Subsidies for the generation of artificial accelerograms

Resumo

Despite an evident relatively low seismic activity, Brazil is not free of earthquakes and the correct
techniques must be used in order to design civil structures and to assess their seismic risk. NBR 15421:2006 is
the Brazilian standard code for the design of seismic resistant structures and it defines four different methods for
the structural analysis, depending on building location site: a simplified procedure, the equivalent horizontal
forces method, the spectral method and the time-history analysis procedure. In fact, it is important to ensure
strength to the structure as well as an adequate performance, what can be evaluated, for example, by the fragility
curves results from the time-history analyses. However, NBR 15421 code presents only a design response
spectrum and defines that input accelerograms should be compatible to this response spectrum. This paper
presents an iterative computational procedure, based on stochastic structural dynamics concepts, to generate
artificial accelerograms compatible with response spectra. After the methodology exposition, some applications
highlighting the influence of important parameters and an example of time-history response are describe. A
contribution to the technical discussion about this topic is important because the NBR 15421 revision process is
coming soon.