Truss Designs

Im SorryYou answer the question incorrectly. Please go back and try again.ReviewSolvingFind which direction has one unknown.You can look and see that the x direction has one unknown.

Steps: FX = 00 = FaxFax = 0Im SorryYou answer the question incorrectly. Please go back and try again.ReviewKing PostIs used to help support the peak or top of the common truss.King Posthttp://www.truss-frame.com/truss-glossary.html48Truss WebOften given to the shorter members that join the top and bottom chords, which form triangular patterns in that truss.Truss Webhttp://www.truss-frame.com/truss-glossary.html47What 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.

http://crawfordfamilywebsite.com/Steamboat%20snowy%20roof%2002-25-06.jpg

6Two Truss CategoriesAll Trusses will fall under these two categories.- Pitched Truss- Parallel Chord TrussThe CategoriesCharacterized for its 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 TrussParts of a Truss

Top Chord GussetKings PostTruss WebBottom ChordClick Each Part to Learn MoreTypes of TrussesDouble FinkBowstring Truss

http://www.ufpi.com/product/rooftrusses/types.htm

16Types of TrussesScissorsDual Pitch

http://www.ufpi.com/product/rooftrusses/types.htm

17Great 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.

What You Need to KnowThe Sign Convention++Y+XWhat You Need to KnowAttachments==FxFyPinRollerFyFormulasFx = 0, all the forces in the x direction must equal zero.Fy = 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.FC = 15lb10in6inFree Body DiagramThis is a drawing that shows all the forces that are acting on the model.

http://ffden-2.phys.uaf.edu/211_fall2004.web.dir/Jeff_Levison/freebody_diagram.jpg24SolvingNow transfer the model into a FBD.FC = 15lb10in6inFAxFAyFBy3inSolvingFind which direction has one unknown.You can look and see that the x direction has one unknown.

Steps: FX = 00 = FaxFax = 0SolvingNow lets look at the y direction.How many unknowns are there?There are two unknowns so we will have to use moments.FC = 15lb10in6inFax = 0FAyFBy3inSolvingSo a moment is a force times its perpendicular distance to the selected point.Ex. M= F d6inFAyFBySo you have to pick a point that will cancel a unknown.So let us pick point ASolving for the MomentSteps:MA = 00 = Fax (d) + Fay (d) + Fby (d) + Fc (d)0 = 0(0) + Fay (0) + Fby (6) -15(3)Fby = 7.5lbSolving For FAyNow that you found one of the unknowns you can solve for FAy.Fay = 00 = Fay + Fby + Fc0= Fay + 7.5 15Fay = 7.5lbWhy are these Important?

Roof FailureWhy are these Important?Bridge Failurehttp://www.youtube.com/watch?v=Ce-PQqkIXe0&feature=related

32Congrats! You have now finished the lesson you may now take the quiz or go back to the main menu.QuizTop ChordAn inclined or horizontal member(s) that establishes the top surface member of a trussTop Chordhttp://www.truss-frame.com/truss-glossary.html54Bottom ChordsHorizontal or inclined member that establishes the bottom edge of the trussBottom Chordhttp://www.truss-frame.com/truss-glossary.html55Truss WebOften given to the shorter members that join the top and bottom chords, which form triangular patterns in that truss.Truss Webhttp://www.truss-frame.com/truss-glossary.html56King PostIs used to help support the peak or top of the common truss.King Posthttp://www.truss-frame.com/truss-glossary.html57

GussetsUsed everywhere the web supports and king post intersect the top and bottom chord as well as at the bearing pointGussetshttp://www.truss-frame.com/truss-glossary.html58Top ChordAn inclined or horizontal member(s) that establishes the top surface member of a trussTop Chordhttp://www.truss-frame.com/truss-glossary.html63Bottom ChordsHorizontal or inclined member that establishes the bottom edge of the trussBottom Chordhttp://www.truss-frame.com/truss-glossary.html64Truss WebOften given to the shorter members that join the top and bottom chords, which form triangular patterns in that truss.Truss Webhttp://www.truss-frame.com/truss-glossary.html65King PostIs used to help support the peak or top of the common truss.King Posthttp://www.truss-frame.com/truss-glossary.html66

GussetsUsed everywhere the web supports and king post intersect the top and bottom chord as well as at the bearing pointGussetshttp://www.truss-frame.com/truss-glossary.html67Top ChordAn inclined or horizontal member(s) that establishes the top surface member of a trussTop Chordhttp://www.truss-frame.com/truss-glossary.html72Bottom ChordsHorizontal or inclined member that establishes the bottom edge of the trussBottom Chordhttp://www.truss-frame.com/truss-glossary.html73Truss WebOften given to the shorter members that join the top and bottom chords, which form triangular patterns in that truss.Truss Webhttp://www.truss-frame.com/truss-glossary.html74King PostIs used to help support the peak or top of the common truss.King Posthttp://www.truss-frame.com/truss-glossary.html75

GussetsUsed everywhere the web supports and king post intersect the top and bottom chord as well as at the bearing pointGussetshttp://www.truss-frame.com/truss-glossary.html76Types of TrussesDouble FinkBowstring Truss

http://www.ufpi.com/product/rooftrusses/types.htm

81Types of TrussesScissorsDual Pitch

Back To Questionhttp://www.ufpi.com/product/rooftrusses/types.htm

82Types of TrussesDouble FinkBowstring Truss

http://www.ufpi.com/product/rooftrusses/types.htm

87Types of TrussesScissorsDual Pitch

Back To Questionhttp://www.ufpi.com/product/rooftrusses/types.htm

88Types of TrussesDouble FinkBowstring Truss

http://www.ufpi.com/product/rooftrusses/types.htm

93Types of TrussesScissorsDual Pitch

Back To Questionhttp://www.ufpi.com/product/rooftrusses/types.htm

94SolvingNow lets look at the y direction.How many unknowns are there?There are two unknowns so we will have to use moments.FC = 15lb10in6inFax = 0FAyFBy3inSolvingSo a moment is a force times its perpendicular distance to the selected point.Ex. M= F d6inFAyFBySo you have to pick a point that will cancel a unknown.So let us pick point ASolving for the MomentSteps:MA = 00 = Fax (d) + Fay (d) + Fby (d) + Fc (d)0 = 0(0) + Fay (0) + Fby (6) -15(3)Fby = 7.5lbSolving For FAyNow that you found one of the unknowns you can solve for FAy.Fay = 00 = Fay + Fby + Fc0= Fay + 7.5 15Fay = 7.5lbBack To QuestionTarget AudienceGrades 9-12People in construction.Home buildersDo-it-yourselfers

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105Learning EnvironmentDuring a lab period.As individuals or in a group of around 2-3 people.

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