Studies On The Expanding Process Of Corrosive Crack In Reinforced Concrete

The concrete durability and concrete structure durability have been a key problem in civil engineering today and much attention has been paid on it. But due to the complexity of the problem, the present research findings are far from meeting the practical application needs.A lot of project examples show that the steel corrosion is a main factor to induce the structural damage and premature failure. Typical phenomenon of steel corrosion in concrete is: steel corrosion causes longitudinal splitting cracks, spalling breaking even scaling. So the analysis of corrosive crack widths expansion is very important in determining durability deteriorated degree of structures.If the relationship between concrete corrosive crack widthes and steel corrosion extent is built, not only the foundation for quantitative analysis of structure's durability deteriorated safety degree is laid, but also the basis of estimating the steel corrosion condition of working structures based on detecting the crack width is provided.The key point in this dissertation is around the whole process of corrosive cracks developing on RC members, via theoretical analysis, experimental method and simulated technique, try hard to reveal the mechanism of reinforced bar corrosive expanding. Main research results are as follows:1,A model for critical corrosion extent was built based on elastic-plasticity theory, considering the creep of concrete, variation of longitudinal reinforcement spacing, relative thickness of cover layer (c/d) and intensity factor of concrete;2,The expansion process of corrosive cracks on RC members has been analyzing theoretically based on elastic-plasticity theory and a model was built for corrosive cracks developing;3,According to the above-mentioned models, the influences of factors, such as parameter of effective stuffing rate(n), function of the stirrup, concrete cover etc. on the development and the restrict of corrosive cracks are researched by theory analysis and experiments. The results validate the accuracy of the model; 4,Emulation analysis has been done on the corrosion process of RC members based on fracture mechanics, by using Franc2D software respectively. A model was built for concrete and steel by introducing interface model to source program, and the corrosive cracking process of concrete was simulated. The results of emulation analysis, theoretical analysis and experimental investigation match well.