EARTHQUAKE TOWERS

EARTHQUAKE TOWERS 8th Grade Ind. Tech Miss Check

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

Unit 2- Gather Information In this activity, you will: -Gather information about the Structural Design for Earthquakes project. - Evaluate factors to make buildings resistant to damage from earthquakes.

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.

What is an earthquake? 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.

What is an earthquake? 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.

What is an earthquake? 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.

Stop Now. Answer questions numbered 1 & 2 in your question packet.

Measuring Earthquakes 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.

Measuring Earthquakes 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.

Summary During an earthquake, the ground moves in all different directions. Earthquakes can range in strength. They can be measured and ranked with different scales.

Buildings Loads on Buildings 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. Live Loads Dead Loads

Live 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.

Dead Loads 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.

Forces on a Building 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. Deflection (bending) Compression Shear Tension Twist

Compression 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.

Tension 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.

Shear 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.

Stop Now. Answer questions numbered 7-9 in your question packet.

Extreme Forces 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.

Summary 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.

Designing Buildings Buildings During 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.

Ground Decisions • 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. Gravel Rock

Foundation Designs 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

Foundation Designs 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.

Frameworks 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. Beam Column

Framework Design 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.

Bracing with Triangles 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.

Bracing with Reinforcement 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)

Bracing with Columns and Beams 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.

Stop Now. Answer questions numbered 16-19 in your question packet.

Design Decisions 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.

Stop Now. Answer question number 20 in your question packet.

Summary 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.

Efficient Buildings 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”.

EARTHQUAKE TOWERS