Research On Mechanical Properties And Bonding Performance Of Corroded Prestressing Steel Strand

Durability of pre-stressed concrete structure based on steel strand corrosion is now in the limelight. The mechanical properties of steel strand and the bonding performance between steel strand and concrete degenerates because of the corrosion, just like what the ordinary steel’s corrosion does, which cuts the role steel strand plays in pre-stressed concrete structures severely and may lead to the failure of pre-stressed structure’s durability. There are few researches on steel strand corrosion, and this thesis carried out theoretical and experimental researches on mechanical properties of corrosive steel strand and its bonding performance with concrete based on the previous studies. The main work and results of the thesis are as follows:(1) Analyzed the geometric characteristics of steel strand (such as intercostal angle, lay length, etc.), grasped the electrochemical principles to get quick corrosion.(2) And mechanical indexes like rust ultimate strength, nominal yield strength, nominal elastic modulus, ultimate elongation was measured by static tensile test of8designed steel strand specimens at different corrosion loss rate. Formula calculating deterioration of mechanical properties of corrosive steel strand and constitutive model were put forward by comparing the conclusions with others.(3) According to the geometry properties of steel strand, bonding performance model and rust expansion stress, the model of ultimate bonding strength of corrosive steel strand with lateral restraint was set up considering the impact of stirrups.(4) Pulling tests were made on8designed steel strand specimens at different corrosion loss rate, and the impact on bonding performance of steel strand caused by corrosion was analyzed to fit a formula for the degradation of ultimate bonding strength. The theoretical model was verified by comparing the experimental results with the theoretical ultimate bonding strength of corrosive steel strand.