Abstract

The specific "seismic design spectrum" proposed by the Algerian seismic design code, namely the "normalized acceleration spectrum", seems to present an anomaly in comparison with other seismic design spectra over the world and with computed spectra, especially in the first branch of the curve, corresponding to the range of short periods, where the spectrum is a decreasing line whereas it must be an increasing one. This anomaly is outlined and confirmed, in one hand, and treated by proposing an appropriate formula instead of the available one, in the other hand. Some numerical applications are made using both available and proposed formula. This work may be considered as a contribution to the revision of the Algerian seismic design code which is continually done in order to make it more realistic and more perfect.

Key words: Algerian seismic design code, response spectrum, seismic force.