The Finite Element Analysis And Experimental Research On The Cables Of Existing Stayed Bridges

The cable of a stayed bridge is one of the important force components. The force size, variation and distribution of cable tension force are an important basis to assess the operational safety of the bridge. In China a large number of cable-stayed bridges were built during the1980s and1990s. Limited to anti-corrosion technology at that time, cable rust, anchorage corrosion diseases affecting the cable force began to appear in large numbers. There are significant risks for bridge safety. On the other hand, limited to the cable force measurement technique, most of the bridges were not embedded cable force sensors in advance, which lead to the limited alternatives for cable force measurement in bridge service. The frequency method is the widely used method for the cable force measurement at present. In this paper, based on theory of frequency method and taking the Xiangjiang River Second Bridge (XRSB) as the engineering background, combining the finite element analysis with field test, cables of the XRSB are studied. The main work and conclusions are as follows:1. Using finite element analysis method and physical modeling, considering the damper and the fluid-structure coupling effect between flow and the steel strand, the effective calculation length and bending rigidity in the frequency method are comprehensively analyzed. The correction coefficient of the effective calculation length with different length of stayed cables and the correction coefficient of the bending rigidity by using equivalent area method are obtained.2. Frequency changes and loss of cable force resulting from uniform corrosion or pit type corrosion of steel strands are analyzed.3. In order to observe the internal corrosion of steel strands,38stay-cables of the XRSB are selected to experiment research with opening window. The cable force dynamic measuring instrument is used to measure cable tension force.Grasping the current cable corrosion and cable force changes will provide help to evaluate the safety of the whole bridge.4. Combining with finite element analysis of the correction formula to modify the effective conversion of cable length of the XRSB will provide reliable evidences for the safety of the bridge operation. In view of the field test and finite element analysis results, considering the service life of the cables, the proposal for immediate replacement of cables is put forward.