The modification method of seismic design spectra according to total and instantaneous input energy

Since the discovery of the long period component in the strong ground motion, it is aware that the influence of long period components on the structures with long periods cannot be ignored. In current design codes, the seismic design for buildings with long periods is conservative, and the values of spectrum are artificially magnified for the specific frequency range of ground motions and specific site conditions, which conflicts with the actual records of ground motions. In view of the deficiency in current design codes, a modified method is proposed for the design spectra in the range of 5Tg to 6s, according to the seismic input spectra of the total energy and the instantaneous energy for a single degree of freedom system. Based on the actual records of ground motions with long period components which possess the characteristic of velocity pulse, the proposed method is evaluated, the modified acceleration spectrum is obtained, and the pseudo-velocity spectrum and the displacement spectrum associated with the acceleration spectrum can also be attained. The proposed method can reflect the characteristics of the seismic input spectra for the total input energy and the instantaneous input energy, which shall be of theoretical importance and practical application for the seismic design of structures. © 2018, Editorial Office of China Civil Engineering Journal. All right reserved.