Damage Identification Research Of Frame Structure

Most of engineering structures,when subjected to the natural disasters such as earthquake and fire or the action of the long-term fatigue loading and erosion,will often induce the damage of 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 damage of the structure and reduce the economy loss.Consequently,great attention is given to the diagnosis technique of the damage of structure in architecture industry domestic and abroad.But as a new study field,its development is incomplete.in this paper,the two methods of damage identification which are based strain mode for column of frame structures are brought forward.The main tasks of this paper are as follows:(1)In the dissertation,the development of 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 tendency of methods of the damage identification are discussed.(2)This part discussed the strain mode as theoretical method of the damage from the knowledge of mechanics of materials.The strain and the curvature shared a linear relationship.The strain is the first order derivative of displacement,furthermore,the strain is related with stiffness.So,the strain mode may be a key to the detection of the change of the stiffness,which structure damage is reflected by the change of change of stiffness.So,the strain may detect the damage of structure,based on change of the strain mode and frequencies damage orientation index can attain better detective effect. With the identification technique of model parameter,the strain mode of frame structure was obtained.Numerical analysis results show that the change of strain mode and frequencies damage orientation index is a sensitive indicator to the frame structure.Damage identification of generalized strain energy density(GSED)is very effective and its physical is clear.It is easy to get GSED from the strain mode result in measuring.The method of need not complex mathematical calculation,then it will not induce noise into result.The method of GSED can judge the structural damage being,and can give the damage position exactly.If the data is enough,we can give round damage extent by this way.(3)The last part offers examples about the two indicators.The numerical analysis of frame structure is carried out to test the two methods.It shows based on change strain mode and frequencies and GSED can not only correctly judge the structural damage being but also give the damage position exactly. The latter is obviously better than the former,the latter can offers a round damage extent.