Research On Simply-Supported Beam's Damage Detection Based On Vibration Testing

Bridge was always under overload condition because of traffic loads increase, coupled with inadequate maintenance. In recent years, lots of collapse accidents of domestic and international bridges not only caused heavy loss of human lives and property, but also raised the general concern of health detection of the bridge. Therefore, structural damage detection and real-time monitoring has become a hot research topic in field of bridge engineering. Because of the convenience, and being able to detect and remote on line, damage detection based on vibration testing attacts more attention.Various damage detection methods based on vibration testing are summarized in this paper. The article takes reinforced concrete beam as research object. Then dynamic dactylogram methods on vibration testing are discussed. Some research on dynamic detection and assessment has been done in the following:1. On the basis of studying home and abroad relevant research literature, some research theory and major methods of the dynamic diagnose are summarized.2. Vibration of simply-supported beam structure was analyzed using structural dynamic theory. And theoretical and practical analysis method of frequencies and mode shapes are given in this paper. Taking a reinforced concrete beam as calculation model, the article gives comparative analysis of theoretical and practical results. Then some of basic theory of random vibration and dynamic test methods are introduced, providing the experiential knowledge to dynamic damage detection and assessment.3. Vibration equation of structure with more degrees of freedom has been analyzed by using matrix perturbation theory. Then function of natural frequency with stiffness and dynamic dactylogram were introduced.4. Damages in simply-supported beam are analyzed and simulated by reducing the stiffness. Effects on natural frequency by typical damages in center of the span and near bearings are simulated by ANSYS10.0.5. Hammer test of reinforced concrete beams has been done in test room. The program of methods to detect dynamic characteristic parameters is developed based on Matlab program language and used to identify the natural frequency of structures in different conditions. Natural frequency is utilized as dynamic dactylogram to detect these damage in reinforced concrete beam. Then some key issues of methods based on vibration testing to detect damage have been discussed.6. In this paper, reinforced concrete three-span simply-supported girder bridge - Cangzhou City Liuzhuang North Bridge is taken as an engineering example. By comparing numerical simulation results with test results, that the power spectrum method to identify modal parameter can be applied to engineering pratice is verified.