| In this paper,the dynamic characteristic and dynamic response changes of super high-rise structures with sudden changes in stiffness and mass at the top are studied under different environmental effect.The means of theoretical analysis,monitoring analysis,numerical simulation and modal parameter tracking are used to reveal the dynamic characteristic and dynamic response differences of the top abrupt structure and the main structure,and interpret the reason of different phenomena.At the same time,the dynamic response of the structure under extreme environment is predicted and analyzed.The dynamic characteristic and dynamic response of super high-rise structures with sudden changes in stiffness and mass at the top are analyzed theoretically.Based on the structural motion equation,the dynamic characteristic of multi-degree-of-freedom structure is studied.Based on the frequency domain method,the relationship between the response spectrum and the excitation spectrum is obtained.The RMS of each mode is calculated by piecewise integration of the response spectrum,and the dominant modal evaluation method of dynamic response is constructed.On this basis,the influence of the top stiffness and mass mutation degree on the dynamic characteristic and dynamic response of the structure is revealed.Based on the Covariance-Driven Stochastic Subspace Identification,combined with Density-Based Spatial Clustering of Applications with Noise and sliding filter method,the long-term automatic tracking and checking of the dynamic characteristic of super high-rise structures are carried out,and the feasibility is verified by the measured data.The tracking algorithm is used to study the dynamic characteristic and response of super high-rise structures under the influence of the environment.Through the analysis of measured data,it is found that the modal frequency of the super high-rise structure is mainly affected by temperature and wind,and the damping ratio increases with the increase of external excitation.Acceleration response analysis results show that super high-rise structure with top steel frame has significant whip effect under the action of normal wind and earthquake.Unlike the main structure,the vibration of the top steel frame structure is dominated by high order modes.While the vibration of the top steel frame structure and the main structure are dominated by the first-order mode under the action of typhoon.Based on the actual monitoring data,the state space numerical model is modified and the numerical simulation is carried out.In this paper,taking King Key Finance Center as an example,the state space numerical model is modified by using Back Propagation Neural Network Improved by Genetic Algorithms,and the measured acceleration response value is compared with the simulated value through the numerical model operation,which verifies the accuracy of the state space model.At the same time,the whipping effect and the dominant modes of vibration in the measured dynamic response are verified by numerical simulation.Based on the super high-rise structure with sudden changes in stiffness and mass at the top,the structural dynamic response and prediction analysis are carried out.Through theoretical analysis,it can be found that the frequency response function of the structural characteristic and the significant frequency of the excitation characteristic lead to the difference in the dynamic response of the top steel frame and the main structure under different environment effect.The whiplash effect is caused by the high-order modes that make a greater contribution to the top mutation structure.Finally,based on the design of the once-in-a-year wind load,the dynamic response of the King Key Financial Center is predicted to provide reference for long-term operation of the structure. |
