Identification For Local Non-Linearity Structures Based On Dynamic Response Sensitivity

In order to reduce the dynamic response of the engineering structures under the action of dynamic loads,some non-linear energy-absorbing and shock-absorbing components are often deployed in the structure.When physical parameters are identified for a structure with local nonlinear components,if a parameter identification method for a linear structure or a structure with nonlinear member in full-structure with is directly used,it is difficult to achieve an optimal recognition accuracy or identification efficiency.Therefore,it is of engineering significance to develop a identification method for both linear and nonlinear parameters of local nonlinear structural systems.Based on this,this dissertation conducts a series of researches on the above issues.The main contents are as follows:(1)A method based on the concept of time-domain dynamic response sensitivity is proposed to synchronously identify structural linear physical parameters and nonlinear parameters by using dynamic responses from only a few degrees of freedom of the structure.A four-story base-isolated frame is used as an example to verify the effectiveness of the algorithm,and the effects of the amplitude and the frequency of excitation signal and the position and the number of the dynamic response measurement points on the identification result of the algorithm are systematically studied.(2)The above-mentioned synchronization identification algorithm is extended to simultaneously identify the physical parameters(including both physical parameters of the linear part and nonlinear parameters)and the input time-history of the local nonlinear structure under unknown support excitation.The four-story base-isolation frame is also used as an example to verify the effectiveness of the algorithm,and the effects of measurement noise and excitation signal form on the identification accuracy of the algorithm are studied.(3)Combining the concept of sub-structures,the synchronization identification algorithm is generalized to simultaneously identify the physical parameters(including both physical parameters of the linear part and nonlinear parameters)and the inter facial forces on the sub-structure to be identified only from the dynamic response on the sub-structure to be identified.The introduction of inter facial forces removes the influence of other parts of the structure on the substructures with local nonlinear members,thus enabling the rapid identification of local nonlinear parameters in large complex structures.The validity of the algorithm is verified from a lower four-level substructure of a thirteen-story base isolation frame and a pier substructure of a four-span continuous beam bridge.The influence of measurement noise on the identification accuracy of the algorithm is also studied.