Effect Of Mechanical Properties Of Corroded Steel On Concrete Member

Reinforced concrete structure is often caused the early destruction due to corrosion of the reinforcement bars in China’s coastal and offshore areas.The research result shows that the corrosion of reinforcement is one of the dominating factor for decreasing the durability of reinforced concrete structures. And then our country building industry is developing vigorously, studying the relation between the function degenerate of reinforced bar and rust degree, design and security carrying out structure durability estimate, that have the significant economic effect and effect on society, and it is worth doing thorough research.At the same time, the bond action is the basic precondition for conjunct work of steel bar and concrete in reinforced concrete structures. When the steel bar is rusted.the bond stress will decrease much.which will impair the safety and durability of the structure severely.Research on bond issue of corroded reinforced concrete is important in both theory and practice. However.due to multitudinous influencing factors and intricate mechanism,bond action of corroded reinforced concrete is a sort of complicated interaction.A comprehensive and credible bond theory system when the steel bar is rusted hasn’t been established.Therefore, research on bond performance of corroded reinforced concrete is one of the most active and promising research fields. This paper mainly studies the content as follows:In order to research mechanics performance degradation of rusty reinforcement bar. accelerate corrosion treatment of the different reinforced type and the different reinforced diameter are conducted with all soaking and impressed current method. Corroded reinforced bars are designed to carry out tension test with hydraulic universal testing machine. The comparative analysis of yield strength, ultimate strength and mass loss rate of rusty reinforcement bar is carried out. The results show that the corrosion resistance of the different reinforced type is different in the same corrosion condition, and the reinforced strength also exist great differences after corrosion. The corrosion rate of rusty reinforcement bar with larger surface area is relatively serious, but the steel nominal yield strength and ultimate strength of those with small sectional area decreased more rapidly. The nominal mechanical performance of corroded reinforced bars degrades more seriously. The external current soaking method to the performance of degradation of the structure caused by corrosion in a short time, and it is more suitable for simulating limit state before the specimens for cracking under natural conditions.In order to research bond properties of the reinforced concrete of corroded reinforcement bar.Accelerate corrosion treatment of the different reinforced diamete.the different reinforced type and the different reinforced diamete and the different concrete strength level with all soaking and impressed current method.Corroded reinforced concrete were designed carry out pullout tests with drawing device.The comparative analysis of bond properties of corroded reinforced bars is carried out.The results show that the change of the bond strength between the different types of steel and concrete is bigger in the same corrosion,and the different concrete strength level have a great impact on the bond strength.The steel rebar and volume expansion in concrete made concrete tension,which will produce the parallel to the cracks of the reinforced direction.The typical bond failure of plain reinforced concrete is pullout failure,but the typical bond failure of ribbed reinforced concrete is splitting failure.the bond strength between steel bar and concrete rises with the increase of concrete strength. With the increase of the extent of corrosion,the plain and ribbed reinforced concrete bond strength showed a decreasing trend after the first increases.In order to verify the test results and the related theory, the pullout test is emulated through the finite element analysis. From the six factors of the different reinforced type and the different reinforced diameter, the stress and strain of the corroded bar and concrete,the slip at the both side of the corroded bar and the both stress between the corroded bar and the concrete which are acted on different kinds of load is got by using the commercial sofeware ANSYS, The results show that there is small difference of bond properties of the reinforced concrete of corroded reinforcement bar between the numerical experiment results and the test measured, indicating that the numerical experiment in good agreement with the model test.