Analysis of structural dynamic nonlinear characteristicbased on Hilbert spectrum
Wu Chen1，Zhou Ruizhong2
1、 Department of civil engineering, Fujian University of Technology, Fujian ,Fuzhou ,3501082、 College of civil engineering, Fuzhou University, Fujian,Fuzhou,350108
Abstract：The Hilbert spectrum and intra-wave modulation are introduced in this paper. In SDOF system and MDOF system, tri-linear stiffness retrograde system is compared with linear system on Hilbert amplitude spectrum and energy spectrum of earthquake absolute acceleration response. The symbols of structural non-linear mechanical behavior are analyzed. It is shown that "Band broadening" and" dominant frequency drift" are important symbols of dynamic nonlinear mechanical behavior. The acceleration energy of linear system is concentrated in a narrow band near the natural frequency and the intra-wave modulation cause band broadening in Hilbert energy spectrum of tri-linear stiffness degradation system. And influenced by yield frequency and cracking frequency, the dominant frequency band drift to the low frequency. In short period structures, band broadening and dominant frequency drift are obvious, but in the long period structures, are not significant.
2013, Vol. 32 
