Reliability Assessment Of Reinforced Concrete Durability Based On Concrete Permeability

Concrete durability means the concrete structure under natural environment, environment for use and internal factor function, keep a kind of characteristic of its one's own ability to work, or means the ability of resisting external environment and erosion that inside produce in design service life in other words. Because of its material characteristic and influence of environment, concrete durability often can't reach designing requirement and it often causes serious damage to structure, so the durability of studying concrete structure has very great meanings.Concrete permeability and durability have close relation, and it is very important for concrete to raise its anti-permeability in order to obtain high durability and long-lived life. Because of this, we think we can try to study concrete durability problem from the angle of the relation of concrete permeability and durability. Based on the analysis of the relation between concrete permeability and durability, this text point out that we can evaluate durability of the concrete through the penetrating index of concrete(such as the chlorine ion spread coefficient of the concrete), and mainly adopt the method of Monte Carlo and reliability theory to assess computer simulation to the durability reliability of concrete under the marine environment finally.According to the chapter order of the thesis, the groundwork herein is as follows:1. Summarize concrete influence factor (carbonization, reinforcing bar corrosion, freeze-thaw and so on), existing assessment method, and put forward the measures of improving concrete durability. Research mechanism of diffusion and infiltration of concrete, analyze the main influence factor of the concrete permeability and summarized the method of testing of the penetrating index of concrete.2. Introduce the basic principle, algorithm and limitation of BP network. Based on improved BP network predict the chlorine ion spread coefficient of concrete and obtain the result that meet with the tested data justly. It also offer the basis for penetrating and durability assessment of the concrete too.3. Study the relation of concrete durability and permeability and point out that we can evaluate concrete durability through the penetrating index. Introduce Monte-carlo method and based on it carries on the computer simulation of the reliability assessment of concrete durability. Finally carries on the analysis to the margin of safety target and the result indicate that concrete antiabrasion layer thickness have a prominent influence to the reliability index of concrete durability.