The Research Of Damage Diagnosis Of Reinforced Concrete Beam And Reinforced Frame Using Dynamic Test Data

With the development of economy, more and more large-span, tall and complicated structures are built. And the damage of such structures could lead to economic loss. So the HRB500 steel will be spread and utilized due to the structure performance and building energy saving. But in China the dynamic performance of the HRB500 reinforced member is hardly studied. This paper can provide the theoretical and test basis for the application of HRB500 bar.The HRB500 reinforced frame and beam are studied in this paper. In the initial stage the concentrated symmetric loads are applied and the deflection and the crack distribution are recorded. And these different data made up of different damage patterns used in the dynamic testing. During the course of the dynamic testing, the modal shape and the natural frequency were obtained under the initial state and different damage degrees of the beams.Based on the analysis of the damage pattern under static loads and the vibration test data, model-based damage diagnosis methods are studied and discussed, which include how to estimate the damage occurring in the structure and how to evaluate the damage position and degree, that is to say, through detecting structure, one can make sure if the damage exists and can tell the degree and position of the damage. Based on structural dynamics, different damage diagnosis index, such as modal frequency variety, modal assurance criterion, modal strain energy, remains force vector, modal strain, rigidity change, flexibility matrix, modal curvature and so on, are studied in this thesis.I turn out to be that the position and degree of damage can not be well detected only by Eigen frequency, while only can detect if the damage has appeared. However, severe damage can be diagnosed if the modal shape and natural period are used together. This index mentioned above can be used to better detect the position and degree of damage. The combination of modal shape and Eigen frequency can be more accurate to detect damage degree and position after damage occurred, for example, the rate of the change of flexibility matrix combined mode shape and frequency, it is the most effective method to identification the location and extent of structural damage.