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| | This page contains the documents produced by the
Chapter. It also includes a photographic archive of the activities of the
Chapter. Click on each photograph to view a enlarged version of it.
Past Events
Documents
Observation from Recent Earthquakes in Japan and Peru
(Professor Santiago Pujol)
The recent earthquakes in Japan
and Peru have produced evidence that challenges a number of our preconceptions
in earthquake engineering. These challenges are related mainly to how we
idealize ground motion intensity and its distribution. They are described to
invite the audience to think critically about the level of confidence that we
place on estimates of ground motion intensity. It is suggested that the
uncertainties involved in estimating ground motion intensity are such that the
most sensible option for the structural engineer is to devote her/his attention
to the structure and how to prevent its collapse. This talk identifies the key
property to prevent the collapse of low-rise buildings.
Damage and Drift Capacity in Reinforced Concrete Columns
Subjected to Simulated Seismic Loading
(Professor Mario Rodriguez)
Observed damage and drift capacity
are evaluated for a database of 76 reinforced concrete (RC) column units tested
in various laboratories under different lateral loading protocols. Typically,
structural damage and drift capacity in RC elements are associated to axial load
ratio, confining reinforcement, and shear span ratio. The reviewed database show
the importance of lateral displacement history on the drift capacity and damage
of structural elements subjected to reversed cyclic loading. Based on these
results, a parameter is proposed which captures the effect of lateral
displacement history on the damage and drift capacity of RC elements subjected
to reversed cyclic loading.
Presentation.
Seismic Design of Underground Structures: Failure of the
Dakai Station
(Professor Antonio Bobet)
There is
compelling evidence that current engineering seismic design of underground
structures needs to be improved. Recent damage and failure of a number of
underground structures and lifelines support this conclusion. The Daikai
station, a cut and cover structure in the subway system in Kobe, collapsed
during the Hyogoken-Nambu earthquake of January 17, 1995 in Japan. The Daikai
station is the first well-documented underground structure not crossing an
active fault that has completely collapsed during an earthquake without
liquefaction of the surrounding soil. What makes this case even more interesting
is that tunnel sections adjacent to the station, with similar structural
characteristics and analogous soil conditions, did not collapse. Dynamic
numerical analyses have been conducted to investigate the load transfer
mechanisms between the underground structure and the surrounding soil and to
identify the causes for different behavior of similar sections of the station
subjected to the same seismic loading. The results from the analyses show that,
for a given earthquake, there are two key factors that determine the response of
an underground structure: the relative stiffness between the structure and the
degraded surrounding ground, and the frictional characteristics of the
interface. A practical procedure for routine seismic analysis of cut-and-cover
structures is proposed based on the experience gained from the failure of the
Daikai station. The procedure is based on an analytical solution for rectangular
structures subjected to far-field shear stresses. The response of the structure
is obtained following a pseudo-static analysis that approximates dynamic
response and an iterative scheme that incorporates the non-linear behavior of
the soil.
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