The Structures in our Lives Unit 1 Structural Engineering Mr. Graves

Any assemblage of materials which is intended to sustain loads What Is a Structure? Any assemblage of materials which is intended to sustain loads

Lets break it down – key words Assemblage – a group of things gathered together Material – what a thing is made of Sustain – carry the weight of or withstand Load – the weight a structure bears or the stresses put upon it

Now – what is a structure? A group of things something is made of which must carry weight and withstand the stresses put upon it

Are they Structures? Drop of water Mosquito Skateboard Tree Chair Pair of glasses Shoe Hockey stick House Human being Thumb tack Piece of paper Bridge Tunnel Space shuttle A planet

Natural or Man-Made? Man-Made - produced by humans Adapts through technology Changes instantly by taking control of the situation Expense – Cash Cost Failure = financial ruin NATURAL – produced by nature Adapts through evolution Changes through time and situation Expense – Energy Failure = death

Natural Structures – Team Activity You will work with a partner – given 5 minutes to prepare and 1 minute to present Describe your structure Describe what makes it unique Identify the forces acting on it Identify why it is the way it is

Man–Made Structures Team Activity You will work with a partner – given 5 minutes to prepare and 1 minute to present Describe your structure Describe what makes it unique Identify the forces acting on it Identify why it is the way it is

Modeling Nature What can we learn and how do we model nature? Spider and artificial silk Velcro and a briar on clothing Dolphin chirps and sonar Lobster and a suit of armor Earthworm and a train Plant cell and a vehicle operating on a hydrogen fuel cell Eiffel Tower and a human skeleton Ribbed low-drag material and shark skin

Biomimetics The technological outcome of the act of borrowing or stealing ideas from nature

Engineering The science concerned with putting scientific knowledge to practical use

To Build Scientific Knowledge You must take time to UNDERSTAND Observe – use you senses and ask why… Think – what makes it work Organize – where does it fit in Apply – how can you use this new found knowledge

Structural Forces

Internal Forces – act within materials Forces exerted by on part of a structure to another. The initial force may be internal or external.

Tension – A force that pulls or stretches Two people pulling on a rope A fish pulling on a line A car towing a trailer A kite string

Tensile Strength – A materials ability to withstand tension without breaking A fishing line that can support the weight of the fish A truck and hitch that can tow a trailer A bungee cord that can support the jumper A kite string that can withstand the wind force

Compression – A force that pushes or squeezes Weight of a person on stilts Weight of a skyscraper on the ground Weight of the bar on a lifter Weight of you on your sneakers

Torsion - Bending – When a straight member becomes curved Torsion - Bending – When a straight member becomes curved. One side in tension – the other in compression Failure of the Tacoma Bridge Dancers stretching Shaping a piece of wood Skis conforming to the terrain

Shear – A force that causes parts to slide past one another Cutting action of shaving Cutting the wool of an animal Wind shear – winds sliding past each other Action of scissors

External Forces – called a Load Caused by the physical weight of a structure or an environmental source such as wind, water, or temperature.

Dead Load – weight of the structure itself The materials that make up a house The materials that make up a bridge The materials that make up an oil rig The materials that make up a ship The materials that make up a person

Live Load – A load that changes or moves Person carrying something Trees acted on by wind Snow on the roof of a building Furniture in your house