Experimental Research Of Structural Damage Identification Based On Mode Parameters

Modern project structures are proceeding at the direction of maximization complication and automation. The complicated environments of service threat functional safety of the structure. Moreover in the real life many disasters structural engineering accident occurrence initiates the people the "health" question widely pays attention to the structure. To guarantee the safety and avoid disaster, the scholars, engineers and technicians are paying attention to the research of identification for the damage of structure real-timely, on-line and accurately.This article elaborates the technology of structural damage identification domestic and foreign research present situation, Introduced each kind of theory and the research technique for structural damage identification. And the mode parameter analysis carries on the structural damage identification to the simple beam structure for the experimental research. Structural damage identification based on mode parameter is a new detection method, which inspects structural damage by mode analysis. According to the modal parameters CMI and MMI, it discusses the theory and technique of the damage identification for structure in detail. The measured analysis of the damage identification techniques for the simple beam modes, confirms that the two mode parameters is valid, it is the emphases of this article. The method of structural damage identification based on mode parameters CMI and MMI includes two stages, and at the first stage calculate Curvature Mode Index (CMI) based on the conception of curvature mode, then according to the results of CMI to identify the location of structural damage. CMI is a parameter derived from the eigenvectors, which is very sensitive to local damages and dependent upon geometric coordinate of structures, these characters enable it a perfect index for damage location. In the second stage, the damage severity of those located segments can be precisely estimated by calculating the Modal Moment Index (MMI) of each element. It is assumed that the modal strain energy differences between damaged and undamaged modes are negligible. Then the equilibrium established, by calculating the deviation of the elastic modulus before and after damage, the damage severity is estimated. Developed the operation using MATLAB software and the Excel tool and collects the chart procedure, as long as vibration shape of the structure is input, the value and the graphic representation of damage identification will be obtained.This article takes the simple steel plate beam as example, the damage is simulated by reducing the sectional area where the damage is designated by theory analysis, from which five damage cases are come into being. Later vibration shapes are extracted from vibration testing experiment. Finally, input these vibration shapes to calculating program CMT2.0 compiled by MATLAB language, and from which the identification results are obtained. It indicates that the method can not only identify the damage location exactly, but also offers practical estimates to damage severity as to specific location.