Research On Structural Dynamic Load Identification Based On Wilson-θ Method

The accurate acquisition of the external load acting on the structure is the basis of structural strength analysis,health monitoring and fault diagnosis.Wilson-θinverse analysis method has the advantages of high accuracy and good numerical stability,so it has been widely used in the field of dynamic load identification in recent years.However,there are still some deficiencies in practical engineering application.the recognition results are distorted.It is a hot and difficult point in the research of dynamic load identification that improving the dynamic load identification method,the accuracy and robustness of identification,and its engineering practicability.The selection of the initial value and the behavior of the inverse matrix are the key factors that affect the accuracy and stability of load identification.This paper focuses on the Wilson-θinverse analysis method,and probes into the problems existing in it,such as initial value sensitivity,transfer matrix ill-conditioned and so on.Combined with the seismic time history analysis theory,this paper attempts to extend the application of this theory to seismic load identification.The main achievements and conclusions are as follows:(1)Aiming at the ill-conditioned problem in the process of dynamic load identification,a combination selection method of measuring points based on prior conditions was explored.Combined with the recurrence formula of Wilson-θ inverse analysis method,based on the derivation of the formula,the causal relationship between the position combination of measuring points and the behavior of transfer matrix was analyzed.By calculated the prior information related to the location of the measuring point,and according to the prior condition judgment formula,the better combination of measuring points was determined.The excessive correlation between any two columns in the transfer matrix is avoided,the morbidity of the transfer matrix is improved,the stability and accuracy of dynamic load identification are improved.It provides a method basis for the selection of measuring point combination in load identification.(2)Aiming at the initial value sensitivity problem in the Wilson-θ inverse analysis method,the initial value was modified by introducing polynomial fitting method.On the basis of deduced the recursive formula of Wilson-θ inverse analysis method,the transfer principle of the initial error in the recursive formula was explored,and the relationship between the initial error and the calculation results of displacement and velocity was obtained.By introducing the polynomial fitting method to calculate the displacement trend term,the correction of the initial displacement and velocity data is realized,the problem of sensitive initial value of Wilson-θ inverse analysis method is solved,and the load identification accuracy and robustness of this method are improved.(3)The recurrence formula of seismic load identification based on Wilson-θmethod was derived.By extracted the characteristic matrix of structural model,the seismic load identification model from ANSYS modeling to MATLAB calculation was realized.On this basis,according to the characteristics of seismic wave action,the formula of seismic load identification was deduced.and the effectiveness and correctness of the method were verified by simulation examples.