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Engineering Loads
Objectives
Identify and explain the differences between tension and compression.
Identify and provide examples of the 4 primary loads affecting structures.
Design and test bridges using West Point software.
Run simulations and manipulate bridge designs to optimize cost and strength.
Primary Structural Forces
Tension- pulling or elongation of materials.
Compression- pushing together or shortening of materials.
What are the implications of a bridge that has excessive tension or compression?
Talk with your neighbor about this
(30 seconds)
Equilibrium
The state in which there are no unbalanced forces acting on a body, balance of tension and compression.
x
y
F =0
F =0
©iStockphoto.com ©iStockphoto.com
Balanced Unbalanced
Structural Loads
The forces applied to a structure.
-With your neighbors (3 or 4 people) discuss a few examples of loads that are applied to everyday structures such as bridges and schools in Minnesota?
-Example loads on bridges and schools on the west coast of the United States?
Structures
A few considerations…
- size
- shape
- geographic location
- materials
- geotechnical
- structural loads to support
Various Structures
Designed dependent on their purpose
Engineers and architects must consider weight requirements
Must design around a structures safety factor
Safety Factor
The ratio of the breaking stress of a structure to the estimated maximum stress in ordinary use
A bridge may typically only carry passenger cars.
Will it support a fully loaded cement truck?
Most structures have a safety factor of 3.
Safety Factor Question
The city of Plymouth is proposing a new 4 lane bridge to be built on Peony Lane with a safety factor of 10. What issues might homeowners and taxpayers have with this proposal?
Take a minute and talk with someone nearby.
Dead Loads
Stationary or permanent parts of a structure.
Walls Floor Ceiling Essentially the weight of
the structure with nothing on or in it.
Live Loads
Weight that travels within or across a structure
A high school hallway
Cars on a bridge
Static Loads
Accumulate over time
It can become a dead load
A steady rain or snow
Cars backing up on a bridge due to an accident
Dynamic Loads
A sudden exertion of force on a structure
A strong gust of wind Earthquake Explosion Collision
Load Miscalculations
Engineers must take all loads into account
Consider….- What will be in or on
the structure- Who will use the
structure- Where is it located
geographically
Exit Question #1
This force shortens structural members.
A. Equilibrium
B. Tension
C. Dynamics
D. Compression
Question 2
This force lengthens or stretches structural members.
A. Statics
B. Tension
C. Safety factors
D. Compression
Question 3
This type of structural load occurs when there is a sudden exertion of force.A. StaticB. DynamicC. DeadD. Live
-List an example
Question 4
This type of structural load accumulates over time.A. StaticB. DynamicC. DeadD. Live -List an example
Question 5
This type of structural load is a permanent part of the structure.A. StaticB. DynamicC. DeadD. Live -List an example
Question 6
This type of structural load moves across or within a structure.A. StaticB. DynamicC. DeadD. Live -List an example
Question 7
This type of structural load is applied during the west point bridge builder simulation.A. StaticB. DynamicC. DeadD. Live