Research On Chloride Transport And Life Prediction Of Concrete Structure Under Multi-factor Coupling Effect

Reinforcement corrosion caused by chloride ion corrosion is a key consideration in the study of concrete durability.It only considers the single factor in the deterioration process of concrete structure during the service life of actural engineering.Concrete structures are often in multi-factor coupling effect environment during the process of service.The durability problem caused by the deterioration of concrete is rarely caused by a single factor during service life,but it is often subjected to the coupling effect of temperature,load and chemical corrosion.The damage caused by the multi-factor coupling is much larger than that the single factor effect,and the deterioration mechanism of concrete is more complicated than that single factor effect.Finally,the structure is damaged due to the lack of durability.Therefore,the research trends and hot spots of concrete durability and life prediction system have been developed from single factor to multi-factor coupling.The main research work of this paper is carried out as follows:Transport research of chloride in concrete.A model is established to describe the transport rule of chloride in concrete.Transport equations of chloride ion are adopted by Hamilton principle.Adsorption effect?time variant characteristics and water saturation of pore are considered in the process of transport behavior of chloride in concrete.The migration of chloride ions in the concrete is simulated by using the finite element method.The calculation results are compared with the experimental datas.Transport research of chloride in concrete under multi-factor coupling.The basic equations and the double constitutive relations of the coupling dynamics are clearly defined in this paper.The coupling model is established by considering the effect of stress gradient?temperature gradient and concentration gradient on chloride diffusion flux.The coupling coefficients are discussed under different factors,and the multi-factor coupling dynamic models are established.Simulation researchs of chloride transport in concrete under multi-factor coupling are carried out.The calculation results are compared with the experimental datas and are analyzed by sensitivity analysis.It shows that the research of the chloride transport under the effect of multi-factor coupling is of great practical significance for the durability design of concrete structures.Service life prediction of concrete structure under chloride environment.Chemo-mechanical-thermo coupling model is adopted.The service life of concrete structure is calculated by using the critical chloride concentration and corrosion width of the steel bar as the evaluation index.Two different forms of critical chloride ion concentration are adopted to predict the durability life of the component of a bridge in Dalian.