The Method Of Damage Identification And Experimental Research On The Plate Struetures

The civil engineering structures,when subjected to the natural disasters such as earthquake and fire or the action of the long-term fatigue loading and corrosion,will lead to the damage of the structure.With the accumulation of the damage,its criticality will be gradually enhanced.The real time repair can be done and the means of the operation can be changed with the help of the judgment of the structure damage and the confirmation of the locality of the damage, so as to degrade the accumulation degree of the damage of the structure and reduce the economy loss. Consequently great attention is given to the identify technique of the damage of the structure in the architecture industry domestic and abroad. But as a new study field, its development is incomplete.In this paper,the bengding stiffness of the structure ie derieved from the bending vibration differential equation based on former research. The main work and conclusions include:(1) The development of the damage identification technique of domestic and abroad is introduced.The classification of all kinds of damage identification methods which are usually adopted at present is simply introduced.The problems and the improvement of the methods of the damage identification are discussed(2) The theories of several methods of structure damage identification which are based on the method of modal curvature difference, the ratio of frequency changes method, modal strain energy method and peak of curvature changes are summarized.The rationale of these methods which are adopted to carry out the structure damageidentification is presented.The advantages and disadvantages about these methods are also compared. Damage identification of plate structure was carried out by using peak of curvature change,neural network and modal strain energy method respectively. The bengding stiffness of derivation process was intrduced in this paper.(3) Considering all modal parameters of the structure, inherent frequency is the easiest one to be acquired and the highest precision. In the paper, we put forward a new damage detection method—moving mass method with repeated detections. The method makes measurement to the structure several times while using moving mass block in different locations, and only use frequency data according to each measurement to determine structure damage. The method improve structural identification precision. Meanwhile, structural moving mass detection method realizes the aim of determining structural damage model frequency only with structural low order model frequency, even the first order, and it also provides a simple method of practical detection for structure in one working state.(4) The change rate of the bengding stiffness of the structure for damage identification of plate structure is suggested in this paper. The first modal parameters obtained by dynamic measuring are needed only in this method. We know that the structure whether has damage according to the change rate of the bengding stiffness of the structure .It is indicated by a testing of frame model damage identification that only low-order modal parameters are needed to identify a structural damage effectively.