Long-term Mechanical Properties Of Reinforced Concrete Compressed Member Under Corrosive Environment And Load

As one of the commonly used structures,reinforced concrete structures are widely used in the field of construction engineering.In general,reinforced concrete structures not only have to withstand the use of loads,but also be eroded by the external environment,affecting their durability.At present,the main research object of structural durability under the action of corrosive environment and load is reinforced concrete beam.The research on the column is relatively rare,and the long-term mechanical properties of the eccentric compression column under the condition of steel corrosion are rare.As a vertical load-bearing structure,reinforced concrete columns will directly affect the service life of buildings.Therefore,the study of long-term mechanical properties of concrete columns under the condition of steel corrosion is important to understand the mechanical properties degradation law during use and reflect the true stress state of the structure.It has important engineering application value and theoretical significance.Aiming at the current research status of reinforced concrete columns,the reinforced concrete large eccentric compression column was selected as the research object.The indoor constant current accelerated corrosion method was used to test the long-term mechanical properties of the structure with corrosive environment and load.The following main research work was completed:(1)A 210-day shrinkage and creep test was performed on 12 reinforced concrete columns,including 4 axial compression columns,4 large eccentric compression columns,and 4 shrink-contrast columns.The results show that the eccentricity has little effect on the creep of concrete,but the final value of creep coefficient is larger than that of axial compression column;The greater the corrosion rate of the steel,the greater the creep of the concrete and the longer the creep stability time;Corrosion large eccentric compression column creep will be affected by eccentric load and steel corrosion,and the two effects overlap each other.(2)The ultimate bearing capacity test of reinforced concrete columns was carried out after uninstall,and the test phenomena and results were analyzed.The results show that the corrosion of steel bars has little effect on the bearing capacity of large eccentric compression columns and has a great influence on the axial compression columns;The corrosion of steel bars has little effect on the deflection value of the large eccentric compression column;When evaluating the durability of a structure,the effects of long-term loads are not negligible.(3)Compare and analyze the calculated values of several commonly used concrete creep models with the calculated values of the test results.According to the age-adjusted effective modulus method,the ACI-209 R creep model was modified,and the creep prediction model of concrete large eccentric compression column considering the eccentricity and the corrosion rate of steel was established.The theoretical calculations are in good agreement with the calculated values of the test results,and the overall prediction results are good.(4)Through the theoretical analysis and fitting test data,the formula of the effect coefficient of steel corrosion and long-term load is established.The calculation model for the ultimate bearing capacity of concrete large eccentric compression columns with corroded steel bars under long-term loading is derived.The theoretical calculations are in good agreement with the experimental results,and the calculation model has certain accuracy.