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1. Introduction
The newly established Working Group 7 (WG7 - Earthquake Re-
sistant Structures) of the International Association for Bridge and
Structural Engineering (IABSE) has proposed, inside its Field of
Activities and Objectives, studies of comparisons among seismic
codes, in order to find out discrepancies and similarities among
them, as well as to identify and fulfil gray areas of knowledge.
This paper is aligned with this objective of the WG7, presenting an
general evaluation of some points of the South American seismic
codes, comparing these codes among themselves and confronted
with the American Standard ASCE/SEI 7/10 [1] and with the Stan-
dard for the European Community, the Eurocode 8 [2]. The study
is focused in the criteria for the design of conventional (residential
and commercial) buildings.
The South America possesses regions with very different degree of
seismicity. The Western border of the continent is one of the most
seismically active regions of the World; it corresponds to the conflu-
ence of the South American and Nazca plates. This region corre-
sponds roughly to the vicinity of the Andes Mountains, present from
North to South extremities of the continent. This seismicity diminishes
in the direction of the comparatively seismically quieter Eastern South
American areas, located in the centre of a stable intraplate region.
Due to this, the South American countries located in the Western
Border of the continent possess standards for seismic design since
some decades ago (Venezuela, Colombia, Ecuador, Peru, Chile
and Argentina). In opposition to this, the Brazilian Standard for
seismic design has been only recently published, in 2006.
This study is focused in some critical topics: definition of the re-
currence periods for establishing the seismic input; definition of
the seismic zonation and respective design seismic ground mo-
tion values; definition of the shape of the design response spectra;
consideration of soil amplification, criteria for soil liquefaction and
for the consideration of soil-structure interaction; classification of
the structures in different importance levels; definition of the con-
sidered seismic force-resisting systems and respective adopted
response modification coefficients; consideration of structural ir-
regularities and definition of the allowable procedures for the seis-
mic analyses, among other comparisons that could be performed
in this type of comparative study.
A simple building structure is analyzed considering the criteria of
the several standards and obtained results are compared. A critical
analysis of the different design criteria is then presented.
2. Standards to be analyzed
The available South American Standards for seismic design of
building structures listed below will be compared with the above
mentioned standards ASCE/SEI 7/10 and Eurocode 8:
n
Venezuelan Standard - COVENIN 1756:2001 [3]
n
Colombian Standard - NSR-10:2010 [4]
n
Ecuadorian Standard - CEC-2002 [5]
n
Peruvian Standard - Reglamento Nacional de Edificaciones [6]
n
Chilean Standard – NCh 433.Of96 [7]
n
Argentinean Standard - INPRES-CIRSOC 103 [8]
n
Brazilian Standard - NBR 15421:2006 [9]
Some details concerning the application of these standards are
discussed in the sequel. This paper enlarges and complements the
studies already presented by the authors in another paper, Santos
et. al. [10].
3. Comparative analysis
3.1 Definition of the recurrence periods for
the definition of the seismic input
The Eurocode 8 recommends, for the no-collapse requirement of
a structure, the consideration of a recurrence period of 475 years.
This corresponds to a probability of 10% of the seismic input being
exceeded in 50 years. Most of the South American standards fol-
low this criterion (Colombian, Ecuadorian, Peruvian and Brazilian).
In the other ones, this definition is not explicitly stated. The stan-
dard ASCE/SEI 7/10 defines a recurrence period of 2475 years,
which corresponds to a probability of 2% of the seismic input being
exceeded in 50 years; nevertheless, economical reasons lead this
standard to allow for a reduction factor of 2/3 to be applied in the
resulting values of the seismic design forces.
3.2 Definition of the seismic zonation and
design seismic ground motion values
The Eurocode 8 transfers the responsibility for defining the seismic
zonation for each of the National Authorities. In this standard, a
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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 6
S. H. C. Santos | S. S. Lima | A. Arai
Figure 1 – Seismicity of South America