Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad Presented by Thomas M. Murray, Ph.D., P.E. Department of Civil and Environmental Engineering Virginia Tech, Blacksburg, Virginia thmurray@vt.edu
XI SIMPOSIO-INTERNACIONAL DE ESTRUCTURASDE ACER 09 March 2011 1
AISC Seismic – SMF Connections
Refers to
Relies on
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
Beam-to-column connections shall satisfy the following Section 9.2a requirements: •
The connection shall be capable of sustaining an interstory drift angle of at least 0.04 radians.
•
The measured flexural resistance of the connection, determined at the column face, shall equal at least 0.80 Mp of the connected beam at an interstory drift angle of 0.04 radians.
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
AISC Seismic – SMF Connections
AISC Seismic – SMF Connections
Requirements of Sect. 9.2a are to be satisfied by one of the following methods: 1. Conduct qualifying cyclic tests in accordance with Appendix S.
•
Tests conducted specifically for the project, with test specimens that are representative of project conditions. or Tests reported in the literature (research literature or other documented test programs), where the test specimens are representative of project conditions.
Flush Moment End-Plate w/ Sixteen 1–½ in A490 Bolts
AISC Seismic – SMF Connections 2. Use connections prequalified for SMF in accordance with Appendix P •
•
Use connection prequalified by an alternative review panel that is approved by the Authority Having Jurisdiction. or Use connections prequalified by the AISC Connection Prequalification Review Panel (CPRP) and documented in Standard ANSI/AISC 358
Seismic App. S Qualifying Cyclic Tests Permitted Test Subassemblages: Actuator Mount
Single Beam Single Column Without a concrete slab
Lateral Brace Points
Test Beam
Reaction Floor
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
Actuator Load Cell
Test Column
•
Project Specific Cyclic Test
Reaction Floor
Reaction Floor
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Seismic App. S Qualifying Cyclic Tests
Test Column Lateral Support Typ.
Composite Slab
W14x257
Rigid Link
Rigid Link
W24x68
W24x68
Load Step Number
Interstory Drift Angle, θ (rad)
Number of Loading Cycles
1
0.00375
6
2
0.005
6
3
0.0075
6
4
0.01
4
5
0.015
2
6
0.02
2
7 0.03 2 Continue with increments in θ of 0.01, and perform two cycles at each step
0.06 0.05 0.04 0.03 0.02 0.01 0
Angle
Actuator
Test Frame
Pin Support
Loading Protocol:
Interstory Drift
Permitted Test Subassemblages:
Seismic App. S Qualifying Cyclic Tests
-0.01 -0.02 -0.03 -0.04 -0.05 -0.06
6
6
6
4
2 2 2 2 2
Number of cycles
Reaction Frame
Note: Quasi-static testing is permitted. There is not a required number of tests.
Seismic App. S Qualifying Cyclic Tests
Seismic App. S Qualifying Cyclic Tests
Interior subassemblage test at UT-Austin
Interior subassemblage test with concrete slab
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
Seismic App. S Qualifying Cyclic Tests Successful Conformance Test
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Seismic App. S Qualifying Cyclic Tests Quasi static test conducted at Virginia Tech
M 0.04 ≥0.8 M p
0.8 Mp
- 0.8 Mp
M 0.04 ≥0.8 M p
Seismic App. S Qualifying Cyclic Tests Quasi static test conducted at Virginia Tech
Column Tip Load vs.Total Rotation
Seismic App. S Qualifying Cyclic Tests Dynamic test conducted at UC San Diego
Column Tip Load vs. Plastic Rotation
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
ANSI/AISC 358 Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications
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Connections Prequalified Including Supplement No. 1 • Reduced Beam Section (RBS) Connection • Bolted Unstiffened and Stiffened Extended End-Plate Connection • Welded Unreinforced Flange – Welded Web • Bolted Flange Plate • Kaiser Bolted Bracket Note: The Conxtech Moment Connection is currently being balloted.
Reduced Beam Section (RBS) Connection
End Plate Moment Connections
Unstiffened 4-Bolt: 4E
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
Stiffened 4-Bolt: 4ES
Stiffened 8-Bolt: 8ES
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad Bolted Flange Plate Connection
Kaiser Bolted Bracket Connection
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Welded Unreinforced Flange – Welded Web Connection
ConXTech Moment Connection
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
Prequalified Unique Requirements • • • • • • •
Provisions apply only to the prequalified connections. Beam and Column cross-section limitations based on specific test matrices Rolled and Built-up Members permitted Specific welding requirements for built-up members Probable maximum moment at hinge specified Plastic hinge location specified for each connection Resistance Factors differ from AISC Specification
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Probable Maximum Moment at Hinge Based upon connecting beam strength: Mpr = Cpr Ry Fy Zx where: Mpr = probable maximum beam moment Ry = 1.1 for Fy = 50 ksi Zx = plastic section modulus of beam
Probable Maximum Moment at Hinge
Connection Design Moment
⎛ F + Fu ⎞ ⎟ < 1 .2 Cpr = ⎜⎜ y ⎟ ⎝ 2Fy ⎠
where: Fy = yield strength Fu = tensile strength
Plastic Hinge
Sh
Plastic Hinge
L’ = distance between plastic hinges
Sh
L = distance between centerline of columns
For A572 Gr 50, CprRy = 1.1 x 1.15 = 1.27 Mpr = 1.27 Fy Zx or 27% increase
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
Sh is specified for each prequalified connection.
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
Connection Design Moment
Plastic Hinge
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Connection Design Moment The connection design moment is the moment at the face of the column: Mf = Mpr + Vu Sh
Vu Mpr Sh
Mf = Mpr + Vu Sh
where: Mpr = probable maximum beam moment Vu = max. shear at the end of the beam = 2Mpr + VuSh Sh = distance from face of the column to plastic hinge location
Resistance Factors
Resistance Factors
Different resistance factors in 358 Prequalified:
Different resistance factors in 358 Prequalified:
Specification:
Ductile Limit States φd = 0.9 Non-Ductile Limit State φn = 0.75
Specification:
Ductile Limit States φd = 0.9 Non-Ductile Limit State φn = 0.75
Specification:
Ductile Limit States φd = 1.0 Non-Ductile Limit States φn = 0.9
Prequalified:
Ductile Limit States φd = 1.0 Non-Ductile Limit States φn = 0.9
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Resistance Factors Reason: Specification limit states represent maximum expected under strength, i.e. φd = 0.9 and φn = 0.75. Whereas, Mpr = Cpr Ry Fy Zx = 1.27 Fy Zx, represents the maximum expected over strength including some strain hardening.
Specific Prequalified Connections Reduced Beam Section (RBS)
If both are used, very conservative designs result. Therefore, the Prequalified resistance factors were increased to φd = 1.0 and φn = 0.90, but only for limit states included in the Prequalified Standard.
Reduced Beam Section (RBS)
Reduced Beam Section (RBS)
RBS Concept:
• Trim Beam Flanges Near Connection
• Reduce Moment at Connection
• Force Plastic Hinge Away from Connection
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
Connection was Prequalified at UT - Austin
Whitewashed connection prior to testing.
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
XI Simposio – Intenacional de Estructurasde Acer
Whitewashed connection prior to testing.
Connection at θ ≅ 0.02 radian.
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Connection at θ ≅ 0.02 radian.
Connection at θ ≅ 0.03 radian.
Connection at θ ≅ 0.04 radian.
Conformance Results 5000 4000
Mp
Bending Moment (kN-m)
3000 2000 1000 0 -1000 -2000 -3000
Mp
-4000
RBS Connection
-5000 -0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0.05
Drift Angle (radian)
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Reduced Beam Section (RBS) Prequalification Requirements for RBS in SMF • Beam depth:
up to W36
• Beam weight:
up to 300 lb/ft
• Column depth:
up to W36 for wide-flange up to 24-inches for box columns
• Beam connected to column flange (connections to column web not prequalified) • RBS shape:
circular
• RBS dimensions:
per specified design procedure
Reduced Beam Section (RBS) Prequalification Requirements for RBS in SMF Beam flange welds: - CJP groove welds - Treat welds as Demand Critical - Remove bottom flange backing and provide reinforcing fillet weld - Leave top flange backing in-place; fillet weld backing to column flange - Remove weld tabs at top and bottom flanges Beam web to column connection: - Use fully welded web connection (CJP weld between beam web and column flange) See ANSI/AISC 358 for additional requirements (continuity plates, beam lateral bracing, RBS cut finish, etc.)
Reduced Beam Section (RBS)
Reduced Beam Section (RBS) Protected Zone
Reduced Section Geometry
0.5bf < a < 0.75bf 0.5d < b < 0.85d 0.1bf < c < 0.25bf
No Shear Studs. No welded, bolted, screwed or shot-in attachments for perimeter edge angles, exterior facades, partitions, duct work, piping or other construction. Decking arc-spot welds are permitted.
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Lateral Brace at Center of RBS Violates Protected Zone
Lateral Brace at Center of RBS Violates Protected Zone
End-Plate Moment Connections
Specific Prequalified Connections End-Plate Concept:
End-Plate Moment Connections
• No Field Welding • Simple Erection • Connection is Stronger than Beam
Unstiffened 4-Bolt: 4E
Stiffened 4-Bolt: 4ES
Stiffened 8-Bolt: 8ES
• Special welding requirements • Concrete slab requirements
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
Connections were prequalified at Virginia Tech
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
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8-Bolt Stiffened Moment End-Plate, 8ES
8-Bolt Stiffened Moment End-Plate, 8ES
8-Bolt Stiffened Moment End-Plate, 8ES 25000
25000
20000
20000
Moment at Column Centerline (in-kips)
Moment at Column Centerline (in-kips)
End-Plate Moment Connections
15000 10000 5000 0 -5000 -10000 -15000 -20000 -25000 -0.08
15000 10000 5000 0 -5000 -10000 -15000 -20000
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
Total Rotation (rad)
Moment at Column Centerline vs Total Rotation
-25000 -0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
Total Plastic Rotation (rad)
Moment at Column Centerline vs Plastic Rotation
8ES-1.25-1.75-30
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
Connection Test with Concrete Slab
Actuator
Test Frame Test Column Lateral Support Typ.
Composite Slab
W14x257 Pin Support
Rigid Link
W24x68
W24x68 Rigid Link
Connection Test with Concrete Slab
Reaction Frame
End-Plate Moment Connections
End-Plate Moment Connections
Prequalification Requirements: • Beam depth:
Min. and max. in Table 6.1
• Beam weight:
No limit
• Column depth:
Up to W36
• Beam connected to column flange (connections to column web not prequalified) • Bolts:
A325 or A490
• Finger Shims:
Permitted
Prequalification Requirements: Beam flange welds:- CJP groove welds except over web - Weld access holes not permitted - Back gouging not required at web Beam web to column connection: - CJP or fillet welds are permitted See ANSI/AISC 358 for additional requirements: (continuity plates, beam lateral bracing, etc.)
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
End-Plate Moment Connections
End-Plate Moment Connections
Weld access hole not permitted because of ruptures that occurred during testing. Rupture
Rupture
End-Plate Moment Connections Recommended welding procedure: • No weld access holes • Surface Preparation: – All surfaces ground clean – Flanges beveled 45º full depth • Minimum root opening
End-Plate Moment Connections Recommended welding procedure:
45°
Typical Beam 45°
Welding Sequence: 1. Fillet welds on both sides of web 1 installed. 2. Fillet welds on inside of flanges installed. 3. Flange groove weld root backgouged and flange groove welds installed.
Backgouge
3
2
Backgouge
3
Note: Welds over webs are not CJP.
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
XI Simposio – Intenacional de Estructurasde Acer
End-Plate Moment Connections
End-Plate Moment Connections
Test 1 with Concrete Slab
Test 1 with Concrete Slab
End-Plate Moment Connections
End-Plate Moment Connections
Test1 with Concrete Slab
Test 2 with Concrete Slab 1'-11 1/4" 3'-4 1/2" NO STUDS HINGE ZONE
4'-8 1/4"
3'-0"
END OF STIFFENER
END OF STIFFENER
4'-8 1/4"
10'-0"
1'-11 1/4" 3'-4 1/2" NO STUDS HINGE ZONE
3'-0"
10'-0"
Premature Bolt Failure
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
5" COMPOSITE SLAB (3" COVER ON 2 COMPOSITE METAL DECK) REINFORCED W/ 4x4-W2.9xW2.9 WWF
1/2" MIN. GAP FORMED W/ NEOPRENE FILLED W/ FOAM INSUL.
3/4"Ø X 4" SHEAR STUDS @ 1'-0" MAX.
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
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End-Plate Moment Connections
Test 2 with Concrete Slab
Test 2 with Concrete Slab 250
250
200
200
150
150
Column Tip Load (kips)
Column Tip Load (kips)
End-Plate Moment Connections
100 50 0 -50 -100
100 50 0 -50 -100 -150
-150 -200
-200
-250 -0.05 -0.04 -0.03 -0.02 -0.01 0.00
0.01
0.02
0.03
Total Rotation (rad.)
Column Tip Load vs Total Rotation
0.04
0.05
-250 -0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
Beam Rotation (rad.)
Column Tip Load vs Beam Rotation
End-Plate Moment Connections
Specific Prequalified Connections
Requirement for all prequalified bolted connections:
Compressible expansion joint material, at least 1 in. thick, shall be installed to isolate the column/connection from the concrete slab.
Bolted Flange Plate (BFP)
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
Bolted Flange Plate (BFP)
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Bolted Flange Plate (BFP)
BFP Concept:
• Shop Welded/Field Bolted • A325 or A490 bolts • Top and bottom flange
Prequalified at U. of California at San Diego
plates must be identical
• Hinge at end of flange plates
Bolted Flange Plate (BFP)
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
Bolted Flange Plate (BFP)
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
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Bolted Flange Plate (BFP)
Bolted Flange Plate (BFP)
Bolted Flange Plate (BFP)
Bolted Flange Plate (BFP)
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
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Bolted Flange Plate (BFP)
Bolted Flange Plate (BFP)
Fracture Location Close-up of Fracture Location
Welded Unreinforced Flange- Welded Web (WUF-W)
Specific Prequalified Connections
WUF-W Concept:
Welded Unreinforced Flange - Welded Web (WUF–W)
• Full beam strength • Shop welded single plate • • •
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
with bolts for erection Field welded beam flange to column flange Field welded single plate to beam web Similar to post-Northridge connection
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
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Welded Unreinforced Flange- Welded Web (WUF-W)
Specific Prequalified Connections Kaiser Bolted Bracket (KBB)
Erection Bolts
Flange Welded
Kaiser Bolted Bracket (KBB)
Flange Bolted
Kaiser Bolted Bracket (KBB)
KBB Concept:
• Proprietary • Cast steel bracket • Welded or bolted to • • • •
beam flange Bolted to column flange Shop welded single plate web connection Pretensioned 1-3/8 or 1-1/2 in. diameter A490 or A354 bracket bolts Used for retrofiting
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
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ConXtech® CONXLTM Moment Connection
Specific Prequalified Connections
Concept: • Propriety • Full strength/biaxial • 16 in. square HSS or built-up box concrete filled columns • Shop welded forged steel fittings on beams and columns • Field bolted with 1-1/2 in. A574 bolts • All beams must be of same nominal depth • Extremely fast erection
ConXtech® CONXLTM Moment Connection
ConXtech® CONXLTM Moment Connection
ConXtech® CONXLTM Moment Connection
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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Conexiones Precalificadas para Estructuras en Zonas de Alta Sismicldad
ConXtech® CONXLTM Moment Connection
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ConXtech® CONXLTM Moment Connection
Achknowledgements
Slides provided by Michael Engelhardt, University of Texas – Austin Chia-Ming Uang, University of California, San Diego
Thank You!!
Scott Adan, Adan Engineering Raymond Kitasoe, ConXtech
Presented by ProfessorThomas M. Murray, Virginia Tech 09 March 2011
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