Research On Identification Method Of Engineering Structure Time-varying Parameters Under Partial Observation Information

Due to coupling factors such as the impact of external load,environmental corrosion and aging of the structural material are damaged,accumulated resulting in degradation of the mechanical properties,the structural parameters vary over time and exhibit mechanical characteristics that vary over time.In addition,under different load conditions and operating environments,the structural parameters clearly show that the structure of the engineering with different time-varying systems,such as the structure comprised of vehicles and bridges and the structure crowd-composed of a large span of space.To ensure the safety of the engineering structure during service,the time-changing mechanical behavior cannot be ignored.As one of the key research texts of structural investigation,identifying structural parameters can intuitively explain the rules of degradation and the evolution of damage over the life of structures.Therefore,it is very important to study the rules of transient changes in structural parameters.To solve this problem,this paper used time-varying structural engineering as a research goal,applied wavelet theory,Kalman filter theory,and other core research methods,and used a combination of theoretical analysis,numerical simulations,and testing model,which is to carry out some observation data research from time-varying structure engineering on how to identify variables.Much of the research content consists of the following:(1)Carried out wavelet multi-resolution analysis(WMRA)and unscented Kalman filter(UKF)estimation theory research.The principles and operating procedures of the multi-resolution wavelet analysis were described,and theoretical research on the estimation of the unscented Kalman filter was conducted.The algorithm flow of unscented Kalman filter and multi-resolution wavelet analysis is given,and the different noise levels are carried.Simulation analysis of unscented Kalman filter to estimate system response.The application of wavelet multiple resolution analysis is described by specifying the parameters of the system structure.The single-degree-of-freedom linear structure and the two-degree-of-freedom linear structure system have been numerically simulated to demonstrate the feasibility of a method.(2)A new iterative method for specifying the WMRA-UKF time-vary parameters is based on some observation data.Under the condition of partial observation data,an estimate of the state of the optimal structural system by UKF technology has been established,which based on the WMRA theory and the integration of UKF technology.A theoretical model of a time-varying parameter identification method was established for a time-varying vibration system in multiple degrees of freedom.It is applied to structural systems of single degree of freedom and multiple degrees of freedom,and the noise suppression of algorithms has been studied,which has shown that the method is accurate,suitable and anti-noise.(3)In order to further verify the applicability of the proposed method,a three-story steel frame shaking table experiment was designed.Based on the response data of some tests,the performance degradation and damage occurrence are simulated through the sudden change of structural stiffness,and the correctness and applicability of the method for identifying the time-varying physical parameters of structural system are verified.