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Slip Resisting Bolted
Connections
Source: Remi M. www.flickr.com/photos/remi_m
By: Joel Kerkhoff
3/26/2009
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Outline
Port Mann Bridge deck connection
(Remi M. – Flikr)
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Introduction
•
Uses
•
History & Code dev.
•
Basic Theory
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•
•
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Code requirements
Spreadsheet
Research
Testing @ UBC
Conclusion
Questions
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Introduction
What is a slip-resisting connection?
Two components
•
Tensioned bolts
•
Steel faying surfaces
source: unknown
A simple friction connection
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Where is it used?
Locations:
• Stress reversal / fatigue
•
Vibration
•
Oversize/slotted holes
•
Bolts & welds share load
•
Where joint slippage is detrimental
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Where is it used? - examples
Source: www.eng.nus.edu.sg/EResnews/9711/nov97p1.html
Slot-bolted connection
Karuah Bridge,
South Wales, Australia
(source www.rta.nsw.gov.au Roads
and Traffic Authority, NSW)
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Where is it used? - examples
Source: www.pbase.com/geoff_c
Falkirk Wheel, Scotland
Source: www.lucs.org.uk/falkirk_wheel.htm
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History and code development
Historical
• Rivets
• Batho & Bateman – 1934
• RCRBSJ (now RCSC) – 1947
• ASTM – 1949
American codes/guides:
• RCSC – www.boltcouncil.org
•
Specification for Structural Joints Using
ASTM A325 or A490 Bolts
• AISC
•
Guide to Design Criteria for Bolted and
Riveted Joints (Kulak, Fisher, Struik)
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Basic Theory
•
•
Bolts provide the Normal Force (N)
m depends on faying surfaces
Ff = mN
Source: en.wikipedia.org/wiki/Friction
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
Vr = ks * [bolt tension]
Complexities in both factors.
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Canadian Code Design
CAN/CSA-S16.1-01
cl. 13.12.2
Vs = 0.53*c1*ks*m*n*Ab*Fu
• Fu = specified minimum tensile strength
• Ab = bolt cross sectional area
• n = number of bolts
• m = number of shear planes
• ks = mean slip coefficient
• c1 = 5th percentile coefficient
Slip resistance is a Service Limit State
Must design as regular bolt connection
for Ultimate Limit States!
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Canadian Code Design
CAN/CSA-S16.1-01 Table 3
Contact Surface of bolted Parts
Class Description
A
B
C
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Clean Mill Scale, or blast-cleaned with
Class A coatings
Blast-cleaned, or blast-cleaned with
Class B coatings
Hot-dip galvanized with wire brushed
surfaces
Friction
ks
c1
A325 bolt
0.33
0.82
0.5
0.89
0.4
0.9
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Excel Spreadsheet
•
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•
•
Compute slip resistance
Compute bolts for given shear
Simplify user input
Check for errors
Eliminate need to use ‘Blue Book’
source: Microsoft
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Research
•
Ongoing
•
International
Source: www.nsel.cee.illinois.edu
Blast cleaned steel test sample
& 50kip clamping force
Source: www.nsel.cee.illinois.edu
Prof. J. Hajjar - University of Illinois
3/26/2009
600 kip MTS Uniaxial testing Machine
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Testing at UBC
•
•
12 samples
o As Is / Mill scale
o Blast-cleaned
3 Samples left…
100 Ton Baldwin testing machine
Steel test sample
Image sources: Jalayer, Stiemer and Youn. “Experimental Investigations
of Slip Resistant Connections for Weathering Steel”
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Testing at UBC - results
Surface Type
As Is
As Is
As Is
Blast-cleaned
Surface
Type
As Is
As Is
As Is
Blastcleaned
Specimen Type
Plate-to-flange
Plate-to-plate
All specimens
Plate-to-flange
Specimen
Type
Plate-to-flange
Plate-to-plate
All specimens
Plate-to-flange
Table: Slip Test Results
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Mean Slip
Load [kips]
Standard Dev
63.0
68.1
65.0
62.6
9.0
5.1
7.9
2.4
[kips]
5th Percentile Coefficient
of Friction [ ]
0.35
0.43
0.37
0.42
COV
0.14
0.07
0.12
0.04
Estimated
ks [ ]
0.42
0.52
0.45
0.46
S16.01
ks
0.33
0.33
0.33
0.50
Data source: Jalayer, Stiemer and Youn. “Experimental Investigations of Slip
Resistant Connections for Weathering Steel”
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Concluding comments
Summary
• Simple
• Complicated
Acknowledgements & Resources
• Professor Stiemer & Professor Youn
•
•
•
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G.L Kulak – Various publications
University of Illinois – NSEL website test pictures
Google – for finding some of the pictures
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Questions
Source: www.ezdiyelectricity.com/?p=526
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