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Loads Lab

Forces Lab | Materials Lab | Loads Lab | Shapes Lab

About This Lab
This lab simplifies the real-life conditions that affect structures, in order to illustrate key concepts.

Forces that act on structures are called loads. All structures must withstand loads or they'll fall apart. In order to build a structure, you need to know what kinds of external forces will affect it.

Dead Load
The weight of the structure itself is called the dead load. Anything permanently attached to the structure is part of its dead load -- including the columns, beams, nuts, and bolts.

Live Load Failure Intro
The weight of the stuff on the structure is called the live load. Things that move around in or on a structure, like people, furniture, and cars, are all examples of live load.

Live Load Failure
The beam failed because it could not support the heavy weight of the live load above it.

Live Load Success Intro
Thick Beam: The thicker a beam, the less likely it is to bend. Thick beams are used in structures that experience live and dynamic loads.

Live Load Success
Thick Beam: The thick beam made this structure very strong. Now the beam won't bend from the heavy weight of the live load on top of it.

Dynamic Load Failure Intro
Loads that change over time are called dynamic loads. Dynamic loads -- from wind gusts to pounding objects -- create vibrations that can become bigger and more dangerous over time.

Dynamic Load Failure
The beam was vibrating too much from the dynamic load. This kind of vibration would be unacceptable to people occupying a building or driving across a bridge.

Dynamic Load Success Intro
Thick Beam: The thicker a beam, the less likely it is to bend. Thick beams are used in structures that experience live and dynamic loads.

Dynamic Load Success
Thick Beam: The thick beam absorbed the vibrations caused by the dynamic load and prevented the structure from bending and galloping wildly out of control.

Wind Load Failure Intro
When wind blows on a structure, it is called wind load. Wind loads push horizontally on a structure.

Wind Load Failure
The structure collapsed because it couldn't withstand the strong gusts of wind.

Wind Load Success Intro
Cross-Bracing: Diagonal braces, usually made of steel, are used to strengthen and stabilize all kinds of structures.

Wind Load Success
Cross-Bracing: Cross-bracing is an excellent way to stiffen a structure experiencing wind load. When the wind blows, the diagonal brace squeezes together and prevents the structure from flopping over.

Thermal Failure Intro
When a structure expands or shrinks with the temperature,it is experiencing thermal load. The temperature causes the beams and columns to change shape and push and pull on other parts of the structure.

Thermal Failure
The intense sun made the beam expand, throwing the entire structure out of whack.

Thermal Success Intro
Roller Joints: Roller joints are used in structures that get really hot or cold. They give columns and beams the freedom to expand and contract as the temperature changes.

Thermal Success
Roller Joints: Thanks to this roller joint, the beam can swell in the sun and slide over the column without damaging the structure.

Earthquake Failure Intro
When the ground beneath a structure jerks back and forth during an earthquake, the structure is experiencing an earthquake, or seismic load. Earthquake loads push and pull horizontally on a structure.

Earthquake Failure
That was more rattling and shaking than this poor structure could handle.

Earthquake Success Intro
Shear Walls: Solid walls of reinforced concrete or masonry -- called "shear walls" -- have great stiffness in the horizontal direction. They resist loads that push or pull horizontally on a structure.

Earthquake Success
Shear Walls: Shear walls can handle being pushed, pulled, rattled, and shaken during an earthquake. They're a great way to strengthen a structure prone to earthquake load.

Settlement Failure Intro
When the soil beneath a structure settles unevenly, it is called settlement load. Structures will sink and change shape when they experience settlement load.

Settlement Failure
This structure is in bad shape -- literally!

Settlement Success Intro
Deep Piles: Heavy concrete pillars, or piles, are used to support structures on soft soil. The piles rest deep in the earth on stable, solid soil and support the weight of the heavy structure above.

Settlement Success
Deep Piles: The massive concrete piles, sunk deep into the earth on hard, solid soil, keep the structure safe and sound where it should be -- above ground!

Flash version of this lab