ANSI/AISC 358-10
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Desig sign Requ Requiirem rements ents All connections connections in this Standard shall be considered to be fully restrained (Type FR) for purpose of seismic analysis. Rolled wide-flange or built-up members permitted as long as conform to cross section profile limitation limitations s applicable to specific connection. (Additional requirements requirements in Chp. 2 on welding for builtup beams and properties of built-up columns columns.) .) 3. Weldi elding ng Requ Requir irem emen ents ts 4. Bolt Boltin ing g Requ Requir irem emen ents ts
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Desig sign Requ Requiirem rements ents All connections connections in this Standard shall be considered to be fully restrained (Type FR) for purpose of seismic analysis. Rolled wide-flange or built-up members permitted as long as conform to cross section profile limitation limitations s applicable to specific connection. (Additional requirements requirements in Chp. 2 on welding for builtup beams and properties of built-up columns columns.) .) 3. Weldi elding ng Requ Requir irem emen ents ts 4. Bolt Boltin ing g Requ Requir irem emen ents ts
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Desig sign Requ Requiirem rements ents 2.4.1 For connection design:
f d = 1.00 for ductile ductile limit limit states f n = 0.90 for nonductile limit states For available strengths calculated in accordance with this Standard.
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Desig sign Requ Requiirem rements ents 2.4.3 Probable Maximum Moment at Plastic Hinge
Factor to account for peak connection strength
Effective plastic section modulus of section (or connection)) at location of connection plastic hinge
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Desig sign Requ Requiirem rements ents 2.4.3 Probable Maximum Moment at Plastic Hinge
Attempts to to account for strain hardening, local restraint, additional reinforcement, other connection conditions
Unless otherwise specifically indicated in this Standard
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Design Requirements 3. Welding Requirements Points to AISC Seismic Provisions for filler metals and welding procedures. Specifics for weld tabs and backing bars at beam-tocolumn and continuity plate-to-column joints. Also, requirements for continuity plate welds. (Also provides information for prohibited welds (e.g., tack welds to connect backing bar to beam flange), including how to repair if welded in error).
ANSI/AISC 358-10 Chapters 1-4 1. General 2. Design Requirements 3. Welding Requirements 4. Bolting Requirements Points to other standards for fastener and installation requirements. Refers to AISC Seismic Provisions for quality control and quality assurance.
Reduced Beam Section (RBS) Moment Connection
RBS Concept: •
Trim Beam Flanges Near Connection
•
Reduce Moment at Connection
•
Force Plastic Hinge Away from Connection
Example of laboratory performance of an RBS connection:
Whitewashed connection prior to testing:
Whitewashed connection prior to testing:
Connection at
0.02
radian......
Connection at
0.02
radian......
Connection at
0.03
radian......
Connection at
0.04
radian......
5000 4000
Mp
3000 ) m - 2000 N k ( t 1000 n e m 0 o M g n-1000 i d n e-2000 B
-3000
Mp
-4000
RBS Connection
-5000 -0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
Drift Angle (radian)
0.02
0.03
0.04
0.05
ANSI/AISC 358: Section 5.3 Prequalification Limits for RBS
•
Beam depth:
up to W36 (for rolled shapes)
•
Beam weight:
up to 300 lb/ft
•
Beam flange:
up to 1-3/4 inch thick
•
Span:depth
clear span-to-depth ratio of beam limited to: 7 or greater for SMF 5 or greater for IMF
•
Lateral bracing requirements and protected zone dimensions specified
ANSI/AISC 358: Section 5.3 Prequalification Limits for RBS
•
•
•
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) Refer to Chapter 2 and AISC Seismic Provisions for other requirements
ANSI/AISC 358: Prequalification Requirements for RBS Beam flange welds: - CJP groove welds - Treat welds as Demand Critical, follow AISC Seismic Provisions -Weld access hole geometry conforms to AISC Specification Beam web to column connection: - For SMF, use fully welded web connection (CJP weld between beam web and column flange) - For IMF, bolted connection to beam web permitted if slip-critical and follows restrictions in Section 5.6
RBS with welded web connection:
ANSI/AISC 358: Prequalification Requirements for RBS
Protected Zone
ANSI/AISC 358: Prequalification Requirements for RBS
Note Section 5.7 for Fabrication of Flange Cuts! (e.g., thermal cutting tolerances, repair of gouges and notches)
Lateral brace at center of RBS - violates Protected Zone
Examples of RBS Connections.....
ANSI/AISC 358: RBS
STEP-BY-STEP
Bolted Unstiffened and Stiffened Extended End-Plate Moment Connections
End-Plate Connections •
• •
•
AISC Design Guide no. 4, 2nd edition, 2003, Murray and Sumner 1st edition in 1990 Literature dates back to at least 1960s A number of tests conducted as part of SAC Joint Venture
End-Plate Connections •
Number of possible limit states: Flexural yielding of beam section Flexural yielding of end plates Tension of end-plate bolts Shear failure of end-plate bolts Etc. Ensure inelastic deformation of connection is achieved by beam yielding Shear resistance from bolts in compression –
– – – –
•
•
End-Plate Connections
Sumner, et al., 2000
End-Plate Connections
Sumner, et al., 2000
End plate and column flange bending strengths are determined using yield line analysis.
Unstiffened Flange
Stiffened
Prying Action?
End-Plate connections are required to be designed as “thick” plates
End-Plate Connections (ANSI/AISC 358-10)
End-Plate Connections (ANSI/AISC 358-10)
End-Plate Connections (ANSI/AISC 358-10)
• •
•
•
No limit on weight per foot of beams or columns Clear span:depth 7 or greater for SMF, 5 or greater for IMF Column depth limited to beam depth or shallower (also W36 maximum) Protected zone depends on stiffened/unstiffened, beam flange width and depth
End-Plate Connections and Floor Slab •
SMF systems with concrete structural slabs prequalified only if: –
–
–
Nominal beam depth not less than 24 in. (in addition to Section 6.3 requirements) No shear connectors within 1.5 x beam depth from face of connected column flange Concrete slab kept at least 1 in. from both sides of both column flanges (e.g., compressible material in gap between column flanges and concrete slab)
(IMF composite slab detailing also adopts these last two requirements; Section 6.9.6)
Connection Detailing (Section 6.9)
Welding details, etc., in Section 6.9 • (need and requirements for) Continuity plates as outlined in Section 6.10 (Design Procedure) and AISC Seismic Provisions Panel zones and column-beam moment ratios (Section 6.6) refer to AISC Seismic •
•
End-plate Yield Line Mechanism parameter
Bolted Flange Plate (BFP)
BFP only prequalified for SMF with concrete structural slabs if slab kept at least 1” from both sides of both column flanges.
Seismic Behavior BFP •
•
•
Initial yielding of beam at last bolt away from column face Slip of flange plate bolts (similar level to yielding in beam flange) Secondary yielding in panel zone As expected moment capacity and strain hardening occur
–
•
Limited yielding of flange plate At maximum deformation
–
BFP tests
Sato, A., Newell, J.D., Uang, C.-M. “Cyclic Behavior and Seismic Design of Bolted Flange Plate Steel Moment Connections,” AISC Engineering Journal,
BFP-3
Sato, et al., 2008
ANSI/AISC 358: Section 7.3 Prequalification Limits for BFP •
Beam depth:
up to W36 (for rolled shapes)
•
Beam weight:
up to 150 lb/ft
•
Beam flange:
up to 1-inch thick
•
Span:depth
clear span-to-depth ratio of beam limited to: 9 or greater for SMF 7 or greater for IMF
•
•
Lateral bracing requirements and protected zone dimensions specified Concrete slab can be utilized (as specified) for lateral bracing
ANSI/AISC 358: Section 7.3 Prequalification Limits for BFP, cont’d
•
Beams shall be connected to flange of the column
•
Column depth:
W36 maximum (for rolled shapes) W14 maximum if no concrete structural slab
•
•
No limit on weight per foot of columns Width-thickness ratios (beams and columns), lateral bracing, panel zones, and column-beam moment ratios shall conform to requirements of AISC Seismic Provisions.
Section 7 .5 Connection Detailing A490 bolts, threads excluded from shear plane, 1-1/8” diameter maximum
CJP groove welds, demandcritical, any backing removed
All connection plates A36 or A572 Gr. 50
Limit two bolts per row; symmetrically placed. Length of bolt group < beam depth. Standard holes; oversized in flange plate only. No punched holes.
Max. overall thickness ¼”; may use finger shims or shims with drilled/punched holes
Section 7.6 Design Procedure •
More limit states to consider than some other connections - e.g., bolt shear, net section fracture, ensuring that beam flange net section fracture resistance > yield resistance
Welded Unreinforced Flange – Welded Web (WUF-W)
ANSI/AISC 358: Section 8.3 Prequalification Limits for WUF-W •
Beam depth:
up to W36 (for rolled shapes)
•
Beam weight:
up to 150 lb/ft
•
Beam flange:
up to 1-inch thick
•
Span:depth
clear span-to-depth ratio of beam limited to: 7 or greater for SMF 5 or greater for IMF
•
•
Lateral bracing requirements and protected zone dimensions specified Concrete slab can be utilized (as specified) for lateral bracing
ANSI/AISC 358: Section 8.3 Prequalification Limits for WUF-W, cont’d
•
Beams shall be connected to flange of the column
•
Column depth:
•
No limit on weight per foot of columns
•
•
W36 maximum (for rolled shapes)
Width-thickness ratios (beams and columns), lateral bracing, panel zones, shall conform to requirements of AISC Seismic Provisions. Column-beam moment ratio as specified for SMF; following AISC Seismic Provisions for SMF
Section 8.5 Beam Flange-to-Column Flange Welds
CJP welds; demand critical, conform to AISC Seismic Provisions
Weld access hole geometry and quality shall conform to AWS D1.8
Section 8.6 Beam Web-toColumn Connection Limitations Shear tab thickness equal at least to that of beam web; overlap with weld access holes as specified
