Research Of The Damage Identification Method Of Frame Structure

I did these research works: A new damage identification index is defined;Relationship ofthe damage identification index and the damage degree is studied , it is discovered that theindex and the change rate varied monotonously with the damage degree and it can be used tojudge and evaluate the structure damage;Damage is set on the structure and identified usingthis index;Compare the result of this index with the results of two time domain and twofrequency domain modal analysis methods.The main contents include:1,A new damage identification index is defined;2,A three-story steel frame structural finite element modeling was built with ANSYS.Damage was simulated by changing the elasticity modulus. Modal analysis and dynamicresponse analysis is done at healthy condition and four damage conditions .3,Based on the dynamic response, the displacement response function and the damageidentification index are calculated;First, The checking computations of the index stability were done at healthy condition;The law of the index with the degree of damage was studied. The result of numericalsimulation showed that the index is sensitive to small damage and it can be used to judge andevaluate the structure damage;4,Free vibration signal of the measuring points were gained by random decrementtechnique.The cross-correlation function of the measuring points relative to reference pointwere gained by the natural excitation technique,taken as impulse response functions. Thenmodal analysis and judgement about damage were done by ITD method and ERA method。Frequency response function was calculated using the response of measuring point and thedynamic loading , and modal analysis is done by two frequency methods——minimal squarecircularity fitting method and orthogonal polynomial curve fitting method;5,Compared the identified results of the new damage index and four methods.