Board of Regents University of Nebraska
Tension: the pulling force:
Tension in structures is a pulling force. It stretches materials. Link
your hands together and pull. You feel tension. Stretch a rubber band. You see tension in
action. The rubber stretches, and th
e band gets longer. Examples of materials in tension: rope
bridges, suspension bridges, telephone wires, tents, steel cables supporting an elevator, and your
hair when someone pulls on it.
Compression: the pushing force:
Compression is a pushing force. It squashes materials. Put
your hands together and push hard. You feel compression. Put a marshmallow on the counter and
push it down with your hand. As you push,
the marshmallow gets shorter. It is in compression.
Examples of materials in compression: pyramids, telephone poles, arch bridges, elephant legs,
tree trunks, and your little brother when you sit on him.
Different parts of a structure are either in tensi
on, or in compression, or both. Therefore, the
materials we use to build structures must be strong in tension, in compression, or both.
All structures have to stand up to the loads placed on them.
Live loads are the things a structure
supports through regular use. These loads can
change and move. Live Loads include snow, rain, people, cars, wind, etc.
Dead loads do not move. The structure always has to support them. Dead Loads
include walls, beams, arches, floors, and