Monitoring And Evaluation Of Tied Bar On Super Long Span Steel Truss Arch Bridge

Arch bridges with steel trusses have the advantages of spectacular shape, long span, high load capacity and etc. The Chao Tian Men Bridge which will be opened to traffic in May 2009 has a span distribution of 190+552+190m. Its span is longer than any other steel truss arch bridge in the world. It is a breakthrough in the steel truss arch bridge history. The main structure of Chong Qing Chao Tian Men Bridge is composed by the primary arch, the rigid tie bars and the perpetual tie bar rope. The rigid tie bar and the tie bar rope together withstand the horizontal load at the feet of the arch. The tie bar is a very important structure in the load path which makes it the key point in the monitoring process.Monitoring the health state of large bridges is quite popular in the bridge engineering field. It's also a difficult task with various subjects. There is no research findings to borrow because both domestic and oversea study are still in exploration.This article discusses the static force of the tie bars, dynamic assessment index and its threshold value based on the construction of Chao Tian Men Bridge. It gives important reference to the choice of monitoring schemes. Firstly, in order to find the tie bar rope monitoring theory and practice experience, the text summarizes and analyzes the monitoring method and theory of Supporting cable, temporary tie bars and permanent tie bar ropes. Then the text analyzes the relationships of tie bar rope stress, axial stress on the rigid tie bar and the internal force and displacement at each monitoring location based on the loss of tie bar rope strength under dead load and basic variable load, which establishes the assessment index of tie bar safety and tidies up the content of finished bridge monitoring. Based on calculation, the tie bar safety assessment index is categorized into normal, under observation, normal alert and severe alert. Preliminarily confirms the static evaluation threshold value of monitoring system of permanent tie bar rope. According to the regularity of damage of permanent tie bar ropes causing the entire bridge changing, looks for the dynamic assessment index..