Novel Integration Method Of Measured Acceleration Based On Zero Initial Condition And Application

In recent years, the damage and collapse of building structures caused by earthquake, typhoon and flood have brought tremendous losses to the safety of people's lives and property, and structural health monitoring (SHM) has become an important research field in civil engineering. The accurate damage location and degree is helpful to repair or take other measures to avoid secondary disasters. In addition, to obtain dynamic response of structure accurately is also beneficial to know the running status during disasters and provide important references for structure disaster prevention design. The work of this dissertation is mainly about novel integration method of measured acceleration based on zero initial condition and its application,and the work done is listed as follows:(1)The first step of structural parameter identification in time domain is to get relatively accurate velocity and displacement. In the first part, a novel integration method is proposed, in which the zero points of velocity and displacement during steady state vibration are sought for and determined utilizing basic rules of vibration, and are regarded as the initial values of integration. Moreover, the "drift" caused by the error of sampling spacing and stochastic vibration is further removed by detrending the integrated displacement. Responses of a single degree of freedom structure and a multiple degree of freedom structure are simulated under harmonic and earthquake excitation. The maximum relative error between the calculated value and the accurate ones are compared. In the end, the proposed method is applied to seven typical seismic motion records. The integrated velocity and displacement are compared with given ones which powerfully demonstrates that the proposed integration method is accurate and practical.(2)Subtle error in structural vibration response will be magnified in parameter calculation, it can lead the results of structural parameter identification deviate from the true values. Therefore, it is necessary to control the error in identification method. The method of least square, extended Kalman filter(EFK) and classical Kalman filter are adopted to identify the structural parameter, and the anti-noise property and computational accuracy of these methods are compared through numerical simulation. In addition, the match level with the above integration method is verified.(3) The judgment and solution of "step" type and linear stiffness reduction is proposed based on innovation of Kalman filter. It can improve the sensitivity of parameter variation, and the accuracy and practicability are verified through numerical simulations.