aisc research program behavior of bolted steel slip critical

University of Illinois at Urbana-ChampaignDecember 5, 2007MUST-SIMMUST-SIM

AISC RESEARCH PROGRAM

Jerome F. Hajjar Mark DenavitProfessor and Narbey Khachaturian Faculty Scholar Graduate Research Chair, Structures Faculty Assistant

Department of Civil and Environmental EngineeringUniversity of Illinois at Urbana-ChampaignUrbana, Illinois

BEHAVIOR OF BOLTED STEEL SLIP CRITICAL CONNECTIONS WITH

FILLERS


Background: ASD 1989 on SC Connections with Fillers

• ASD 1989 Section J3.8 on Slip Critical ConnectionsRn = FvAbNsFv is from RCSC Specification for oversized: 29 ksi for A490 Class B surface

• ASD 1989 Section J6 on FillersException on developing fillers for slip critical connections, but fills are developed for bearing connections


Background: AISC 2005 on SC Connections with Fillers

• AISC 2005 Section J3.8 on Slip Critical ConnectionsRn = µDuhscTbNsConnections with standard holes or slots transverse to the direction of the load shall be designed for slip as a serviceability limit state, Ω = 1.50Connections with oversized holes or slots parallel to the direction of the load shall be designed to prevent slip at the required strength level, Ω = 1.76

• AISC 2005 Section J5 on FillersFor fillers with t ≥ ¼” or greater, one of the following shall apply:1. For fillers with t ≤ ¾”, Rn for bolt shear should be reduced

by [1-0.4(t-0.25)]. 2. Connection shall be extended and the filler developed3. Joint shall be extended to equivalent of #24. Joint shall be designed to prevent slip at required strength


Fillers: Effect on Slip and Bolt Shear• W14x730

Standard holes and oversized holes• W14x455

Full (2 rows, with duplicate), half (1 row), and no development (0 rows)

• W14x159Full (4 rows), half (2 rows), and no development (0 rows, with duplicate)Two ply filler, no development (duplicate)TC bolts, half and no developmentWelded filler, full and half development


Fillers: Effect on Slip and Bolt Shear

• To develop the filler to be fully developed, e.g., W14x159: 3.75”/(3.75”+1.19”)=76% of the slip critical strength of 24 splice plate bolts

• W14x159Actual number of rows needed to develop the filler:o 4.56 rows (fully developed) – we used 4 rowso 2.28 rows (half developed) – we used 2 rows

• W14x455Actual number of rows needed to develop the filler:o 2.01 rows (fully developed) – we used 2 rowso 1.00 rows (half developed) – we used 1 row


Scenarios

• AISC 2005 strength with measured material properties and no φ or Ω factors should provide the best estimate of the test results

• If expected slip value can be reached consistently for all connections, we may be able to:

Verify ability to use different safety factors at “serviceability”and “required strength” levelLower the Ω of 1.76 (raise the φ of 0.85) for connections in which prevention of slip is at required strength level (i.e., oversized holes)Verify that the filler need not be developed if you design at the required strength level (noting that we are not using standard holes)

• If expected bolt shear value can be reached consistently for all connections, we may be able to:

Ensure that a new reduction formula is not needed for thick fillers even when designing at required strength levelEliminate required reductions for bolt shear strength (noting that we are not using standard holes)


Scenarios

• If expected slip value cannot be reached consistently for all connections, that may indicate:

The Ω of 1.76 is appropriate for oversized holesThe filler needs to be developed (we can try to determine if it is a function of filler thickness)

• If expected bolt shear value cannot be reached consistently for all connections, that may indicate:

Recommend reductions for bolt shear strength for thick fillers or oversized holes to ensure safety

• If some test values meet the expected values and some do not, it will be necessary to reduce the data carefully


AISC Test Specimen 159n-2ply1

University of Illinois at Urbana-ChampaignDecember 5, 2007

“Required Strength” = slip critical strength of 24 bolts in splice plateComparison of ASD Codes (using design values)

AISC 2005 ASD 1989Specimen 11159n-2ply1

Pn

(kips) rank Pn/Ω(kips) rank Pallow

(kips) rank

between splice and filler 922 1 524 1 692 1

between filler and top column

922 1 524 1 692 1slip

between splice and bot. column

2,459 5 1,397 1,845

between splice and filler 1,789 3 895 3 954 3

between filler and top column

1,789 3 895 3 954 3


4,771 2,386 2,545

between splice and filler (overstrength) 2,460 6 1,230 5 1,312 5

between filler and top column (overstrength) 2,460 6 1,230 5 1,312 5

shear

between splice and bot. column (overstrength) 6,561 3,280 3,499

splice plate 7,449 3,725 3,221bearing

w shape 4,432 2,216 1,916


AISC Test Specimen 159n-2ply1


“Required Strength” = slip critical strength of 24 bolts in splice plate

Comparison of Limit States (using measured values)

AISC 2005Specimen 11159n-2ply1 Pn

(kips)rank Pn/Ω

(kips)rank

slip between splice and filler 1,173 1 666 1between filler and top column 1,173 1 666 1between splice and bot. column 3,128 1,777

shear between splice and filler 2,429 3 1,214 3between filler and top column 2,429 3 1,214 3between splice and bot. column 6,476 3,238

splice in compression 3,752 2,247W shape in compression 2,615 6 1,566 6fracture splice plate 4,551 2,276

w shape 2,473 5 1,237 5bearing splice plate 9,397 4,699

w shape 4,978 2,489


AISC Test Specimen 730-over“Required Strength” = slip critical strength of 24 bolts in splice plate

Comparison of ASD Codes (using design values)AISC 2005 ASD 1989Specimen 02

730-over Pn

(kips) rankPn/Ω(kips) rank

Pallow

(kips) rank

between splice and top column

922 1 524 1 692 1slip

between splice and bot. column 2,459 3 1,397 4 1,845 4

between splice and top column

1,789 2 895 2 954 2


4,771 5 2,386 5 2,545 5

between splice and top column (overstrength)

2,460 4 1,230 3 1,312 3shear

between splice and bot. column (overstrength)

6,561 6 3,280 6 3,499

splice plate 7,449 3,725 3,221 6bearing

w shape 18,287 9,144 7,907



AISC Test Specimen 730-over“Required Strength” = slip critical strength of 24 bolts in splice plate

Comparison of Limit States (using measured values)

AISC 2005Specimen 02730-over Pn

(kips) rank Pn/Ω(kips) rank

between splice and top column 1,173 1 666 1

slipbetween splice and bot. column 3,128 3 1,777 3between splice and top column 2,429 2 1,214 2

shearbetween splice and bot. column 6,476 6 3,238 6

splice in compression 3,752 4 2,247 4

W shape in compression 13,330 7,982splice plate 4,551 5 2,276 5

fracturew shape 13,335 6,668splice plate 9,397 4,699

bearingw shape 23,633 11,816



Measured Material Properties

Nominal MeasuredMaterial Yield Stress

Fy (ksi)Ultimate Stress

Fu (ksi)Yield Stress

Fy (ksi)Ultimate Stress

Fu (ksi)Top Column(W14x730) 50 65 62 84

Bottom Column(W14x730) 50 65 62 84

Splice Plates(2″ thick) 50 65 56 82


84626550Bottom Column(W14x730)

MaterialNominal Measured

Yield StressFy (ksi)

Ultimate StressFu (ksi)

Yield StressFy (ksi)

Ultimate StressFu (ksi)

Top Column(W14x159) 50 65 56 73

Filler Plates(3½″ thick) 50 65 50 71

Filler Plates(¼″ thick) 50 65 53 75

Splice Plates(2″ thick) 50 65 56 82

LengthNominal Measured

PretensionTb (kips)

Shear StrengthFv (ksi)

PretensionTb (kips)

Shear StrengthFv (ksi)

9″(all bolts) 80 75 115 102

159n-2ply1Bolts

Bolts

159n-2ply1

730-over


AISC Test Specimen 01Slip Shear

1,085 kips

1,789 kips

Design Strength(Nominal Values)

1,380 kips

2,429 kips

Design Strength(Measured Values)

1,697kips

2,542 kips

Observed Strength


-0.05 0 0.05 0.1 0.15 0.20

500

1000

1500

2000

2500

3000Load vs. Splice/Column Relative Displacement

Splice/Column Relative Displacement (in)

Load

(kip

s)

01t2s-1w01t2s-2w


AISC Test Specimen 01

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50

500

1000

1500

2000

2500

3000Load vs. Top Column Displacement

Top Column Displacement (in)

Load

(kip

s)

01top-1e01top-1w

0 50 100 150 200 250 300 350 4000

500

1000

1500

2000

2500

3000Load vs. Splice Plate (1 row bolts) Strain

Splice Plate (1 row bolts) Strain (µmm/mm)

Load

(kip

s)

01spl-5n01spl-6n01spl-5s01spl-6s

0 50 100 150 200 250 300 350 400 450 5000

500

1000

1500

2000

2500

3000Load vs. Splice Plate (3 rows bolts) Strain

Splice Plate (3 rows bolts) Strain (µmm/mm)

Load

(kip

s)


0 100 200 300 400 500 600 700 800 900 10000

500

1000

1500

2000

2500

3000Load vs. Splice Plate (6 rows bolts) Strain

Splice Plate (6 rows bolts) Strain (µmm/mm)

Load

(kip

s)




AISC Research ProgramKeeping Steel Competitive Through Research

Answer questions that arise in steel performanceo Simplify the specification while retaining safe and reliable designso Examples:

Allowing no continuity plates in high seismic zonesEnable steel to be the premier material for projects ranging from fast and simple construction to the most sophisticated building structures in the world o New building topologies demand new technologieso Steel is sustainableGenerate new ideas and new productso Examples:

New doubler plate details that lessen the amount of weldingBuckling restrained brace can rejuvenate steel braced frames in seismic zonesDirect analysis can lead the way internationally in stability design to enable diverse building configurations while simplifying calculationsComposite construction provisions are improving continuously

Stay current with evolving mill, fabrication, and construction practiceso Other materials are innovatingFacilitate adaptation to or drive innovation in new information technology


New Doubler Plate Details

45° beveleddoubler plate

Heavy filletwelds

Approx. 7/8" gap

Heavy filletwelds

Approximately2/3 width of girder

flange

Act as bothdoubler plate andcontinuity plate

Full penetration welds

Heavy CJPweld

Potential fracture regionCurrent practice:

Alternatives:

Fillet I Fillet II Box


Typical Full-Scale Cruciform Test Specimen

144"

144"

85.5"

85.5"

171"

132"140"

72"

W14x176

W24x94W24x94

Two 77-kipactuators

Two 77-kipactuators

Pin

Pin


Local Flange Bending and Local Web Yield Limit States

Local web yielding (LWY)

Girder Flange

Local flange bending (LFB)

Column web

Column flangePull hard

Pull hard


AISC Research Program• Innovation in Steel Is Best Spearheaded by

AISC-funded ResearchNSF and other federal agencies typically do not fund research needed to aid directly a design specification or manual (however, they may partner on such projects) AISC funds can be used to provide excellent leverage (order of magnitude or more) for funds from NSF, DOT, etc.o Typical NSF project: $300K-$750K for three years,

$1.6M for four years, $2M for five yearso Typical DOT project: $150K-$200K for two yearsAISC has strong influence over outcome and use of research


AISC Relations with Universities

• Future employees for steel and consulting industries are typically hired from structural engineering programs at research-oriented universities

These universities are driven by researchThe faculty are expected to obtain research funds and projects and publish resultsAISC is an outstanding and critical partner for faculty interested in steel structures nationwide

MUST-SIMMUST-SIM

University of Illinois Structures Program

• 52 Faculty, 15 in Structures• 60 MS and 60 PhD Full-Time Students• Graduate 40 MS and 10 PhD Students per year

Nathan M. Newmark, Head of CE, 1956-1976

MUST-SIMMUST-SIM

University of Illinois Structures Program

• Consistently Top Ranked CEE Department with many distinguished alumni who are contributing to the steel industry:– Jim Fisher– Stan Rolfe– Bruce Ellingwood– Shankar Nair– Jim HarrisEmeritus Faculty:– Bill Munse– Jim Stallmyer– Doug Foutch– Bill Hall– Nathan Newmark

MUST-SIMMUST-SIM

NEES@IllinoisNEES@Illinois: MUST: MUST--SIM: SIM: MultiaxialMultiaxial FullFull--Scale Scale SubstructuredSubstructured

Testing and Simulation FacilityTesting and Simulation Facility

http://http://nees.uiuc.edunees.uiuc.edu

MUST-SIMMUST-SIM

Network for Earthquake Engineering Simulation: Experimental Sites

Oregon State Universityhttp://nees.orst.edu/

University of California, Davishttp://nees.ucdavis.edu/

Rensselaer Polytechnic Institutehttp://nees.rpi.edu/

Brigham Young University/ University of California, Santa Barbara

http://nees.ucsb.edu/

University of Texas at Austinhttp://nees.utexas.edu/

University of California, Los Angeleshttp://nees.ucla.edu/

University of Illinois atUrbana-Champaignhttp://nees.uiuc.edu/

University of California, Berkeleyhttp://nees.berkeley.edu

Lehigh Universityhttp://www.nees.lehigh.edu/

University of Minnesotahttp://nees.umn.eduUniversity of Colorado, Boulder

http://nees.colorado.edu/

Embedded pipeline experiment

Low modular wall(13 segments total)

Ductile highway support system experiment

0.9m

seg

men

ts,

up to

7.2

m

1.8m

1.8m

1.2m

High modular walls (16 segments total)

1.2m 3m

3m

Low modular wall(13 segments total)

1.8m

1.8m

1.2m

High modular walls (16 segments total)

1.2m 3m

3m

Cornell Universityhttp://nees.cornell.edu/

University of California, San Diegohttp://nees.ucsd.edu/

University of Nevada, Renohttp://nees.unr.edu/

University at Buffalo, SUNYhttp://nees.buffalo.edu/


Composite Columns

• Steel reinforced concrete (SRCs, Encased Composite Columns)

• Concrete-filled tubes (CFTs, Filled Composite Columns)

From R. Kanno, Nippon Steel Corporation

From R. T. Leon, Georgia Institute of Technology


MAST Facility

From NEES@Minnesota

• The MAST facility permits the comprehensive testing of a wide range of composite beam-columns subjected to three dimensional loading at a realistic scale.

Degree of Freedom

Load Stroke/ Rotation

X-Translation ±880 kips ±16 in

X-Rotation ±8,910 kip-ft ±7°

Y-Translation ±880 kips ±16 in

Y-Rotation ±8,910 kip-ft ±7°

Z-Translation ±1,320 kips ±20 in

Z-Rotation ±13,200 kip-ft ±10°

Maximum non-concurrent capacities of MAST DOFs


Database Development

• Work of previous researchers (Aho, Kim, Goode) combined to create a comprehensive worldwide database

• Database will be used to identify gaps in test data and calibrate computational model

P/Po

RCFT CCFT SRC

P/PoP/Po

λλ

M/MdM/Md

λ

M/Md

CCFT RCFT SRC

Columns 762 455 119Beam-

Columns395 189 120

Number of Tests


Preliminary Test Matrix

MUST-SIMMUST-SIM

Controlled Rocking of Steel Frame Structures

• Corner of frame is allowed to uplift.

• Fuses absorb seismic energy

• Post-tensioning brings the structure back to center.

Result is a building where the structural damage is concentrated in replaceable fuses with little or no residual drift

MUST-SIMMUST-SIM

UIUC Half Scale Tests

Post-Tensiong

Strands

Fuse

Stiff Braced Frame

Bumpers

Loading and Boundary Condition Box (LBCB)

Strong Wall

MUST-SIMMUST-SIM

E-Defense Testbed Structure

Plan View

shaking direction

Section

E-Defense

University of Illinois at Urbana-Champaign13 November 2007

AISC TC 5: Composite ConstructionThinking of composite structural members (SRC beam-columns,

Composite Walls, Composite Base Conditions; note that CFTs coveredcommonly by AISC rarely have shear connectors)...

Beam-columns Infill Walls

Composite Base


Shear Connector Provisions: MonotonicnFACV usVVs ⋅⋅⋅⋅=⋅ φφ

Steel Failure:-Tension:

-Shear: nFACN ustts ⋅⋅⋅⋅=⋅ φφ

n: number of studsAs: cross sectional area of studFu: ultimate strength of stud

φv Cv φt Ct

1.00* -

1.00

0.75

0.80

0.70

-

1.00

-

0.90

1.00

1.00

1.00

0.65

0.75

0.65

0.80 -

1.00

0.75

1.00

1.00

1.00

0.80

ACI 318-05ACI 318-08

φv ·Cv φt ·Ct

AISC 1.00 -

PCI 4th 0.75 0.90

PCI 6th 0.65 0.75Ductile steelelement 0.75 0.80

Brittle steelelement 0.65 0.70

EC-4 0.64 -

- * The reduction factor is grouped with the flexural phi factor, φb, which is 0.85 for plastic redistribution of stress or0.90 for an elastic stress distribution on the section- Canadian Standard and CEB are similar to ACI 318-05


Shear Connector Provisions: Cyclic

ξ

AISC 341-05 0.75

ACI 318-05

ACI 318-08 0.30

Klingner et al. (1982) 0.50*,**

0.83*Hawkins and Mitchell (1984)

0.71**

Makino (1985) 0.50

NEHRP (2003) 0.75

0.75

Gattesco and Giuriani (1996) 0.90*

mc RR ⋅⋅=⋅ φξφ Rc : cyclic resistanceRm : monotonic resistance

-*: faliure of the stud-**: failure of the concrete

Reduction factor by cyclic loading (ξ):

0.60 *, **Civjan and Singh (2003)

AISC

EC-4 0.75*,**Zandoniniand Bursi (2002) 0.55*,**

Bursi and Gramola (1999) 0.68 *,**

ξ

-*: faliure of the stud-**: failure of the concrete


Shear Connector Strength

Proposal: φ, 0.9 ·CvAISC

AISC Stud StrengthSteel Failure in Test

0.00

0.50

1.00

1.50

2.00

0 50 100 150Test Number

Vs(te

st)/V

s(pr

edic

ted)

AISC Stud Strength (Steel Only)Steel Failure in Test

0.00

0.50

1.00

1.50

2.00


Vs(te

st)/V

s(pr

edic

ted)

Proposal: φ, 0.8 ·Cv

AISC Stud Strength (Steel Only)Steel Failure in Test

0.00

0.50

1.00

1.50

2.00


Vs(te

st)/V

s(pr

edic

ted)

136 Shear Tests AISC (φ, Cv) AISC (φ, 0.9·Cv) AISC (φ, 0.8·Cv)

1.052

0.135

1.184

0.151

Average 1.009

Stand. Dev. 0.122

36

Mid-America Earthquake Center

Mid-America Earthquake Center: Consequence-Based Risk Management (CRM)

• The Component (Engineering) Solution– Addresses the vulnerability of a component– Judges its adequacy on its own merit

• The Network (Single System) Solution– Addresses the vulnerability of one system– Judges its adequacy on its own merit

• The CRM (Integrated) Solution– Addresses the vulnerability of all systems– Judges adequacy on their

integrated performance

__

_ _

__ _

_ _

__

__

_

Iowa

Kansas

IllinoisOhio

Nebraska

Missouri

Okl h

outh Dakota Wisconsin

Vir

Indiana

Michigan

Kentucky

Tennessee

Penns

North C

West VirginiaTopeka

Lincoln

LansingMadison

Columbus

Frankfort Charleston

Des Moines

Springfield Indianapolis

Jefferson City

Nashville-Davidson

37

Mid-America Earthquake Center

Memphis Test Bed: Scenario Event Prediction

MAEvizStudy Region:

Shelby County, TNDamage Assessment of Buildings

HAZARD MODEL (earthquake intensity contours are shown):

Deterministic

New Madrid Seismic Zone

Moment Magnitude 7.7

LEGEND FOR BUILDING TYPE

Red crosses: hospitals

Purple squares: schools

Orange squares: fire stations

Blue diamonds: police stations

White circles: bridges

Yellow triangle: airport

LEGEND FOR DAMAGE BARS

Red: % extensive damage

Yellow: % moderate damage

Blue: % light damage

Damage to critical facilities

Structural Integrity Modeling and Laser-Based Verification

Examples of Models:

Collapse modeling of an office structure (ASI)

Collapse modeling vs. the real demolition of a building (ASI)

Collapse modeling vs. the real demolition of a stadium (ASI)

Discrete Element Modeling of Severely Damaged Structures• Prediction of structural integrity

• New modeling approaches for extreme loadings

• Determine minimum requirements for steel structures

Laser-Based Verification of Severely Damaged Structures

• High-speed accurate lasers

• Capture dynamic collapse and verify against models

MUST-SIMMUST-SIM

Modeling of Moulin Formation in Ice Shelves

MUST-SIMMUST-SIM

Steel Construction within a Global Context

Google earth

French, Sritharan

et al. 2006

-4000

-2000

0

2000

4000

6000

8000

0 3000 6000 9000 12000 15000Time (seconds)

Mic

rost

rain

Cycle G4-3-A

Cycle G4-3-A

SBBSBG1-a

SBBSBG1-b

-4000

-2000

0

2000

4000

6000

8000

0 3000 6000 9000 12000 15000Time (seconds)

Mic

rost

rain

Cycle G4-3-A

Cycle G4-3-A

SBBSBG1-a

SBBSBG1-b

Collaborative Augmented Reality and

Analysis

www.iris.edu

MAE Center

MUST-SIMMUST-SIM

Acknowledgments: UIUC, NEES and MAEC Projects

MUST-SIM and MAEC Co-Investigators: Amr Elnashai, Bill Spencer, Dan Kuchma

Composite Column Co-Investigators (CC): Roberto Leon

Controlled Rocking Co-Investigators (CR): Gregory Deierlein, Sarah Billington, Helmut Krawinkler

Research Engineers: Hussam Mahmoud, Michael Bletzinger, Greg Banas, shop personnel

Graduate Students: Comp Col: Mark Denavit (UIUC), Tiziano Perea (GIT)Rocking: Matthew Eatherton (UIUC), Noel Vivar (UIUC)

Xiang Ma and Alex Pena (Stanford)Comp Conn: Luis Palleres (post-doctoral associate)

MAEC CRM: Josh SteelmanIntegrity: Sara Walsh, Lily Rong

Ice Shelves: Maribel Gonzalez

Undergraduate Students: Mark Bingham, Michael Kehoe, Matthew Parkolap, Brent Mattis, Lina Rong, Angelia Tanamal

Sponsors: National Science FoundationAmerican Institute of Steel Construction

University of Illinois at Urbana-ChampaignGeorgia Institute of Technology (CC)

Stanford University (CR)

In-Kind Funding: W&W SteelUniversity of Cincinnati

LeJeune Steel Company (CC)Tefft Bridge & Iron (CR)

Infra-Metals (CR)

MUST-SIMMUST-SIM

THANK YOU

Chicago, Illinois

Urbana-Champaign,

Illinois

aisc research program behavior of bolted steel slip critical

Documents