short course imf and smf connection

8/14/2019 Short Course IMF and SMF Connection

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ANSI/AISC 358-10


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ANSI/AISC 358-10

Chapters 1-4

1. General

2. Design Requirements

3. Welding Requirements

4. Bolting Requirements

All 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 limitations

applicable to specific connection.

(Additional requirements in Chp. 2 on welding for built-up beams and properties of built-up columns.)


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ANSI/AISC 358-10

Chapters 1-4

1. General


2.4.1 For connection design:

fd= 1.00 for ductilelimit states

fn= 0.90 for nonductile limit states

For available strengths calculated in accordance with

this Standard.


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ANSI/AISC 358-10

Chapters 1-4

1. General


2.4.3 Probable Maximum Moment at Plastic Hinge

Effective plastic sectionmodulus of section (or

connection) at location of

plastic hinge

Factor to account forpeak connection

strength


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ANSI/AISC 358-10

Chapters 1-4

1. General


2.4.3 Probable Maximum Moment at Plastic Hinge

Attempts to account forstrain hardening, local

restraint, additional

reinforcement, other

connection conditions

Unless otherwise specifically

indicated in this Standard


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ANSI/AISC 358-10

Chapters 1-4

1. General



Points to AISC Seismic Provisions for filler metals and

welding procedures.Specifics for weld tabs and backing bars at beam-to-

column and continuity plate-to-column joints. Also,

requirements for continuity plate welds.

(Also provides information for prohibitedwelds (e.g.,

tack welds to connect backing bar to beam flange),

including how to repair if welded in error).


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ANSI/AISC 358-10

Chapters 1-4

1. General



4. Bolting Requirements

Points to other standards for fastener and installation

requirements.

Refers to AISC Seismic Provisions for quality control

and quality assurance.


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RBS Concept:

Trim Beam Flanges Near

Connection

Reduce Moment at

Connection

Force Plastic Hinge Away

from Connection

Reduced Beam Section (RBS) Moment Connection


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Example of laboratory performance of an RBS connection:


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Whitewashed connection prior to testing:


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Whitewashed connection prior to testing:


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Connection at 0.02 radian......


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-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

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)

BendingM

oment(kN-m)

RBS Connection

Mp

Mp


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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


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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


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ANSI/AISC 358:

Prequalification Requirements for RBS

Beam flange welds: - CJP groove welds- Treat welds as Demand Critical, followAISC

Seismic Provisions

-Weld access hole geometry conforms toAISC

Specification

Beam web to column connection:

- For SMF, use fully welded web connection (CJP

weld between beam web and column flange)

- For IMF, boltedconnection to beam webpermitted if slip-critical and follows restrictions in

Section 5.6


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RBS with weldedweb connection:


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ANSI/AISC 358:

Prequalification Requirements for RBS

Protected Zone


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ANSI/AISC 358:

Prequalification

Requirements for

RBS

Note Section 5.7 for

Fabrication ofFlange Cuts!

(e.g., thermal

cutting tolerances,repair of gouges

and notches)


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Lateral brace at center of RBS - violates Protected Zone


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Examples of RBS Connections.....


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ANSI/AISC 358:

RBS

STEP-BY-STEP


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Bolted Unstiffened and Stiffened Extended End-Plate

Moment Connections

End Plate Connections


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End-Plate Connections

AISC Design Guide

no. 4, 2nd

edition,2003, Murray andSumner

1stedition in 1990

Literature datesback to at least1960s

A number of testsconducted as part ofSAC Joint Venture



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Number of possible limit states:

Flexural yielding of beamsection

Flexural yielding of end plates

Tension of end-plate bolts

Shear failure of end-plate bolts

Etc.

Ensure inelastic deformation ofconnection is achieved by beamyielding

Shear resistance from bolts incompression



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Sumner, et al., 2000




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Sumner, et al., 2000



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End plate and column flange bending strengths are

determined using yield line analysis.


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Unstiffened Flange Stiffened


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Prying Action?

End-Plate connections are required to be

designed as thick plates


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End-Plate

Connections(ANSI/AISC 358-10)

End Plate Connections (ANSI/AISC 358 10)


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End-Plate Connections (ANSI/AISC 358-10)

End Plate Connections (ANSI/AISC 358 10)


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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 greaterfor 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


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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 ingap between column flanges and concrete slab)

(IMF composite slab detailing also adopts these lasttwo requirements; Section 6.9.6)

Connection Detailing (Section 6 9)


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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) andAISCSeismic Provisions

Panel zones and column-beam moment ratios(Section 6.6) refer toAISC Seismic


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End-plate Yield Line Mechanism parameter


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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


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Seismic Behavior BFP

Initial yielding of beam at last bolt away

from column face Slip of flange plate bolts (similar level toyielding in beam flange)

Secondary yielding in panel zoneAs expected moment capacity and strain

hardening occur

Limited yielding of flange plateAt maximum deformation

BFP tests


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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,

Fourth Quarter, 2008.

BFP-3


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BFP-3

Sato, et al., 2008

ANSI/AISC 358


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ANSI/AISC 358:

Section 7.3 Prequalification Limits for BFP



Beam flange: up to 1-inch thick


limited to:


7 or greater for IMF

Lateral bracing requirements and protected zone dimensionsspecified

Concrete slab can be utilized (as specified) for lateral bracing

ANSI/AISC 358


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ANSI/AISC 358:

Section 7.3 Prequalification Limits for BFP, contd

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 ofAISC Seismic Provisions.

Section 7 5 Connection Detailing


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Section 7 .5 Connection Detailing

All connection plates

A36 or A572 Gr. 50

Max. overall thickness ;

may use finger shims or shims

with drilled/punched holes

Limit two bolts per row;

symmetrically placed.

Length of bolt group < beamdepth. Standard holes;

oversized in flange plate

only. No punched holes.CJP groove

welds,

demand-critical, any

backing

removed

A490 bolts, threads

excluded from shear plane,

1-1/8 diameter maximum

Section 7 6 Design Procedure


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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 sectionfracture resistance > yield resistance

W ld d U i f d Fl W ld d W b (WUF W)


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Welded Unreinforced FlangeWelded Web (WUF-W)

ANSI/AISC 358:


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ANSI/AISC 358:

Section 8.3 Prequalification Limits for WUF-W



Beam flange: up to 1-inch thick


limited to:


5 or greater for IMF

Lateral bracing requirements and protected zone dimensionsspecified

Concrete slab can be utilized (as specified) for lateral bracing

ANSI/AISC 358:


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ANSI/AISC 358:

Section 8.3 Prequalification Limits for WUF-W, contd

Beams shall be connected to flange of the column

Column depth: W36 maximum (for rolled shapes)

No limit on weight per foot of columns

Width-thickness ratios (beams and columns), lateral bracing,

panel zones, shall conform to requirements ofAISC Seismic

Provisions.

Column-beam moment ratio as specified for SMF; followingAISC

Seismic Provisionsfor SMF

Section 8 5 Beam Flange-to-Column Flange


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Section 8.5 Beam Flange-to-Column Flange

Welds

Weld access hole geometry

and quality shall conform to

AWS D1.8

CJP welds; demand critical,

conform toAISC SeismicProvisions

Section 8 6


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Section 8.6Beam Web-to-

ColumnConnection

Limitations

Shear tab thickness

equal at least to that

of beam web;

overlap with weldaccess holes as

specified

Section 8.7 Design Procedure WUF-W


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Section 8.7 Design Procedure WUF W

Sh=0 value chosen to simplify the design

calculations.Cprvalue calibrated in combination with Sh=0 to

reflect values (moments at column face) measured

in experiments

short course imf and smf connection

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