Concrete Today May 2010 - the Irish Concrete Federation

concrete today - designing for earthquake - precast concrete
cases of mass construction of Precast
structures, speed of construction and low
cost featured more as design considerations,
rather than ‘conceptual design aspects’
which would contribute to increased safety
against earthquakes, even taking into
account the more limited level of scientific
knowledge at that time.
In this respect, the case of the Armenia
earthquake of 1989 is worth mentioning
in which, among other damage, two
cities in particular, Leminakan and
Spitak which were built extensively using
prefabrication techniques were completely
destroyed. According to the findings of the
International Scientific Community, the
extent of the disaster was not due to the use
of prefabrication itself but, much more due
to completely inefficient design concepts,
e.g. lack of proper lateral resisting systems,
very bad detailing of Precast members
and their connections and finally very bad
quality of the concrete and improper use
of steel.
Such cases and other cases of collapse of
Precast structures after strong earthquakes
in the past (Kocaeli earthquake 1999,
Northridge earthquake 1994, Vrancea
earthquake 1977 etc), gave the rather
unjustified impression to the international
community that Precast concrete
constructions performed poorly under seismic
actions due to the fact that prefabrication was
used.
Findings of International Scientific
Community
Nevertheless, according to the findings of
the International Scientific Community,
it is a fact that there are many examples of
excellent behaviour of Precast structures, if
properly designed and constructed in a way
which takes into account the fundamental
requirements of non-collapse and damage
limitation, within acceptable cost limits. In
this respect it is worth mentioning that the
only buildings which survived the strong
earthquake motions in one of the above
mentioned two cities of Armenia were some
multi-storey large-panel buildings which
were designed and constructed, taking into
account basic conceptual design aspects.
L’Aquila earthquake central Italy 2009
Considerable research has been reported
worldwide in the last decades due to the
work of individual companies and by
relevant institutions, which has contributed
to the reliability of Precast structures
built in seismic regions. Among them the
PRESS (Precast Seismic Structural System)
research programme carried out by the
USA and Japan may be considered the
most notable experimental investigation
of the response of Precast structures to
earthquake. Through this research project,
new concepts and technologies have
been invented and experimentally and
theoretically supported, using innovative
connections and prestressing.
The SAFECAST Programme
In March 2009, a new European
Research Programme was initiated,
entitled SAFECAST – Performance of
innovative mechanical connections in
Precast building structures under seismic
conditions’ , financed under the 7th
L’Aquila earthquake central Italy 2009
Framework Programme ‘Research for
Small and Medium Enterprises (SME)
Associations action’. The project derives
from two previous research projects, the
ECOLEDER and the PRECAST EC8
project and completes them thoroughly.
Both of these projects dealt with the
seismic behaviour and ductility capacity
of Precast concrete structures compared
to corresponding cast insitu structures.
However, it was clear from the findings
that the actual design of the connections
was not fully covered and therefore
difficult to be modelled properly for
the numerical studies used in the design
of Precast building structures. Thus,
SAFECAST has been established to
investigate, both experimentally and
numerically, the seismic behaviour of
several types of connections between
Precast members. The success of this
project is critical to the design of Precast
concrete structures, as reliable as cast
insitu concrete structures.
concrete today
7