STUDY ON THE DURATION SPECTRA OF STRUCTURAL MOMENTARY INPUT ENERGY RESPONSE

Most of current methods in the aseismic design of structures require the provision of sufficient strength against anticipated seismic effects. The corresponding design response spectra can not reflect the effect of the time duration of an earthquake. The energy based aseismic design is known as an alternative design methodology. A parameter study is carried out on input the duration of the structural energy response based on the momentary input energy and statistical theory, which can reflect the effects of the duration on structures. By establishing the duration of momenary input energy spectra of a linear single degree of freedom (SDOF) system, the effects of the structural dynamic parameters and the characteristics of seismic on the duration were observed. It is found that peak value of the duration of momentary input energy spectrum decreases obviously with damping ratio increase and the changing of peak ground acceleration do not have effects on the duration of momentary input energy spectrum. Based on a total of 100 ground motion records from many significant earthquakes with different peak ground velocities to acceleration (V/A), two parts simple function is suggested according to the shapes of spectra. A simplified model is developed for calculating the duration of momentary input energy spectra to the linear SDOF system with 5% damping. This research conclusion provided a theoretical foundation for more research of the quantization to the cumulative damage in time process based on input energy time histories.