ANALYSIS ON ENERGY DEMAND FOR INELASTIC SDOF SYSTEMS UNDER NEAR-FAULT IMPULSIVE GROUND MOTIONS

摘要

In the recent two decades, the motion characteristics of forward directivity, fling step and hanging wall effect of near-fault ground motions cause severe structural damage and collapse. At present, for structural seismic analysis and design, it is quite significant and indispensable to conduct the energy demand analysis of structures under the near-fault impulsive ground motions with the duration effect. This paper takes the near-fault ground motion records from the Chi-Chi, Taiwan and Northridge, California earthquake as seismic input, and analyzes the influence of ground motion characteristics and structural parameters to the average input energy spectra ?, and energy ratio spectra EH/Et of bilinear single degree of freedom (SDOF) systems. Numerical results indicate that the distinct pulse the significant duration of near-fault ground motions impose remarkable effects on the peak and shape of mean input energy spectra ?, and energy ratio spectra EH/EI. Moreover, the ductility factor, damping ratio and natural period of systems produce important effects on the energy spectra of bilinear SDOF systems, and the effect of yield stiffness ratio can be neglected. Finally, the mean input energy spectra ?, and energy ratio spectra EH/EX are fairly different for the two different earthquake events such as the Chi-Chi and Northridge earthquake.