Final Project Topics
Seismic Control of Structures for
Dynamic Actions
A Brief Review of Fundamentals
of
Earthquake Resistant Design
Earthquake Engineering can be defined
as the branch of engineering devoted to
mitigating earthquake hazards. In this
broad sense, earthquake engineering
covers the investigation and solution of
the problems created by damaging
earthquakes, and consequently the work
involved in the practical application of
these solutions, i.e. in planning,
designing, constructing and managing
earthquake-resistant structures and
facilities.
Title: Roof-top water tank induced damage
Date: 2001
Earthquake: Bhuj, India earthquake, Jan. 26, 2001
Magnitude: 7.7
General Goals in Seismic-Resistant
Design and Construction
The philosophy of earthquake design
for structures other than essential
facilities has been well established and
proposed as follows:
a.To prevent non-structural damage in
frequent minor ground shaking
b.To prevent structural damage and
minimize non-structural damage in
occasional moderate ground shaking
c.To avoid collapse or serious damage in
rare major ground shaking
Title: Damage from out-of-plane deformation
Location: Turkey/ASIA/Western Asia
Earthquake: Izmit, Turkey earthquake, Aug. 17,
1999 Magnitude: 7.4
Building structures may be of many types and configurations and there is, of course,
no universal ideal configuration for any particular type of building. However, there
are certain basic or guiding principles of seismic-resistant design that can be used as
guidelines in selecting an adequate building configuration structural layout,
structural system, structural material and the non-structural components. These
basic guidelines are as follows:
1. Building (superstructure and
non-structural components)
should be light and avoid
unnecessary masses.
Superstructure should have the
largest possible number of
defense lines, that is, it should be
composed of different tough
structural subsystems which
interact or are interconnected by
very tough structural elements
(structural fuses) whose inelastic
behavior would permit the whole
structure to find its way out from
a critical stage of dynamic
response.
Plan view of the Banco de
America, Managua, Nicaragua.
This building generally
performed very well during the
1972 Managua Earthquake. Its
excellent performance can be
attributed to the symmetry
and uniformity of distribution
of the masses and structural
stiffnesses throughout the
building.
2. Building and its superstructure should be
simple, symmetric, and regular in plan and
elevation to prevent significant torsional
forces, avoiding large height-width ratio and
large plan area.
Hotel Terminal, Guatemala
City. Overall view of this 6-story
hotel, illustrating the torsional failure
of the second story during the 1976
Guatemala Earthquake.
Refer to type of irregularities in structures
3. Building and its superstructure should have
a uniform and continuous distribution of mass,
stiffness, strength and ductility, avoiding
formation of soft stories.
Commercial Building Casa
Micasa S.A., Managua,
Nicaragua. This 2-story
reinforced concrete frame
building suffered
significant lateral
displacement at the
second floor level during
the 1972 Managua
Earthquake.
Detailed view of the behavior of
one of the first and second story
columns in the building of Slide J72
during the 1971 San Fernando
Earthquake. Note the large
permanent distortion of the first
story column (because it was part
of the soft story at this
level). While the well-confined
concrete of the spirally reinforced
core of this column was capable of
holding the building up, the
unconfined concrete cover had
spalled off. Note also the shear
failure of the second story column,
induced by the shortening of this
column by the wall panels that
were placed at the top and bottom
of this story.
Olive View Hospital, Psychiatric Unit, San
Fernando, California. 1971 San Fernando
Earthquake. This unit was a 2-story reinforced
concrete building. The structural system was a
moment resisting frame. However, in the
second story there were masonry walls that
added significantly to the stiffness of this story.
4. The non-structural components
should either be well separated so that
they will not interact with the rest of
the structure, or they should be
integrated with the structure. On the
latter case, it is desirable that the
structure should have sufficient lateral
stiffness to avoid significant damage
under minor and moderate earthquake
shaking, and toughness with stable
hysteric behavior (that is, stability of
strength, stiffness and deformability)
under the repeated reversal of
deformations which could be induced
by severe earthquake ground motion.
The stiffer the structure, the less
sensitive it will be to the effects of the
interacting non-structural components,
and the tougher it is, the less sensitive
it will be to effect of sudden failure of
the interacting non-structural
elements.
Two-story reinforced concrete building, Managua,
Nicaragua, damaged in the 1972 Managua Earthquake.
The slide shows a reinforced concrete column which was
part of the structural system and which failed due to its
shortening because of the effect of the masonry wall. The
masonry walls were considered as non-structural elements.
Innovative Earthquake Resistant
Design and Control Methods
Motivation for Controlling of
Earthquake Forces
• Control earthquake forces in order to
• Obtain better building performances
• Controlling can be through design details,
passive control or active control
PED: Passive Energy Dissipation
An Example for a Passive Control
Seismic Isolation
� Seismic Isolation Technologies
� The basics – How it works?
� Design related issues
Seismic Performance GoalsOur goals are to Preserve Life Safety and Prevent Collapse
If collapse can be prevented, which level of damage is acceptable?
Local Failure
Permanent
Failure
L’Aquila Earthquake
2009 - Italy
Van Earthquake
2011 - Turkey
Total collapse
Seismic Performance Goals
In Earthquake Engineering the challenge is to build structures for different
performance levels (e.g.,):
� Life safety for strong eartquakes (rare events),
� Limited damage for design based eartquakes.
RESILIENT STRUCTURES
Ductility Design vs. Force
Control StrategyChallenges in “ductile design” strategy:
� Strong column – weak beam mechanism may not form due
to existence of wall,
� Shear failure of columns may occur due to wrong
proportioning or short-column effect,
� Construction difficulty at beam-column joints due to
complexity of steel reinforcement,
So, why not control the inertial forces
attracted to the structure?
Seismic Isolation – Controlling Forces
How It Works?
� The structure is decoupled
from the ground by isolators
with low horizontal stiffness,
� This results in fundamental
frequency that is much lower
than the fixed-base frequency,
� The first dynamic mode of the
isolated structure involves
deformation only in the
isolation system,
Seismic Isolation – Controlling Forces
How It Works?
� These higher modes do not
participate in the motion,
reducing drift (orthogonality),
� The isolation system does not
absorb the earthquake energy,
but rather deflects it through the
dynamics of the system.
Building with a Seismic Isolation
� Schematic representation of a
building with base isolation
system
Building with a Seismic Isolation
Seismic Isolation
�Smaller structural members
�Smaller foundations
�Smaller accelerations
With a seismically isolated structure, the seismic
forces are reduced, this leads to:
Seismic Isolation
How It Works? – A Demonstration!
Seismic Isolation
Requirements of a Base Isolated Device1. Isolating the building from the ground,
2. Supporting the weight of the structure,
Seismic Isolation
Requirements of a Base Isolated Device3. Damping of response amplitude,
4. Restoring to the original position after an earthquake,
Seismic Isolation
Isolated
Building
Increasing the period will reduce the
acceleration
Seismic Isolation
Isolated
Building
Increase in period will increase the displacements, therefore
high damping is needed!
Seismic Isolation
� Laminated elastomeric bearings,
Types of Isolators
Video
� Pendulums (low friction
sliders – stainless
steel/PTFE)
Types of Isolators
A Test Video of a Friction Pendulum
� Elasto-plastic devices
Types of Isolators
Devices at Bolu Viaducts
Application of anti-seismic
systemOver 10.000 new and existing structures:
� Bridge and viaduct
� Industrial plants and components
� Buildings including cultural heritage