Modal Analysis And Damage Detection Method Of A Concrete-Filled Steel Tube Arch Bridge Model

Damages such as cracks,ageing and Corrosion, which will due to the hidden danger when arch bridge are in service. For the sake of insuring security of the health and belongings, research vibration performance (frequency, mode shape), identify the damage location effectively, know the status of the structure quickly, is an emerging field in structural health monitoring.The damage of structure will alter the vibration characteristic because of connection between vibration characteristic and physical model. So if establish a mapping of vibration characteristic and damage, damage can be identified using measured vibration data.The basic theory of Eigensystem Realization Algorithm (ERA) and Natural Excitation Technique (NExT) are introduced firstly. Then, vibration is tested on arch bridge model, accelerations corresponding of deck and arch are gained, mode parameters are identified use ERA and NEXT. Finally, mode parameters between gained from ERA and finite element modal are compared, analyze the reason why error is produced in finite element modal and give some advice of modal updating.Structure damage identification is the major of the thesis. A damage detection method based on signal processing-transmittance function damage detection method is presented. Unlikely the literature that before, transmittance function damage detection use output vibration measurements to detect damage, but without measuring the excitation force or using a model of the structure. Arithmetic is sample which can have little computing error, and also can uses to online structural health monitoring, so it can solve some problems that we faced currently. In accordance with difference data processing, two centralized damage detection method, absolute difference transmittance function method (ADTF) and curvature difference transmittance function method (CDTF) are presented. Based on the damage detection method above, considering the characteristic of smart sensor and distributed sensing network, a method that based on distributed computing strategy (DCS)-DCSADTF,DCSCDTF and DCSCOMBINED is then proposed that is suitable for implementation on a network of densely distributed smart sensors. Ultimately, to demonstrate the capability of the proposed approaches, examples of a numerical planar truss and a three-dimension truss experimental model is used to carry out the evaluation of the damage detection algorithm and discuss the feasibility of smart sensor network. Finally, a concrete-filled steel tube arch bridge model is establish in ANSYS and the dynamic characteristic in random white noise is simulated, which used in the proposed approaches that introduced above to discuss the efficiency of the damage detecting method in arch bridge structure. Analyze the benefits and shortcomings of the proposed approaches and the direction of development or improvement.