# Structures and Forces

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Structures and Forces by

1.1.1. Plane

1.2.1. Giraffe

## 3. Types of Forces

### 3.1. Internal Forces

3.1.1. An internal force occurs when one part of a structure puts force on other parts of the structure.

3.1.1.1. Compression

3.1.1.1.1. The force of a structure being pressed together.

3.1.1.2. Tension

3.1.1.2.1. The force of a structure being pulled apart.

3.1.1.3. Torsion

3.1.1.3.1. The force of a structure being twisted.

3.1.1.4. Shear

3.1.1.4.1. The force of a structure being bended or moved in opposite directions.

### 3.2. External Forces

3.2.1. An external force occurs when any force is acted upon on the outside of the structure.

3.2.1.1. Friction

3.2.1.1.1. When a structure is resisting being slid on another object, usually the ground.

3.2.1.2. Gravity

3.2.1.2.1. The force that brings structures down on earth or any other mass. The bigger the mass, the more gravity it has.

## 4. Design of structures

### 4.2. Structural Stress

4.2.1. Stability

4.2.1.1. Stability is the structure's capability to keep it's posture when a external force has been put on it.

4.2.1.1.1. An example of stability can be a bridge.

4.2.1.1.2. Another example could be a building/tower.

### 4.3. Structural Fatigue

4.3.1. When a structure is overloaded with internal and external forces for too long, and the structure cannot return to it's original shape.

4.3.1.1. An example of structural fatigue can be a smashed aluminum can.

4.3.1.1.1. Aluminum Can

4.3.1.2. Another example can be a crumpled piece of paper.

4.3.1.2.1. Paper

### 4.4. Structural Failure

4.4.1. When a structure has experienced such a large amount of structural stress and structural fatigue that it is no longer able to function properly.

4.4.1.1. An example of structural failure can be a collapsed bridge.

4.4.1.1.1. Collapsed Bridge

4.4.1.2. Another example can be a broken car.

4.4.1.2.1. Broken Car

4.4.1.3. Another example could a fallen house

4.4.1.3.1. Fallen house

### 4.5. Structural components

4.5.1. Materials that can help the structure be stabler and have more strength.

4.5.1.1. An example of a structural component can be I beam.

4.5.1.1.1. Beam

4.5.1.2. Another example could be a column.

4.5.1.2.1. Column

4.5.1.3. Another example could be an arch.

4.5.1.3.1. Arch

## 8. The strength of a structure is the structure's capability to hold off forces.

### 8.1. Direction is where the force is coming from.

8.1.1. Another example could be where a golf club hits a golf ball (left, right, middle).

### 8.2. An example of a structure's strength can be a house not getting knocked down by the wind.

8.2.1. House pushing against wind

### 8.3. Another example of a structure's strength could be a bridge not collapsing under a truck's weight.

8.3.1. Bridge with truck

### 8.4. Another example could be a building being able to withstand the force of snow hitting it..

8.4.1. Snow hitting building

## 9. Types of structures

### 9.1. Shell Structures

9.1.1. Shell structures are hollow, light and strong structures.

9.1.1.1. An example of a shell structure can be an igloo.

9.1.1.1.1. Igloo

9.1.1.2. Another example could be an egg.

9.1.1.2.1. Egg

9.1.1.3. Another example could be a balloon.

9.1.1.3.1. Balloon

### 9.2. Solid Structures

9.2.1. Solid Structures are structures that are solid all the way through. Solid structures are heavier and use up more materials to make.

9.2.1.1. An example of a solid structure can be a sandcastle.

9.2.1.1.1. Sandcastle

9.2.1.2. Another example could be a banana.

9.2.1.2.1. Banana

9.2.1.3. Another example could be a mountain.

9.2.1.3.1. Mountain

### 9.3. Frame Structures

9.3.1. Frame Structures are parts put together. A frame structure connects itself to different parts of the structure.

9.3.1.1. An example of frame structures can be a skeleton.

9.3.1.1.1. Skeleton

9.3.1.2. Another example could be a car.

9.3.1.2.1. Car

9.3.1.3. Another example could be a spider web.

9.3.1.3.1. Spider Web

### 9.4. Combination structures

9.4.1. Combinations structures are made up of combinations of the different types of structures(shell, frame and solid structures).

9.4.1.1. An example of combination structures can be a house.

9.4.1.1.1. House

9.4.1.2. Another example could be a person.

9.4.1.2.1. Person

9.4.1.3. Another example could be the One World Trade Center.

### 9.5. Strength

10.1.1.1.1. Chair

10.1.1.2. Another example could be a pencil case.

10.1.1.2.1. Pencil Case

10.1.1.3. Another example could be a bridge.

10.1.1.3.1. Bridge

10.2.1.1. An example of a live load can be a person sitting on a chair(live load is the person)

10.2.1.1.1. A Person Sitting

10.2.1.2. Another example could be bacon on a pan(live load is the bacon).

10.2.1.2.1. Bacon

10.3.1. A dynamic load is a force that is acting upon a structure that can change the shape or directions of the object.

10.3.1.1. An example of a dynamic load can be wind pushing against a building(the dynamic load is the wind).

10.3.1.1.1. Wind

10.3.1.2. Another example could be rain.

10.3.1.3. Another example could be snow.

10.3.1.3.1. Snow

### 10.4. Rain

10.5.1. A static load is a force that is constantly being applied to an object; like weight.

10.5.1.1. Another example could be the weight of the soil on the earth.

10.5.1.1.1. Soil

10.5.1.2. Another example could be the gravity that pulls down on a chair.

10.5.1.2.1. Chair

10.5.1.3. An example of a static load is the weight of the tree on the tree.

10.5.1.3.1. Pingus

10.5.1.3.2. Tree

## 11. Describing Forces

### 11.1. Magnitude

11.1.1. Magnitude is the amount of force being applied to a certain point of a structure.

11.1.1.1. Another example could be a car traveling at 100 kilometers an hour.

11.1.1.1.1. Car

11.1.1.1.2. Ball

11.3.1. Building

### 11.4. Point of application

11.4.1. The point of application is the exact place where the force is hitting the structure.

11.4.1.1. Another example could be the building window being smashed.

11.4.1.1.1. Smashed Window

11.5.1. Standing