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Truss Design Considerations-Slides

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

Truss Design Considerations

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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.

Truss Design Considerations

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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

Truss Design Considerations

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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

Truss Design Considerations

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