Study On Long-term Mechanical Properties Of Reinforced Concrete Columns Under Corrosive Environment And Load

When reinforced concrete structures are used in corrosive environment,the internal reinforcement is often eroded by external corrosive medium while bearing loads.As time goes by,the overall mechanical properties of the structure will deteriorate and even endanger the safety of the structure.In terms of durability studies,long-term mechanical properties of reinforced concrete columns under the joint action of load holding and corrosive environment are relatively rare.Moreover,the degradation of mechanical properties of reinforced concrete structures in practical engineering is not only affected by single factors of corrosive environment,but also other influencing factors cannot be ignored.Therefore,the commonly used empirical formula and creep model considering a single influence factor are no longer applicable due to the inability to obtain accurate prediction results,so it is necessary to carry out relevant tests and theoretical studies for such real working conditions of reinforced concrete structures.The long-term mechanical properties of reinforced concrete columns under the influence of various factors were obtained through long-term tests of the joint action of load holding and corrosion environment,and relevant prediction models were proposed.The main research contents and work of this paper are as follows:(1)The compressive strength test of concrete cube was carried out in two groups,namely soaked group and non-soaked group,and the change rule of concrete cube compressive strength in chlorine solution was studied.Based on the age correction of concrete compressive strength,a calculating model of concrete compressive strength subjected to chlorine corrosion is established.The results show that the duration of immersion and the concentration of chloride ion in the corrosive solution are the main factors affecting the compressive strength of the concrete cube,and the change rule of the compressive strength of the corroded concrete cube is that it develops rapidly to a certain strength at first and then decreases gradually,reaching its peak value at the 45 th day of immersion.(2)The long-term mechanical properties of reinforced concrete columns under the combined action of load holding and corrosive environment are studied by using the self-developed corrosion-loading device and corrosive solution circulation system.The results show that the rust swelling crack is significantly affected by loading age and corrosion rate.The crack width decreases with the extension of loading age and increases with the improvement of corrosion rate.The creep increases with the increase of eccentricity and increases with the shortening of loading age and the final value is larger.The corrosion rateand creep influence each other,and the influence is more significant with the increase of eccentricity.When there is no corrosion,the deflection of reinforced concrete bias column increases with the increase of eccentricity and decreases with the extension of loading age,and loading age and eccentricity are superimposed on each other.Loading age,eccentricity and corrosion rate are coupled to each other.When the corrosion rate is low,loading age and eccentricity dominate.With the increase of corrosion rate,corrosion rate dominates all factors.(3)Based on the effective modulus method of age adjustment,the creep prediction model of reinforced concrete bivariate columns is modified,which is suitable for corrosion condition of reinforced concrete(non-severe corrosion environment).The results show that the theoretical value is close to the experimental value,and the error is kept within a reasonable range,which can provide a theoretical basis for the durability design of reinforced concrete biasing columns under non-harsh corrosion environment.