Forces and Structures
What is a push or pull that can change the shape, speed, or direction of an object?
A Force
A load that does not move and stays in place is called this.
Static Load
What is the name of a strong, long bridge made of triangles that helps spread out the load?
Truss Bridge
What kind of natural force can shake the ground and damage structures?
Earthquake
These are arrows used in diagrams to show the direction and strength of a force.
Vectors
Give the definition of a Dynamic Load
A load that moves or changes over time, like people walking on a bridge
In a truss bridge, what parts are usually under compression and tension?
The top beams are under compression and the bottom beams are under tension.
What kind of forces can an earthquake cause on buildings?
Vibrations and side-to-side forces (shear forces) that can break walls and supports.
A force from outside a structure, like wind or gravity, is called this.
External Force
These two types of forces act within materials—one pulls apart, and one pushes together.
Tension and compression
Name one pro and one con of a truss bridge.
Pro: Very strong and uses less material. Con: Complex to build and not very attractive.
When rainwater soaks into the ground and weakens the foundation of a structure, this type of natural force is at work.
Water and/or erosion
What kind of diagram shows the direction and size of all forces acting on a structure?
Force Diagram
What is the difference between static and dynamic loads and give an example
Answers will vary
What does a diagram of a truss bridge usually show?
Triangular shapes with arrows showing tension and compression.
What is the definition of gravity and why is it important?
What is the force called that pulls everything toward the Earth’s center and affects how structures stay standing
What forces does an engineer consider when designing a building?
Gravity – pulls everything downward and must be supported.
Wind – pushes sideways and can cause swaying.
Snow or Ice Loads – adds weight to the roof.
Earthquakes – create shaking and side-to-side (shear) forces.
Tension – pulling forces that can stretch materials.
Compression – pushing forces that can squash materials.
Torsion – twisting forces from things like wind or movement.
Shear – sliding forces that can make parts of a building move in different directions.
A tall tower is twisting during a strong windstorm. The internal force caused by this twisting motion is known as this.
Torsion
Name two materials commonly used to build modern bridges and why they are used.
Steel (for strength and flexibility) and concrete (for compression resistance)
Describe one natural force and explain how engineers design structures to withstand it.
Example: Wind is a natural force. Engineers design tall buildings with flexible materials and aerodynamic shapes to reduce wind resistance and prevent collapse.