The Brazilian Standard for Seismic Design: General Aspects and Seismological Basis

The Brazilian territory presents generally low seismicity. Two regions are exceptions, with non- negligible seismicity: part of the Brazilian Northeast and part of the Brazilian Northwest. Due to this low seismicity, up to 2006 Brazil was practically the only South-American country without a seismic design standard. In this year, the first Brazilian Standard for Seismic Design was issued. The available seismological data and the studies performed for defining the probabilistic distribution functions of seismic magnitudes, in several Brazilian regions, are reviewed herein. The considered probabilistic analyses performed for the definition of the nominal values of horizontal accelerations are also presented. Equal probability design spectra are generated and compared with the ones defined in the standard. Some other aspects of the standard, such as, definition of the seismic design spectra and the allowed methods of analysis are also commented.