Random Vibration Response And Reliability Analysis Of Interlayer Seismic Isolated Structure System

Seismic isolated structure system is a passive control system, which is different from the traditional anti-seismic structure system. Through setting isolation layer, earthquake energy is absorbed and dissipated and earthquake response of the structure is reduced, so that the safety of the structure is ensured. Isolated structure system changes the energy dissipation mechanism of traditional anti-seismic structure, i.e. the earthquake energy is absorbed and dissipated by energy dissipative device set in an isolation layer rather than by the structure and structure element. This excellent energy dissipation characteristic can not be realized by traditional anti-seismic structure. With the development of the earthquake isolation, its shortcomings, which have limited the techniques of earthquake isolation, begin to emerge. As a result, interlayer seismic isolation technology has been adopted accordingly, and the flexible laminated rubber bearings are inserted between floor and columns of the structure to control the seismic response.Firstly, a dynamic model of the interlayer seismic isolation is established and the global mass and stiffness matrixes for the structure are deduced. In the analysis process, a comprehensive power spectrum model which combines the low frequency simulation method in seismology and the high frequency simulation method in engineering is adopted to simulate the power spectrum of earthquake ground motion. Secondly, pseudo excitation approach is employed to analyze random response to increase the calculating efficiency. Finally a 12-story interlayer seismic isolation frame is used as numerical example and the effects of different isolation schemes on the random response of each floor relative lateral displacement are discussed. By using structural reliability theory, the reliabilities of each floor relative lateral displacement and the isolated structural system are obtained.By comparing of structure dynamical characteristics and vibration reduction effects for all interlayer isolating schemes, we can obtain some useful conclusions. The results illustrate that there are generally a couple of mode which can control the vibration of the interlayer isolation system. The lower the position of isolation floor lies, the better the effect of vibration reduction. It is important to analyze force and deformation of the infrastructure when isolation floor lies in taller position of the interlayer isolation system.