Two Methods Of Damage Detection In Reinforced Concrete Beam Based On The Response Of Structural Dynamic

The structures of bridge play an important position in the transportation. So many reports of bridges collapsion can be found in recent years. The safety of bridge has brought a great threat to the safety of productions and lives. The damage detection and health assessment of the bridges are very important. During the methods of damage detection, the way witch based on the response of structural dynamic is the most convenient one. Presently, many studies based on the responses of structural dynamic parameters are limited to the simulation stage, lacked of experimental data to support the theory. In order to compensate this lack of inadequate, in this paper, two different damage identification methods which were all based on the response parameters of structural dynamic have been simulated and experimented. The feasibility of the simulation results was verified by the experiments.The method of damage detection based on vibration mode is accepted. Vibration mode is the parameter that can reflect the change. Theoretical analysis shows that the shape curve mutation of curvature modal could be caused by damage of part such as cracks and corrosion. Because of the vibration mode is sensitive to local damage, the method base on the vibration mode can be used to detect the location of the damage.The damage detection base on the frequency change of the structural was a very popular way. Section stiffness will be reduced by the damage of structural, and it can cause change in the natural frequency. Obviously, there is relationship between the location of the structural damage and the frequency change ratio. It is known that the natural frequency can be easily obtained by the vibration responses with only a few measurement points. Consequently, the methods by using the changes in frequency can be used to detect the location of the structural damage effectively.The main works are as follows:1) The displacement and the curvature mode of a reinforced concrete beam before and after the damage ware simulated. Get the conclusion of that the displacement mode is not sensitive to damage, while the curvature mode can be used for the identification of damage. The correctness of the conclusion was verified by the data of experiments.2) The reinforced concrete beams at various damage conditions ware simulated, and the method based on the rate of frequency changes was used to identification the damage. The conclusion was that the method based on the rate of frequency changes can be used to identify not only the single location of damage, the multi-location of damages, but also the degree of damage qualitatively. And the correctness of the conclusion was verified by the data of experiments.3) The differences and advantages of the two methods above ware compared and discussed.