of the bridge in the process of its construction. According t o the calculating results of limited elements and the continuously surveying data of the actual cable force along with the sunlight changing, this paper analyses the working fashion about the temperature effecting on the state of the bridge, and presents a modified method about the cable force affected by the temperature in the process of the construction, and also put forward a numerical value and a calculational method often used to study the solid side beam cross affected by the temperature in the modern cable stayed bridge. Through the detail analysis for the mensuration of cable force and the affecting factors of its precision, this paper solves the problem that the measuring error is usually big because the short-cable is affected by the the moment of inertia, accordingly guarantees the precision of the frequency method to measure the cable force. And through the analysis for the gravity droops of the cable impacting on its characteristic, this paper gives a formula to calculate the cable force on tower, effective vetical component force of the cable force on beam and the obliquity of the cable, and presents a simple and effective method to deal with the difference between the nominal cable force and effective cable force.In conclusion, this paper integrates the practice of construction control into Hongfenghu Bridge, and discusses some problems about control and detection of the cable force in the construction process of the concrete cable stayed bridge, and presents some practicable transaction methods, which give reference points for the design and construction control of the cable stayed bridge.