Experimental Study Of Cable Environmental Corrosion Damage Under Alternating Stress

As continuous development of bridge technology and the rise of the bridge span,cable-stayed bridge is becoming one of mainstream bridge of long-span bridges becauseof its superior crossing ability and single of framework style. Cable is the mainload-bearing structure of cable-stayed bridge, its durability will directly affectfull-bridge safety. As cable structures bearing alternating loads and exposed to thenatural environment, especially with a lot of SO₄^2-,Cl^-,NO₃^-and other corrosive mediain the environment, it will be corrosion easily, directly affect the bridge safety andservice life, even cause of major accidents and economic losses. At home and aboard,most the Corrosion research of cable focus on pure corrosion studies, these studies arefar from the actual service conditions that cable corrosion under alternating loads, thesystematic research of cable under the coupled action of alternating stress and corrosionenvironment experiment is less. Therefore, questing a corrosion experiment method ofcable under alternating stress, develop a corrosion experiment of cable under alternatingstress, research the corrosion law of cable under alternating stress to extend the cablelifespan, improved anti-corrosion cable design and avoid the occurrence of majoraccidents has important theoretical significance and engineering application value.This article relying on the national973project “Bridge structure evolution theoryand behavior safety monitoring methods study” and the ministry of transport appliedbasic research project “Mechanism and performance evaluation method study of cableenvironment corrosion damage under alternating stress”, the main research content areas follows:1. Collect domestic and foreign research data of cable corrosion, summarize thedevelopment status of cable corrosion，Compare the advantages and disadvantages ofthese methods, find a clear research ideas.2. On the basis of summarizing and referencing to previous cable corrosionexperiment method, put forward a corrosion experiment method of cable underalternating stress.3. Do the alternating stress state cable corrosion experiments and analysis theresults to explore the corrosion regularity of cable in real service conditions.The main research results of this paper are as follows:1. Collecting and summarizing domestic and foreign cable corrosion experimentalmethod. Put forward a experimental method of study alternating stress state cable corrosion.2. By the alternating stress state strand corrosion experiments we find:1) corrosionspeed of alternating stress state strand is faster than strand with no stress or static stress,and corrosion begin with corrosion pit;2) Plastic deformation cause by stress is themain factor at the early time of corrosion;3) The peak load is the important factor ofcorrosion speed at low frequency alternating load;4) Corrosion of steel strand conformto the protective film rupture theory of several corrosion fatigue theory, Frequency ofalternating load affect the speed of corrosion by affect the cycle of “formation andrupture of protective film”.3. According to the experimental results, described the corrosion mechanism of thesteel strand cables preliminarily after cable lost its external protection, discuss thecorrosion experimental method of strand under alternating stress, summarize thedeficiencies of the experimental method, put forward some direction of optimization.