Truss Design Considerations-Slides

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  • Truss Design Considerations

    1

    Truss Design ConsiderationsTruss Design Considerations

    Design Implications Considering the Effects of Loading, Member

    Orientation and Support

    Truss Design Considerations

    Effect of tension vs. compression on member sizesPotential buckling failure modes and approaches to preventingPotential for stress reversalOverall lateral stability (lateral-torsionalbuckling)Member redundancy: Determinate vs. Indeterminate Trusses

    Truss Design Considerations

    Effect of tension vs. compression on member sizesPotential buckling failure modes and approaches to preventingPotential for stress reversalMember redundancy: Determinate vs. Indeterminate TrussesOverall lateral stability (lateral-torsionalbuckling)

    Truss Pedestrian Bridge

  • Truss Design Considerations

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    Munich Airport Pedestrian Bridge

    Truss Design Considerations

    Effect of tension vs. compression on member sizesPotential buckling failure modes and approaches to preventingPotential for stress reversalMember redundancy: Determinate vs. Indeterminate TrussesOverall lateral stability (lateral-torsionalbuckling)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Member Buckling Considerations(Schodek fig. 4.28)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Member Buckling Considerations(Schodek fig. 4.29) Truss Pedestrian Bridge, Greece

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    Theoretical zero force members that provide buckling resistance to top chord

    Truss Design Considerations

    Effect of tension vs. compression on member sizesPotential buckling failure modes and approaches to preventingPotential for stress reversalMember redundancy: Determinate vs. Indeterminate TrussesOverall lateral stability (lateral-torsionalbuckling)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004 Variations in Truss Member Forces

    (Schodek fig. 4.23)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004 Variations in Truss Member Forces

    (Schodek fig. 4.23)

  • Truss Design Considerations

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    Truss Design Considerations

    Effect of tension vs. compression on member sizesPotential for stress reversalPotential buckling failure modes and approaches to preventingOverall lateral stability (lateral-torsionalbuckling)Member redundancy: Determinate vs. Indeterminate Trusses

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Lateral Buckling(Schodek fig. 4.30)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Methods of Providing Resistance to Truss Lateral Buckling(Schodek fig. 4.31)

    Kansai International Airport, Japan, Renzo Piano

    Truss Design Considerations

    Effect of tension vs. compression on member sizesPotential for stress reversalPotential buckling failure modes and approaches to preventingOverall lateral stability (lateral-torsionalbuckling)Member redundancy: Determinate vs. Indeterminate Trusses

  • Truss Design Considerations

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    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Stability & Determinacy(Schodek fig. 4.18)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Stability & Determinacy(Schodek fig. 4.18)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Stability & Determinacy(Schodek fig. 4.18)

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    Truss Stability &

    Determinacy(Schodek fig. 4.05)

    Truss Determinacy Formula

    n = 2j 3 for determinacy n = Number of truss bars j = Number of joints

    n > 2j -3 indeterminaten < 2j -3 unstable

    Illustrations: Daniel L. Schodek: Structures, fifth edition; Pearson Prentice-Hall, 2004

    n = 8, j = 62(6)-3=9 >8 Unstable!

    n = 9, j = 6 2(6)-3=9 =9 O.K.

    n = 10, j = 62(6)-3=9 < 10 indeterminate, but stable

    n = 11, j = 72(7)-3=11 =11 O.K.

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    Truss Assembly DetailsTruss Assembly Details

    Truss Connection Considerations

    (Onouye fig. 10.2)

    Illustration Source: http://www.ce.berkeley.edu/~boza/courses/cee122/lectures/lecture2/connect-brace.jpg

    Truss Connection Considerations

    Illustration Source: http://www.ce.berkeley.edu/~boza/courses/cee122/lectures/lecture2/connect-brace.jpg

    Truss Connection Considerations

    Connection Eccentricity Produces Moment Pedestrian Bridge in Greece Knife-Plate Connections Cutler Anderson Architects

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    Grace Episcopal Church, Bainbridge Island, WA Cutler Anderson Architects

    Capitol Hill Library, Seattle, WA Cutler Anderson Architects

    Curvilinear faade supported by 3D linear truss framework:

    Band Shell, Millennium Park, Chicago, IL Frank O. Gehry

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