External and Internal Forces
The force that acts on a structure from the outside
External Force
Why are bridges important
They connect us with each other and help make travelling easier
True or False: Tension and Compression are types of forces that do not have any effect on structures.
False
What is a pulley?
A pulley is a wheel that has a cable wrapped over it. It is used to help lift an object.
What is a load?
A load is a weight, pressure or force that a structure takes.
The force that acts between two different parts of a structure
Internal Force
What is the acronym used to remember the different kinds of bridges?
B.A.T.S
What is Tension and what is an example?
Tension is a pulling force. Making something longer by stretching it.
What can pulleys do?
Transfer motion from one object to another and change the amount of force needed to move the object
How many types of loads are there? Name them.
Six Loads include...
Thermal Load, Live Load, Wind Load, Earthquake Load, Settlement Load, Dead Load.
The location on an object where an external force is applied
Point of application
What is an abutment?
a structure built to support the lateral pressure of an arch
What is compression and what is an example?
Compression is a pushing force. Making something shorter by squeezing it.
What is the mechanical advantage as it relates to pulleys?
Mechanical advantage means that by using a simple machine you have made your work easier.
Mechanical advantage describes the amount of force and effort you save when lifting an object.
What are deep piles and what load needs the support of Deep Piles?
Deep Piles are added to hard soil to support the weight of a structure.
Settlement Load
The imaginary flat surface through which the applied force passes
Plane of application
The Truss bridge. Every bar is under tension and compression.
Something that can resist both types of forces. Example - steel
What are the types of pulleys and explain them.
Fixed Pulley - This allows us to pull down to lift the object. Does not make the object lighter, but it is easier to lift because you pull it down.
Moveable Pulley - The pulley shares the load of the object being lifted. The cable you are using to lift the object is doubled up and therefore the amount of force it takes to lift the same object is half but you have to pull the rope further to lift the weight.
What load did builders not consider when building the Leaning Tower of Pisa? What should they have done?
Settlement Load. They should have considered deep piles.
The types of internal forces and their definitions
Tension (an internal force pulling the particles of an object apart), Compression (an internal force that presses or squeezes the particles of an object together), Torsion (internal twisting forces created in an object as a result of a twisting motion being applied to the object), Shear (forces acting in an object as a result of pushes and/or pulls in opposite directions; usually results in rips of tears in an object)
Types of bridges and a brief explanation of each
Beam (simple bridge, place beams next to each other, not designed to span a large length), Arch (the curve that allows forces to be carried all along the arch), Truss (like a beam bridge but added triangular support), Suspension (designed to span a large distance, helpful over water).
True or False: Concrete is an example of an elastic material.
What happens if you add more pulleys?
The weight of the object is divided among the number of pulleys. There is an increase in mechanical advantage and make the load easier to lift.
What load defines a structure that has its own weight that needs to be supported.
A dead load