Structures and Forces: Lesson 2.1 & 2.2

Lesson 2.1: What is a Structure, Types, Form, and Function

• A structure is an object with a specific size, shape, purpose, and ability to hold a load or weight.

• Form refers to the shape, size, and materials of a structure, influenced by many factors.

• Function is the purpose or ability of a structure to perform a task.

• Shell structures use an outer layer for support, like a metal can or egg.

• Frame structures utilize interconnected parts, like a fence or house frame, to create support

• Two-dimensional frames have connected parts in a flat plan

• Three-dimensional frames have connected parts in space

• Solid structures are comprised of a single solid piece of material, such as concrete dams or pyramids. These structures are also known as mass structures.

Lesson 2.2: Forces and Static/Dynamic Loads

• A force is a push or pull that can start or stop movement.
• External forces act on a structure from the outside, such as gravity.
• Internal forces occur within a structure, including compression, tension, shear, and torsion.
• Static loads are constant in size, direction, and position. An example is the weight of a structure.
• Dynamic loads change over time, such as wind or snow.

Lesson 2.3: Symmetry and Forces on Bridges

• Symmetry means an object is the same on both sides, creating a sense of balance in a structure.
• A line of symmetry divides an object into mirror-image halves.

Lesson 2.4: Structural Safety and Materials

• The Ontario Building Code ensures building safety and sturdiness, promoting public health and safety considerations including fire prevention and accessibility.
• Sensors detect building vibrations, which are monitored through a computer by engineers.
• Loads on structures are designed to withstand higher loads than expected to ensure safety.

Materials

• Material properties should benefit a product or structure.
• Material availability, cost, and aesthetics are crucial design factors.
• Disposal and environmental impact of materials must also be considered.

Vocabulary

• Force: A push or pull that can make an object move.
• Internal force: A force within a structure, like compression, tension, shear, or torsion.
• External force: A force on a structure from outside, like gravity.
• Shear: A force that pushes in both directions.
• Torsion: A force that twists.
• Tension: A force that stretches or lengthens.
• Compression: A force that squeezes or shortens.
• Sensor: A device that detects and measures a specific condition.
• Ergonomics: Relating to efficiency and comfort for humans in the work environment.

Additional Concepts

• Point of Application: The exact location on an object where a force is applied.
• Static load: A force that does not change (position, size, direction).
• Dynamic load: A force that changes (over time/position).
• Symmetry: When an object or structure mirrors itself on both sides.
• Form follows Function: The design should be directed by its intended use.
• Structural Safety: Buildings and structures need to be designed for safety.