2012 01 07 seari welds - structures · pdf filed1.1 structural welding code – steel...

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SEARI - DESIGN OF WELDED CONNECTIONS

SEARIWELDS

Erik Nelson, PEStructures Workshop

Erik Anders Nelson PE SEJan 10, 2012

A. General Information

B. Weld Strength Calculations

C. Weld Symbols

D. Quiz (Discussion)

E. Moment Connections CJP Welds (If Time)

F Sh C ti (U lik l )

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F. Shear Connections (Unlikely)

G. Weld Procedures(Unlikely)

A. General

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D1.1 Structural Welding Code – Steel

• one of the most consulted codes in the world, isproduced by The American Welding Society(AWS) a nonprofit organization with a goal to

Structural WeldingWelding Codes

advance the science, technology andapplication of welding and related joiningdisciplines

D1.5 and D1.8

AISC 360 - The Steel Specification (Ch J and Ch N – New to 2010)

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New to 2010)

AISC 358 - Prequalified Connections for SMF and IMF

AISC 341 – Seismic Provisions (App Q and W)

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Weld Types

1 Fillet

2 Groove2.1 CJP

2.2 PJP

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3 Plug/Slot

Most Common Weld Types

1 Fillet

2.1a Single Bevel2 1b S

85% of All Welds

2 Groove2.1 CJP

2.2 PJP

2.1b SquareEtc

2.2a Single Bevel2.1b Double Bevel2.2c Flare BevelEtc

10% of All Welds

5% of All Welds

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3 Plug/SlotEtc

<1% of All Welds

Fillet Welds

• The most commonly used weld is the fillet weld

Symbolic Profiles

Actual Profiles

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• Fillet welds are theoretically triangular in cross-section

• Fillet welds join two surfaces at approximately right angles to each other in lap, tee, and corner joints

(AISC & NISD 2000)

Groove Welds (CJP/PJP)

Groove welds are specified when a fillet weld is not appropriate

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Groove welds are specified when a fillet weld is not appropriate

• The configuration of the pieces may not permit fillet welding

• A strength greater than that provided by a fillet weld is required

Groove welds are made in the space or groove between the two piecesbeing welded

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Full Penetration Groove WeldsCJP

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Partial Penetration Groove WeldsPJP

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Welding TerminologyLength of Welds

Tack Weld (above left) - A temporary weld used to hold parts in place whilet i fi l ld d

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more extensive, final welds are made

Continuous Weld - A weld which extends continuously from one end of a jointto the other

Stitch Weld (above right) - A series of welds of a specified length that arespaced a specified distance from each other

Weld SizeMulti Pass Welds

Larger weld sizes may require multiple passes to meet the sizerequirement

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Common single pass welds include fillet welds up to and including 5/16inch and thin plate butt welds with no preparation

Common multiple pass welds include single bevel full penetration groovewelds, single bevel partial penetration groove welds, and fillet weldsover 5/16 inch

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Welding Positions

There are four recognized welding positions:

• Flat – The face of the weld is approximately horizontal and weldingis performed from above the joint

• Horizontal – The axis of the weld is horizontal

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• Vertical – The axis is approximately vertical or in the upright position

• Overhead – Welding is performed from below the joint

The flat position is preferred because it is easier and more efficient to weldin this position

B. Weld Strength Calculations

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Weld Capacity

Weld Capacity = Strength x Area

R = F x A

where F = Strength of Weld or Base MetalA = Area (Effective Throat x Width)

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Weld Capacity


ASD: R/Ω = F/Ω x A where Ω = 2 0ASD: R/Ω = F/Ω x A where Ω = 2.0

R = F x ALRFD: Φ R= ΦF x A where Φ = 0.75

where F = Strength of Weld or Base Metal – See J2.5 F = 0.6 x 70ksi = 42 ksi for 70ksi Weld

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(21 ksi for ASD and 31.5 ksi for LRFD)

A = Effective Throat x Width

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Weld Capacity


ASD: R/Ω = F/Ω x A where Ω = 2 0ASD: R/Ω = F/Ω x A where Ω = 2.0

LRFD: Φ R = ΦF x A where Φ = 0.75

where F = Strength of Weld or Base Metal – See J2.5A = Effective Throat x Width

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For Fillet = Leg x 0.707For PJP = Leg – 1/8 (or see Tables J2.1, J2.2)For CJP = Thickness of Thinner MaterialFor Plug/Slot, Area = Area

Fillet Weld Nomenclature

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Strength of Fillet Weld

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Fillet Weld Strength in Shear (Parallel)Throat Dimension = 0.707 (Leg Dim) for strength calculations

Check 1/4” fillet (10” long) LRFDPhi Rn = 0.75 x 0.6 x 70ksi x

= 0 75(0 6)(70ksi)(0 25”)(0 707)(10”)(2sides) = 111 kips= 0.75(0.6)(70ksi)(0.25 )(0.707)(10 )(2sides) = 111 kips

or = 1.392 x 4 x 10” x 2 sides = 111 kips

(For LRFD you can use .75 x .6 x 70 x 0.707/16 = 1.392 k/in per 1/16” fillet)(For ASD you can use .6 x 70 x 0.707/(16 x 2) = 0.928 k/in per 1/16” fillet)

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Fillet Weld Strength

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Fillet Weld Strength in Shear (Perpendicular) 50% Increase for “Tension” Welds

Check 1/4” fillet (20” long) LRFDPhi Rn = 0.75 x 0.6 x 70ksi x Ae

= 0.75(0.6)(70ksi)(0.25”)(0.707)(20”) x 1.5 = 166 kips

(For LRFD you can use .75 x .6 x 70 x 0.707/16 x 1.5 = 1.392 k/in per 1/16” fillet) x 1.5(For ASD you can use .6 x 70 x 0.707/(16 x 2) x 1.5 = 0.928 k/in per 1/16” fillet) x 1.5

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Comparison (ASD)

Fillet Capacity (Shear) = 0.6 (70ksi) / 2.0 = 21.0 ksi x 0.707 LegFillet Capacity (Tension) = 0.6 (70ksi) / 2.0 x 1.5 = 31.5 ksi x 0.707 Leg

Technically there is no such thin as tension in a fillet weld, but I am using this word to describe the load orientation is perpendicular to the weld

Fillet Weld Tension = 31.5 ksi x 0.707 Leg = 22.3 ksi x LEG

Plate in Tension = Fy /1.67 = 21.5 ksi x LEG

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y= Fu /2 = 29.0 ksi x LEG

So instead of a 1.5 multiplier, you could justify 1.45 max for A36

Strength of PJP

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Strength of PJP has Changed

If Base Metal is 50ksi, PJP capacity = 50/1.67 = 30 ksi (2005 ASD)If Base Metal is 50ksi, PJP capacity = 65/2 = 32.5 ksi (2010 ASD)

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Effective Throat of PJP

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Effective Throat of PJP

Weld Size – 1/8” = Effective Throat

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PJP - Flare Bevel Detail

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(Part of Table J2.5 AISC 2005)Strength of CJP

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ASD Shear Strength (36 ksi Base Metal) ASD Shear Strength (50 ksi Base Metal)

E70XXASD Strength

in ksiControlling Capacity

What Controls?

Effective Throat

ASD Shear Strength k/in E70XX

ASD Strength in ksi

Controlling Capacity

What Controls?

Effective Throat

ASD Shear Strength k/in

Fillet 0.6 (70ksi)/2 21.0 ksi Weld 0.707 Leg 14.8 ksi Fillet 0.6 (70ksi)/2 21.0 ksi Weld 0.707 Leg 14.8 ksi

PJP 0.6 (70ksi)/2 0.6(36 ksi)/1.5

14.4 ksi Base Leg ‐ 1/8 Varies PJP 0.6 (70ksi)/2 0.6(50 ksi)/1.5

20.0 ksi Base Leg ‐ 1/8 Varies

Comparison – Weld in Shear

CJP 0.6(36 ksi)/1.5 14.4 ksi Base PL Thick 14.4 ksi CJP 0.6(50 ksi)/1.5 20.0 ksi Base PL Thick 20.0 ksi

ASD Shear Strength (36 ksi Base Metal) ASD Shear Strength (50 ksi Base Metal)Size Fillet PJP CJP Size Fillet PJP CJP1/16 0.928 k/in ‐ 0.900 k/in 1/16 0.928 k/in ‐ 1.250 k/in1/8 1.856 k/in ‐ 1.800 k/in 1/8 1.856 k/in ‐ 2.500 k/in3/16 2.784 k/in 0.900 k/in 2.700 k/in 3/16 2.784 k/in 1.250 k/in 3.750 k/in1/4 3.712 k/in 1.800 k/in 3.600 k/in 1/4 3.712 k/in 2.500 k/in 5.000 k/in5/16 4.640 k/in 2.700 k/in 4.500 k/in 5/16 4.640 k/in 3.750 k/in 6.250 k/in3/8 5.568 k/in 3.600 k/in 5.400 k/in 3/8 5.568 k/in 5.000 k/in 7.500 k/in7/16 6.496 k/in 4.500 k/in 6.300 k/in 7/16 6.496 k/in 6.250 k/in 8.750 k/in1/2 7.424 k/in 5.400 k/in 7.200 k/in 1/2 7.424 k/in 7.500 k/in 10.000 k/in9/16 8.351 k/in 6.300 k/in 8.100 k/in 9/16 8.351 k/in 8.750 k/in 11.250 k/in5/8 9.279 k/in 7.200 k/in 9.000 k/in 5/8 9.279 k/in 10.000 k/in 12.500 k/in

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11/16 10.207 k/in 8.100 k/in 9.900 k/in 11/16 10.207 k/in 11.250 k/in 13.750 k/in3/4 11.135 k/in 9.000 k/in 10.800 k/in 3/4 11.135 k/in 12.500 k/in 15.000 k/in13/16 12.063 k/in 9.900 k/in 11.700 k/in 13/16 12.063 k/in 13.750 k/in 16.250 k/in7/8 12.991 k/in 10.800 k/in 12.600 k/in 7/8 12.991 k/in 15.000 k/in 17.500 k/in15/16 13.919 k/in 11.700 k/in 13.500 k/in 15/16 13.919 k/in 16.250 k/in 18.750 k/in1 14.847 k/in 12.600 k/in 14.400 k/in 1 14.847 k/in 17.500 k/in 20.000 k/in

ASD Tension Strength (36 ksi Base Metal) ASD Tension Strength (50 ksi Base Metal)

E70XXASD Strength in

ksiControlling Capacity

What Controls?

Effective Throat

ASD Tension Strength k/in E70XX

ASD Strength in ksi

Controlling Capacity

What Controls?

Effective Throat

ASD Tension Strength k/in

Fillet 1.5x0.6 (70ksi)/2 31.5 ksi Weld 0.707 Leg 22.3 ksi Fillet 1.5x0.6 (70ksi)/2 31.5 ksi Weld 0.707 Leg 22.3 ksi

PJP 0.6 (70ksi)/1.88 (58 ksi)/2

22.3 ksi Base Leg ‐ 1/8 Varies PJP 0.6 (70ksi)/1.88 (65 ksi)/2

22.3 ksi Weld Leg ‐ 1/8 Varies

CJP (36 ksi)/1 67 21 6 ksi Base PL Thick 21 6 ksi CJP (50 ksi)/1 67 29 9 ksi Base PL Thick 29 9 ksi

Comparison – Weld in Tension

CJP (36 ksi)/1.67 21.6 ksi Base PL Thick 21.6 ksi CJP (50 ksi)/1.67 29.9 ksi Base PL Thick 29.9 ksi

ASD Tension Strength (36 ksi Base Metal) ASD Tension Strength (50 ksi Base Metal)Size Fillet PJP CJP Size Fillet PJP CJP1/16 1.392 k/in ‐ 1.347 k/in 1/16 1.392 k/in ‐ 1.871 k/in1/8 2.784 k/in ‐ 2.695 k/in 1/8 2.784 k/in ‐ 3.743 k/in3/16 4.176 k/in 1.396 k/in 4.042 k/in 3/16 4.176 k/in 1.396 k/in 5.614 k/in1/4 5.568 k/in 2.793 k/in 5.389 k/in 1/4 5.568 k/in 2.793 k/in 7.485 k/in5/16 6.960 k/in 4.189 k/in 6.737 k/in 5/16 6.960 k/in 4.189 k/in 9.356 k/in3/8 8.351 k/in 5.585 k/in 8.084 k/in 3/8 8.351 k/in 5.585 k/in 11.228 k/in7/16 9.743 k/in 6.981 k/in 9.431 k/in 7/16 9.743 k/in 6.981 k/in 13.099 k/in1/2 11.135 k/in 8.378 k/in 10.778 k/in 1/2 11.135 k/in 8.378 k/in 14.970 k/in9/16 12.527 k/in 9.774 k/in 12.126 k/in 9/16 12.527 k/in 9.774 k/in 16.841 k/in5/8 13.919 k/in 11.170 k/in 13.473 k/in 5/8 13.919 k/in 11.170 k/in 18.713 k/in11/16 15 311 k/in 12 566 k/in 14 820 k/in 11/16 15 311 k/in 12 566 k/in 20 584 k/in

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11/16 15.311 k/in 12.566 k/in 14.820 k/in 11/16 15.311 k/in 12.566 k/in 20.584 k/in3/4 16.703 k/in 13.963 k/in 16.168 k/in 3/4 16.703 k/in 13.963 k/in 22.455 k/in13/16 18.095 k/in 15.359 k/in 17.515 k/in 13/16 18.095 k/in 15.359 k/in 24.326 k/in7/8 19.487 k/in 16.755 k/in 18.862 k/in 7/8 19.487 k/in 16.755 k/in 26.198 k/in15/16 20.879 k/in 18.152 k/in 20.210 k/in 15/16 20.879 k/in 18.152 k/in 28.069 k/in1 22.271 k/in 19.548 k/in 21.557 k/in 1 22.271 k/in 19.548 k/in 29.940 k/in

C. Weld Symbols

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Groove Weld Nomenclature

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Groove Weld Nomenclature

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Symbols

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Symbols

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Symbols

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Fillet Symbols

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CJP Symbol B-L1a

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CJP Symbol B-U4a

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CJP Symbol TC-U4a

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PJP Symbol BTC-P4

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PJP Symbol BTC-P10

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C. Quiz

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Quiz #1: Which Weld Symbol is Shown Wrong?

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#1 Examples Wrong Faying Surface on HSS

OK

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Quiz #2: Which weld(s) is shown wrong?

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Quiz #3: What is very problematic with this detail?

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#3 Examples of Welds and Bolts Sharing Shear Plane

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#3 Examples of Welds and Bolts Sharing Shear Plane

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Quiz #4: Which weld is shown wrong?

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#4 Examples of Mirrored Welds

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Quiz #5 Which weld is shown wrong?

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#5 Examples of All Around Shown Wrong

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Quiz #6: What is wrong here?

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Quiz #8 Info on Plug Welds

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Why “nor greater”?

Quiz #9

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#9 Examples of Wrong Use of Butt Welds

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#9 Examples of Wrong Welds Shown

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Quiz #10 – Prequalified?

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Quiz #11: Anything Missing Here?

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Quiz #13 – Anything wrong here?

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Quiz #14 Plan

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Quiz #14 – Comments?

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Quiz #14 – Comments?

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Quiz #15: Min fillet. Anything Change Here?

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Quiz #16: Fillet Max Thickness for Lap Joint

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Is there a max fillet weld for a T or L joint?

16 Max Fillet to Develop Steel Capacity

D = Fu (t) / 6 19Dmax = Fu (t) / 6.19

So 1/2” PL, use 5/16” Weld

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Dmax = Fu (t) / 3.09

So 1/2” PL, use 5/8” Weld

Quiz #17: Does Reinforcing Fillet Increase Capacity?

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Quiz #18: How should an Engineer Specify a CJP?

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Quiz #19: How do you know what is more expensive?

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Quiz #20: Which is preferred weld for Backing bar?

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Quiz #21: Length of Runoff Tabs?

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Quiz #22: Corner Detailing (To Avoid Laminar Tearing)

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Quiz #23: Is a longer 5/16 weld better than a shorter 3/8” weld?

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23: Two Small Triangles better than One

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Quiz #23: Does increasing thickness of A36 help?

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Quiz #24: Problem?

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Quiz #25: How much should EOR show?

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Quiz #26: What is a shelf bar?

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Quiz #26: What is a shelf bar?

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Quiz #27: When to use PJP instead of Fillet?

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4 Moment Connections (If there is time!)

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AWS 5.17 Weld Access Holes

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Good Notes on MC Connections

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MC Connection

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Strategies for Improved Performance of Moment Connections:

Improved practices for backing bars and weld tabs

Remove bottom flange backing barSeal weld top flange backing barRemove weld tabs at top and bottom flange welds

Greater emphasis on quality and quality control (AISC Seismic Provisions - Appendix Q and W)

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Bottom Flange

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Top Flange

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MC Connections - Comments

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5 Sh C ti (If th i ti !)5 Shear Connections (If there is time!)

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Welding Procedure Specifications

WPS contain welding parameters in AWS D1.1 2010 Table 3.8 (for prequalified welding processes)

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6 W ld P d (If th i ti !)6 Weld Procedures (If there is time!)

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SMAW

Shielded Metal Arc Welding (SMAW) is also known as manual, stick, orhand welding

An electric arc is produced between the end of a coated metal electrodeand the steel components to be welded

The electrode is a filler metal covered with a coating

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The electrode is a filler metal covered with a coating

The electrode’s coating has two purposes:

• It forms a gas shield to prevent impurities in the atmosphere fromgetting into the weld

• It contains a flux that purifies the molten metal

Elements of SMAW

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GMAW

Gas Metal Arc Welding (GMAW) is also known as MIG welding

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It is fast and economical - A continuous wire is fed into the welding gun

The wire melts and combines with the base metal to form the weld

The molten metal is protected from the atmosphere by a gas shield which isfed through a conduit to the tip of the welding gun

This process may be automated

FCAW WeldingFCAW

Flux Cored Arc Welding (FCAW) is similar to the GMAW process

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Flux Cored Arc Welding (FCAW) is similar to the GMAW process

The difference is that the filler wire has a center core which contains flux

With this process it is possible to weld with or without a shielding gas

This makes it useful for exposed conditions where a shielding gas may beaffected by the wind

SAW WeldingSAW

Submerged Arc Welding (SAW) is only performed by automatic orsemiautomatic methods

Uses a continuously fed filler metal electrode

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Uses a continuously fed filler metal electrode

The weld pool is protected from the surrounding atmosphere by a blanket ofgranular flux fed at the welding gun

Results in a deeper weld penetration than the other process

Only flat or horizontal positions may be used

Welding Equipment

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Equipment used for welding will vary depending on the welding process andwhether the welding is being done in the shop or in the field

A Flux Cored Arc Welding machine for shop welding is pictured above left

A Shielded Metal Arc Welding machine for field welding is pictured aboveright

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on WeldingWeather Impacts

Welding in the field is avoided if possible due to welding condition requirements

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Welding in the field is avoided if possible due to welding condition requirements

Field welding is not to be performed while it is raining, snowing, or below 0° F

In certain ambient temperatures preheating of the material to be welded is required

AWS Code D1.1 (2004b) specifies minimum preheat and interpass temperatures, whichare designed to prevent cracking

Weld Inspections

In addition to the erector’s quality control program, tests and inspections are specified by theEngineer of Record and/or the local building authority

A local building inspector may request that tests in addition to those specified by the Engineer of

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A local building inspector may request that tests in addition to those specified by the Engineer ofRecord be performed

Some problems that can be found in welds include:

Lack of fusion

Porosity

Cracks

Insufficient penetration

There are several weld tests and inspections that are commonly used

Wrong size

Poor workmanship

Visual Inspection

Visual inspection is the most frequently used inspection and is the only inspection required unless

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the specification calls for a more stringent inspection method

Inspection is done by the welder before, during, and after welding

When outside inspection is required it should also be done before, during, and after welding

Minor problems can be identified and corrected before the weld is complete

(AISC & NISD 2000)

Dye Penetrant Test

Dye penetrant testing locates minute surface cracks and porosity

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Dye penetrant testing locates minute surface cracks and porosity

Dye types that may be used include:

Color contrast dye - which shows up under ordinary light

Fluorescent dye – which shows up under black light

The dye is normally applied by spraying it directly on the weld

(AISC & NISD 2000)

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Magnetic Particle Inspection

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Magnetic particle inspection uses powdered magnetic particles to indicate defects in magneticmaterials

A magnetic field is induced in the part

The magnetic powder is attracted to and outlines cracks within the material

Ultrasonic Inspection

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Ultrasonic inspection can be used to detect flaws inside welds

High frequency sound waves are directed into the metal with a probe held at a specific angle

The flaws reflect some energy back to the probe

Flaws show up as indications on a screen (above) and are subject to interpretation by an inspector

Radiographic Inspection

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Radiographic inspection, or X-ray, can also be used to detect flaws inside welds

Invisible rays penetrate the metal and reveal flaws on an x-ray film or fluorescent screen (above)

This is the most costly of the inspection methods

Cost

Fillet weld is less expensive than groove weldNo special preparation no backing required less volume of weld

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No special preparation, no backing required, less volume of weld

Partial penetration groove weld is less expensive than fullpenetration groove weld

Labor represents the majority of the cost associated with welding

2012 01 07 seari welds - structures · pdf filed1.1 structural welding code – steel...

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