Research On Structural Damage Detection Method Based On Change Rate Of Curvature Mode

Today most engineering structures have being experienced complex and large-oriented development. While all sorts of factors, which include the erosion of external environment, the impact of traffic load and damage caused by natural disasters, would easily bring about material aging, the increasing fatigue effect and decreasing resistance. Then the structure would emerge a decrease in safety performance, as well as in applicability and durability to various degrees. The structural health monitoring and early damage diagnosis could repair the injured location timely and reduce the extent of the damage accumulation, which could reduce the economy loss.Since the 50s of last century, people have realized the importance of bridge health monitoring. Damage detection, which is based upon dynamic characteristics, has become a hot point of research around the world, and it is the core component part of the bridge health monitoring system.Firstly, the background and significance of bridge structural health monitoring and damage detection was introduced. The current researches of damage detection both inland and outland were described. The problems and improvements of damage detection were discussed.Second, the basic theory of modal analysis and research contents were systematically summarized. Peak Value Method and Frequency Domain Decomposition were introduced.Furthermore, the theoretical basis of curvature modal analysis and its characteristics were discussed. A simply supported beam was studied. The structural damage was simulated by changing the elastic modulus of elements and two cases were simulated involved damage in mid-span and one-quarter-span. The impaction to frequency, modal displacement, and curvature mode was analyzed as a result of the structural damage. The conclusion is presented that curvature mode is sensitive to structural damage in the non-node location.Then, as to the deficiency of curvature mode, curvature modal curve was differentiated by difference method and the change rate curve of curvature mode was obtained. Different types of beam damage were simulated. We analyzed the influence of damage location and the damage degree to the change rate of curvature mode. Simulation data shows that: the change rate of curvature mode is a more sensitive indicator of structural damage than curvature modeFinally, the conclusion part is about summary of the contents and results based on the researches mentioned above, and the suggestions as well as outlook for the future work are also presented and discussed.