| In the past few decades, China is developing massive construction projects, and during the period many problems in practical applications continue to be reflected, and thus continue to be in the study of the solution. Structural damage identification is an important research topic in the majority of engineering researches. Structure damage identification is demonstrated according to the structure of state to determine the structural damage occurs, the location and extent. And the damage discern method based on mode analysis is still the most general and basic method.The modal parameter of Reinforced concrete structure contains much information that connected with damage, find out the parameters and information, analyze statistics, and get the corresponding relations to the damage information. In this paper, research is carried on dynamic identification of damage of RC simple-supported beam, through loading and unloading tests step by step of RC simply-supported beams, an experimental dynamic monitoring is performed on the beam after each step of unloading. By measuring and identifying the modal parameters of the reinforced concrete beam in different damage modes and stages, we obtained the first few natural frequencies and mode shapes and analyzed the trends in frequency after the damage occurred. Vibration modes are operated by The Central Difference Method to obtain the modal curvature, and then the scope of damage location can be determined by searching the peak of the modal curvature curve. And then through the vibration polynomial fitting residual method to analyze the degree of injury and identification of damage location, we fit the modal shape using polynomial fitting method by Matlab program and calculated the residuals. The experimental results show that the modal polynomial fitting of the square of the residuals increased with the increase in the extent of structural damage, and the peak of residual appeared at the damage location. Experimental verification shows that the method of judging the damage level and locating the damage position by polynomial fit residuals is practicable. Through using the ANSYS analyze different injury conditions of reinforced concrete simply supported beam modal frequency, results show that the finite element analysis results and experimental test results are in good agreement in the state of small damage. |
