Seismic design of near-fault ground motions using energy concept

Due to the tremendous energy input of earthquake ground motions near the faults, the traditional inelastic seismic design method based on single index of displacement ductility reduction can't take into account effectively the pulse-type energy input. With some typical near-fault ground motion records and artificial earthquake waves by trigonometric function simulation,, the relationship between the accumulative input energy and the maximum structural deformation was discussed. An index of equivalent velocity ratio was adopted to form the steady relation between these two parameters. Base on this expression, amelioration was done for Fajfar normal energy dissipation index to form non-elastic seismic design spectrum with energy concept. A strength reduction factor considering the seismic energy demand was introduced. It is found that the energy and displacement demands can be considered more effectively compared to traditional elastic response reduction based on single index when the structure is excited by the impulse-type ground motions. The validity and stability of the proposed method are testified with some representational seismic records, and this method can be taken as a rational supplementary for conventional ductility-based seismic design.