Made by Nick Johnson Continue. Table of Content Start Lesson How to QuizTeachers.

Made by Nick Johnson Continue

Table of Content Start Lesson How to QuizTeachers

The Interface Use this to move back a slide Use this to go back to the Table of Contents Use this to move forward a slide

The Lessons Design Analysis (statics) (RECOMMENDED TO DO FIRST)

What Is A Truss?  A truss consists of straight members that connect at joints that form a triangular shape.

What Does A Truss Do?  Trusses are engineered to help hold the forces that will be placed on the object.  An example is snow on a roof.

Two Truss Categories All Trusses will fall under these two categories. - Pitched Truss- Parallel Chord Truss

The Categories  Characterized for it’s triangular shape  Usually used for roof construction  Will always have a parallel top and bottom chords.  Is often used for bridge design or floor construction. Pitched TrussParallel Chord Truss

Parts of a Truss Top Chord Gusset Kings Post Truss Web Bottom Chord Click Each Part to Learn More

Top Chord  An inclined or horizontal member(s) that establishes the top surface member of a truss Top Chord

Bottom Chords  Horizontal or inclined member that establishes the bottom edge of the truss Bottom Chord

Truss Web  Often given to the shorter members that join the top and bottom chords, which form triangular patterns in that truss. Truss Web

King Post  Is used to help support the peak or top of the common truss. King Post

Gussets  Used everywhere the web supports and king post intersect the top and bottom chord as well as at the bearing point Gussets

Types of Trusses Common TrussFlat Truss

Types of Trusses Double FinkBowstring Truss

Types of Trusses ScissorsDual Pitch

Great Job!  You have just finished one half of the lesson. Go ahead and take a short 5 minute break and come back and finish the other lesson.

Statics Example: F C = 15 lb 10in 6in

What You Need to Know The Sign Convention + +Y +X

What You Need to Know Attachments == FxFx FyFy PinRoller FyFy

Formulas  ∑F x = 0, all the forces in the x direction must equal zero.  ∑F y = 0, all the forces in the y direction must equal zero.  ∑M = 0, all the moments around one point must equal zero.

Solving  Lets go back to the example. F C = 15 lb 10i n 6in

Free Body Diagram  This is a drawing that shows all the forces that are acting on the model.

Solving  Now transfer the model into a FBD. F C = 15 lb 10in 6in F Ax F Ay F By 3in

Solving  Find which direction has one unknown.  You can look and see that the x direction has one unknown. Steps: ∑ F X = 0 0 = F ax F ax = 0

Solving  Now lets look at the y direction.  How many unknowns are there?  There are two unknowns so we will have to use moments. F C = 15 lb 10in 6in F ax = 0 F Ay F By 3in

Solving  So a moment is a force times it’s perpendicular distance to the selected point. Ex. M= F ∙ d 6in F Ay F By  So you have to pick a point that will cancel a unknown.  So let us pick point A

Solving for the Moment  Steps: ∑M A = 0 0 = F ax (d) + F ay (d) + F by (d) + F c (d) 0 = 0(0) + F ay (0) + F by (6) -15(3) F by = 7.5lb

Solving For F Ay  Now that you found one of the unknowns you can solve for F Ay. ∑ F ay = 0 0 = F ay + F by + F c 0= F ay + 7.5 – 15 F ay = 7.5lb

Why are these Important? Roof Failure

Why are these Important? Bridge Failure

Congrats! You have now finished the lesson you may now take the quiz or go back to the main menu. Quiz

Question 1 1) What is a Truss used for? a) Support forces from above. Support forces from above. b) It is used for looks. It is used for looks. c) They are used to frame a door. They are used to frame a door.

I’m Sorry You answer the question incorrectly. Please go back and try again. Review

What Does A Truss Do?  Trusses are engineered to help hold the forces that will be placed on the object.  An example is snow on a roof. Back To Question

That’s Right You answered the question correct! Next Question

Question 2 a) Roof Failure Roof Failure b) Bridge Failure Bridge Failure c) Nothing will happen Nothing will happen d) Both A & B Both A & B 2) What can happen if a truss is made wrong?

Why Is This Important?  Roof Failure  Bridge Failure  It maximize the amount of strength that can be held. Back To Question

Question 3 a) Bottom Chord Bottom Chord b) Top Chord Top Chord c) King Post King Post d) Truss Web Truss Web 3) Name this Part.

Parts of a Truss Top Chord Gusset Kings Post Truss Web Bottom Chord Click Each Part to Learn More Back To Question

Question 4 a) Gusset Gusset b) Bearing Point Bearing Point c) Top Chord Top Chord d) Truss Web Truss Web 4) Name this Part.

Question 5 a) Clear Span Clear Span b) Gable Gable c) King Post King Post d) Truss Web Truss Web 5) Name this Part.

Question 6 a) Top Chord Top Chord b) Truss Web Truss Web c) Gusset Gusset d) Bottom Chord Bottom Chord 6) Name this Part.

Question 7 a) Common Common b) Flat Flat c) Bowstring Bowstring 7) What is the name of this truss?

Types of Trusses ScissorsDual Pitch Back To Question

Question 8 a) Scissors Scissors b) Dual Pitch Dual Pitch c) Double Fink Double Fink 8) What is the name of this truss?

Question 9 a) Double Fink Double Fink b) Flat Flat c) Bowstring Bowstring 9) What is the name of this truss?

Question 10 a) 5lb 5lb b) 4lb 4lb c) 5lb 5lb d) 4lb 4lb 10) Solve for F ay ? F C = 10 lb 5in 4in F Ax F Ay F By 2in

Solving  Find which direction has one unknown.  You can look and see that the x direction has one unknown. Steps: ∑ F X = 0 0 = F ax F ax = 0

Solving  Now lets look at the y direction.  How many unknowns are there?  There are two unknowns so we will have to use moments. F C = 15 lb 10in 6in F ax = 0 F Ay F By 3in

Solving  So a moment is a force times it’s perpendicular distance to the selected point. Ex. M= F ∙ d 6in F Ay F By  So you have to pick a point that will cancel a unknown.  So let us pick point A

Solving for the Moment  Steps: ∑M A = 0 0 = F ax (d) + F ay (d) + F by (d) + F c (d) 0 = 0(0) + F ay (0) + F by (6) -15(3) F by = 7.5lb

Solving For F Ay  Now that you found one of the unknowns you can solve for F Ay. ∑ F ay = 0 0 = F ay + F by + F c 0= F ay + 7.5 – 15 F ay = 7.5lb Back To Question

Congrats! You have completed the Quiz!

Objectives:  After completing with lesson, students will be able to distinguish the all of the different parts when given a truss.  After completing this lesson, students will be able to analyze the forces on the truss when given specific numbers to about 80% accuracy.

Target Audience  Grades 9-12  People in construction.  Home builders  Do-it-yourselfers

Learning Environment  During a lab period.  As individuals or in a group of around 2-3 people.

Made by Nick Johnson Continue. Table of Content Start Lesson How to QuizTeachers.

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