Hello
Sixth graders, we are learning much more with the PBL! This the next homework which is going to be discussed next Friday, April 27, 2018.
Here you are going to see what Chile and Japan can teach us.
Read the following material and answer the questions that follow.
Each group must present a written report which is going to be corrected with the following rubric. Make sure to remember who was NOT willing to help. Deadline: April 27 ,2018
Rubric:
Questions were answered out correctly. /5
The drawing or pictures are accurate. /5
Houses, buildings and bridges codes are mentioned. /5
Uses English to describe what must be done. /5
Uses creativity to share the information /5
It is handed in to the teacher on time /5
5: Proficient: A high degree of competence
4: Capable: An above average degree of competence
3: Satisfactory: A satisfactory degree of competence
2: Emerging: A limited degree of competence
1: Beginning: No key elements are adequately developed
How do
they do it?
The
Chile earthquake — at a magnitude of 8.8 — was much stronger than the one that
hit Haiti, but casualties and damages appear to be far less. Why?
(Shutterstock)
The
opinion of the experts consulted by BBC Mundo is clear: the first secret behind
the tough Chilean buildings is the structure of
reinforced concrete and steel, sufficiently flexible and resistant to allow the
building to move, wobble and not fall; insulators and seismic energy
dissipating elements that allow the Earth’s movement to not be transferred to the building and, if
transferred, that energy is absorbed.
Another
crucial element is the use of soil study so that the foundations are
appropriate.
This is
a very specialized analysis that guarantees the stability of the building
according very strict rules: “To each soil type corresponds a specific
calculation for size, shape, depth and strength of the foundations,” explains
the President of the Architects College of Chile, Sebastián Gray.
The
second key factor is the awareness that auto-building without following these
rules is harmful and a key element in the few landslides that have happened.
Experts agree that a key is in
the structure of reinforced concrete and steel, sufficiently flexible and
resistant to allow the building to move, wobble and not fall.
Sebastian Gray, Architect talks about the real problem behind those
buildings that did not resist an earthquake in Chile. Can you tell what that
reason is?
Despite the code, some buildings did fall, most notably the one in
Maipú and the other in Concepción. In your opinion, was this due to problems
with the code, code enforcement, or something else?
Code enforcement, clearly. This appears to be a matter
of a relaxation in building procedures and hasty construction, which is
the responsibility of builders and developers, rather than a matter of
structural design or the quality of materials, which are not an issue
here. As part of the deregulation policies of the neoliberal economic
model enacted in the 1980s, local authorities and professional
associations were deprived of direct on-site supervision powers in the 1980s.
Structural design in Chile is reliable, based on state-of-the-art
technologies, and has even developed innovations adopted in other regions
around the world.
This is an example of a quake proof house.
Natural rubber bearings
support isolate this building from the ground, protecting the structure during
an earthquake.
Japan’s Solution
After the Kobe earthquake, more buildings in Japan were
constructed using base isolation, including apartments and condominiums, which
are normally constructed using traditional methods. Today, about 100 base
isolated buildings are built in Japan each year, not including single family
homes.
Now, Japanese engineers are taking the concept of isolation a
step further with “ground isolation.” In Sagamihara City outside Tokyo, they
have built 21 separate buildings—six to 14 stories tall—on top of a
three-acre concrete slab. The slab then sits on 150 isolation devices,
including many very large rubber bearings, and all of the buildings move in
sync. Ground isolation shows great promise and could bring base isolation to
even more high-rise complexes.
Another idea
we can get from Japan.
A closer look at the bearings that isolate
the structure from the ground and the flexible utility hook-ups.
What can be
done to improve the earthquake resistance of a bridge?
Tuned mass dampers are used in tall buildings
as well as in bridges to counteract the movement due to earthquakes as well as
wind and other lateral loads. The Akashi Kaikyo bridge uses TMDs in the
suspension towers for example.
Base isolation is one of the most common techniques
used to resist earthquake movement. These are devices which essentially
separate the horizontal movement of the foundation from the rest of the
structure by using some form of sliding bearings. If designed properly this can
drastically reduce earthquake damage.
Seismic Dampers are also common. These are
a range of devices which act to remove seismic energy from the structure
similar to how shock absorbers on a car remove the vibration energy of the car
going over a rough road.
These technologies are well understood and are frequently used
in bridges and buildings. There are more experimental techniques which are also
possible such as: rocking isolation, or active damping systems
(computer controlled dampers).
If desired these devices can also
be used in combination in order to further enhance the earthquake response.
In standard seismic design
practice a structure is designed to accommodate some damage. This damage is,
wherever possible, concentrated in elements which are more easily replaced
(beams and braces), and which will not result in a disproportionate collapse if
damaged.
It is certainly technically
feasible to design large bridges to resist earthquake loading. Especially if
there were no financial constraints.
What are the most important elements in Chile's structures?
In accordance to Sebastian Gray, Which was the problem that caused some buildings to fall during the earthquake?
Who does Sebastian Gray blame for this?
What is Japan using to build new buildings?
Japan also uses TDM's. What is that?
You can use this information and pictures to prepare you poster and newspaper articles. Be creative!
