Damage Diagnosis Of Prestressed Concrete Beams Based On Information Fusion And Vague Set Theory

The research purpose of the structure damage diagnosis is to ensure the reliability andsafety of the engineering structure or component, and also to provide references for theirlife estimation and maintenance, but how to do the injury diagnosis effectively andaccurately is currently the foreword subject of the civil engineering sector.In this paper, based on the careful summary and analysis of the results of previousstudies, for the research status that most of the damage detection method is still based onthe diagnostic methods of a single or improved single at home and abroad, the static anddynamic tests is made on parts of five different series of unbonded prestressed concretebeams. The research and discussion is done mainly from the comprehensive diagnostic andhealth monitoring ideas and the research results are as follows:1. All the beams in the whole process of the static load, whose average strain along thebeam section height direction are well consistent with the assumption of plane crosssection, the development of whose cracks are all occurred in the pure bending sections ornear of the specimen and the damage control section is occurred in the area near the cross.There are obvious signs of destruction, which is the destruction of plastic failure,indicating that the static test is a reasonable testing program.2. The damage identification of the test beam is done respectively by the traditionalvibration model difference method, the vibration model difference rate method andcurvature poor value method. The larger damage changes area mainly occur in purebending section, which is identical with the positions of the test beam maximum crack andconcrete crushing, and the identification results of all the test beams can reflect themaximum damage location when the damage happened, which illustrates the power testscheme is reasonable.3. There exists the linear relationship Between Static stiffness and the square of naturalfrequency, which indicates that frequency and stiffness values of the damage identificationare equivalent on the damage index, combining static and dynamic, and can be substitutesfor one another. With the methods of combining static and dynamic, the initial state dataneeded to be referred to, can be compensated in the process of the damage detection, whichespecially is of great significance for the online real-time health monitoring of thestructure.4. With the help of D-S evidence theory, the diagnosis results of integrating the vibrationmodel difference and modal curvature obtained from the test beam, are basically coincide with the actual test results, and after the fusion of the grey absolute curvature differenceand the vibration mode difference got from the numerical simulation, the damage locationand degree injury can be accurately identified on any condition, which illustrates that themethod is feasible and effective for structural damage diagnosis.5. The injury diagnosis method based on Vague Set Theory is proposed, and the samplelibrary of vague set damage diagnosis system is established. Whether in single or multipleinjury diagnosis, the set condition for damage is consistent with the types of injury in theactual samples library and the position of the damage also can be accurately identified.Meanwhile, the accuracy and effectiveness of this method in the identification of buildingstructural reliability are demonstrated by examples.