Research On Temperature Influences In Bridge Model Frequency Identification

Transportation is the economic lifelines of today’s society while bridges are the guarantee system of smooth traffic. If the traffic is not as smooth as before, the all society’s development will be restricted. So it is significant that the functionality and safety of bridges should be protected. According to the statistical data, although the number of bridges in China is very large, on the one hand, some existed bridges have already reach the design life and these bridges’ situation of aging and damage is very serious; on the other hand, there are many new bridges built every year. The new bridges should be health monitoring and the existed bridges should be tested damage identification and reliability appraisal in order to ensure these bridges’ security and avoid terrible accident. Recently, the recognition method based on Damage Diagnosis of Vibration Structure has been developed widely and at the same time, it has been the research emphasis of civil engineering. The temperature on the modal frequencies of the bridge often conceals the existence of Bridge Damage. The relationship between temperature and modal frequency has seek and established a model in order to eliminate the influence of temperature in Bridge Damage, which has been a research emphasis. In this essay, the experiment’s main idea is seeking the inherent mechanism of modal frequency in different bridge damage. Revealing the temperature on the bridge modal frequency of the law, as well as damage to the bridge under different modal frequency variation, as an effective solution temperature on the seasonal frozen bridge foundation damage identification problem.The main conclusion and finding in this essay:1.For the modal frequency of temperature on the bridge theoretical quantitative analysis of the impact of the following conclusions:Temperature can influence the elastic modulus of the concrete. As the temperature raising, the elastic modulus of the concrete will decrease.2. The elastic modulus of concrete bridge affects the natural frequency directly. So the temperature of the concrete and the temperature modal frequency of the elastic modulus of concrete of the same trend.3. The application of dynamic tests of the variable temperature conditions for different degrees of damage bridge frequency measurement and the results plotted after the tables and charts for analysis, draw conclusions about:in the same damage conditions, the frequency decreases with increasing temperature; the same time, at a certain temperature, the structural damage, its stiffness drop caused the decrease of the frequency, the frequency with the degree of damage increases. Similarly, the structure of the modal frequencies of injury is relatively low if the measured temperature environment, it is possible to draw the structure actually damage "no damage" or "running good" wrong conclusions, which illustrates the bridge health monitoring, eliminate environmental factors on the impact of the bridge modal frequencies is critical.