3. Earthquake
An earthquake (also known as a tremor or
temblor) is the result of a sudden release of
energy in the Earth's crust that creates
seismic waves.
Earthquakes are recorded with a seismometer,
also known as a seismograph.
4. WHAT CAUSES EARTHQUAKES?
Earthquakes are caused mostly by rupture of
geological faults, but also by volcanic activity,
landslides, mine blasts, and nuclear experiments.
But most naturally-occurring earthquakes are
caused by the movement of the earth's tectonic
plates.
5. ONE OF THE MOST DIFFICULT
SETS OF FORCES FOR
ENGINEERS TO ASSESS IS
THAT CAUSED BY
EARTHQUAKES.
The base shear and distribution of forces are based on the
properties of the building itself, as well as the ground motions
of an earthquake, which are impossible to predict.
In addition, the actual stiffness of a building is only an
estimate and can change during the earthquake as members
yield.
6. A Possible Solution to the
EARTHQUAKES
To survive a large earthquake, a building’s structure
must dissipate the energy imparted by the ground
accelerations.
Introducing a fuse into the structural frame can
provide this dissipation, as well as create a
predictable structural response to an unpredictable set
of forces.
7. FUSE
The word fuse has several meanings:
Fuse (electrical), a device used in electrical systems
to protect against excessive current.
Fuse (hydraulic), a device used in hydraulic systems
to protect against sudden loss of fluid pressure
Fuse (explosives), a trigger for an explosive device or
fireworks, also spelled fuze to distinguish between a
simple burning fuse and one which contains
mechanical and/or electronic components
8. Earthquake Fuse
It is an Analogy of an Electrical Fuse
that allows the dissipation of extra
energy from the system by
disconnecting itself from the main
Structure thereby making the
remaining structure less affected.
9. The Fuse Concept
Non- Structural components (i.e. other than main
structure) having mass are added to the structure
so that at the time of Ground Motion they allow
the dissipation of extra energy from the system.
The Fuse gets disconnected from the main
Structure thereby making the remaining structure
less affected.
By forcing the ductility demand to the fuses, the
behavior of the system becomes more
predictable.
10. These members are generally required to have
low width-to-thickness ratios to avoid local
buckling, and eventually fractures, well into
the elastic range.
The remaining frame members are designed to
remain essentially elastic while the fuse yields
dissipate the energy.
These members are often sized based on the
expectation that the fuse is the overloaded
element in the system.
12. The Structural Fuse
An alternative to the empirical approach to
earthquake-resistant design of buildings is the
Structural Fuse.
Instead of strengthening every member to resist
deformation under earthquake loads, deliberately
makes some members, mostly beams, weaker, so that
they will yield in a controlled fashion during an
earthquake.
Yielding beams dissipate energy, reducing stress on
the more crucial columns and walls.
13. Structural Fuse
Structural fuses help increase the
predictability of a building’s behavior and
dissipate seismic energy in the event of
an earthquake.
The FUSE must be highly DUCTILE, it
will have to accommodate most of the
Imposed Deformations.
14. Why Structural Fuse ?
In seismic design, the loads resulting from an
earthquake are reduced by a response modification
factor, which allows the structure to undergo inelastic
deformations.
This methodology relies on the ability of the
structural elements to accommodate inelastic
deformations.
Furthermore, inelastic behavior translates into some
level of damage on these elements.
15. This damage leads to permanent system deformations
following an earthquake, leading to high cost for
repair works, in the cases when repairs are possible.
To achieve stringent seismic performance objective
for buildings, an alternative design Approach is
desirable.
In that perspective, it would be attractive to
concentrate damage on disposable and easy to repair
structural elements (i.e., “structural fuse”), while the
main structure would be designed to remain elastic or
with minor inelastic deformations.
19. Our Focus: Plastic Hinge
Pinned connection between
column and foundation.
Rotation prevented by
small vertical members.
These small bars act as
fuses, allowing rotation
before yielding of column
- called Fuse Bars.
20. Functions of Plastic Hinge
Type of energy dampening device.
Yielding and subsequent deflection of fuse
bars absorb energy.
Reduces fatigue in column during repeated
ground motion.
Post-earthquake, fuse bars can be replaced
relatively easily.
Column-hinge system is then restored to
original condition.
22. Results in:
Stiffness of column-hinge
system lower than expected.
Rotational stiffness much
less than expected.
23. Benefits of Fuse Concept
Seismically induced damage is concentrated on the
fuses.
Following a damaging earthquake only the fuses
would need to be replaced.
Once the structural fuses are removed, the elastic
structure returns to its original position.
24. Conclusions
Energy dissipation protects column from excess strain
and fatigue.
Fuse-bars designed to be replaced easily after they
wear out.
Additional energy can be absorbed by small
component yielding or slipping.
(Not desired, may wear out component over time )
26. What To Do In the Event of an
Earthquake
Prepare a Home Earthquake Plan.
Prepare a Disaster Supplies Kit for home and car.
Identify what to do after the shaking stops.
Examine walls, floors, doors, staircases, and windows
for damage.
Look for fire hazards.
Check for gas leaks or electrical system damage.
Help injured or trapped persons.
Use the telephone only for emergency calls.
27. REFERENCES
Analysis of Rotational Column with Plastic Hinge Michael
Long and Corey Bergad retrieved November 5, 2006.
"Plastic Hinge Integration Methods for Force-Based Beam-
Column Elements." Scott, M.H. and G.L. Fenves. Journal of
Structural Engineering, 132(2):244-252, February 2006.
Seismic Fuses (BY JASON ERICKSEN, S.E).
Understanding the basics of earthquake design (BY DAVE
TIPLER, P.ENG).
Investigation of the Structural Fuse Concept
Ramiro Vargas and Michel Bruneau
