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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 6
S. H. C. Santos | S. S. Lima | A. Arai
5. Conclusions
The analysis of the text of the several South American seismic
standards indicates a general agreement regarding the desired
main characteristics of a seismic resistant structure: simplicity,
symmetry, uniformity, redundancies, etc. An essential point also
generally focused is the necessity that the structural design and
detailing should provide enough ductility for the dissipation of en-
ergy in the non-linear range.
On the other hand, apart from the already discussed very particular
case of the Eurocode 8, differences in the shapes of the design
spectra lead to differences in the results, in some cases, superior
to 50%. Obviously, this is a point to be better analyzed in future
comparative studies.
The differences that have been found between the Eurocode 8,
ASCE/SEI 7/10 and the South American codes can be partially
explained by the technical tradition present in each country, but
also are due to specific seismological and geological particulari-
ties, such as distances to active faults, different behavior of seis-
mically active or intraplates regions, available seismic records in
each country, among others.
In some of the standards, as the Colombian code, the design re-
quirements are very well detailed; in other ones, it is noticed the
lack of definition in some relevant aspects. It is recommended that
these requirements should be completed in the future revisions of
these standards.
Another point, already stressed, to be further investigated, regards
the definition of the spectral shape. In all the South American stan-
dards, apart from the soil characteristics, this shape is governed by
a single parameter, the peak ground acceleration. The Eurocode 8
defines two different spectral types, associated with the magnitude
that prevails in the seismic risk of the analyzed site. In standard
ASCE/SEI 7/10, the spectral shape is defined with three basic pa-
rameters, i.e., the peak ground accelerations for the spectral pe-
Figure 4 – Schematic perspective
Figure 5 – Elastic response spectra according
the several standards
Table 1 – Modal participation mass ratios
Mode Period
UX
UY
UZ
SumUX
SumUY
SumUZ
RX
RY
RZ
1
1,12661
0,91
0
0
0,91
0
0
0
0,73
0,15
2
0,84910
0
0,82
0
0,91
0,82
0
0,91
0
0,45
3
0,81283
0
0
0
0,91
0,82
0
0
0
0,24
4
0,38956
0,0727
2,90E-18
1,31E-16
0,98
0,82
1,31E-16
8,15E-19
0,03171
0,01236
5
0,31303
2,58E-20
0,13
7,94E-19
0,98
0,95
1,32E-16
0,00696
1,10E-18
0,07201
6
0,27775
1,15E-20
0
1,34E-19
0,98
0,95
1,32E-16
1,09E-20
4,81E-19
0,02628
7
0,21320 0,01396 8,14E-17 1,65E-17 0,99
0,95 1,49E-16 9,38E-17 0,00020 0,00237