Download Earthquakes

Table of Contents
Unit 1- Understand the Problem
Unit 2- Gather Information
Unit 3- Develop Solutions
Unit 4- Implement A Solution
Unit 5- Test and Evaluate
Unit 6- Redesign and Communicate
In this activity, you will:
-Gather information about the Structural
Design for Earthquakes project.
- Evaluate factors to make buildings
resistant to damage from earthquakes.
During an earthquake the ground moves in all different directions.
Occasionally, the ground may even rupture or split open. Buildings above
the moving ground are sometimes damaged or even destroyed.
The earth may seem like a solid surface. But the Earth is made up of many
layers that are always changing. The Earth’s outer layer is called the crust.
The crust is broken up into large pieces, or plates, that can move around. When the
plates move, bend, stretch, or push against each other, they can cause earthquakes.
While earthquakes can occur anywhere at any time, most earthquakes occur along
a fault line. A fault line is the boundary between two pieces of the Earth’s crust.
Earthquakes can range in strength.
Small earthquakes are common and cause little damage.
But as the strength of an earthquake increases, the damage to structures tends to
increase.
In the most severe earthquakes, buildings may collapse. Even
modern, reinforced structures, may be damaged.
The strength of earthquakes can be measured. Scientists
rank the strength of earthquakes with different scales.
-One way to measure the strength of an earthquake is with
the Richter scale. The Richter scale is based on the size or
magnitude of the vibrations cause by a quake.
-Another way to measure the strength of an earthquake is
the Mercalli scale. The Mercalli scale is based on the
amount of damage to buildings.
During an earthquake, the ground moves in all
different directions.
Earthquakes can range in strength. They can
be measured and ranked with different scales.
A building is a collection of materials which together support other materials,
such as walls, windows, furniture, and people. The materials and their weight
supported by buildings are called loads.
In a building, furniture and people can be live loads. A
live load is the weight of a non-permanent and movable
part of a structure.
Wind, rain, and earthquakes are live loads caused by the
environment and affect a structure for a limited period of time.
In a building, walls and floors are dead loads. A dead load is the
weight of a permanent and non-movable part of a structure.
The loads on a building will add stress to its structure. Stress is a force that can change
the shape of a structure. If the stress is large enough, it can damage the structure, or
even destroy it.
Types of stress include compression, tension, deflection or bending, shear, and twist.
In an earthquake, compression, tension, and shear often affect structures.
Stress that squeezes or presses on a
material is called compression.
For example, the columns of a building may be damaged
by compression if the columns support severe loads.
Stress that pulls on a material and stretches it so that it becomes thinner in the middle
is called tension.
For example, the floors of a building may be
damaged by tension if the floors support severe
loads.
Stress that pushes one part of a material past another is called shear.
For example, a section of a building may be damaged by shear if the section supports
severe loads.
Like all buildings, the structures of the courthouse
will have to support the dead loads cause by the
building itself. And it will also have to support the
live loads of people and weather.
Due to its location, the courthouse will also have to
withstand the extreme and sudden loads caused by
occasional earthquakes.
The loads on a building will add stress to its structure. If
the stress is large enough, it can damage the structure, or
even destroy it.
The structure of the courthouse will have to support the
dead loads caused by the building itself. And it will also
have to support the live loads of people and weather
and the extreme and sudden loads cause by occasional
earthquakes.
Recall that during and earthquake, the ground moves in some combination of shaking,
sudden jolts, or moving up and down.
Earthquakes place extreme and sudden loads on buildings. There is no such thins as an
earthquake-proof building. Older buildings may not even remain after a quake. But newer
buildings can be designed to resist the damage that can be caused by most earthquakes.
The location of a building and the ground beneath the structure are key factors when
designing a building to resist earthquakes.
- Loose, gravelly soil behaves like quicksand during an earthquake. Even during a
minor tremor, buildings built on loose, gravelly soil may sink and collapse.
- Solid rock and firmly packed soils are the most stable types of ground during an
earthquake. Bu during a sever earthquake, buildings built on solid rock and firmly
packed soil may be damaged.
- The ground beneath the courthouse is solid rock covered with packed soil.
The design of the foundation is another key factor when designing a building to
resist earthquakes. A foundation is the base or support of a building.
Some engineers believe that the
foundation and the framework
should move as one single unit
during an earthquake. These
foundation designs tend to have
long columns driven deep below
surface soil into solid rock.
Pic I drew
Other engineers believe that the foundation and the framework should move as
two separate units during an earthquake. They feel these foundations will absorb
most of the vibrations and the framework does not move as much. These
foundation designs tend to have flexible rubber pads between the building and
the ground.
The foundation and the framework of
the courthouse will be designed to
move as one unit during and
earthquake. The framework will be
secured to the foundation.
The design of the framework is another key factor when designing a building to resist
earthquakes. The framework holds up the other parts of the building, such as walls and
floors. Frameworks are made from members. Vertical members are called columns.
Horizontal members are called beams. A framework is a combination of columns and
beams that support the building. You will design the framework for the courthouse.
A framework designed with only squares or rectangles may change shape when stress is
applied. But frameworks can be strengthened by adding bracing. Bracing increases the
stability of framework. Bracing is using additional materials to offer extra support.
You will now gather some information about bracing with triangles, bracing with
reinforcement, and bracing with columns and beams.
Triangles can brace a structure. They add strength and stability to a structure. Triangles
reinforce the framework. When you design the courthouse framework, you can use
triangles to brace the framework.
Reinforced members can brace a structure. They add strength and stability to a
structure. Reinforced members reinforce the framework. When you design the
courthouse framework, you can reinforce members by gluing two members together
lengthwise to brace the framework.
Reinforced Members (Double Bracing)
Columns and beams can brace a structure. Recall that columns are vertical members and
beams are horizontal members. They add strength and stability to a structure. Columns
and beams reinforce the framework. When you design the courthouse framework, you
add columns and beams to brace the framework.
When you design your courthouse, keep in mind that the structure must support everyday
loads. And it must resist the sudden and extreme loads of an earthquake.
You will have many design decisions to make. You can decide to add triangles, columns,
beams, or reinforced members to increase the strength and stability of the frame work.
After designing and creating the prototype you will test it.
Simulate the dead loads on the courthouse by using weight.
Simulate the extreme live loads of an earthquake on the
courthouse by testing the prototype on an earthquake simulation
machine.
Buildings can be designed to resist the damage that can be caused by most earthquakes.
Loose, gravelly soil behaves like quicksand during an earthquake. And solid rock and firmly
packed soils are the most stable types of ground during an earthquake.
Some engineers believe that the foundation and the framework should move as one single
unit during an earthquake. And other engineers believe that the foundations and the
framework should move as two separate units during an earthquake.
Bracing, with triangles, columns, beams, or reinforced members can increase the strength
and stability of the framework.
When you are building your courthouse prototype, explore designs to make the building
efficient. An efficient building will use the least possible amount of materials to meet the
design goals.
Congratulations! You have completed Unit Two –
Gather Information. You will now move onto Unit 3.
The power point is titled “EQT- Unit 3”.