sessione 2.3 - Ogs

GNGTS 2009 SESSIONE 2.3
Fig. 4 – Comparison of potential
damage computed with geo-morphotypes
and the one without.
parameters in some of the geo-morphotypes individuated (Fig. 3c and 3d). The first evaluation of
the geo-morphotypes in Gemona del Friuli and Tarcento allows the authors to compare the results
obtained for the school buildings by using:
- the action (PGA) in correspondence to the bedrock;
- the action obtained by considering also the NEHRP class of the soil;
- average relative amplification factors (ARAF) of each geo-morphotype (Fig. 4).
Looking at Fig. 4 it is possible to observe that the potential damage always increases when geomorphotypes
are considered (if the value of PGA is fixed). If then we compare the positions of the
buildings in the ranking list (created just for the two areas) we see that for most of the buildings the
ranking position will change (for example the building that would be the 16 th position without geomorphotypes
is 4 th in the ranking with geo-morphotypes). The data analyzed give us a certain variability
on the results and certainly the intrinsic variability of the ARAF takes the authors to use it
just as an indicator of potential critic zone that requires further analyses (i.e. microzonation).
Works in progress will lead the authors to define the geo-morphotypes for all the Region and to
improve therefore the knowledge of the values of ARAF and on their variability. This mean values
should be considered just as a
raw indication for the possible
increase of the action in correspondence
to a certain scenario.
Certainly they indicate the
necessity of further (and deeper)
analysis of the whole scenario in
which the building is set (comprehending
also the analysis of
Fig. 5 – Comparison among the ranking
list obtained with geo-morphotypes
and the two lists without them
(with ag defined from seismic zones
and with ag defined punctually).
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