MAXIMUM ACCELERATIONS OF DIFFERENT GROUNDS WITH VARIOUS MAGNITUDES

Since 1980 (date of the seism of El Asnam magnitude 7.3), the Algerian authorities became aware of the reduction of the effects of the seisms through the implementation of certain number of action. Among these actions it was necessary to work on the site him even to include/understand the seismic risk and to establish charts of microzoning. The area of Constantine being located in seismic zone, the assumption of responsibility relating to the parameter of the seismicity requires micro precise zoning.The compilation of the historical seismic data of the area of Constantine, as those of the neighbouring areas will make it possible to determine the impact of the historical seismicity on the establishment maximum on the ground which will be an essential data for the establishment of the spectra of response for the area of study. As relations of attenuation can vary from country with another and even from an area with another, the local spectra of answer can be of an appreciable contribution for the estimate of the seismic effects on constructions. In this article, starting from the historical seismicity and of the parameters influencing the acceleration of the ground to build maximum accelerations for the area of Constantine. It arises that the acceleration of ground (PGA), given essential in the construction of the spectra of answer, varies with the distance. The more one moves away from the seismic fault, the more it decrease. The Algerian parasismic regulation (RPA 99) gives accelerations for whole area independently of the position of the seismic fault. So there is under estimate of the acceleration of ground (PGA) compared to those calculated

Keywords:

seism , maximum acceleration , seismic faults , relations of attenuation