Research On Dynamic Damage Evolution Law Of Marine Concrete Components Under Wave Loading

Marine concrete structures are often damaged heavily due to the erosion of chloride ions in the long-term seawater and external loadings(vehicle loading?wave loading),these lead to the reduction of bearing capacity and the problem of durability.The damage degree of the concrete will be deepened with the increase of the corrosion degree of the internal reinforcement and the accumulation of the times of the external loadings.Therefore,it is necessary to study the damage evolution law of marine concrete components,which can provide references for damage assessment,bearing capacity prediction,health monitoring and safety warning for such structures.Combined with relevant existing researches and supported by the National Natural Science Fund Project“Research on dynamic damage experiment of marine concrete structure with wave loading(51508234)”,this paper established damage equation of marine concrete under wave loading and reinforcement corrosion based on theory of damage and elastic mechanics,and relevant experimental research was carried out to explore the law of damage evolution.The main research contents are as follows:(1)Study on dynamic damage equation of marine concrete under wave loading.Based on the continuum damage theory,the residual strain was used to establish the load damage equation;Based on the theory of thick-walled cylinder,the ratio of the ring stress due to corrosion to the concrete tensile strength was defined as the degree of corrosion damage,the relationship between steel corrosion rate and other material parameters and corrosion damage degree was established..Considering the mutual influence between the loading damage and corrosion damage,the study focused on load damage,corrosion damage as auxiliary,and the influence coefficient of corrosion damage was added to analyze the influence of corrosion damage on the development of load damage.(2)Experimental study on dynamic damage of concrete components under wave loading.Based on the linear wave theory and the Morison equation,the wave force was simplified into a simple harmonic wave and the cyclic loading was simulated by mechanical loading.The steel corrosion test,the cyclic loading test and the bearing capacity test were carried out by order,and the damage evolution law of concrete?the effect of different corrosion rate and loading frequency on the damage development of concrete components were studied.According to test data,the residual crack width,residual strain,load damage degree of concrete components with loading times follow the law of three stages,and there is a logarithm model relationship between damage degree of the components and loading times.What's more,the greater the corrosion damage,the greater the impact on the development of load damage and bearing capacity.(3)Study on the law of bearing capacity degeneration.Because damage of the components inevitably leads to the degradation of its bearing capacity,based on the test data of this paper,the ratio of the bearing capacity loss to the intact components was defined as the degree of bearing capacity loss D_F.It was found that D_F has a good exponential relationship with the load damage degree D,and the change of D_F with D has obvious stages,when D<0.15,the D_F value is close to0;when 0.15<D<0.35,D_F increases steadily with the increase of D;when D>0.35,D_F grows very fast until the components failure,and D_F value reaches 1.(4)This paper summarizes the existing methods of damage detection and puts forward some suggestions for damage detection of wave loading and steel corrosion.Based on the Lian yungang port berth no.69 to set up a project example.In addition,some protection measures of pier structures also are put forward.