A General Extended Kalman Filter With Unknown Inputs With Integrations In Substructural Identification And Vibration Control

In the past decades,the theory,techniques and equipment of structural health monitoring(SHM)developed rapidly.At present,there are more and more engineering projects to install the SHM system,which provides a convenient way to analyze the safety and performance of the structure.At the same time,it also brings many challenges.Among them,the real-time identification of structural parameters under unknown excitation has attracted the attention of scholars.In addition,the linear and nonlinear parameter identification is a hot spot for large structures.Moreover,the integration of health monitoring and vibration control has received much attention due to its rationality.The extended Kalman filter(EKF)has been widely used for structural identification and damage detection with limited observations.However,conventional EKF requires the information of external inputs.Although some researchers have investigated extended Kalman filter under unknown input(EKF-UI)in recent years,previous approaches are only applicable when acceleration responses at the locations of unknown inputs are measured.For the identification and structural damage detection of large size structures,substructure identification is an efficient approach.However,it is still a challenging task for substructure identification without the observation of responses at the interfaces of substructures.In addition,when a building structure requires both vibration control system and health monitoring system,integrating two systems together will be affective and cost-eflfective.How to reduce the number of using sensors is a key problem to solve.Based on the above research background,the main work of this paper is as follows:In the first part,a general extended Kalman filter(GEKF-UI)is proposed,in which existing constraints on sensor configuration can be removed enabling more general application.In the proposed GEKF-UI,the equation of motion is discretized by the first order hold(FOH)and the analytical formulations for the GEKF-UI is derived based on the framework of the conventional EKF.Moreover,data fusion of partially measured displacement and acceleration responses is applied to prevent the drifts in the estimated structural displacements and unknown external inputs.In the second part(chapter3 and chapter4),an substructural identification approach combine the GEKF-UI and substructure method is proposed to identify the linear and nonlinear structure.The proposed GEKF-UI is adopted for the implementation of substructure identification and damage detection in a large-size structure.The interconnections between adjacent substructures are treated as 'additional unknown inputs' to the concerned substructure.Without the observation at substructure interfaces,element structural parameters in the substructure can be identified by the GEKF-UI,and substructure damage can be detected by tacking the degradation of these parameters.The last piece of work,the GEKF-UI and the vibrtion control are combined to realize the integration of structural identification and vibration control.Comparing to other approach exist,this method can reduce the number of using sensor,realize the paticial observation.In addition,numerical simulations are carried out respectively to validate the the proposed methods,which could serve as an alternative approach for structural dynamic analysis.