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Transcript of Truss Design Considerations - Structural Engineers · Truss Design Considerations 3 Theoretical...
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 determinacyn = Number of truss barsj = 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 façade supported by 3D linear truss framework:
Band Shell, Millennium Park, Chicago, IL — Frank O. Gehry
Truss Design Considerations
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