aisc 341-significant changes-2005 to 2010
DESCRIPTION
AISC 341 - Significant Changes between 2005 and 2010 issuesTRANSCRIPT
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CHANGES in AISCs SEISMIC PROVISIONS: AISC 341-05 to AISC 341-10
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AISC Seismic Provisions
AISC Seismic Provisions provide System Ductility
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System Ductility
System Ductility is the ability of system to maintain stability after yielding/overload of some elements
Ductility
V
Ability of yielding/overloaded elements to deform
Ability of non-yielding elements to withstand forces redistributed by yielding
Ability of non-yielding elements to withstand deformations caused by yielding
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Seismic Provisions Measures
For each Seismic Force Resisting System Identify target yield mechanism of the system Designate deformation-controlled elements Design remaining elements as force-controlled Protect critical locations
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Seismic Provisions Measures
Identify target yield mechanism of the system
Flexural Yield
Tension yield and compression buckling
Shear Yield
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Stable yield
Seismic Provisions Measures
Designate deformation-controlled elements Design for element ductility
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Design remaining elements as force-controlled Design to keep members essentially elastic at
capacity of ductile elements
Resist redistributed forces
Seismic Provisions Measures
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Accommodatedeformations
Seismic Provisions Measures
Design remaining elements as force-controlled Design for deformations caused by yielding
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Protected Zones
Seismic Provisions Measures
Amplify forces
Demand Critical Welds
Protect critical locations
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Key Points
Reorganized chapters for consistency with AISC 360
Increased protection of critical locations
Added new systems and connections
Provided consistent capacity analysis requirements
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ROADMAP
Chapter Reorganization General Members Connections Moment Frames Braced Frames
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Seismic Provisions 341-05 Part I:1: Scope2: Referenced Specifications, Codes, and Standards3: General Seismic Design4: Loads, Load Combinations, Nominal Strengths5: Structural Drawings and Specifications, Shop Drawings,
and Erection Drawings6: Materials7: Connections, Joints, and Fasteners8: Members9-17: Structural Systems18: Quality Assurance Plan (Appendix Q)Appendices P, R, S, T, W, X
Part II: Composite Systems
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AISC 341-10 Organization
A. General RequirementsB. General Design RequirementsC. AnalysisD. General Member and Connection Design RequirementsE. Moment-Frame SystemsF. Braced-Frame and Shear-Wall SystemsG. Composite Moment-Frame SystemsH. Composite Braced-Frame and Shear-Wall SystemsI. Fabrication and ErectionJ. Quality Control and Quality AssuranceK. Prequalification and Cyclic Qualification Testing Provisions
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Chapter Reorganization
Preface to AISC 341-10
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AISC 341-05 - Part I1. Scope2. Referenced Specifications,
Codes, and Standards
AISC 341-10A. General Requirements
B. General Design Requirements3. General Seismic Design4. Loads, Load Combinations,
Nominal Strengths
A. General RequirementsI. Fabrication and Erection
5. Structural Drawings and Specifications, Shop Drawings, and Erection Drawings
6. Materials
Chapter Reorganization
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AISC 341-05 - Part I7. Connections, Joints, and
Fasteners
AISC 341-10D. General Member and
Connection Design Requirements
I. Fabrication and Erection
8. Members D. General Member and Connection Design Requirements
7.3b. Demand Critical Welds A. General RequirementsA3.4b. AWS D1.8
Chapter Reorganization
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AISC 341-05 - Part I AISC 341-10
9. Special Moment Frames10. Intermediate Moment Frames11. Ordinary Moment Frames12. Special Truss Moment
Frames
E. Moment-Frame SystemsE3. Special Moment FramesE2. Intermediate Moment FramesE1. Ordinary Moment FramesE4. Special Truss Moment
FramesE5. Ordinary Cantilever Column
SystemsE6. Special Cantilever Column
Systems
Chapter Reorganization
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AISC 341-05 - Part I
13. Special Concentrically Braced Frames
14. Ordinary Concentrically Braced Frames
15. Eccentrically Braced Frames16. Buckling-Restrained Braced
Frames17. Special Plate Shear Walls
AISC 341-10F. Braced-Frame and Shear-
Wall SystemsF2. Special Concentrically Braced FramesF1. Ordinary Concentrically Braced FramesF3. Eccentrically Braced FramesF4. Buckling-Restrained Braced FramesF5. Special Plate Shear Walls
Chapter Reorganization
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AISC 341-05 - Part I18: Quality Assurance Plan
(Appendix Q)
AISC 341-10J. Quality Control and Quality Assurance
Appendix P: Connection PrequalificationAppendix S: Qualifying Cyclic Tests of Beam-to-Column and Link-to-Column ConnectionsAppendix T: Qualifying Cyclic Tests of BRBF Braces
K. Prequalification and Cyclic Qualification Testing Provisions
Chapter Reorganization
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J. Quality Control and Quality Assurance No significant change within
AISC 341 2012 IBC: Special Inspection
1705.2.1 Structural steel. Special inspection provisions
for structural steel are now by reference to AISC 360-10 (see Chapter N)
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Appendix X: Weld Metal/Welding Procedure Specification Notch Toughness Verification Test
AISC 341-05 - Part I
Appendix W: Welding Provisions
AISC 341-10
A. General RequirementsA4.4a. AWS D1.8
I. Fabrication and Erection
Appendix R. Seismic Design Coefficients and Approximate Period Parameters
A. General RequirementsA4.4a. AWS D1.8
REMOVED
Chapter Reorganization
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AISC 341-05 - Part II1. Scope2. Referenced Specifications,
Codes, and Standards
AISC 341-10A. General Requirements
B. General Design Requirements3. General Seismic Design4. Loads, Load Combinations,
Nominal Strengths
D. General Member and Connection Design Requirements
5. Materials
6. Composite Members7. Composite Connections
A. General Requirements
Chapter Reorganization
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G. Composite Moment-Frame Systems
G4. Composite Partially Restrained Moment Frames
G3. Composite Special Moment Frames
G2. Composite Intermediate Moment Frames
G1. Composite Ordinary Moment Frames
AISC 341-05 - Part II
8. Composite Partially Restrained Moment Frames
9. Composite Special Moment Frames
10. Composite Intermediate Moment Frames
11. Composite Ordinary Moment Frames
AISC 341-10
Chapter Reorganization
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H. Composite Braced-Frame and Shear Wall Systems
H2. Composite Special Concentrically Braced Frames
H1. Composite Ordinary Braced Frames
H3. Composite Eccentrically Braced Frames
AISC 341-05 - Part II
12. Composite Special Concentrically Braced Frames
13. Composite Ordinary Braced Frames
14. Composite Eccentrically Braced Frames
AISC 341-10
Chapter Reorganization
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H. Composite Braced-Frame and Shear Wall Systems
H4. Composite Partially Restrained Moment Frames
H5. Composite Special Moment Frames
H6. Composite Intermediate Moment Frames
AISC 341-05 - Part II
15. Ordinary Reinforced Concrete Shear Walls Composite with Structural Steel Elements
16. Special Reinforced Concrete Shear Walls Composite with Structural Steel Elements
17. Composite Steel Plate Shear Walls
AISC 341-10
Chapter Reorganization
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AISC 341-05 - Part II18. Structural Design Drawings
and Specifications, Shop Drawings, and Erection Drawings
AISC 341-10A. General RequirementsI. Fabrication and Erection
19. Quality Assurance Plan J. Quality Control and Quality Assurance
Chapter Reorganization
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Structural System Chapters: E - H
Consistent organization of system requirements1. Scope2. Basis of Design
Intended response/inelasticity
3. Analysis4. System Requirements
Stability Bracing Moment Ratio for SMF Special Configurations (V- or Inverted V-Bracing)
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Structural System Chapters: E - H
Consistent organization of system requirements5. Member Requirements
Width-to-thickness limitations Protected Zone
6. Connections Demand Critical welds Column Splices Required Connection Strengths
7. Additional requirements
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ROADMAP
Chapter Reorganization
General Applicable Building Code Demand Critical Welds Amplified Seismic Loads
Members Connections Moment Frames Braced Frames
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A. General Requirements
A1. Scope These Provisions shall apply unless specifically
exempted by the applicable building code. Applies to buildings and other structures
Other structures are designed, fabricated and erected like buildings with vertical and lateral systems similar to buildings
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Including Supplement No. 1
Applicable Building Code
AISC 341-05
Including Supplement No. 1
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Including Supplement No. 1
Applicable Building Code
AISC 341-05
Including Supplements No. 1 and No. 2
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Applicable Building Code Loads and load combinations Systems and limitations Design requirements Requirements for steel design codes
AISC 360-10 AISC 341-10
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ASCE 7-10 Table 12.2-1
AISC 341 NOT required
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Demand Critical Welds
A. General Requirements
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A. General Requirements
Demand Critical Weld Requirements
SystemColumn Beam Flange
to Column Flange
Beam Web/Shear Plate to Column
FlangeBases Splices
OMF (E1.6a.) ---- ---- CJP CJPIMF (E2.6a.) All Types Groove CJP CJPSMF (E3.6a.) All Types Groove CJP CJP
STMF (E4.6a.) All Types Groove ---- ----OCCS (E5.6a.) ---- ---- ---- ----SCCS (E6.6a.) All Types Groove ---- ----
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A. General Requirements
Demand Critical Weld Requirements
SystemColumn Link Flange or
Web to ColumnBuilt-up Link: Web to FlangeBases Splices
OCBF (F1) ---- ---- ---- ----SCBF (F2.6a.) All Types Groove ---- ----EBF (F3.6a.) All Types Groove All Types All Types
BRBF (F4.6a.) All Types Groove ---- ----SPSW (F5.6a.) All Types Groove ---- ----
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B. General Design Requirements
B2. Load and Load Combinations
12.4.3 Seismic Load Combinations Including Overstrength FactorEm = Emh + Ev
= 0QE 0.2SDSD
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B. General Design Requirements
B2. Load and Load Combinations (with Amplified Seismic Loads)
AISC 341-10 Provisions
Emh in ASCE 7 Section 12.4.3
Requires Amplified Seismic Load 0QE
Defines EDefines Emh
Capacity Analysis
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B. General Design Requirements
AISC 341-05: Defines E (neglects
vertical effect) E = Em = Emh + 0
AISC 341-10: Defines Emh Em = Emh + Ev = Emh +
0.2SDSD
B2. Load and Load Combinations (with Amplified Seismic Loads)
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C. Analysis
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C. Analysis
C1. General Requirements: Analysis shall conform to the applicable building code Elastic analysis of composite systems shall consider cracked
sections
C2. Additional Requirements: Additional analysis as required for each structural system shall be
performed
C3. Nonlinear Analysis: When used, nonlinear analysis shall conform to Chapter 16 of
ASCE 7
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BREAK!
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If you have any questions, please type them in
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Question and Answer Session
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If you have any questions, please type them in
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ROADMAP
Chapter Reorganization General
Members Ductility Classification Required Axial Strength of Columns
Connections Moment Frames Braced Frames
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D1. General Member Requirements
D1.1 Classifications of Sections for Ductility D1.1b Width-to-Thickness Limitations
Highly Ductile Moderately Ductile
D1.2 Stability Bracing of Beams Highly Ductile Moderately Ductile
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D1. General Member Requirements
D1.1b Width-to-Thickness Limitations Highly Ductile
replaces Seismically Compact (AISC 341-05)
Moderately Ductile replaces Compact (AISC 360-05)
Courtesy of S. MahinU.C. Berkeley, 2004
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AISC 341-05: Seismically Compact
Footnotes indicated to which members and structural systems each row applies
Type of member
force
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AISC 341-05: Compact
Type of member
force
AISC 360-05Compact Limits
Compact does not apply for Uniform Compression
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D1.1b Width-to-Thickness Limitations
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D1.1b Width-to-Thickness Limitations
D1.1b Width-to-Thickness Limitations Limits are based on:
Element type (flange, web, etc.)Section type (I-shaped, HSS, etc)Member type (beam, column, brace)
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D1.1b Width-to-Thickness Limitations: Table D1.1
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D1.1b Width-to-Thickness Limitations
Member ductility classificationSystem Beam Column Brace Link
OMF (E1) --- --- --- ---IMF (E2.5a) Moderately Moderately --- ---SMF (E3.5a) Highly Highly --- ---
OCBF (F1.5a) --- ---SeismicallyCompact
Moderately---
SCBF (F2.5a) Moderately Highly Highly ---EBF (F3.5a) Moderately Highly Moderately Highly
BRBF (F4.5a) Highly Highly --- ---SPSW (F5.5a) Highly Highly --- ---
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Beams and columns: b/t limit comparison
*Includes flanges of built-up I-shapes, channels and tees; legs of single angles or double angles with separators; outstanding legs in pairs of angles in continuous contact**Includes webs of channels and built-up I-shapes
D1.1b Width-to-Thickness Limitations: Highly Ductile
Table indicates factor on (E/Fy)Element AISC 341-05Seismically Compact
AISC 341-10Highly Ductile
Flanges of I-Shapes* 0.30 0.30
Web of I-Shapes**
Ca 0.1253.14(1-1.54Ca)
Ca 0.1252.45(1-0.93Ca)
Ca > 0.1251.12(2.33-Ca) 1.49
Ca > 0.1250.77(2.93-Ca) 1.49
SMFFlanges of Boxed I-Shaped and Built-Up Box Columns
NA 0.60
0.30(E/Fy)
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D1.1b Width-to-Thickness Limitations: Highly Ductile
W18X40 = 2.11
W18X65 = 1.48
Fy = 50 ksi
Ca = Pu/(cPy) (LRFD)Ca = (cPa)/Py (ASD)
Webs of I-Shaped Beams and Columns: Highly Ductile h
d/(E
/Fy)
3.14
2.52.452.16
1.49
2010: Highly Ductile
2005: Seismically Compact
2005: Seismically Compact for Flexure of SMF Beams
0.125 1.0(b/t)
(E/Fy) =
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D1.1b Width-to-Thickness Limitations: Highly Ductile SCBF braces: b/t ratio limit comparison
*Includes flanges of built-up I-shapes, channels and tees; legs of single angles or double angles with separators; outstanding legs in pairs of angles in continuous contact**Includes webs of channels and built-up I-shapes ***Includes walls built-up box sections and side plates of boxed I-shaped sections
Table indicates factor on (E/Fy)Element AISC 341-05Seismically Compact
AISC 341-10Highly Ductile
Flanges of I-Shapes* 0.30 0.30
Webs of I-Shapes**
Ca 0.1253.14(1-1.54Ca) 1.49Ca > 0.125
1.12(2.33-Ca) 1.49Rect. HSS Walls*** 0.64 0.55
Rnd. HSS Walls 0.044 0.038Stems of tees 0.30 0.30
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D1.1b Width-to-Thickness Limitations: SCBF Braces
Fy = 50 ksi
Ca = Pu/(cPy) (LRFD)Ca = (cPa)/Py (ASD)
Webs of I-Shaped Braces: Highly Ductile h
d/(E
/Fy)
3.14
2.50
1.49
2010: Highly Ductile
2005: Seismically Compact
0.125 1.0
W10X17 = 1.53
W12X45 = 1.21
(b/t)(E/Fy)
=
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Beams and columns: b/t ratio limit comparison
*Includes flanges of built-up I-shapes, channels and tees; legs of single angles or double angles with separators; outstanding legs in pairs of angles in continuous contact**Includes webs of channels and built-up I-shapes
D1.1b Width-to-Thickness Limitations: Moderately Ductile
Table indicates factor on (E/Fy)Element AISC 360-05
CompactAISC 341-10
Moderately Ductile
Flanges of I-Shapes* 0.38 (Flexure)0.56 (Compression) 0.38
Web of I-Shapes** 1.49 (Compression)3.76 (Flexure)
Ca 0.1253.76(1-2.75Ca)
Ca > 0.1251.12(2.33-Ca) 1.49
IMFFlanges of Boxed I-Shaped and Built-Up Box Columns
NA 0.55
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D1.1b Width-to-Thickness Limitations: Moderately Ductile
Fy = 50 ksi
Ca = Pu/(cPy) (LRFD)Ca = (cPa)/Py (ASD)
Webs of I-Shaped Beams and Columns: Moderately Ductile h
d/(E
/Fy)
3.76
2.50
1.49
2010: Moderately Ductile
2005: NonCompact for Compression
0.125 1.0
2005: Compact for Flexure
W18X40 = 2.11
W18X65 = 1.48
(b/t)(E/Fy)
=
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D1.1b Width-to-Thickness Limitations: Moderately Ductile EBF braces: b/t ratio limit comparison
*Includes flanges of built-up I-shapes, channels and tees; legs of single angles or double angles with separators; outstanding legs in pairs of angles in continuous contact**Includes webs of channels and built-up I-shapes ***Includes walls built-up box sections and side plates of boxed I-shaped sections
Table indicates factor on (E/Fy)Element AISC 360-05
CompactAISC 341-10
Moderately Ductile
Flanges of I-Shapes* 0.38 (Flexure)0.56 (Compression) 0.38
Webs of I-Shapes** 1.49 (Compression)3.76 (Flexure) 1.49Rect. HSS Walls*** 1.12 0.64
Rnd. HSS Walls 0.07 (Flexure)0.11 (Compression) 0.044
Stems of tees 0.75 0.38
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D1.1b Width-to-Thickness Limitations: OCBF Braces OCBF braces: b/t ratio limit comparison:
*Includes flanges of built-up I-shapes, channels and tees; legs of single angles or double angles with separators; outstanding legs in pairs of angles in continuous contact**Includes webs of channels and built-up I-shapes
Table indicates factor on (E/Fy)Element AISC 341-05Seismically Compact
AISC 341-10Moderately Ductile
Flanges of I-Shapes* 0.30 0.38
Webs of I-Shapes*
Ca 0.1253.14(1-1.54Ca) 1.49Ca > 0.125
1.12(2.33-Ca) 1.49Rect. HSS Walls 0.64 0.64Rnd. HSS Walls 0.044 0.044Stems of tees 0.30 0.38
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D1.1b Width-to-Thickness Limitations: OCBF Braces
Fy = 50 ksi
Ca = Pu/(cPy) (LRFD)Ca = (cPa)/Py (ASD)
Webs of I-Shaped Braces: OCBF Moderately Ductile
hd/
(E/F
y)
3.14
2.50
1.49
2010: Moderately Ductile
2005: Seismically Compact
0.125 1.0
W12X26 = 1.96
W12X35 = 1.48
(b/t)(E/Fy)
=
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D1. General Member Requirements
D1.2 Stability Bracing of Beams Maximum unbraced length for Highly Ductile and
Moderately Ductile beams Strength and stiffness of braces per Appendix 6 of
AISC 360
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D1.2 Stability Bracing of Beams
Maximum unbraced length of beams
*Beams in V or Inverted-V systems only
Member AISC 341-05, Lb AISC 341-10, Lb
SMF Beams (E2.4a) 0.086ry(E/Fy)Highly Ductile0.086ry(E/Fy)
IMF Beams (E3.4b)SPSW HBE (F5.4c) 0.17ry(E/Fy)
Moderately Ductile0.17ry(E/Fy)
SCBF Beams* (F2.4b)BRBF Beams* (F4.4a) [0.12+0.076(M1/M2)](E/Fy)ry
Moderately Ductile0.17ry(E/Fy)
OCBF Beams* (F1) [0.12+0.076(M1/M2)](E/Fy)ry NONE
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D1.2 Stability Bracing of Beams
Beams in V- or Inverted V-Braced Frames
M1/M2
L b/[(E
/Fy)r
y]
AISC 341-05 (Appendix 1 of AISC 360-05)Lb = [0.12+0.076(M1/M2)](E/Fy)ry
AISC 341-10: Moderately DuctileLb = 0.17(E/Fy)ry
0.196
0.120
0.044
-1.0 1.000
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D1.4 Columns
All SFRS columns now are required to use amplified seismic load combinations to determine Pr in the absence of moments
AISC 341-05LRFD
Pu/cPn > 0.4
ASDcPa/Pn > 0.4
Amplified Seismic Load Combinations
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ROADMAP
Chapter Reorganization General Members
Connections Column Splices Column Bases/Anchorage
Moment Frames Braced Frames
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D2.5. Column Splices: SFRS
Seismic Force Resisting Column Splices: Increased required strength More restrictions on partial
joint penetration groove welds (PJP)
Push towards complete joint penetration groove welds (CJP)
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D2.5. Column Splices: SFRS
D2.5b. Required Strength: largest of Required strength of the column Effect of amplified seismic loads Structural system requirements
D2.5c. Required Shear Strength: greater of Required strength from D2.5.b Mpc/H (LRFD) or Mpc/(1.5H) (ASD)
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SFRS Column Splices: Table Notes
Mr, Vr, Pr are required strengths of the splice Mpc = lesser nominal plastic flexural strength Mn = lesser nominal flexural strength Mpc = sum of nominal plastic flexural strengths H = story height Hc = clear story height 0E = Effect of Amplified Seismic Load Combinations Mr_col, Vr_col, Pr_col are required strengths of the column Special additional requirements apply for splices in net
tension
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D2.5 Column SplicesRequired Strength for SFRS: LRFD
System WeldsMr Vr Pr
Largest of Mr_col, 0E, and
Largest of Vr_col,0E, Mpc/H, and
Largest of Pr_col, 0E, and
OMF (E1) ---- ---- ---- ----
IMF (E2.6g) No PJP Bolted: RyFyZx Mpc/H ----
SMF (E3.6g) No PJP Bolted: RyFyZx Mpc/H ----
STMF (E4.6c) No PJP Bolted: RyFyZx Mpc/H ----
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D2.5 Column SplicesRequired Strength for SFRS: LRFD
System WeldsMr Vr Pr
Largest of Mr_col, 0E, and
Largest of Vr_col,0E, Mpc/H, and
Largest of Pr_col, 0E, and
OCBF (F1) ---- ---- ---- ----
SCBF (F2.6d) No PJP Mn/2 Mpc/Hc ----
EBF (F3.6d) No PJP Mn/2 Mpc/Hc ----
BRBF (F4.6d) No PJP Mn/2 Mpc/Hc ----
SPSW (F5.6d) No PJP Mn/2 Mpc/Hc ----
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D2.5 Column SplicesRequired Strength for SFRS: ASD
System Welds
Mr Vr Pr
Largest of Mr_col, 0E, and
Largest of Vr_col,0E, Mpc/(1.5H),
and
Largest of Pr_col, 0E, and
OMF (E1) ---- ---- ---- ----
IMF (E2.6g) No PJP Bolted: RyFyZx/1.5 Mpc/(1.5H) ----
SMF (E3.6g) No PJP Bolted: RyFyZx/1.5 Mpc/(1.5H) ----
STMF (E4.6c) No PJP Bolted: RyFyZx/1.5 Mpc/(1.5H) ----
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D2.5 Column SplicesRequired Strength for SFRS: ASD
System Welds
Mr Vr Pr
Largest of Mr_col, 0E, and
Largest of Vr_col,0E, Mpc/(1.5H),
and
Largest of Pr_col, 0E, and
OCBF (F1) ---- ---- ---- ----
SCBF (F2.6d) No PJP Mn/2 Mpc/(1.5Hc) ----
EBF (F3.6d) No PJP Mn/2 Mpc/(1.5Hc) ----
BRBF (F4.6d) No PJP Mn/2 Mpc/(1.5Hc) ----
SPSW (F5.6d) No PJP Mn/2 Mpc/(1.5Hc) ----
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D2.6 Column Bases
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D2.6 Column Bases: SFRS
D2.6a Required Axial Strength: Sum of vertical components: Braces: required member connection strength Columns: greater of
Required member strength Axial load from 0E combinations Required axial strength of column splices
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Axial: OCBF or SCBF - LRFD
D2.6 Column Bases: SFRS
T = RyFYAg orC = 1.1(1.14FcreAg)
Pr_col 0E
Pr = vertical components
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D2.6 Column Bases: SFRS
T = RyFYAg
Pr_col 0EC = 0.3[(1.14FcreAg)]
Axial: SCBF w/ Compression Buckling - LRFD
Pr = vertical components
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D2.6 Column Bases: SFRSLRFD Example Example member vs. connection required strength
SCBF: A500 Gr B; Fy = 46 ksi; Ry = 1.4; KL = 19 ft
0 = 2 for SCBF
Brace KL/r Pn RyFyAg (RyFyAg)/PnHSS8x8x5/8 76.3 459 kips 1056 kips 2.30
HSS6x6x1/2 102 200 kips 627 kips 3.14
HSS4x4x5/16 163 39.6 kips 264 kips 6.66
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D2.6 Column Bases: SFRS
D2.6b Required shear strength: Sum of horizontal components: Braces: required connection strength Columns: greater of
Shear load from 0E combinations 2RyFyZx/H (LRFD) (2/1.5)RyFyZx/H (ASD) Required shear strength of column splices
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D2.6 Column Bases: SFRS
D2.6b Required Shear Strength - LRFD
System
AISC 341-05 (8.5b) AISC 341-10
Lesser of2RyFyZx/H, 0E, and
Greatest of Vr_col, 0E, Mpc/H, and
OMF (E1), OCBF (F1) ---- ----IMF (E2.6g), SMF (E3.6g),
STMF (E4.6c) ---- Mpc/H
SCBF (F2.6d), EBF (F3.6d), BRBF (F4.6d), SPSW (F5.6d) ---- Mpc/Hc
Mpc/Hc = Mpc/Hc = FyZx/Hc 2RyFyZx/HMpc/Hc 0E
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D2.6 Column Bases: SFRS
T = RyFYAgLargest ofVr_col, 0EMpc/Hc
C = 1.1(1.14FcreAg)
Shear: SCBF - LRFD
Vr = horizontal components
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D2.6 Column Bases: SFRS
D2.6b Required Shear Strength - ASD
System
AISC 341-05 (8.5b) AISC 341-10
Lesser of(2/1.5)RyFyZx/H, 0E
Greatest of Vr_col, 0E, Mpc/(1.5H)
OMF (E1), OCBF (F1) ---- ----
IMF (E2.6g), SMF (E3.6g), STMF (E4.6c) ---- Mpc/(1.5H)
SCBF (F2.6d), EBF (F3.6d), BRBF (F4.6d), SPSW (F5.6d) ---- Mpc/(1.5Hc)
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D2.6 Column Bases: SFRS
D2.6c Required Flexural Strength: Sum of flexural components: Braces: required connection strength Columns: lesser of
1.1RyFyZ (LRFD) or (1.1/1.5) RyFyZ (ASD) Moment from 0E combinations
User Note: Ignore moments for pinned bases
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D2.6 Column Bases: Non-SFRS
D2.6b Required Shear Strength: Non-SFRS Columns: Required shear strength of column splices
Mpc/H (LRFD) or Mpc/(1.5H) (ASD)
VrMpc
Vr
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D2.6 Column Bases: Anchorage
AISC 360 and 341
ACI 318 Appendix D
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D2.6 Column Bases: Anchorage
AISC 341-10 Section D2.6 Exception: The special requirements in ACI 318,
Appendix D for regions of moderate or high seismic risk, or for structures assigned to intermediate or high seismic performance or design categories need not apply.
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*ACI 318-11 no longer applies a 0.75 factor on shear strength
AISC 341 and ACI 318 Appendix D.
Design for AISC 341 Required StrengthsCodes and Standards
0.75 Strength Factor (0.75Nn)
Ductility RequirementsAppendix D.
AISC 341-052006 IBC: ACI 318-052009 IBC: ACI 318-08
D.3.3.3Exempted
D.3.3.4Exempted
AISC 341-102012 IBC: ACI 318-11
D.3.3.4.4 Tension*: Applied to concrete
failure modes
D.3.3.4.3 - Tension:Option (c) or (d) satisfied
D.3.3.5.3 Shear:Option (b) or (c) satisfied
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BREAK!
If you are encountering technical difficulties, please call (847) 991-2700
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- 90 -
Question and Answer Session
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ROADMAP
Chapter Reorganization General Members Connections
Moment Frames Prequalified Connections Cantilever Column Systems
Braced Frames
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E. Moment-Frame Systems
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E. Moment-Frame Systems
Summary of changes Ordinary Moment Frames
Text revised to allow use of non wide-flange members Continuity plate requirements removed (E1.6b.)
Intermediate and Special Moment Frames Prequalified connections added to AISC 358-10
Ordinary Cantilever Column Systems (OCCS) added Special Cantilever Column Systems (SCCS) added
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Prequalified ConnectionsAISC 358-10
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Prequalified ConnectionsAISC 358-10
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Extended End-Plate
Prequalified ConnectionsAISC 358-05Reduced Beam Section
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Welded Unreinforced Flange Welded Web (WUF-W)
Prequalified ConnectionsAISC 358-05 with Supplement No. 1Bolted Flange Plate
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Prequalified ConnectionsAISC 358-05 with Supplement No. 1Kaiser Bolted Bracket
By Steel Cast Connections, LLC
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Conxtech CONXL
Prequalified ConnectionsAISC 358-10 with Supplement No. 1
By ConXtech Inc.
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E5 and E6. Cantilever Column Systems
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Cantilever Column Systems
New to AISC 341-10 ASCE 7-10:
Table 12.2-1: OCCS: R= 1.5, Limited to 35 ft and SDC B and C SCCS: R = 2.5, Limited to 35 ft in all SDC
12.2.5.2: Required axial strength for seismic load combinations, shall not
exceed 15% of available axial strength, Pr 0.15Pc Foundations used for overturning resistance shall be designed to
resist amplified seismic load combinations
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E5. Ordinary Cantilever Column Systems E5.2. Provides minimal inelastic drift capacity
through flexural yielding of the columns
Flexural yielding of columns
E5.4a. Axial LoadBased on amplified seismic
load combinationsFor seismic load
combinations, Prc 0.15Pc
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E6. Special Cantilever Column Systems
E6.2. Provides limited inelastic drift capacity through flexural yielding of the columns
Flexural yielding of columns E6.4a. Axial Load
Based on amplified seismic load combinations
For seismic load combinations, Prc 0.15Pc E6.4b. Unbraced length: Moderately Ductile E6.5a. b/t limitations: Highly Ductile E6.5c. Protected Zone: 2dc from column base
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ROADMAP
Chapter Reorganization General Members Connections Moment Frames
Braced Frames Connection Deformation Compatibility Capacity Analysis
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F. Braced-Frame and Shear-Wall Systems
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F. Braced-Frame and Shear-Wall Systems Summary of Changes
Ordinary Concentrically Braced Frames F1.4b. K-Braced frames prohibited
Special Concentrically Braced Frames F2.3. Analysis requirements added F2.6b. Connection deformation compatibility requirement added F2.5b(1). Brace slenderness ratio limit relaxed from Kl/r 4(E/Fy)
to Kl/r 200 F2.5b(3). Effective net area requirements for braces edited
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F. Deformation Compatibility
F2.6b. Beam-to-Column Connections: Brace connects to beam and column Provide simple connection per B3.6a. of AISC 360 Design connection for Mr; lesser of:
1.1RyMp_bm (LRFD) or (1.1/1.5)RyMp_bm (ASD) 1.1RyFyZcol (LRFD) or (1.1/1.5)RyFyZcol (ASD)Welds are Demand Critical
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F. Deformation Compatibility
Provide simple connection per B3.6a. of AISC 360
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F2. Special Concentrically Braced Frames
F2.3. Analysis Determine required
strengths of beams, columns, and connections using capacity analysis
Capture large forces caused by post-elastic behavior of braces
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F2.3. SCBF Analysis
Two analyses to determine Emh1. Expected strength
Brace in Tension - consider expected strengthBrace in Compression - consider expected strength
2. Post-Buckling strengthBrace in Tension - consider expected strengthBrace in Compression - consider post-buckling strength
It is permitted to neglect flexural forces resulting from seismic drift.
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F2.3. SCBF Analysis
Braces in Tension or Compression? Neglect the effects of gravity
loads Consider only the first mode of
deflection
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Expected Strength
Expected strength in compression:
Cexp = Min RyFyAg1.14Fcre
Expected strength in tension:Texp = RyFyAg
Fcre = Fcr with RyFy
F2.3. SCBF Expected Strength Analysis
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Expected StrengthElastic
Compression
Tension
F2.3. SCBF Expected Strength Analysis
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F2.3. SCBF Expected Strength Analysis
Expected StrengthElastic
Shear
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Post-Buckling
Post-Buckling strength in compression:
Cpb = 0.3*Min RyFyAg1.14Fcre
Expected strength in tension:Texp = RyFyAg
Fcre = Fcr with RyFy
F2.3. SCBF Post-Buckling Analysis
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F2.3. SCBF Post-Buckling Analysis
Post-BucklingElastic
Compression
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F2.3. SCBF Post-Buckling Analysis
Compression
Uplift
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F2.3. SCBF Post-Buckling Analysis
Unbalanced shear force
AISC 341-05 considered this force
Post-Buckling
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F3. Eccentrically Braced Frames
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F3. Eccentrically Braced Frames
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F. Braced-Frame and Shear-Wall Systems Summary of Changes
Eccentrically Brace Frames F3.3. Analysis requirements revised F3.5b(1). Built-up box sections allowed (no HSS) F3.6b. Connection deformation compatibility requirement added
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F3. Eccentrically Braced Frames
F3.3 Analysis Emh = forces in beams, columns, braces, and
connections when ALL links reach their adjusted shear strength
Adjusted shear strength I-shaped links: 1.25RyVnBox links: 1.40RyVn
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F3. Eccentrically Braced Frames
I-Shapes: 1.25RyVnor
Boxes: 1.40RyVn
Determine forces in beams, columns,
braces, and connections
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F3. Eccentrically Braced Frames
F3.3 Analysis Permitted to take Emh = 0.88 times forces from
analysis for: Beams outside link Columns in frames with 3 or more stories
Permitted to neglect effects of seismic drifts on the moments
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F3. Eccentrically Braced Frames
Required Strength in AISC 341-05 15.6a. Diagonal Brace
E = forces in brace when shear in link reaches 1.25RyVn 15.6b. Beam Outside Link
E = forces in brace when shear in link reaches 1.1RyVn 15.8. Columns
E = forces in brace when shear in link reaches 1.1RyVn in ALL levels above the column
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F3. Eccentrically Braced Frames
Effective shear in links
ElementAISC 341-05
I-Shaped LinksAISC 341-10
I-Shaped LinksAISC 341-10Box Links
Braces 1.25RyVn 1.25RyVn 1.40RyVn
Beams 1.10RyVn0.88*(1.25RyVn) =
1.10RyVn0.88*(1.40RyVn) =
1.23RyVnColumns < 3
stories1.10RyVn 1.25RyVn 1.40RyVn
Columns 3 stories
1.10RyVn0.88*(1.25RyVn) =
1.10RyVn0.88*(1.40RyVn) =
1.23RyVn
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F3. Eccentrically Braced Frames
Required Strength in AISC 341-05 15.4 Link-to-Column Connections
Must be tested or prequalified
15.6c. Bracing Connections At least required strength of brace (when shear in link reaches
1.25RyVn) 15.7. Beam-to-Column Connections
At least required strength of beam (when shear in link reaches 1.1RyVn)
If moment connection, meet OMF requirements
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F3. Eccentrically Braced Frames
Required Connection Strengths F3.3. Required connection strengths are determined
from the same capacity analysis as the members F3.6e. Link-to-Column connections
Must be tested or prequalified
Beam-to-column moment connections must meet OMF requirements
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F. Braced-Frame and Shear-Wall Systems Summary of Changes
Buckling-Restrained Braced Frames F4.3. Analysis requirements added F4.6b. Connection deformation compatibility requirement added
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F. Braced-Frame and Shear-Wall Systems Summary of Changes
Special Plate Shear Walls F5.4a. Horizontal Boundary Element stiffness
minimum added F5.4b. Beam-Column moment ratio limit added F5.5c. Protected Zones added F5.7. Requirements for perforated webs and
corner cut-outs added
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Key Points
Reorganized chapters for consistency with AISC 360
Increased protection of critical locations
Added new systems and connections
Provided consistent capacity analysis requirements
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Resources
Download AISC 341-10 FREE from www.aisc.org/FreePubs Commentary to AISC 341-10
Download AISC 358-10 FREE from www.aisc.org/FreePubs AISC Steel Solutions Center
Free technical support email: [email protected] 2010 AISC T.R. Higgins Award Lecture by James O. Malley
The AISC Seismic Provisions: Past, Present, and Future http://www.aisc.org/content.aspx?id=572
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Resources
The AISC Seismic Design Manual, 2nd, Edition
www.aisc.org/Store
- 134 -
Question and Answer Session
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Thank You!!
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