steel_ch6 - connections2

8/19/2019 Steel_Ch6 - Connections2

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68402/61420 Slide # 1

68402: Structural Design ofBuildings II

Design of Connections

Monther DwaikatAssistant rofessor

De!art"ent of Building #ngineeringAn$%a&ah %ational 'ni(ersit)



68402/61420 Slide # 2

Types of ConnectionsSimple Bolted Shear ConnectionsBearing and Slip Critical ConnectionsEccentric Bolted Connections

oment !esisting Bolted ConnectionsSimple "elded Connections

Eccentric "elded Connectionsoment !esisting "elded Connections

Bolted Connections



68402/61420 Slide #

*)!es of ConnectionsSimple Connections

Bolted Connections Welded Connections

Common Bolts High Strength Bolts

Slip Critical

Bearing Type

Filet Weld

Groove Weld

Eccentric Connections



68402/61420 Slide # 4

*)!es of Connections

Simple Connections

Bolted Connections Welded Connections

ElasticAnalysis

Eccentric Connections

UltimateAnalysis

MomentResisting

ElasticAnalysis

UltimateAnalysis

MomentResisting



68402/61420 Slide # 6

Si"!le Bolted Connections

Tension mem%er

Connection/ splice

Beam end

Simple shear connection

.

.

.

.



68402/61420 Slide #

Si"!le Bolted Connections

. .

.

-anger connection

Tension

oment resisting

connection



68402/61420 Slide # 8

Si"!le Bolted ConnectionsThe %olts are s*%+ected to shear or tension loading&

( )n most %olted connection the %olts are s*%+ected to shear&

( Bolts can fail in shear or in tension&

( 3o* can calc*late the shear strength or the tensile strength of a %olt

Simple connection )f the line of action of the force acting onthe connection passes thro*gh the center of gra5ity of theconnection then each %olt can %e ass*med to resist an e *al

share of the load&The strength of the simple connection 7ill %e e *al to thes*m of the strengths of the indi5id*al %olts in the connection&



68402/61420 Slide #

Bolt *)!es + Materials 9 0 : Unfinished Ordinary or Common %olts

lo7 car%on steel 9 6 F u ; 41 .afor light str*ct*res *nder static load

9 2$ : High strength %olts heat:treated medi*mcar%on steel F u ; 82 .a

for str*ct*ral +oints 94 0 : High strength %olts <*enched and

Tempered 9lloy steel F u ; 10 .a

for str*ct*ral +oints 944 : High strength %olts 7ith diameter = 1 >?

anchor %olts lifting hoo,s tie:do7ns



68402/61420 Slide # 10

Co""on Bolts 9ST 9 0 %oltsCommon %olts are no longer common for c*rrent str*ct*raldesign %*t are still a5aila%le

bolt vn A f R =

75.0=φ nu R P φ ≤

MPa f v

165=



68402/61420 Slide # 11

,igh Strength Bolts-igh strength %olts -SB are a5aila%leas 9ST 9 2$ and 9ST 94 0

Slip Critical

Bearing Type

Courtesy of Kao Wang Screw Co., Ltd.

Advantages o HSB over A!"# $olts

Fe%er $olts %ill $e &sed compared to !"# cheaper connection'

Smaller %or(man orce re)&ired compared to !"#

Higher atig&e strength

Ease o $olt removal changing connection

Bolt

Washer

Nut



68402/61420 Slide # 12

,igh Strength BoltsSnug tight( 9ll plies of the connection are in firm contact to

each other @o pretension is *sed&( Easer to install and to inspect

Pre-tensioned

( Bolts are first %ro*ght to sn*g tight stat*s( Bolts are then tensioned to 0A of their tensilestresses

Courtesy of www.halfpricesurplus.com

( Bolts are tensioned *sing direct tension indicator cali%rated 7rench or othermethods see 9)SC

Slip critical( Bolts are pre:tensioned %*t s*rfaces shall %e treated to de5elop specific friction&

( The main difference is in design not installation& oad m*st %e limited not toe ceed friction capacity of the connection Strength Ds& Ser5icea%ility

( @ecessary 7hen no slip is needed to pre5ent fail*re d*e to fatig*e in %ridges&



68402/61420 Slide # 1

,SB - Bearing *)!e ConnectionsThe shear strength of %olts shall %e determined as follo7s

bolt vn A f R =

75.0=φ nu R P φ ≤

*+#,+!A,-"

,+!!!"A!.*

Type / ThreadType 0 ThreadType

( )f the le5el of threads is not ,no7n it is conser5ati5e toass*me that the threads are type @&

AISC Table !."

The table bellow shows the values of f v (MPa) for different types of bolts



68402/61420 Slide # 14

Bolted Shear Connections "e 7ant to design the %olted shear connections so thatthe factored design strength φ! n is greater than or e *alto the factored load& φ ! n ≥ . *

So 7e need to e amine the 5ario*s possi%le fail*remodes and calc*late the corresponding design strengths&

.ossi%le fail*re modes are( Shear fail*re of the %olts

( Fail*re of mem%er %eing connected d*e to fract*re or yielding or G&( Edge tearing or fract*re of the connected plate

( Tearing or fract*re of the connected plate %et7een t7o %olt holes

( E cessi5e %earing deformation at the %olt hole



68402/61420 Slide # 1$

.ailure Modes of BoltedConnections

Bolt Shearing

Tension Fract*re

.late Bearing

Bloc, Shear



68402/61420 Slide # 16

Actions on Bolt

Shear %earing %ending

P P

P

P

P P

P/2 P

P/2

P/2

P/2 P

Lap oint

#utt oint

Bearing and single plane Shear

Bending

Bearing and double plane Shear



68402/61420 Slide # 1

Bolted Shear Connections1ossi$le ail&re modes

Fail&re o $olts2 single or do&$le shear

Fail&re o connected elements2

Shear3 tension or $ending ail&re of the connected elements ( e4g4 $loc( shear )Bearing ail&re at bolt location

Single shear

5o&$le shear

bolt vShear Single A f P =

bolt vShear Double A f P 2= P

P P

2/ P

2/ P



68402/61420 Slide # 18

Bolted Shear Connections

Shear fail*re of %olts

( 95erage shearing stress in the %olt ; f 5 ; ./9 ; ./ πd%2/4

( . is the load acting on an indi5id*al %olt

( 9 is the area of the %olt and d% is its diameter

( Strength of the %olt ; . ; f 5 πd%2/4 7here f 5 ; shear yieldstress ; 0&6F y

( Bolts can %e in single shear or double shear as sho7n a%o5e&

( "hen the %olt is in do*%le shear t7o cross:sections are effecti5ein resisting the load& The %olt in double shear 7ill ha5e the t7icethe shear strength of a %olt in single shear&



68402/61420 Slide # 1




68402/61420 Slide # 20

Bolted Shear ConnectionsFail*re of connected mem%er ( "e ha5e co5ered this in detail in this co*rse on tension mem%ers

( em%er can fail d*e to tension fract*re or yielding&

Bearing fail*re of connected/connecting part d*e to%earing from %olt holes

( -ole is slightly larger than the fastener and the fastener is looselyplaced in hole

( Contact %et7een the fastener and the connected part o5erappro imately half the circ*mference of the fastener

( 9s s*ch the stress 7ill %e highest at the radial contact point 9 &-o7e5er the a5erage stress can %e calc*lated as the applied forcedi5ided %y the pro+ected area of contact



68402/61420 Slide # 21


( 95erage %earing stress f p ; ./ d % t 7here . is the force applied tothe fastener&

( The %earing stress state can %e complicated %y the presence ofnear%y %olt or edge& The %olt spacing and edge distance 7ill ha5e

an effect on the %earing strength&( Bearing stress effects are independent of the %olt type %eca*se

the %earing stress acts on the connected plate not the %olt&

( 9 possi%le fail*re mode res*lting from e cessi5e %earing close tothe edge of the connected element is shear tear:o*t as sho7n%elo7& This type of shear tear:o*t can also occ*r %et7een t7oholes in the direction of the %earing load&

R n = 2 !"# $ u %c t = &"2 $ u %c t



68402/61420 Slide # 22

The $earing strength is independent o the $olt material as it is ail&re inthe connected metal

The other possi$le common ail&re is shear end ail&re (no%n as 6 sheartear$out 7 at the connection end

t d f P bolt p Bearing =


uucn F t d F t L R !.22.1 ≤=75.0=φ nu R P φ ≤

Shear limitation Bearing limitation

c Lc L



68402/61420 Slide # 2




68402/61420 Slide # 24




68402/61420 Slide # 2$

S!acing and #dge$distancere/uire"ents

The 9)SC code gi5es g*idance for edge distance and spacing toa5oid tear o*t shear

2h

L L ec −=

S e Ldia eter holetheish d h bolt 6.1+=

08TE2 "he actual hole diameter is 1.6 mm bigger than the bolt#

$e use another 1.6 mm for tolerance $hen $e calculate net area. %ere use +49 mm onl& not !4.

bolt d S '22≥

Bolt spacing is a &nction o the $olt diameterCommon %e ass&me

The A:SC minim&m spacing is

e L

bolt d S '=

AISC Table !.%



68402/61420 Slide # 26

Bolt S!acings + #dge Distances

Bolt Spacings: .ainted mem%ers or mem%ers not s*%+ect to corrosion

2 2/ d H Bolt Spacings ≤ 24 t or 0$ mm !FI J & !FI J &$

: Knpainted mem%ers s*%+ect to corrosion d H Bolt Spacings ≤ 14 t or 1 8 mm

Edge DistanceDal*es in Ta%le J &4 ≤ Edge Distance ≤ 12 t or 1$2 mm

!FI J &4 !FI J &$

d - bolt diametert - thickness of thinner plate



68402/61420 Slide # 2


( To pre5ent e cessi5e deformation of the hole an *pper limit isplaced on the %earing load& This *pper limit is proportional to thefract*re stress times the pro+ected %earing area

R n = ' $ u bearing area = ' $ u d b t

( )f deformation is not a concern then C ; )f deformation is aconcern then C ; 2&4

( C ; 2&4 corresponds to a deformation of 6& mm&

( Finally the e *ation for the %earing strength of a single %olts is φ! n

( 7here φ ; 0& $ and ! n ; 1&2 c t F * L 2&4 d% t F *

( c is the clear distance in the load direction from the edge of the%olt hole to the edge of the ad+acent hole or to the edge of thematerial

p& p& p&



68402/61420 Slide # 28


( This relationship can %e simplified as follo7sThe *pper limit 7ill %ecome effecti5e 7hen 1&2 c t F * = 2&4 d% t F *

i&e& the *pper limit 7ill %ecome effecti5e 7hen c = 2 d %

)f c L 2 d % ! n ; 1&2 c t F *

)f c = 2 d % ! n ; 2&4 d % t F *

F u - specified tensile strength of the connected material

Lc - clear distance, in the direction of the force, between the edge ofthe hole and the edge of the adjacent hole or edge of the material.

t - thickness of connected material



68402/61420 Slide # 2

I"!ortant %otes

c M Clear distance



68402/61420 Slide # 0

Design ro(isions for BoltedShear Connections

)n a simple connection all %olts share the load e *ally&

! !

!/n !/n

!/n !/n

!/n !/n

! !

!/n !/n

!/n !/n

!/n !/n



68402/61420 Slide # 1


)n a %olted shear connection the bolts are subjected toshear and the connecting/connected plates are s*%+ectedto %earing stresses&

Bolt in shear

Bearing stresses in plate


! !

!

!

Bolt in shear



Bolt in shear



! !

!

!



68402/61420 Slide # 2


The shear strength of all %olts ; shear strength of one %olt n*m%er of %olts

The %earing strength of the connecting / connected platescan %e calc*lated *sing e *ations gi5en %y 9)SCspecifications&

The tension strength of the connecting / connected platescan %e calc*lated as disc*ssed in tension mem%ers&



68402/61420 Slide #

AISC Design ro(isions

Chapter J of the 9)SC Specifications foc*ses onconnections&

Section J foc*ses on %olts and threaded parts

9)SC Specification J & indicates that the minim*mdistance s %et7een the centers of %olt holes is 2&6 & 9distance of d % is preferred&

9)SC Specification J &4 indicates that the minim*m edge

distance e from the center of the %olt to the edge of theconnected part is gi5en in Ta%le J &4&Ta%le J &4 specifiesminim*m edge distances for sheared edges edges ofrolled shapes and gas c*t edges&



68402/61420 Slide # 4


9)SC Specification indicates that the ma im*m edgedistance for %olt holes is 12 times the thic,ness of theconnected part %*t not more than 1$2 mm & The ma im*mspacing for %olt holes is 24 times the thic,ness of thethinner part %*t not more than 0$ mm &

Specification J &6 indicates that the design tension orshear strength of %olts is φF n 9 %

∀φ ; 0& $

( Ta%le J &2 gi5es the 5al*es of F n

( 9 % is the *nthreaded area of %olt&

( )n Ta%le J &2 there are different types of %olts 9 2$ and 94 0&



68402/61420 Slide # $


( The shear strength of the %olts depends on 7hether threads areincl*ded or e cl*ded from the shear planes& )f threads are incl*dedin the shear planes then the strength is lo7er&

"e 7ill al7ays ass*me that threads are incl*ded in the

shear plane therefore less strength to %e conser5ati5e&

"e 7ill loo, at specifications J & M J & later&

( 9)SC Specification J &10 indicates the %earing strength of plates at

%olt holes&( The design %earing strength at %olt holes is φ! n

( ! n ; 1&2 c t F * H 2&4 d% t F * : deformation at the %olt holes is adesign consideration



68402/61420 Slide # 6

Co""on olt ter"inologies

9 2$:SC M slip!critical 9 2$ %olts 9 2$:@ M snug!tight or bearing 9 2$ %olts 7ith

thread included in the shear planes& 9 2$:N : snug!tight or bearing 9 2$ %olts 7ith

thread e"cluded in the shear planes&

#age $ center:to:center distance of %olts indirection perpendic*lar to

mem%erOs a is%itch $ &&&parallel to mem%erOs a isEdge Distance $ Iistance fromcenter of %olt to ad+acentedge of a mem%er

p

g

p p

p #dgedistance



68402/61420 Slide #

#1 3 $ Design Strength

Calc*late and chec, the design strength of the simpleconnection sho7n %elo7& )s the connection ade *ate forcarrying the factored load of 00 ,@&

1.25 2.50 1.25

1.25

2.50

1.25 65

'6

'6 5 * +

'/, in.

- in. bolts

1.25 2.50 1.25

1.25

2.50

1.25 65

'6

'6 5 * +

'/, in.

- in. bolts

6 ,

10 mm

120 1$ mm

20 mm 9 2$:@%olts

0 mm

60 mm

0 mm

0 mm 60 mm 0 mm

00 ,@



68402/61420 Slide # 8

Step " Shear strength of %olts( The design shear strength of one %olt in shear ; φF n 9 % ; 0& $

0 π 20 2/4000 ; &8 ,@

∀φ F n 9 % ; &8 ,@ per %olt See Ta%le J &2

( Shear strength of connection ; 4 &8 ; 11&2 ,@




68402/61420 Slide #

Step " inim*m edge distance and spacing re *irements( See Ta%le J &4 minim*m edge distance ; 26 mm for rolled edges

of plates

( The gi5en edge distances 0 mm = 26 mm& Therefore minim*m edge

distance re *irements are satisfied&

( inim*m spacing ; 2&6 d % ; 2&6 20 ; $ &4 mm&

( S' Specifications *+"+)

( .referred spacing ; &0 d % ; &0 20 ; 60 mm&

( The gi5en spacing 60 mm ; 60 mm& Therefore spacing re *irementsare satisfied&




68402/61420 Slide # 40


Step "Bearing strength at %olt holes &( Bearing strength at %olt holes in connected part 120 1$ mm plate

( 9t edges c ; 0 M hole diameter/2 ; 0 M 20 P 1&6 /2 ; 1 &2

∀φ! n ; 0& $ 1&2 c t F * ; 0& $ 1&2 1 &2 1$ 400 /1000 ; 10 & ,@

( B*t φ! n H 0& $ 2&4 d% t F * ; 0& $ 2&4 20 1$ 400 /1000 ; 216 ,@

( Therefore φ! n ; 10 & ,@ at edge holes &

( 't other holes( s ) *+ mm ( c ) *+ $ ,-+ . /&*0 ) 12&3 mm&

∀φ! n ) +&45 " ,/&- c t F u 0 ) +&45",/&- " 12&3 "/5 "3++06/+++ ) -+4&3 78

( But( φ! n ≤ +&45 ,-&3 d b t F u 0 ) -/* 78& 9herefore φ! n ) -+4&3 78



68402/61420 Slide # 41


( Therefore φ! n ; 216 ,@ at other holes( Therefore %earing strength at holes ; 2 10 & P 2 20 &4 ; 622&2 ,@

( Bearing strength at %olt holes in g*sset plate 10 mm plate

( 9t edges c ; 0 M hole diameter/2 ; 0 M 20 P 1&6 /2 ; 1 &2 mm&

∀φ! n ; 0& $ 1&2 c t F * ; 0& $ 1&2 1 &2 10 400 /1000 ; 6 &1,@

( B*t φ! n H 0& $ 2&4 d% t F * ; 0& $ 2&4 20 10 400 /1000 ; 144,@&

( Therefore φ! n ; 6 &1 ,@ at edge holes&



68402/61420 Slide # 42


( 9t other holes s ; 60 mm c ; 60 M 20 P1&6 ; 8&4 mm&

∀φ! n ; 0& $ 1&2 c t F * ; 0& $ 1&2 8&4 10 400 /1000 ; 1 8&2,@

( B*t φ! n H 0& $ 2&4 d% t F * ; 144 ,@

( Therefore φ! n ; 1 8&2 ,@ at other holes( Therefore %earing strength at holes ; 2 6 &1 P 2 1 8&2 ; 414&6 ,@

( Bearing strength of the connection is the smaller of the %earingstrengths ; 414&6 ,@



68402/61420 Slide # 4


Connection Strength

Shear strength '11.2

Bearing strength (plate) 622.2

Bearing strength (gusset) !1!.6

Connection strength , φ : n 0 ; applied factored loads , γ <0&1//&- ; 1++ 9herefore o7&

( Qnly connections is designed here

@eed to design tension mem%er and g*sset plate



68402/61420 Slide # 44

#ccentricall)$ oaded Bolted Connections

Eccentricit in the plane ofthe fa ing surface

Iirect Shear P 9dditional Shear d*e tomoment %e

P & &e

e

P &

&e

e

Eccentricit normal to the planeof the fa ing surface

Iirect Shear P Tension and Compressiona%o5e and %elo7 ne*tral a is

$% $%



68402/61420 Slide # 4$

.orces on #ccentricall)$ oaded Bolts

Eccentricity in the plane of the faying surface!FI Spec& presents 5al*es for comp*ting design

strengths of indi5id*al %olt only& To comp*teforces on gro*p of %olts that are eccentrically

loaded there are t7o common methods

: Elastic =ethod> Conser5ati5e& Connected partsass*med rigid& Slip resistance %et7eenconnected parts neglected&

: Ultimate Strength =ethod ,or ?nstantaneous Center of#ra@ity =ethod0> ost realistic %*t tedio*s to apply



68402/61420 Slide # 46

.orces on #ccentricall)$ oaded Boltswith #ccentricit) on the .a)ing Surface

Elastic ethod

9ss*me plates are perfectly rigid and %olts perfectly elastic → rotational displacement at each %olt is proportional to its distancefrom the C# → stress is greatest at %olt farthest from C#

$%

e P

$%

&e P

&'!

&'!

&'!d &

d 2

d ' r (

r "

r !



68402/61420 Slide # 4


= C# ) %e ) r / d / . r - d - . r 1 d 1 Since the force on each %olt is proportional to its distance

from the C#>

S*%stit*te into e n& for = C# >1

'1

'1

21

21

11

1'

'

2

2

1

1

d

d r r

d

d r r

d

d r r

d

r

d

r

d

r ===⇒==

( )

∑∑∑ ===

∑=

++=++=

2'

'22

221

1

2

1

1

2'

22

21

1

1

1

2'1

1

221

1

211

d d M

r d d M

r d d M

r

d d r M

d d d d r

d d r

d d r

d d r

M

$%$%$%

$%

$%



68402/61420 Slide # 48


∑∑∑∑

∑

==

==

===

21

21

21

21

21

11

1

111 sin

d

( Pe

d

( M p

d

) Pe

d

) M p

d d )d M

d )r r p

$%)

$%(

$%( θ

$%

d & r ( ( &

) &

* &

+ &θ

Total Forces in Bolt i 2

*ori,ontal $o ponent

+ertical $o ponent - ∑

∑±

2

2

d

Pe(n

P

d

Pe)

i

i



68402/61420 Slide # 4

#1 6 5 - #ccentric Connections -#lastic Method

Ietermine the force in the most stressed %olt of the gro*p*sing elastic method

e

$%

&2.

100mm

P-& 0 1N

Eccentricity 7rt C#e ) /-5 . 5+ ) /45 mm

Direct Shear in each %olt%6n ) /3+62 ) /4&5 78

@ote that the *pper right:hand andthe lo7er right:hand %olts are themost stressed farthest from C# andconsider direction of forces

100mm

100mm

100mm



68402/61420 Slide # $0

#1 6 5 - #ccentric Connections -#lastic Method

'dditional Shear in the *pper and lo7er right:hand %oltsd*e to moment = ) %e ) /3+"/45 ) -35++ 78&mm>

The forces acting on the *pper right:hand %olt are asfollo7s

The res*ltant force on this %olt is

2.10120000

)50)(2!500(

6.'0

120000

)150)(22500(

120000)15050)(!()50)(,(

2

2

222222

===

===

=++=+=

∑∑

∑ ∑∑

d M(

p

d

M) p

) (d

)

(

'0.6 10.2

17.5 '.!1)6.'0()5.172.10( 22 =++= R



68402/61420 Slide # $1

Eccentricity 8ormal to %lane of Faying Surfacea @e*tral 9 is at CR


2r ut

Shear force per bolt due to concentric force P u

r uv - P u /n n of boltsBolts abo3e are in tension. Bolts belo$ are in compression. "ension force per bolt4

r ut - ( P ue3/n4d

n4 of bolts abo3e

d moment arm bet$een resultant tensile andcompressi3e forces



68402/61420 Slide # $2

Shear per %olt d*e to concentricforce % u>

r u! " # u $n

Select first trial location of @9 as 1/6of the total %rac,et depth&

Effecti5e 7idth of the compression%loc,b eff ) 8t f ≤ b f for ":shapes S:shapes 7elded plates andangles

Eccentricity 8ormal to %lane of Faying Surface% @e*tral 9 is @ot at CR


2r ut

D e p t h

d - D e p t h / 5

)

$%6tension

group3

7 7

t f

beff

NA

Bolts a%o5e @9 resist tension

Bearing stress %elo7 @9 resist compression



68402/61420 Slide # $

Chec, location of @9 %y e *ating the moment of the %olt areaa%o5e the @9 7ith the moment of the compression %loc, area%elo7 the @9

Σ ' b y ; b eff d d6-

%b " sum of areas of bolts abo!e the &% " distance from '-' to the () of bolts abo!e &%

d " depth of compression block *adjust until satisf +

Qnce the @9 has %een located the tensile force per %olt

r ut " *# u ec% b +$

c " distance from &% to most remote bolt in group " combined moment of inertia of bolt group and compression block

about &%




68402/61420 Slide # $4

Bolts Su &ected to Shear and *ension( @ominal Tension Stress F t of a %olt s*%+ected to com%ined

factored shear stress f @ )A u 68 b ' b 0 and factored tension stress f t )9 u 68 b ' b 0 can %e comp*ted as f*nctions of f @ as>

∀ φ " ./0

( F1 nt " nominal tensile strength modified to include the effect of shear

( F nt " nominal tensile strength from 2able 34.5 in *% S( Spec.+

( F n! " nominal shear strength from 2able 34.5 in *% S( Spec.+

( f ! " the re6uired shear stress

nt vnv

nt nt nt F f

F F

F F ≤−=′φ

'.1

#;"A,-"9."A!.*

F nt <M1a=Bolt Type



68402/61420 Slide # $$

#1 6 - Co" ined *ension + shear

)s the %earing:type connection %elo7 satisfactory for thecom%ined tension and shear loads sho7n

Shear stress per %olt f @ ) A u 68 b ' b )514+++ / 8 80 ; 1 6&6 .aφ F n@ ; 0& $ 41 ; 10 .a ; f @ ) /4*&* =%a Q

Tension stress per %olt

f t ) 9 u 68 b ' b )/+41+++ / 8 80 ; $ .a

@ominal Tension Strength F t Ta%le J &$ φ F t ) +&45 ,/&1"*-+ $ ,*-+61/+0"/4*&*0 ≤ *-+ ; 4 6 .a H 620U ; 4 6 .a = f t ) $ .a Q

ight 22 mm'25 bolts

1200 5'7

107' 12



68402/61420 Slide # $6

Si"!le 7elded Connections

Str*ct*ral 7elding is a process %y 7hich the parts thatare to %e connected are heated and f*sed 7iths*pplementary molten metal at the +oint&

9 relati5ely small depth of material 7ill %ecome molten

and *pon cooling the str*ct*ral steel and 7eld metal 7illact as one contin*o*s part 7here they are +oined&

Fillet 8eld

Fillet 8eld

Fillet 8eld Fillet 8eld

Fillet 8eld Fillet 8eld .

. .

.



68402/61420 Slide # $

Introductor) Conce!ts

"elding .rocess M Fillet "eld"elding .rocess M Fillet "eld



68402/61420 Slide # $8


The additional metal is deposited from a specialelectrode 7hich is part of the electric circ*it that incl*desthe connected part&

( )n the shielded metal arc 7elding S 9" process current arcs

across a gap %et7een the electrode and the %ase metal heatingthe connected parts and depositing part of the electrode into themolten %ase metal&

( 9 special coating on the electrode 5apori'es and forms aprotecti5e gaseo*s shield pre5enting the molten 7eld metal from

o idi'ing %efore it solidifies&( The electrode is mo5ed across the +oint and a 7eld %ead is

deposited its si'e depending on the rate of tra5el of the electrode&



68402/61420 Slide # $


( 9s the 7eld cools imp*rities rise to the s*rface forming acoating called slag that m*st %e remo5ed %efore the mem%er ispainted or another pass is made 7ith the electrode&

( Shielded metal arc 7elding is *s*ally done man*ally and is theprocess *ni5ersally *sed for field 7elds&

For shop 7elding an a*tomatic or semi a*tomatic processis *s*ally *sed& Foremost among these is the s*%mergedarc 7elding S9"

)n this process the end of the electrode and the arc ares*%merged in a gran*lar fl* that melts and forms agaseo*s shield& There is more penetration into the %asemetal than 7ith shielded metal arc 7elding and higherstrength res*lts&



68402/61420 Slide # 60


Qther commonly *sed processes for shop 7elding aregas shielded metal arc flu" cored arc and electro!slag

elding &

<*ality control of 7elded connections is partic*larlydiffic*lt %eca*se defects %elo7 the s*rface or e5en minorfla7s at the s*rface 7ill escape 5is*al detection& "eldersm*st %e properly certified and for critical 7or, specialinspection techni *es s*ch as radiography or *ltrasonictesting m*st %e *sed&



68402/61420 Slide # 61


The t7o most common types of 7elds are the fillet 7eldand the groo5e 7eld& Fillet 7eld e amples lap +oint M fillet7elds placed in the corner formed %y t7o platesTee +oint M fillet 7elds placed at the intersection of t7o

plates&Rroo5e 7elds M deposited in a gap or groo5e %et7een t7oparts to %e connectede&g& %*tt tee and corner +oints 7ith %e5eled preparededges

.artial penetration groo5e 7elds can %e made from one or%oth sides 7ith or 7itho*t edge preparation&



68402/61420 Slide # 62

7elded Connections

Classification of 7elds( 9ccording to type of 7eld

( 9ccording to 7eld position

( 9ccording to type of +oint( B*tt lap tee edge or corner

( 9ccording to the 7eld process( S 9" S9"

Fillet 7eld Rroo5e 7eld

Flat( Hori ontal( @ertical or o@erhead eld



68402/61420 Slide # 6




68402/61420 Slide # 64

7eld i"it States

The only limit state of the 7eld metal in aconnection is that of fract*re

3ielding is not a factor since any deformation thatmight ta,e place 7ill occ*r o5er s*ch a shortdistance that it 7ill not infl*ence the performance ofthe str*ct*re

Design of 7elded



68402/61420 Slide # 6$

Design of 7eldedConnections

Fillet 7elds are most common and *sed in all str*ct*res&"eld si'es are specified in 1 mm increments

9 fillet 7eld can %e loaded in any direction in shear

compression or tension& -o7e5er it al7ays fails inshear &

The shear fail*re of the fillet 7eld occ*rs along a planethro*gh the throat of the 7eld as sho7n in the Fig*re

%elo7&

Design of 7elded



68402/61420 Slide # 66


a

a

"hroat a * cos!5 o

0.707 a

a

a

"hroat a * cos!5 o

0.707 a

ailure 8lane

9

root

hypoten*se

L 7 length of the weld a 7 si8e of the weld

Design of 7elded



68402/61420 Slide # 6


Shear stress in fillet 7eld of length s*%+ected to load .

; f 5 ; )f the *ltimate shear strength of the 7eld ; f 7

! n ;

φ! n ; i&e& φ factor ; 0& $f 7 ; shear strength of the 7eld metal is a f*nction of theelectrode *sed in the S 9" process &( The tensile strength of the 7eld electrode can %e 41 482 $$1 620

688 $8 or 82 .a&

( The corresponding electrodes are specified *sing the nomenclat*reE60NN E 0NN E80NN and so on& This is the standard terminology

for 7eld electrodes&

$$ 9a707.0f ×××

$$ 9a707.0f 75.0 ××××

$9a707.08

Design of 7elded



68402/61420 Slide # 68


( The t7o digits VNNV denote the type of coating&

The strength of the electrode sho*ld match the strength ofthe %ase metal&

( )f yield stress σy of the %ase metal is ≤ 41 : 448 .a *seE 0NN electrode&

( )f yield stress σy of the %ase metal is ≥ 41 : 448 .a *seE80NN electrode&

E 0NN is the most pop*lar electrode *sed for fillet 7eldsmade %y the S 9" method&

E 7 electrode / 7 tensile strength of electrode *ksi+ " 9:5 ;#a

'' 7 t pe of coating



68402/61420 Slide # 6

.illet 7eld

Stronger in tension and compression than in shear

Fillet 7eld designations12 mm S 9" E 0NN fillet 7eld 7ith e *al leg si'e of 12 mm

formed *sing Shielded =etal 'rc elding .rocess 7ith filler metalelectrodes ha5ing a minim*m 7eld tensile strength of 0 ,si& mm:%y:12 mm S9" E110NN fillet 7eld 7ith *ne *al leg si'es

formed %y *sing Submerged 'rc =etal process 7ith filler metalelectrodes ha5ing a minim*m 7eld tensile strength of $8 .a&

Leg

Leg

!hroat

$onve(Surface

Leg

Leg

!hroat

$oncaveSurface

9ne:ual leg fillet 8eld



68402/61420 Slide # 0

.illet 7eld Strength

Stress in fillet eld ) factored load6eff& throat area

imit state of Fillet "eld is shear fract*re thro*ghthe throat regardless of ho7 it is loaded

Iesign Strength

For e *al leg fillet 7eld

#77 8 F 5 ;0 f <.;0

==φ

88n L 3a<0< ;06 f + φ φ =8e8n Lt f + φ φ

=

Design of 7elded



68402/61420 Slide # 1


Ta%le J2&$ in the 9)SC Specifications gi5es the 7eld designstrength

( f 7 ; 0&60 F ENN

( For E 0NN φf 7 ; 0& $ 0&60 482 ; 21 .a

9dditionally the shear strength of the %ase metal m*st also%e considered

∀φ! n ; 0& 0&6 Fy area of %ase metal s*%+ected to shear

( 7here F y is the yield strength of the %ase metal&

Design of 7elded



68402/61420 Slide # 2


"

le3ation8lan

"

le3ation8lan

Strength of 7eld in shear ; 0& $ 0& 0 a 7 f 7

)n 7eld design pro%lems it is ad5antageo*s to 7or, 7ithstrength per *nit length of the 7eld or %ase metal&

For e ample



68402/61420 Slide #

4i"itations on 7eld Di"ensions

inim*m si'e a min

( F*nction of the thic,ness of the thinnest connected plate

( Ri5en in Ta%le J2&4 in the 9)SC specifications

a im*m si'e a maC

( f*nction of the thic,ness of the thinnest connected plate

( for plates 7ith thic,ness ≤ 6 mm a ma ; 6 mm&

( for plates 7ith thic,ness ≥ 6 mm a ma ; t M 2 mm&

inim*m length 7

( ength 7 ≥ 4 a other7ise a eff ; 7 / 4 a ; 7eld si'e

( !ead J2&2 % page 16&1: $

( )ntermittent fillet 7elds 7:min ; 4 a and 8 mm&

i"itations on 7eld Si e AISC



68402/61420 Slide # 4

i itations on 7eld Si e - AISCS!ecifications 92 2 age 36 3$

The minimum length of fillet 7eld may not %e less than 4 the 7eld leg si'e& )f it is the effecti5e 7eld si'e m*st %ered*ced to W of the 7eld lengthThe ma"imum si e of a fillet 7eld along edges of materialless than 6 mm thic, e *als the material thic,ness& Formaterial thic,er than 6 mm the ma"imum si e may note ceed the material thic,ness less 2 mm& to pre5entmelting of %ase materialThe minimum eld si e of fillet 7elds and minimum effecti@ethroat thic7ness for partial:penetration groo5e 7elds aregi5en in !FI Ta%les J2&4 and J2& %ased on the thic,nessof the %ase materials to ens*re f*sion and minimi'edistortion=inimum end return of fillet 7eld ≥ 2 7eld si'e



68402/61420 Slide # $

4i"itations on 7eld Di"ensions

Ma i,u, effective length - read S' *2"2b( )f 7eld length 7 L 100 a then effecti5e 7eld length 7:eff ; 7

( )f 7 L 00 a then effecti5e 7eld length 7:eff ; 7 1&2 M 0&002 7 /a

( )f 7 = 00 a the effecti5e 7eld length 7:eff ; 0&6 7

eld Ter,inations - read S' *2"2b( ap +oint M fillet 7elds terminate at a distance = a from edge&

( "eld ret*rns aro*nd corners m*st %e = 2 a



68402/61420 Slide # 6

;uidelines for .illet 7eld design

T7o types of fillet 7elds can %e *sed( Shielded etal 9rc "elding S 9"

( 9*tomatic S*%merged 9rc "elding S9"

a

a707.0at eff 707.0=

at eff = 9)SC M Section J2&2

S h e a

r f a i l * r e

p l a n e

7eld S)" ols



68402/61420 Slide #

7eld S)" ols <A"erican 7elding Societ) A7S=

Fillet 7eld on arro7 side& "eldOs leg si'e is 10 mm&"eld si'e is gi5en to the left of the 7eld sym%ol& "eldlength 200 mm is gi5en to the right of the sym%ol

Fillet 7eld 12 mm si'e and $ mm long intermitten7elds 12$ on center on the far side

Field fillet 7elds 6 mm in si'e and 200 mm long %othsides&

Fillet 7elds on %oth sides staggered intermitten 10mm in si'e $0 mm long and 1$0 mm on center

"eld all aro*nd +oint

Tail *sed to reference certain specification or process

10 200

12 75:125

6 200

10 50:150



68402/61420 Slide # 8

;uidelines for .illet 7eld design

Fillet 7eld design can %e go5erned %y the smaller 5al*e of

( "eld material strength

( Base etal Strength

3 f La<0< ;06 P 88eld Weld = u φ =

#((8 F f 6.0=75.0=φ

a

a707.0

)6.0( ; > 8eld base BM u F Lt P φ =

<.0=φ

**+E;"//

,;.E#"//

F E// <M1a=Electrode

X

AISC Table ".) *ield Limit State



68402/61420 Slide #

;uidelines for .illet 7eld designThe 7eld strength 7ill increase if theforce is not parallel to the 7eld

3 f La<0< ;06 P 88eld Weld = u φ =

( )θ 5.1sin5.016.0 +=

#((8 F f 75.0=φ

θ

a im*m 7eld si'e

≥−≤≤

mm6mm2mm6mm6

ma* ; base etal base

base8eld t if t

t if t part thinner in = 8eld t t ≤

X

inim*m 7eld si'e

AISC Table ".%



68402/61420 Slide # 80

Ca!acit) of .illet 7eldThe 7eld strength is a f*nction of the angle θ

S t r e n g t h

Weld go+erns

#ase metal go+erns

θ

)6.0( ; > 8eld base ) BM u F Lt P φ =

( )θ φ 5.1 ; sin5.016.0707.0 += #((8eld 8eld Weld u F 8L P

Angle θ -

7 ; 7eld si'e7 ; 7eld si'e

#1 > - Design Strength of 7elded



68402/61420 Slide # 81

#1 > Design Strength of 7eldedConnection

Ietermine the design strength of the tension mem%er and connectionsystem sho7n %elo7& The tension mem%er is a 100 mm 10 mmthic, rectang*lar %ar& )t is 7elded to a 1$ mm thic, g*sset plate *singE 0NN electrode& Consider the yielding and fract*re of the tensionmem%er& Consider the shear strength of the 7eld metal and the

s*rro*nding %ase metal&

125 mm

125 mm

12 mm

12 mm

100 mm * 10 mm

t 15 mm

a 6 mm




68402/61420 Slide # 82


Step " Chec, for the limitations on the 7eld geometry( tmin ; 10 mm mem%er

tma ; 1$ mm g*sset

Therefore a min ; $ mm : 9)SC Ta%le J2&4

a ma ; 10 mm M 2 mm ; 8 mm : 9)SC J2&2% page 16&1: $

Fillet 7eld si'e ; a ; 6 mm : 9herefore( OG

( 7:min ; 4 6 ; 24 mm and 8 mm : Q &

( 7:min for each length of the 7eld ; 100 mm trans@erse distancebet een elds see *2"2b

( Ri5en length ; 12$ mm 7hich is = min & Therefore OG




68402/61420 Slide # 8





68402/61420 Slide # 84

g gConnection

( ength/7eld si'e ; 12$/6 ; 20&8 : 9herefore( ma"imum effecti@elength *2"2 b satisfied&

( End ret*rns at the edge corner si'e : minim*m ; 2 a ; 12 mm:9herefore( OG

Step " Iesign strength of the 7eld

( "eld strength ; φ 0& 0 a 0&60 FENN 7

; 0& $ 0& 0 6 0&60 482 2$0/1000

; 2 0 ,@Step " Tension strength of the mem%er

∀ φ! n ; 0& 44 100 10/1000 ; 10 ,@ : tension yield




68402/61420 Slide # 8$

#1 Design Strength of 7eldedConnection

∀φ! n ; 0& $ 9 e 448 : tension fract*re( 9 e ; K 9

( 9 e ; 9 g ; 100 10 ; 1000 mm

( Therefore φ! n ; 6 ,@

( The design strength of the mem%er:connection system ; 2 0 ,@&"eld strength go5erns& The end ret*rns at the corners 7ere notincl*ded in the calc*lations&



68402/61420 Slide # 86

#lastic Anal)sis of #ccentric 7eldedConnections:t is ass&med here that the rotation o the %eld at ail&re occ&r aro&nd

the elastic centre <EC= o the %eld4 The only di erence rom $olts is %eare dealing %ith &nit length o %eld instead o a $olt

? d M f =2

The shear stress in %eld d&e to torsionmoment M is

M

M is the moment3 d is the distance rom the centroid o the%eld to the %eld point %here %e eval&ate the stress3 > isthe polar moment o inertia o the %eld

F

ed

A:SC Man&al 1art ;



68402/61420 Slide # 8

) ( @ @ ? +=

e F M =

? d M

f =2

#lastic Anal)sis of #ccentric 7eldedConnections - Shear + *orsion

stresses d&e to torsional moment 6M7 is

? ) M f ( =2 ?

( M f ) =2

=

? Calc&lation shall $e done or t e

8t eff

707.0=? 8r or t e @ + mm



68402/61420 Slide # 88

( ( ( f f f 21 +=

8eld

( ( A

F f =1

#lastic Anal)sis of #ccentric 7eldedConnections - Shear + *orsion

Forces d&e to direct applied orce is

Total stress in the %eld is

8eld n ) (v R f f f ; 22 φ ≤+=

8eld

) ) A

F f =1

) ) ) f f f 21 +==

#1 > > - Design Strength of 7elded



68402/61420 Slide # 8

g gConnection - Shear and *orsion

>etermine the si?e of $eldre@uired for the brac et connectionin the figure. "he ser3ice deadload is 50 # and the ser3ice li3eload is 120 . '6 steel is used

for the brac et# and <<2 steel isused for the column.

Calc*lations are donefor t eff ; 2$ mm

2$0 mm

200mm

00mm

I ; $0 ,@

; 120 ,@

1$ mm .




68402/61420 Slide # 0


Step ) Calc*late the *ltimate load P u - &;2D &;5L - &;26.03 &;56&203 - 2.2 1N

Step )) Calc*late the direct shear stress

Step ))) Comp*te the location of the centroid

Step )D Comp*te the torsional moment e - 2.0 200 .<;& - 'C2;C M - Pe - 2.26'C2;C3-CC0&& 1N ;

/mm '60200'00200

10002521 =++ ×= ) f

mm57.1or)2)(100(200)700( == ( (




68402/61420 Slide # 1


Step D Comp*te the moments of inertia of the total 7eldarea @ ( - &6'003 ' 6&/&23 2620036&.032-&&;2.E&0 5

@ ) - 2 62003 ' 6&/&23 620036&00 .<;&32 G '006.<;&3 2-';0.E&0 5

? - @ ( @ ) - 6&&;2. ';0.3E&05

- & ;'E&05

Step D) Comp*te stresses at critical location

( ) /mm170')'60<,<()10'<(

/mm<,<10'.1!

1000)1.57200(<<011

/mm10'<10'.1!

1000)150(<<011

22221

22

62

62

=++=++=

=×

×−==

=×

×==

) ) (v

)

(

f f f f

? ( M f

?

) M f




68402/61420 Slide # 2


Step D)) Chec, the shear strength of the %ase metalThe shear &ield strength of the angle leg is4

/ n 0 1.2-1.34 yt 0 1.2 1.3- "%5- ()- 0 "112 0 mm

"he base metal shear strength is therefore4 200< /mm A 170' /mm ( C).

Step D))) Calc*late the 7eld si'e ass*ming F 8 - 0;5F

#77

6se (" mm

Answer7 Use a +.?mm illet %eld3 E#" electrode4

mm11.1)!,26.0)(707.0(75.0

170')707.0(

=×

==W

n

F R

aφ

φ

#lastic Anal)sis of #ccentric 7elded



68402/61420 Slide #

)Connections - Shear + *ension

l l) f ld d



68402/61420 Slide # 4

A F

f v =

e F M =

(

(t @

c M f =

#lastic Anal)sis of #ccentric 7eldedConnections - Shear + *ension

stresses d&e to torsion moment 6M7 is

? Calc&lation shall $e done or t e

at eff

707.0=? 8r or t e @ + mm

4 0 applied force

e 0 eccentricity of load I 8 0 moment of inertia around 8$a8is

c 0 distance from neutral a8is of weld to the farthest weld point

#1 > 8 - Design Strength of 7elded



68402/61420 Slide # $

g gConnection - Shear + *ension

9n 6 4 1/2 is *sed in a seated %eam connection as sho7n in thefig*re& )t m*st s*pport a ser5ice load reaction of 2$ ,@ dead load and a$0 ,@ li5e load& The angles are 9 6 and the col*mns in 9 2& E 0NNelectrodes are to %e *sed& "hat si'e fillet 7eld are re *ired for theconnection to the col*mn flange

1$2mm

20mm

20 mm 82 mm




68402/61420 Slide # 6

Connection - Shear + *ension

Step . calc*late the eccentricity of the reaction 7ith respect tothe 7eld is

e ; 20 P 82/2 ; 61 mm

Step . Calc*late the moment of inertia for the 7eldconfig*ration

@ - 26&36&.23' / &2 - .H.'00 mm ! c - &.2/2 - <5

Step .Calc*late the factored:load reaction is P u - &;2D &;5L - &;262.3 &;56.03 - &&0

M u - P ue - &&065&3 - 5<&0 mm




68402/61420 Slide #

Connection - Shear + *ension

Step /. The re *ired 7eld si'e a ( a ; 4 / 0& 0& 0 0&6 482 ; 6&2 mm

/mm<!')'62(),71(

/mm'62)152)(1(2

110000

/mm,715,5'00

1000)76(6710

2222 =+=+=

===

=×

==

vt r

uv

ut

f f f

A P

f

@ c M

f

( Step .Calc*late the factored:load reaction is




68402/61420 Slide # 8

Connection - Shear + *ensionThe re *ired si'e is therefore a - <

Step /. Chec, minim*m and ma im*m 7eld si'e( From 9)SC Ta%le J2&4 inim*m 7eld si'e ; $ mm( From 9)SC Ta%le J2&2% a im*m 7eld si'e ; 1 : 2 ; 11 mm

( Try a ; mm

Step / . Chec, the shear capacity of the %ase metal theangle controls

( 9pplied direct shear ; f 5 ; 62 @/mm( The shear yield strength of the angle leg is/ n 0 1.291.34 yt 0 1.2-1.3 "%5- (!- 0 (:%( ;'mm

( The %ase metal shear strength is therefore1 41 @/mm = 62 @/mm Q &

'l i" S h A l) i f



68402/61420 Slide #

'lti"ate Strength Anal)sis of#ccentric 7elded ConnectionsWhen comparing elastic analysis to e perimental on eccentric %elded

connections3 it $ecomes o$vio&s that elastic analysis is over conservative4

F e

θ

@$

sr

5e ormation

oad

!" o

-" o

" o

Elastic analysis

'l i" S h A l) i f



68402/61420 Slide # 100

'lti"ate Strength Anal)sis of#ccentric 7elded ConnectionsSimilar to $olts3 %eld can $e divided into segments%hich rotate a$o&t an instantaneo&s centre <:C=

:nstead o s&mming the orces %e can integrate overthe length o the %eld to get the $asic e)&ations oe)&ili$ri&m2

∫ ∫ += * + L L

d(r Rd)r R M

F eθ

@$

sr

∫ ∫ +=

* L+ L

d($os Rd)$os R F φ φ θ

@$

r φ

θ

r

φ

Th&s λ µ )1( ∆−−= e R R

'l i" S h A l) i f



68402/61420 Slide # 101

'lti"ate Strength Anal)sis of#ccentric 7elded ConnectionsHo%ever3 in %eld2 The orce in each segment 6R7 is

also &nction o the angle θ $et%een the orcedirection and the %eld4

'.05.1 )D<.0<.1()E5.01(6.0 p pSin F R #77 −+= θ

s p∆∆

=5e ormation o the segment at ma stress

5e ormation o the segment

8'2.0)2(20<.0 −+=∆ θ ? Similar to $olts3 the ar %eld element might have a higher proportion o orce4

F e

θ

@$

sr

'lti" t St th A l) i f



68402/61420 Slide # 102

'lti"ate Strength Anal)sis of#ccentric 7elded Connections

The &ltimate de ormation & happens or the segment %ith smallest m rs

88u 17.0)6(0,7.1 65.0 ≤+=∆ −θ

min)/( s r ∆

F e

θ

@$

sr

5etermine the segment that has

Ho%ever3 the critical %eld is that o the smallest m rs

8'2.0)2(20<.0 −+=∆ θ

'lti" t St th A l) i f



68402/61420 Slide # 10

'lti"ate Strength Anal)sis of#ccentric 7elded Connections

8'2.0

)2(20<.0 −

+=∆ θ

88u 17.0)6(0,7.1 65.0 ≤+=∆ −θ

In all e<uations = θ > is in radian ranges from ?ero to π '"

'lti" t St gth A l) i f



68402/61420 Slide # 104

'lti"ate Strength Anal)sis of#ccentric 7elded ConnectionsTh&s to estimate the orce in the critical segment %e do the ollo%ing steps2

+? 5ivide the %eld into segments and ass&me an :C

.? Calc&late the de ormation o each element

!? Comp&te the ratio m r and determine r crit

,? For this critical segment comp&te the &ltimate de ormation &

*? Comp&te the de ormation o each other segment

8'2.0)2(20<.0 −+=∆ θ

ucrit

s r r ∆=∆

F e

θ

@$

sr

minisr

8hichat r r crit

∆=

88u 17.0)6(0,7.1 65.0 ≤+=∆ −θ

'lti" t St gth A l) i f



68402/61420 Slide # 10$

'lti"ate Strength Anal)sis of#ccentric 7elded ConnectionsSteps contin&ed2

9? Comp&te the stress in each segment

#? Chec( e)&ili$ri&m e)&ations

F e

θ

@$

sr '.05.1 )D<.0<.1()E5.01(6.0 p pSin F R #77 −+= θ

s p∆

∆=

(

n

i ( F R

i=∑

=1D ,ero F (

=∑

D ,ero F )

=∑

D ,ero M @$

=∑

)

n

i ) F R

i =∑=1

)(. 01

er F r Rii n

n

in +=∑

=

@<n (-

@<n "-

@<n !-

#1 Slid



68402/61420 Slide # 106

#1tra Slides

Sli!$critical Bolted



68402/61420 Slide # 10

Connections

-igh strength 9 2$ and 94 0 %olts can %e installed 7iths*ch a degree of tightness that they are s*%+ect to largetensile forces&These large tensile forces in the %olt clamp the connectedplates together& The shear force applied to s*ch atightened connection 7ill %e resisted %y friction as sho7n inthe Fig*re %elo7&

"ightened

8

8

"ightened"ightened

8

8

8

8




68402/61420 Slide # 108

Connections

" b

" b

" b

" b

8

µ

" b

" b

µ

" b

" b

8

" b

" b

" b

" b

" b

" b

8

µ

" b

" b

8

µ

" b

" b

" b

" b

µ

" b

" b

8

µ

" b

" b

" b

" b

8




68402/61420 Slide # 10

ConnectionsTh*s slip!critical bolted connections can %e designed toresist the applied shear forces *sing friction& )f the appliedshear force is less than the friction that de5elops %et7eenthe t7o s*rfaces then no slip 7ill occ*r %et7een them&

-o7e5er slip 7ill occ*r 7hen the friction force is lessthan the applied shear force& 9fter slip occ*rs theconnection 7ill %eha5e similar to the %earing:type %oltedconnections designed earlier&

Ta%le J &1 s*mmari'es the minim*m %olt tension thatm*st %e applied to de5elop a slip:critical connection&



68402/61420 Slide # 110

Sli!$Critical Connections

oads to be transferred ≤ Frictional:esistance tension force in bolt coefficient

of friction µ ⇒ @o slippage %et7een mem%ers

⇒ @o %earing and shear stresses in %olt

!FI J &10 re *ires bearing strength to %e chec,ed for %othBearing!9ype connections and Slip!Critical connections e5en

tho*gh there is s*pposed to %e little or no %earing stresses on the%olts in Slip!Critical connections




68402/61420 Slide # 111

The shear resistance of f*lly tensioned %olts to slip atfactored loads X ser5ice loads is gi5en %y 9)SCSpecification J &8Shear resistance at factored load ; φ! n ; φ 1&1 µh sc T% @s

φ - .:0 for factored loads < =. for ser!ice loadsµ - friction coefficient 2 b - minimum bolt tension gi!en in 2able 34.=

h sc 7 hole factor determined as>For standrad si8e holes h sc " =.

For o!ersi8ed and short-slotted holes h sc " .:0 For long-slotted holes h sc " ./

& s - number of slip planes

Connections




68402/61420 Slide # 112


Slip Coefficients !FI J &8

Surface µ

Class 9 *npainted clean mill scale or

s*rfaces 7ith class 9 coating on %last:cleaned steel

Class B *npainted %last:cleaned s*rfaces ors*rfaces 7ith Class B coating on %last:

cleaned steel

0& $

0&$0




68402/61420 Slide # 11

( "hen the applied shear force e ceeds the φ! n 5al*e stated a%o5eslip 7ill occ*r in the connection&

The final strength of the connection 7ill depend on theshear strength of the %olts and on the %earing strength ofthe %olts& This is the same strength as that of a %earingtype connection&

Slip critical connections shall still %e chec,ed as %earingtype in case slip occ*rs as a res*lt of o5erload&

Connections

#1 2 $ Sli!$ i i l C i



68402/61420 Slide # 114

#1 2 $ Sli!$critical Connections

Iesign a slip:critical splice for a tension mem%ers*%+ected to 600 ,@ of tension loading& The tensionmem%er is a "8 28 section made from 9 6 material&The *nfactored dead load is e *al to 100 ,@ and the*nfactored li5e load is e *al to 00 ,@& Kse 9 2$ %olts&The splice sho*ld %e slip:critical at ser5ice loads&

#1 2 $ Sli!$ iti l C ti



68402/61420 Slide # 11$

Step " Ser5ice and factored loads( Ser5ice oad ; I P ; 400 ,@&

( Factored design load ; 1&2 I P 1&6 ; 600 ,@

( Tension mem%er is "8 28 section made from 9 6 steel& Thetension splice m*st %e slip critical i&e& it m*st not slip at ser5iceloads&

Step " Slip:critical splice connection ser5ice load

∀φ! n of one f*lly:tensioned slip:critical %olt ; φ 1&1 µh sc T% @s

See Spec& J &8





68402/61420 Slide # 116

( 9ss*me d % ; 20 mm&∀φ! n of one %olt ; 1&0 1&1 0& $ 1&0 142 1 ; $6&2 ,@

( @ote T% ; 142 ,@ from Ta%le J &1

∀

φ! n of n %olts ; $6&2 n = 400 ,@ splice m*st %e slip:critical atser5ice

( Therefore n = &12





68402/61420 Slide # 11


Step " ayo*t of splice connection( Flange:plate splice connectionSplice plate

Splice plate

F, * 2, F, * 2,

Splice plate

Splice plate

F, * 2, F, * 2,

C4 4C4 4




68402/61420 Slide # 118


( To %e symmetric a%o*t the centerline need the n*m%er of %olts to%e a m*ltiple of 8&

( Therefore choose 16 f*lly tensioned 20 mm 9 2$ %olts 7ith layo*tas sho7n a%o5e&

(inim*m edge distance e ; 4 mm from Ta%le J &4

( Iesign edge distance e ; 40 mm&

( inim*m spacing ; s ; 2P2/ d % ; 2&6 20 ; $ &4 mm&Spec& J &

( .referred spacing ; s ; &0 d % ; &0 20 ; 60 mm Spec& J &( Iesign s ; 60 mm&

( 9ss*me 10 mm thic, splice plate




68402/61420 Slide # 11


Step /" Connection strength at factored loads( The splice connection sho*ld %e designed as a normal

shear/%earing connection %eyond this point for the factored load of600 ,@&

(Shear strength of a %olt ; &8 ,@ see E ample &1

( The shear strength of %olts ; &8 ,@/%olt 8 ; 622&4 ,@

( Bearing strength of 20 mm %olts at edge holes e ; 0 mm ; 6 &1,@ see E ample &1

( Bearing strength of 20 mm %olts at non:edge holes s ; 60 mm ;1 8&2 ,@ see E ample &1

( Bearing strength of %olt holes in flanges of 7ide flange section

( ; 4 6 &1 P 4 1 8&2 ; 82 &2 ,@ = 600 ,@ Q




68402/61420 Slide # 120


Step /" Iesign the splice plate( Tension yielding 0& 9 g F y = 00 ,@Y Therefore 9 g = 1 44 mm 2

( Tension fract*re 0& $ 9 n F * = 00 ,@

( Therefore 9 n ;9 g : 2 20 P &2 10 = 1000 mm 2

( Beam flange 7idth ; 166 mm

( 9ss*me plate 7idth 160 mm 10 mm 7hich has 9 g ; 1660 mm 2

Step / " Chec, mem%er strength

( St*dent on his/her o7n&

'lti"ate Strength Anal)sis of# t i B lt d C ti



68402/61420 Slide # 121

#ccentric Bolted ConnectionsE perimental st&dy $y Cra% ord and &la( <+-#+= sho%ed2 F

e

? The load?de ormation relationshipo any $olt is non?linear

A:SC Man&al 1art #

'lti"ate Strength Anal)sis of#ccentric Bolted Connections



68402/61420 Slide # 122

#ccentric Bolted ConnectionsThe ollo%ing concl&sions %ere also sho%n2

Fail&re rotation does not happen aro&nd the elastic center $&taro&nd an instantaneo&s centre <:C=

The :C does not coincide %ith the EC

The de ormation o each $olt is proportional to its distance romthe :C

Similar to the elastic analysis3 the connection capacity isgoverned $y the orce in the arthest $olt

F

e

D M

ir #$

@$

e F

e′




68402/61420 Slide # 12

ma*ma*

∆=∆r r b

b

e F M =#ccentric Bolted Connections

mm6.,=all) #(peri ent

Meas&red at the elastic centroid

At ail&re

(

n

i ( F R

i=∑

=1D ,ero F (

=∑

D ,ero F )

=∑

D ,ero M @$

=∑

)

n

i ) F R i =∑=1

3ee6 F r ; R in

n

&iin +′=∑

=

@<n (-

@<n "-

@<n !-

ir #$ @$

e F

e′




68402/61420 Slide # 124

#ccentric Bolted Connections

There ore3 getting the ma im&m orce in the arthest $olt re)&iresdetermining the &n(no%n 6e 7

Beca&se o the non?linear relationship3 e can $e determined $y trialand error

A spreadsheet can $e &sed to determine e

ir #$ @$

e F

e′

.orces on #ccentricall)$ oaded Boltswith #ccentricit) on the a)ing Surface



68402/61420 Slide # 12$

Ultimate Strength =ethod ,?nstantaneous Center of:otation =ethod0

: ) : ult ,/ $ e !+&1I3 ∆ 0+&55

with #ccentricit) on the .a)ing Surface

C IC

1 2

' !

ee4 & u

d & d 2

d 'd

/ (

/ "

/ % / !

R - ominal shear strength of 1 bolt at a deformation ∆#

Rult - Gltimate shear strength of 1 bolt#

∆ "otal deformation# including shear# bearing and bending deformation in the bolt and bearingdeformation of the connected elements# in. ( ∆ a( - H;5

for 20 mm AS!M A'2. bolt3∆& /d & - ∆2 /d 2 - I - ∆ a( /d a(

e - 2;<&HI base of the natural logarithm

'lti"ate Strength Method <InstantaneousCenter of ?otation Method=



68402/61420 Slide # 126

Center of ?otation Method=

9rial and error>( 9ss*me eJ

( Comp*te ∆i ) d i ∆ma" 6d ma" ∆ma" is ass*med for %olt at farthestdistance from )C

(Comp*te : i ): ult ,/! e !+&1I3∆i 0+&55

( Chec, for % u) Σ :d06,eJ.e0

( )f not satisfied repeat 7ith another eJ

λ µ )1( be R Rult b

∆−−=

ma*

ma*

∆=∆r

r bb

#1 6 4 - #ccentric Connections -'lti"ate Method



68402/61420 Slide # 12

lti ate MethodIetermine the largest eccentric force % u for 7hich the designshear strength of the %olts in the connection is ade *ate *singthe )C method& Kse %earing:type 20 mm 9 2$N %olts

C IC

1 2

' !

e - &00e4-50

& u

d & d 2

d 'd

/ (

/ "

/ % / !

75mm

75mm

>esign shear strength per bolt ( *. 7 1)

Ru - φ Rn- <<;H 1N

fter se3eral trials# assume e4- 60 mm.Bolts 2 and ! are furthest from the HI#therefore ∆2 - ∆ - ∆ a( - H;5

Iompute ∆i and Ri in tabulated form4

$ mm

#1 6 4 - #ccentric Connections -'lti"ate Method



lti ate Method0olt

1

h

*mm+

!

*mm+d *mm+

*mm+? *k&+ ? *k&+ ?d

*k&.mm+1 22&$ $ 8& $&4 2& 20& $6 2

2 &$ $ 12 8&6 &8 61&6 $8$

22&$ $ 8& $&4 2& 20& $6 2

4 &$ $ 12 8&6 &8 61&6 $8$

=&# "&3

= 2# 3

Ihec 4

P u- (Σ Rd )/(e4 e) (2655!/(60J100))

steel_ch6 - connections2

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