1 Wardenier “Tubular Structures Course” Examples Hollow Section Trusses Design Procedure

2 Wardenier “Tubular Structures Course” Truss Design Procedure Determine truss layout, span, depth, panel lengths, truss spacing by usual methods. Keep connections to a minimum. Determine loads at connections and on members. Simplify these initially to equivalent loads at panel points. Determine axial forces in all members by assuming that joints are pinned and assume all member centre lines are noding

3 Wardenier “Tubular Structures Course” Truss Design Procedure Axial load Corrosion protection (surface area) Wall slenderness Determine chord member sizes considering: 4.

4 Wardenier “Tubular Structures Course” Truss Design Procedure 5. Determine web member sizes considering: Axial load t web < t chord 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

5 Wardenier “Tubular Structures Course” Truss 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.

6 Wardenier “Tubular Structures Course” Check effect of primary moments on chord design. Use proper load positions on members Use 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 webs Continuous chords with pin-ended webs Design welded joints. Design welded joints. Fillet welding cheapest Fillet welding cheapest (Note: Weld Design can be left to the fabricator but not connection verification) 10. Check truss deflections under specified loads 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 Procedure

7 Wardenier “Tubular Structures Course” Some Golden Rules to Avoid Connection Problems General Tips for forDesigners General Tips for forDesigners

8 Wardenier “Tubular Structures Course” Deflections of Trusses Check Deflections Under Specified Loads or OverlapJoints Gap Joints or braces

9 Wardenier “Tubular Structures Course” Design Example of Design Guide 1

10 Wardenier “Tubular Structures Course” CHS K joint

11 Wardenier “Tubular Structures Course” EfficiencyCHS K joint

12 Wardenier “Tubular Structures Course” Effect Chord Pre-stress

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15 Wardenier “Tubular Structures Course” Note: Gap of joint 2 is decreased to satisfy joint strength and the eccentricity is taken into account for the member check the eccentricity is taken into account for the member check

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17 Wardenier “Tubular Structures Course” Design Example of Design Guide 3

18 Wardenier “Tubular Structures Course” RHS K joint

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20 Wardenier “Tubular Structures Course” EfficiencyRHS K joint

21 Wardenier “Tubular Structures Course” Effect Chord stress

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