Research On Influence Of Reinforcement On Creep Effect Of Axially Compressed Concrete

The creep problem of concrete has always been a problem that is difficult to solve in engineering practice.It is a time-varying characteristic of viscoelastic materials such as concrete under continuous load.Due to the generation mechanism of creep and the complexity of its influencing factors,it is difficult to accurately consider and calculate the creep effect in concrete members or structures.Although there are many kinds of concrete creep prediction models at present,most of them are based on plain concrete,but in actual engineering,most of them are reinforced structures,so the applicability of existing creep prediction models to reinforced concrete needs to be studied.At the same time,in the actual project,if the structure or component stress reduction or unloading will involve the problem of creep recovery,and the research on the creep recovery of the concrete after unloading is less,and it has not received enough attention.Therefore,it is of great theoretical significance to carry out structural creep analysis of reinforced concrete under complex stress conditions.This paper studies the creep and recovery of reinforced concrete under axial compression.First,the basic theory of concrete creep is summarized,and the existing concrete creep models are compared and analyzed.The age-adjusted effective modulus method is combined with geometric equations,physical equations and static equations to obtain the creep calculation method of reinforced concrete at any time.The method is used to analyze the examples and predict the current creep specification The model was modified with reinforcement factors,and the revised creep prediction model was compared and verified through test data.Using the same analysis method,the effect of different reinforcement ratios on creep recovery was studied,and the reinforcement factor of MC78 creep recovery model was modified.The revised creep model and creep recovery model were used to make an overall prediction and analysis of the creep after loading and the creep recovery after unloading.The research results show that the reinforcement has obvious restraining effect on the development of concrete creep,and with the increase of the reinforcement ratio,the greater the restraining effect on the concrete,the current concrete creep model is no longer applicable.The calculated value of the creep model without considering the reinforcement is significantly higher than the test value,and the corrected model has a higher agreement with the test value.After unloading,the creep recovery strain and residual strain decrease as the reinforcement ratio increases.The results of the paper can provide a reference for the system to solve the problem of continuous deflection and cracking of long-span continuous box girder bridges,and at the same time establish a safety evaluation method and explore reliable maintenance and reinforcement techniques.