Structure

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Welcome to an IncreDIble IllinoisStructure
Workshop
Please check in! 1230- 100 p.m.
Brainstorming One idea per Post it

• "Structure"
• 1. "What exactly IS a structure? Can you give
  examples? What other words come to mind ?
• 2.List questions you want
• answered today
• 3. Then add your Post its
• to designated papers on wall

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What is a Structure?

• A structure is anything made up of a number of
  parts that are held together in a particular way
  and has a base or foundation.
• All structures give support or provide a
  framework. You can find structures everywhere.
  Bridges, buildings, chairs, shoes, plants, spider
  webs, tables, and even your own body are all
  structures. A structure's shape, size, and what
  it's made of depend on what the structure does
  and how strong it needs to be.

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• Form and Function
• Every structure has form and function. Form and
  Function are interconnected.The shape (or form)
  of something affects its purpose (or
  function).Something with a certain shape can
  have more than one purpose or function.
• Forces of Tension and Compression
• Every structure is affected by forces.The
  force of one structure can affect another.The
  affect can go back and forth with a push and pull
  force.Compression and Tension are examples of
  push and pull forces.Compression the state of
  a material pressed together or forced into less
  space.Tension a stress on a material made by
  the pull of forces extending outwards.

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Structures in the Real World
You can find inspiration all around you if you
just look
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6 Flags Texas Giant
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6 Flags G Force
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6 Flags Bob Sled
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6 Flags Judge Roy Scream Roller Coaster
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Construction Project Masonry Scaffolding
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DFW Airport Tower Cranes used constructing new
Terminal
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Six Flags The Titan
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DFW Airport Doppler Radar
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Six Flags Mister Freeze
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Electrical Wire Transmission Tower
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Six Flags Oil Derrick
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DFW Airport - Scaffolding holding up concrete
forms
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BasicConceptsDefinitions
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Intro to teaching basic structure

• Wood
• Jigs
• Forces
• Glue
• Tools and More Tools
• Construction Area
• This years Challenge
• The Duct Tape Challenge
• Summary

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Construction Area
A large open table, where team can place building
jigs, weigh wood, saw and cut materials,
assemble, finish structures. Cover the table
top (sheet of thick plastic or masonite) Make
sure that work areas are kept well ventilated,
especially when teams are using glues with
harmful vapors.
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Cutting Tools and Equipment
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Helping teams learnabout wood characteristics

• Wood
• Wood comes in a variety of dimensions (sticks and
  planks).
• Hobby stores carry balsa and basswood (basswood
  generally denser and heavier)
• USA Balsa and SIG has a large assortment of wood
  (www.sigmfg.com)
• Factors to consider

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Wood Hands on

• Examine the wood for
• Texture
• Grain
• Smoothness
• Kerf marks
• How porous is it?
• How easy does a stick bend?
• How much does it weigh?

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Sanding Balsa Wood prior to sorting
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Comparison of woods
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Wood Characteristics

• Anistropic means having properties that differ
  depending on direction
• Wood has grain to it and will react differently
  depending on the grain
• Consider how grain affects how wood reacts and
  build your structure with this in mind

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Moisture

• Wood absorbs moisture from the air (especially
  balsa wood)
• When weight is a consideration teams may want to
  consider ways to remove moisture from their
  structure
• Many teams try to control the moisture absorption
  by the wood
• Others try to remove moisture prior to weigh in

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Moisture

• Teams may find that certain glues degrade when
  exposed to extreme heat(thus the structure is
  weaker after drying)
• Teams should brainstorm, quantify and test any
  techniques they consider for removing moisture
  from their structure

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General Definitions

• Structure
• Column
• Brace
• Member
• Stress / (Forces)

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Stress (Forces)that act on a structure

• Compression
• Tension
• Shear
• Twisting/ Rotation

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Compression
Compression forces try to crush things
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Compression
Compression forces also try to buckle things
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Tension
Tension forces try to pull things apart
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Shear
Shear forces try to break things
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Hands on

• Take a 12 piece of wood
• Stand on its end and push down on itYou are
  putting the wood in compression
• Now try to pull it apart
• Now lay it ½ over the edge of your table and
  press down on the outside piece

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More Definitions/Concepts

• Buckling load
• The amount of weight required to cause a
  structure to fail
• Critical Length
• The length where wood no longer bends but crushes

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Law of Squares (cont)

• If I have a 12 column and a 4 column
  constructed from the same material the 4 column
  will hold 9 times as much weight as the 12
  column.
• 4 1/3 of 12. So Invert 1/3 to get 3 and then
  square it to get 9

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Hands OnLaw of Squares
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Demonstrations

• The next few slides come from a computer program
  that allows a user to build a structure on screen
  and then test the structure. We are using screen
  shots form this program to demonstrate a few of
  these concepts

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Simple 4 column 8 tall structure with
compression load
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110.74 grams
Held 110 grams of weight
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Simple Tower horizontal braces in middle
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444.68 grams
Tested to failure 4 x 110 440 grams
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Columns are now braced twice (1/3 length)
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899.23 grams
Tested to failure
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Not testing to failure
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Adding another force acting on the side of the
structure (only 1 gram)
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Disaster strikes
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Correcting the problem
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The Diagonal Braces kept the structure stable
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Bracing

• Horizontal Bracing
• Typically horizontal bracing is used to resist
  buckling in a column
• Diagonal Bracing
• Typically diagonal bracing resists twisting in
  the structure (adds stability)

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35.05 grams
With compression force applied straight down
column held 35.05 grams
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140.38 grams
4 x 35 140
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140.38 grams
Total Column height is 12
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140.38 grams
Total Column height is 12
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Cutting

• Cut (dont squash) the wood
• Cutting can damage cells at end of the piece
• Think of ways to keep that from happening

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Cut by rocking blade straight back and forth
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Helping teams learn about glue characteristics

• Glue
• Expose team to many different types of glue, read
  directions
• Hot glue
• Super glue
• CYANOACRYLATE (pronounced "sigh-ano-ack-relate")
  adhesive specially formulated to meet the tough
  demands of building and flying model airplanes.
  Available in three different viscosities. Each
  viscosity has different application and cure
  characteristics.
• Wood glue (Gorilla glue)
• Epoxy
• Carpenters wood glue (Elmers)
• Factors to consider
• Strength
• Drying time
• Weight
• Ease of use

Provide Adequate Ventilation !
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Pill bottles to clean CA Glue Tips
Acetone
Wood Glues
Contact Cement
Gorilla Glue
Airplane Glue
CA Super Glues
Old Razor - to clean glass
Extra CA Glue Tips
Glass Surface to build on
Glues
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Glue Testing Device

• Teams may want to construct testing devices to
  test the different types of glues.
• Plans for a device for testing glue strength are
  available at
• http//www.specializedbalsa.com/strength_test_inst
  ructions.php

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Glue Safety Rules

• No Horseplay
• Read and Follow Safety Instructions
• If you cant use it safely dont use it
• Dont mix glues together
• If using CA Glue keep Acetone on hand

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Tools Safety

• Tools such as saws, X-acto knives, and razors can
  be used to cut wood. When any sharp tool is
  used, sharp edges should always be directed away
  from flesh.
• Let team members experiment with cutting, sawing,
  and sanding wood with various tools. Encourage
  them to explore any tool they think will allow
  them to build better/easier.

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Useful tools
X-acto fine tooth razor saw Plastic holder
holding a single edge razor blade
Other useful building items Flat tile or
mirror Building square Emery boards, sand
paper
small aluminum mitre box for razor saw
All tools should be readily available to
consumers and of the teams own choosing
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Level/Straight Edge 
Levels are usually used to see if a surface
is
perfectly level (meaning it wont tilt up or
down).  They can also be used to draw a straight
edge.
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Other Useful Things to Have

• Gram scale accurate to 0.1 grams
• Permits weighing wood and completed structures
• Ohaus has a low-cost one (lt90) but you can
  probably borrow or get access to one (school lab,
  workplace, post office, police station (ask for
  confiscated scales)
• Ebay frequently has deals.
• Hair Dryer
• Speeds up glue drying
• Removes excess moisture from wood (weight)

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More Useful Things to Have

• Structure Tester
• TM or other parents are allowed to construct a
  tester for the team
• Instructions are available (http//www.farnorthdi.
  org/TRAINING/How_to_build_tester.doc)
• Try borrowing a tester
• Weights
• Olympic style (2 inch hole)
• flat metal weights

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Woodworking Basics Measuring Tools
Clear Plastic Ruler comes in handy when youre
cutting sticks of balsa wood.  When you mark the
balsa wood, make sure of three things One, make
sure that you have the edge of the ruler aligned
with the edge of the stick.  Two, make sure you
mark the length with a single dot.  Otherwise, if
you mark it with a line, it will be crooked for
sure.  Three, once youve measured it, be sure
to measure it again.  There is an old woodworking
saying Measure twice, cut once.  Thats because
it is a lot easier to fix a mistake before you
make it than afterwards.
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Woodworking Basics Measuring Tools
Top T square is used to put one piece of wood
at a right angle to another.  Bottom L Square
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Woodworking BasicsMeasuring Tools

• A combination square is used to mark a line
  lengthwise down the middle of a long piece of
  wood.  A combination square consists of two main
  parts.  The first part is a foot long metal ruler
  with a notch at the end to hold a pencil.  The
  second part is an adjustable steel bar that
  slides.  This lets you adjust where you want the
  mark to be. 

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Jigs
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Jig (template)

• A gauge, pattern, or mold used as a guide to the
  form of a piece being made
• Jigs can be 2 dimensional or 3 dimensional
• It is not necessary to use a Jig
• A Jig helps you to build consistently
• ANY jigs used by the team must be BUILT by the
  team

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Plastic and brass square tube from Hobby store
Aluminum Square Tube from hardware store
Steel keystock from hardware store
1x1 from lumber yard
Sample materials that can be used to make
templates
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This Years ChallengeE The Inside
DImensionIf walls could talk.!Educational
Focus Architectural Design, StructuralEngineerin
g, Construction, Research, Innovationand Design
Process, Mathematics, Theater Arts,Teamwork
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Inside DImension

• Structure Specification Details (applies to both
  structures)
• 7 1/2 height above tester surface 9
• Combined wt. of both structures 14.0 grams
• Weight difference between 2 structures 2.0
  grams
• fits over 2 cylinder
• Any wood allowed as long as it is just natural
  wood (no plywood, laminates, composites,
  coatings)
• Glue may only be used as an adhesive
• Glue may not extend beyond ¼ of a joint

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Closeup of a Tester

• Loaded with structure, presser board weights

• Base alone

Presser Board supported about 1 above corner
posts by structure
The Presser Board weights are fully supported
by structure
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Tester setup
Top of red tape is 1 below top of pole
Metal Weights
Pressure Board
Team Designed Structures
7.5 to 9
Floor surface
Traditional Tester
Supporting Blocks
2nd structure inside first structure
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More Hands on
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The Duct Tape Challenge

• Focus The Testing process for structure
  challenges
• Architectural Design, Structural Engineering,
  Construction, Teamwork.
• The Destination Where This Challenge Will Take
  You!
• One of the keys to building REALLY strong
  structures is to spend the time following
  through on the details. Without doing so could
  turn a wonderfully constructed structure into a
  leaning tower of Pisa unless it is checked to
  be sure it is plumb.
• The process of placing weights on the structure
  is an area many first-time structure teams do not
  give sufficient attention.
• What happens if all the parts of the structure
  that have to carry load do not actually contact
  the upper and lower surfaces of the tester? What
  happens when the weights are placed on the
  structure? Is there a way to anticipate those
  things and plan for them?
• This goal of this challenge is to help teams
  anticipate these questions and develop a team
  plan. Teams that plan, practice and brainstorm
  issues in advance will have a plan and a
  contingency plans- so they dont have to make
  snap decisions at tournament that they might
  regret.

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• Your team will
• ?? Build and test a Structure made completely of
  Wood and Tape. ??
• Time Limit The team must complete the solution
  on site within one hour which will include
  weigh-in and testing of the structure.
• Team Materials Required Teams will provide their
  own duct tape and masking tapes, and may prefer
  to bring a ruler for their use. The pre-cut balsa
  wood for the structure, a template and jig,
  gram scale for weighing it, testing device and
  Olympic weights will be provided by the Trainers.
• Roadmap for Success Teams must work together and
  plan a strategy in order to successfully solve
  this Challenge!
• a. Team will open kit and construct the
  structure.
• b. When complete they can raise their hand and
  let the Trainer know they are ready for
  weigh-in
• c. The team will test the strength of their
  Structure by stacking weights on the Pressure
  Board of a Structure Tester while the Structure
  rests on the Tester Base.
• d. The testing will result in an Official Weight
  Held. Normally, at each level of competition, the
  Structures with the highest Official Weight Held
  score will receive 160 points. The score for all
  other teams in that Level would be based on the
  percentage of that Official Weight Held for that
  competition Level. In this challenge, the focus
  is not on the weight held but on how well the
  teams can place the weights on their structure so
  that it will hold as much weight as possible.
• Building the Structures Specifications
• a. A level playing field has been ensured for
  all teams in regard to the design and the
  materials of the structure. The test here will be
  in how they construct and TEST the structure.
• b. Height of Structures Each Structure must have
  a minimum height of 7.5in. (19.1cm) and a maximum
  height of 8 in. (21.9cm).
• c. Weight of Structures The weight for Middle
  and Secondary team Structures may not exceed 40
  grams The weight for all other levels is
  unlimited but the teams will want to know what it
  is for their records and to note the efficiency
  of their structure.
• d. The Structures are designed to support weights
  stacked on the Pressure Board of the Structure
  Tester
• e. The Structures must have an opening, running
  their entire height, which can accept a circular
  column with an outside diameter of 2in. (5.1cm).
  The Structure must rest upon the Tester Base and
  fit over the Safety Pole. The Structure must fit
  entirely on the Tester Base and may not touch any
  of the Safety Supports or the Safety Pole.
• f. The Structures will be constructed using ONLY
  natural Wood and Tape- Duct tape and Masking
  Tape no other materials will be allowed. The
  Balsa Wood included in the kit was not weighed in
  advance and has not been screened in any way.
  Pieces were placed randomly in the kits.
• Laminates in the Structures. Team may use duct
  tape as a laminate in this structure but should
  realize it will add to the weight of the finished
  product.
• Jig provided is a simple block of wood with L
  square.

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Weight Placement

• Practice, practice, practice
• Have a plan
• Be prepared to modify your plan
• What will happen when you mishandle a weight
• How can you protect your fingers from being
  pinched?

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Analyzing

• Analyze broken structure to determine what failed
• Use safety shields and watch what happens make
  notes
• Analyze the video tapes
• Use a sports camera
• Incremental testing

Analyzing tested structures is the best way to
discover where you can improve
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Design Considerations

• Record pertinent information about every
  structure
• Glues used
• Materials used
• Weight and weight held
• Dont change too many variables between tests

Dont change too many things at once
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Whats the Secret?
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Thoughts onthe Tournament
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Tournament Day Considerations

• How are your going to transport your structure
  safely to tournament
• What supplies do you need for repairs?
• What will you store your structures in when you
  turn them over to the Appraisers

Tournament Day Thoughts
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. . . . . (continued)

• Before tournament do your own mock check in with
  the structure does it meet the challenge
  specifications
• Do you think you need a spare structure?

Tournament Day Thoughts
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Closing Thoughts

• Good structures look good
• Keep it simple
• Keep in Level
• Keep it Well-glued
• Have Fun!

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Questions?
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Good Luck!
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Acknowledgements
Victor Tom Bill Allen Pre-engineering Corp
(pictures) Reggie Bunis Ernie Chang Special
thanks to Charles Compton, Arlington TX, for
creating the structure of this presentation and
offering suggestions, corrections,
technicalexplanations and commentary