Identification Of Wind Load And Structural Parameters Based On Minimum Variance Unbiased Estimation

Wind load and wind-induced vibration are the main factors for the safety and usability of wind-sensitive structures such as tall and long span structures.Direct measurement and indirect measurement are the two main methods for obtaining wind load.However,the distribution of wind pressure on the engineering structure is complicated and the complete distribution of wind pressure cannot be obtained based on the information from a limited number of measurement points and measurement locations.In comparison,structural responses measurement is easier and more accurate than that of force.Wind load identification from measured structural responses becomes an important approach for wind load research.However,wind load estimation appraoches require the structural model to match the true system,it is difficult to calculate structural parameters exactly due to the material aging and damage in the structure.For the reason,it is necessary to study on the composite inversion method for wind load and structural parameters identification,and to verify the applicability and robustness of the inversion method.This paper proposed a wind load and structural parameters identification approach based on unbiased minimun variance estimation.The feasibility of the inversion methods under conditions such as incomplete measurements and complex engineering structures are discussed.The proposed method is discussed and verified by numerical simulation and wind tunnel tests.The contents of this dissertation are as follows:A time-varying wind load identification approach is proposed based on minimum variance unbiased estimation algorithm.The structural acceleration responses are measured as “measurements” and the formula is derived based on minimum variance unbiased estimation.In addition,the complete measurement of structural acceleration responses is limited in practical application.Hence,the estimation approach is derived in modal space based on modal coordinate transformation.The accuracy and feasibility of the inverse approach is numerically investigated by identifying the wind load on a twentystory shear building structure.The effects of the number and location of accelerometers,the errors in crucial factors such as natural frequency and damping ratio are discussed.For the problem of wind load identification with unknown structural parameters,the wind load inversion method is extended,and a composite inversion method of wind load and structural parameters is proposed.The state vector is redefined including structural displacement responses,velocity responses and unknown parameters.Then,the state vector becomes nonlinear.With linearization,the quantities in state vector and unknown input can be estimated based on extended minimum variance unbiased estimation.Through the numerical simulation on a ten-story shear building structure,results indicate that signification drifts exist in the estimated displacement and wind load when only structural acceleration responses are measured.Data fusion of structural inter-story displacements and accelerations are used to circumvent the drafts in identified results.The influence of measurement noises and the time duration are studied and discussed.Results indicate that the method is accurate and anti-noise for structural parameters and wind load identification.A novel method of identifying structural state,parameters and unknown wind load from incomplete measurements is proposed.The estimation is performed in a modal extended minimum variance unbiased manner,based on incomplete measurements of wind-induced structural displacement and acceleration responses.Eigenvalue and eigenvector sensitivity is used in the formula derivation.The feasibility and accuracy of the proposed method are numerically validated by identifying the wind load and structural parameters on a ten-story shear building structure with incomplete measurements.The effects of sampling duration and number of measurements are discussed.A rigid model wind tunnel test for estimation method study is carried out.The research object of the wind tunnel test is a 234 m frame-core-tube structure.Firstly,a rigid model wind tunnel test is performed to obtain the real wind load acting on the structure.Then,combined with the finite element model,the wind-induced vibration analysis of the structure is carried out.Consider that it is complicated or even impossible to estimate the wind load and structural parameters strictly according to the prototype structure,a simplified equivalent model with less degrees of freedom is proposed based on workenergy equivalent theory.Finally,the practical application of the developed inverse method is evaluated based on the comparison results between the identified results and wind tunnel test results.