Department CivilEngineering, Engineering, University ofof Toronto Department ofofCivil University Toronto
HOLLOW STRUCTURAL SECTION CONNECTIONS DESIGN GUIDE
Jeffrey A. Packer
North American Steel Construction Conference Phoenix, Arizona April 2009
Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
AISC Design Guide on HSS – 2008
• “Design Guide for Hollow Structural Section Connections”, by J.A. Packer, D.R. Sherman and M. Lecce
Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
AISC Design Guide on HSS – Format Example
• In accord with the AISC 360-05 Steel Building Specification • For statically loaded connections only • Presented in LRFD and ASD formats, using a connection “nominal strength” approach • 22 design examples
Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
AISC Design Guide on HSS – Contents 1. 2. 3. 4. 5.
Introduction Welding Mechanical Fasteners Moment Connections Tension and Compression Connections 6. Branch Loads on HSS Connections – An Introduction 7. Line Loads and Concentrated Forces on HSS 8. HSS-to-HSS Truss Connections 9. HSS-to-HSS Moment Connections Notation References
Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 1. Introduction
• •
HSS steel grades Shapes and designations, tolerances
• •
Connection design standards Advantages of HSS
Rock and Roll Hall of Fame, Cleveland, Ohio Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 1. Introduction
Federation Square, Melbourne, Australia
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Department of Civil Engineering, University of Toronto
Chapter 1. Introduction
•
Steel Grades Grade
Minimum Yield Stress Fy ksi (MPa)
Minimum Ultimate Stress Fu ksi (MPa)
ASTM A500 CHS
B
42 (289)
58 (400)
ASTM A500 CHS
C
46 (317)
62 (427)
ASTM A500 RHS
B
46 (317)
58 (400)
ASTM A500 RHS
C
50 (345)
62 (427)
ASTM A53 Pipe
B
35 (241)
60 (415)
ASTM A501 (Hot-formed)
B
50 (345)
70 (482)
350W
51 (350)
65 (450)
Specification
CAN/CSA-G40.20/G40.21 (Class C or Class H)
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Department of Civil Engineering, University of Toronto
“One Size Fits All” Approach to Manufacturing HSS
At present it is sensible to specify just the highest grade Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 2. Welding •
•
•
Weld types: • Fillet welds, skewed fillet welds • Flare-bevel- and Flare-Vgroove welds Effective fillet weld size (tabulated equations) Weld inspection as applied to HSS
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Department of Civil Engineering, University of Toronto
Chapter 3. Mechanical Fasteners
•
HSS connections with mechanical fasteners in shear or in tension
Fasteners in shear
HSS Limit States • Bolt bearing • Block shear
Fasteners in tension
HSS Limit States • Chord wall plastification • Pull out through HSS wall
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Department of Civil Engineering, University of Toronto
Chapter 4. Moment Connections
•
W-beam to HSS-column moment connections • Beam over column
• Directly welded
HSS Limit States • Wall local yielding • Wall local crippling
HSS Limit States • Shear yielding • Sidewall failure
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Department of Civil Engineering, University of Toronto
Chapter 4. Moment Connections
•
W-beam to HSS-column moment connections • Through plate
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Department of Civil Engineering, University of Toronto
Chapter 5. Tension and Compression Connections •
End connections commonly used for HSS bracing members •
End Tee connections Limit States: • Weld shear • HSS local yielding, wall crippling • T-flange shear yielding, shear rupture • Bolting bearing, bolt shear • Stem yielding, rupture, block shear, buckling
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Department of Civil Engineering, University of Toronto
Chapter 5. Tension and Compression Connections •
End connections commonly used for HSS bracing members •
Slotted HSS/gusset bolted connection Limit States: • Weld shear and base metal shear • Bolt bearing, bolt shear • Gusset plate yielding, rupture, block shear • HSS local yielding, shear lag*
Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 5. Tension and Compression Connections •
End connections commonly used for HSS bracing members •
Slotted HSS/gusset bolted connection Limit States: • Weld shear and base metal shear • Bolt bearing, bolt shear • Gusset plate yielding, rupture, block shear • HSS local yielding, shear lag*
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Department of Civil Engineering, University of Toronto
Chapter 5. Tension and Compression Connections •
End connections commonly used for HSS bracing members •
Side gusset plate bolted connection for rectangular HSS •
Reduced shear lag effects
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Department of Civil Engineering, University of Toronto
Chapter 5. Tension and Compression Connections •
End connections commonly used for HSS bracing members •
Bolted flange plate connections Limit States: • Yielding of end plate • Strength of welded joint • Tensile strength of bolts, including prying Bolt Weld Hollow Section
Flange-Plate
Rogers Centre, Toronto, Canada Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 5. Tension and Compression Connections •
End connections commonly used for HSS bracing members •
Bolted flange plate connections
Example • Bolts along two sides of HSS • Connection behavior is representative of 2dimensional prying models
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Department of Civil Engineering, University of Toronto
Chapter 6. Branch Loads on HSS Members - An Introduction • •
Description of classic failure modes for HSS welded connections Principle limit states considered in Chapters 7 (Plate-to-HSS), and Chapters 8 and 9 (HSS-to-HSS)
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Department of Civil Engineering, University of Toronto
Chapter 6. Branch Loads on HSS Members - An Introduction Limit State: Column or Chord Wall Plastification
•
Prevalent in HSS connections due to flexible nature of connecting HSS face
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Department of Civil Engineering, University of Toronto
Chapter 6. Branch Loads on HSS Members - An Introduction Limit State: Chord Shear Yielding (Punching Shear)
•
May govern for connections with medium to high branchto-chord width ratios
•
Failure can occur under a tension or compression branch provided it is physically capable of shearing through the chord wall
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Department of Civil Engineering, University of Toronto
Chapter 6. Branch Loads on HSS Members - An Introduction Limit State: Local Yielding (due to uneven load distribution)
•
Applies to transverse plates or transverse walls of a rectangular HSS, under both tension and compression loading
•
Common failure mode for overlapped K-connections
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Department of Civil Engineering, University of Toronto
Chapter 6. Branch Loads on HSS Members - An Introduction Limit State: Chord Sidewall Failure (Yielding or Buckling) •
Failure of the chord member side wall
•
May occur in rectangular HSS “matched box connections”
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Department of Civil Engineering, University of Toronto
Chapter 6. Branch Loads on HSS Members - An Introduction •
Design tips to optimize welded HSS connection design • Select relatively stocky chord • Select relatively thin branch • Consider virtues of gapped K-connections
Overlapped
Gapped
•
Easier and cheaper to fabricate
• •
Higher static and fatigue strength, generally Produces stiffer truss (reduces truss deflections)
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Department of Civil Engineering, University of Toronto
Chapter 7. Line Loads and Concentrated Forces on HSS
•
Follows Chapter K Section K1 of AISC (2005) Specification
•
Local line loads on the face of HSS (longitudinal or transverse)
•
Shear tab and cap plate connections
•
Tabulated design criteria • plate-to-round HSS • plate-to-rectangular HSS
Cable-stayed roof connections, Ratner-Center, Chicago
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Department of Civil Engineering, University of Toronto
Chapter 7. Line Loads and Concentrated Forces on HSS •
Branch plate connections to HSS
(a) Longitudinal branch plate
(b) Through branch plate
(c) Stiffened branch plate
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(d) Transverse branch plate
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Chapter 7. Line Loads and Concentrated Forces on HSS •
Some possible failure modes for Plate-to-HSS connections
Chord punching shear
Chord face plastification
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Chord side wall yielding
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Chapter 7. Line Loads and Concentrated Forces on HSS Shear Tabs • Relatively thin shear tabs & nonslender HSS are required • Limit state of plate yielding and HSS punching shear
Cap Plates • Limit state of local yielding considering shear lag, • Limit state of HSS sidewall local crippling
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Department of Civil Engineering, University of Toronto
Chapter 8. HSS-to-HSS Truss Connections •
Follows Chapter K Section K2 of AISC (2005) Specification
•
Planar truss type connections between HSS (or box sections)
•
T-,Y-,Cross-, K- (or N-) gapped or overlapped connections
•
Tabulated design criteria • round-to-round HSS • rectangular-torectangular HSS
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Department of Civil Engineering, University of Toronto
Chapter 8. HSS-to-HSS Truss Connections
Typical Failure Modes
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•
Chord wall plastification
•
Shear yielding (punching)
•
Yielding of tension branch or compression branch
•
Shear of chord side walls
•
Chord side wall failure
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Chapter 8. HSS-to-HSS Truss Connections
Connection Classification K- Y-, Cross(X)connections
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Reference to AISC Manual Tables
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Reference to Spec. Section and Guide Tables Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K) Table 8.2A Limits of Applicability of Table 8.2 (for Rectangular HSS-to-HSS Truss Connections)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Checks for limits of applicability as applied to a Gapped Kconnection
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Checks for limits of applicability as applied to a Gapped Kconnection
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Load and Resistance Factor Design
Allowable Stress Design
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K) Table 8.2. Nominal Strengths of Rectangular HSS-to-HSS Truss Connections
Limit state: chord wall plastification
Gapped KConnections Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K) Table 8.2. Nominal Strengths of Rectangular HSS-to-HSS Truss Connections (continued)
Functions
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Equations used to check the limit state of chord wall plastification
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Reference to Equations in the Specification and Guide Tables
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Design Example: Gapped K-Connection (Spec. Chapter K)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K) Table 8.2. Nominal Strengths of Rectangular HSS-to-HSS Truss Connections
Gapped KConnections
Limit state: shear yielding (does not apply since branches are square)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K) Limit state: shear of chord side walls (does not apply since chord is square) Limit state: local yielding of branch due to uneven load distribution (does not apply since branches are square)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Checks for limits of applicability as applied to a Crossconnection
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K) Limit state: chord wall plastification
Crossconnection
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Crossconnection
All other limit states where 1.0 ≥ β ≥ 0.85 do not apply since β = 0.667
Limit state of shear of chord side walls does not apply (no shear plane evident)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
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Department of Civil Engineering, University of Toronto
Design Example: Gapped K-Connection (Spec. Chapter K)
Reference to other relevant documents provided throughout the Guide Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 9. HSS-to-HSS Moment Connections
Scotia Bank Plaza, Toronto, Canada
•
Follows Chapter K Section K3 of AISC (2005) Specification
•
Planar truss type connections between HSS (or box sections)
•
T-,Y-,Cross-connections
•
Partially or fully restrained moment connections (eg. Vierendeel truss)
•
Tabulated design criteria • round-to-round HSS • rectangular-torectangular HSS
Department of Civil Engineering, University of Toronto
Department of Civil Engineering, University of Toronto
Chapter 9. HSS-to-HSS Moment Connections
Typical Failure Modes
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•
Chord wall plastification
•
Shear yielding (punching)
•
Yielding of tension branch or compression branch
•
Shear of chord side walls
•
Chord side wall failure
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Chapter 9. HSS-to-HSS Moment Connections
In-Plane bending
Out-of-Plane bending
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Department of Civil Engineering, University of Toronto
AISC Design Guide on HSS – published in 2009
2008 Olympic Games “Bird’s Nest” Stadium, Beijing, China
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Department of Civil Engineering, University of Toronto
Thank you
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