Study On The Durability Behavior Of Marine Concrete Structures Under Loading And Ocean Environment

The service life of the reinforced concrete structures is shrunk because of the early deterioration of property.The reason of such phenomenon is often the lack of durability not the insufficient strength.At present,the domestic and overseas has already carried relevantly mature on the area that single environmental factor(chloride ion erosion,carbonation,etc.)degrade the durability of the concrete structures.However,it is worth noting that in the actual condition the reason why the concrete’s service property is deteriorated because of deficient durability is the combined impact of load,environment,climate,etc.There is a significant difference of degenerated regularity between the combined factors with the single factor.Furthermore,he coupling effect of environment and load is not simply added together.To reveal the influence mechanism of the coupling effect in the coastal structure’s macroscopic deterioration,it is necessary to study the concrete’s chloride ion penetration and its variation regularity under the load and marine environment and build the connection between the micro-variation inner the concrete structures and the macroscopic deterioration.This paper is based on conduct the research coastal concrete structures’ durability under the coupling effect of the load and the marine environment.The research and analysis has been conducted on the load level under the wharf’s normal usage conditions.A new equipment of the load and the marine environment coupling is developed,and it is applied to the chloride ion penetrating experiment for the coastal concrete structures under the dynamic load and compares the result with the still load.The quantitative influence regularity of the load applied to chloride ion penetration has been revealed.The result of it has been applied to the life prediction of the concrete structures’ durability.The main research context and result is as following:(1)By combination of theoretic calculation and practical monitoring,the harbor engineering in southern China is investigated as the object.The loading state and internal force of the typical components during use are analyzed.If the influence of weight component isn’t considered,load levels of the beam in wharf construction value are about from 0.1 to 0.47.(2)The dynamic and still load and marine environment coupling experiment device is developed.This device could provide multi-frequency and multi-approach dynamic load.Also,the marine environment character of the ocean underwater area,water level changing area and splash area could be modeled.Hence,it could actual simulate the coastal constructions’ service environment under the coupling effects of loads and environment and realized dynamic load and marine environment coupling loading.(3)By using the load and the marine environment coupling experiment device,the experiment that dynamic loading and marine environment coupling(the load level is 0.5,0.3 and 0.15 separately,the loading frequency is 2Hz,5Hz and 10 Hz,separately.The spraying and loading started and finished at the same time.The spraying amount was 15L/h).The penetration law chloride in the concrete structure under the load and erosion effects is studied.Subsequently,the durability deterioration mechanism of concrete structure under the load and erosion coupling effect is revealed.(4)By the means of doing sample test on the pure bending section specimens,the chloride ion eroded mechanism and model under the load and erosion coupling effect is studied.The chloride ion transport behavior under the different load level and different loading frequency is analyzed.The interaction between the load and environment is explored.The loading impact factors of on diffusion coefficient are obtained.And then,the original chloride ion penetrating model is amended.(5)By using the picture processing and analyzing method,though the inner damage CT scanning test on the component,the crack shape and its evolution law are explored.The connection between damage conditions with loading value and time is found.The damage law of concrete under salt spray marine environment and loading effects is determined.The microscopic damage mechanic characteristics and durability deterioration law are explored.(6)Based on the research result,the critical character in the reinforced concrete structures of the corrosion induction period based on the reliability theory and built the reinforced concrete structures’ durable life predicted model under the load and environment coupling effect is amended.Subsequently,the life prediction model is used to calculate durability life of the pile wharf’s beam.The prediction result agrees with the test result.The life prediction model is also used to design the durability lifespan of the new wharf.