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Wardenier Wardenier “Tubular Structures Course”“Tubular Structures Course”

ExamplesExamples

Hollow Section TrussesHollow Section Trusses

Design ProcedureDesign Procedure

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Truss Design ProcedureTruss Design Procedure

Determine truss layout, span, depth, panel lengths, truss spacing by Determine truss layout, span, depth, panel lengths, truss spacing by usual methods.usual methods. Keep connections to a minimum.Keep connections to a minimum.

Determine loads at connections and on members.Determine loads at connections and on members. Simplify these Simplify these initially to equivalent loads at panel points.initially to equivalent loads at panel points.

Determine axial forces in all membersDetermine axial forces in all members by assuming that joints are by assuming that joints are pinned and assume all member centre lines are noding.pinned and assume all member centre lines are noding.

2.2.

3.3.

1.1.

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Wardenier “Tubular Structures Course”

Truss Design ProcedureTruss Design Procedure

Axial load

Corrosion protection (surface area)

Wall slenderness

Determine chord member sizes considering:4.

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Wardenier “Tubular Structures Course”

Truss Design ProcedureTruss Design Procedure

5. Determine web member sizes considering: Axial load

tweb < tchord

K = 0.75 for compression webs

6. Standardize the brace member sizes: e.g. to 2 or 3 sizes Same width, different thickness? Inspection problem Check availability!

7. Layout connections: Try gap connections first Check connection geometry is within validity range Check member sizes are within validity range Pay attention to eccentricity limits Consider fabrication procedure

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Wardenier “Tubular Structures Course”

Truss Design ProcedureTruss Design Procedure

8. Check connection efficiencies(with charts) or resistances (with formulae or tables) Usually only a few connections need to be checked.

If efficiencies or resistances are not adequate, modify the connection layout (e.g. overlap instead of gap), or

Modify the members;Re-check connections.

9.

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Wardenier Wardenier “Tubular Structures Course”“Tubular Structures Course”

Check effect of primary moments on chord design.Check effect of primary moments on chord design. Use proper load positions on membersUse proper load positions on members Determine member bending moments assuming:Determine member bending moments assuming:

Pinned joints everywhere or Pinned joints everywhere or Continuous chords with pin-ended websContinuous chords with pin-ended webs

Design welded joints.Design welded joints. Fillet welding cheapestFillet welding cheapest

(Note: Weld Design can be left to the fabricator but not connection verification)(Note: Weld Design can be left to the fabricator but not connection verification)

10.10.

Check truss deflections under specified loads.Check truss deflections under specified loads.11.11.

12.12.

For compression chord, also consider noding For compression chord, also consider noding eccentricity moment.eccentricity moment. Check member (axial and bending) interactions.Check member (axial and bending) interactions.

Truss Design ProcedureTruss Design Procedure

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Wardenier “Tubular Structures Course”

Some Golden Rules to Avoid Connection ProblemsSome Golden Rules to Avoid Connection Problems

General TipsGeneral Tips for for

DesignersDesigners

General TipsGeneral Tips for for

DesignersDesigners

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Wardenier “Tubular Structures Course”

Deflections of TrussesDeflections of Trusses

Check Deflections Under Specified LoadsCheck Deflections Under Specified Loads

or Overlap Overlap JointsJoints

Gap Joints Gap Joints

oror

bracesbraces

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Wardenier “Tubular Structures Course”

Design Example of Design Guide 1Design Example of Design Guide 1Design Example of Design Guide 1Design Example of Design Guide 1

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Wardenier “Tubular Structures Course”

CHS K jointCHS K joint

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Wardenier “Tubular Structures Course”

EfficiencyEfficiencyCHS CHS

K jointK joint

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Wardenier “Tubular Structures Course”

Effect Chord Pre-stress

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Wardenier “Tubular Structures Course”

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Wardenier “Tubular Structures Course”

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Wardenier “Tubular Structures Course”

Note: Gap of joint 2 is decreased to satisfy joint strength andNote: Gap of joint 2 is decreased to satisfy joint strength and the eccentricity is taken into account for the member checkthe eccentricity is taken into account for the member check

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Wardenier “Tubular Structures Course”

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Wardenier “Tubular Structures Course”

Design Example of Design Guide 3Design Example of Design Guide 3Design Example of Design Guide 3Design Example of Design Guide 3

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Wardenier “Tubular Structures Course”

RHS K jointRHS K joint

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Wardenier “Tubular Structures Course”

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Wardenier “Tubular Structures Course”

EfficiencyEfficiencyRHS RHS K jointK joint

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Wardenier “Tubular Structures Course”

Effect Chord stress

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Wardenier “Tubular Structures Course”

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Wardenier “Tubular Structures Course”

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Wardenier “Tubular Structures Course”