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Reliability Analysis And Life Span Prediction Of Strand Cable

Posted on:2012-03-31Degree:MasterType:Thesis
Country:ChinaCandidate:Q F ChenFull Text:PDF
GTID:2132330335452581Subject:Bridge and tunnel project
Abstract/Summary:PDF Full Text Request
The design life span of cables are mainly upper 30 years, most cable stayed bridge are in cities with large spans and long cables, the cables are loaded with heavy wind and traffic load, and influenced by the humid and pollution atmospheric, the resistance of cables are deteriorated quickly, which lead the life span of cables are mainly between 10~20 years, the frequently cable replacement project make the great loss of society in economics and efficiency. The resistance deterioration of cables make the reliability of cables become a restriction of the overall reliability of cable-stayed bridge, and become a hidden danger of allover structure. To research the main reasons and mechanism of the cable resistance deterioration are meaningful to enhance the life span and reliability of cables.The cable resistance deterioration are coupling influenced by many factors, the reliability analysis of cable exert present are mainly base on the parallel wires cables, which supposed that the wires of cable do not interact with each other, while to the strand cables, as the existence of the angers between the wires make the force between the wires are large enough to taken fretting fatigue into account when an analysis of strand cable are carried out. What's more, the deterioration of cables are a process of randomness,uncertainty and dynamicity, which classic ultimate capacity method can't descries, so a time-dependent reliability method should be developed to analyze the reliability of strand cables.This document based on a Yangtze river bridge which is constructing, according to the natural frequency of the cables, getting reasonable amplitude and frequency of cables. Based on the FEM program ANSYS to build a strand wire mechanics contact model, finding the anchor-end interaction force of the wires in strand when the cables are vibrating, based on the metal corrosion and fatigue theory to derived the time-dependent reliability analysis modal of cables which considering the fretting-fatigue and corrosion-fatigue, and finally to calculate the reliability index of strand cables, the conclusion as following: (1) According to the calculate outcome of the FEM wires contact modal, the stresspoint is distributing according to the spiral chainlike on the surface of the wires,then the interaction force of wires was calculated. (2) According to the theory derived and FEM analysis, grasping the calculation formula of fretting-fatigue wearing depth with time consumption.(3) To calculate the time-dependent reliability index of strand cable, to estimate the cable life-span according to the reliability-GB, the conclusion drawn that the reliability of cable decrease more quick when the fretting-fatigue factors was considered, comparing with the cable modal which wasn't consider the fretting-fatigue, the life-span of the former reduced, the decrease range is 6.3years.
Keywords/Search Tags:Cable-stayed Bridge, Strand Cable, Fretting-fatigue, Corrosion, Time-dependent Reliability
PDF Full Text Request
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