Skills Baseplate En

7/30/2019 Skills Baseplate En

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SKILLS Project



BASE PLATE CONNECTIONS



Design process for pinned and fixed column base joints

Base-plate resistance

Anchor bolt resistance

Concrete resistance

Weld resistance

Application of the component method to pinned and

fixed column base joint.

3

LEARNING OUTCOMES



Introduction

Pinned column base joint

Rigid column base joint

Application

Conclusion

4

LIST OF CONTENTS



INTRODUCTION



Typical pinned column base joint

6

INTRODUCTION

Grout

Anchor bolt

Concrete foundation

Column

Base plate



Typical fixed column base joint

7

INTRODUCTION

Concrete foundation

Column

Base plate

Anchor bolts



Analysis of the joint according to EN 1993-1-8

Joint is modelled by a typical components : T-stub

Two models for loadings :

Resistance in compression : T-stub in compression with concrete,

Resistance in tension : T-stub in tension (anchor bolts + base plate

+ column web).

8

INTRODUCTION

F T,Rd

l eff

F T,Rd



Recommended partial safety factors according to EN 1993-1-8 :

g M0 =1 : column web in tension, bending of the base-plate

g M2 =1,25 : Anchor bolts in tension/shear, weld resistance

Recommended partial safety factors according to EN 1992-1-1 :

g C =1,5 : Concrete in compression, bond anchorage resistance

The national annexes may give indications

9

INTRODUCTION



PINNED COLUMN BASE JOINT



beff

l eff

F c,Rd

jd

Evaluation of the resistance in compression of T-stubs in

contact with concrete.

Resistance in compression of the joint : association of

resistances of T-stubs in compression.

11

PINNED COLUMN BASE JOINT - RESISTANCE IN COMPRESSION

EN 1993-1-8 § 6.2.5

Concrete resistance reached : f jd

Web T-stub : F c,bw,Rd

Flange T-stubs : F c,fc,Rd



Foundation bearing strength

Where:

a bf coefficient which accounts for diffusion of concentrated

force within the foundation. b j may be taken as 2/3 (see Note)

f cd Concrete design strength :

f ck Compressive cylinder strength of concrete at 28 days

a cc = 1

g c

= 1,512


EN 1993-1-8 § 6.2.5

EN 1992-1-1 §6.7 jd bf j cd f f a b

ck

cd cc c

f f a

g



Expression of a bf :

Note : b j = 2/3 if :

Strength of grout ≥ 0,2× f cd

Else :

13


bf hbf

p p p p

= min 1+ ; 1+2 ; 1+2 ; 3max( , )

ed e

h b h ba

m p

p

50 mm

min 0,2

0,2

e b

h

Axis z-z

Axis y-y

Axis x-x

bp

hp

d f

eb

eh

em

jd cd f f



Resistance in compression of a T-stub :

Where:

l eff Effective length of the T-stub

beff Effective width of the T-stub such as :

c Additional bearing width of the flange :

f yp Yield strength of base plate

g M0 =1

14


C,Rd jd eff eff F f b l

EN 1993-1-8 (6.4)

eff 2b t c

yp

p

jd M03

f c t

f g

beff

l eff

F c,Rd

jd t p

c

c

t



Large and short projections :

Flange T-stub : Flange T-stub :

Web T-stub :

15


eff fcb t c c b eff fc 2b t c

eff wc 2b t c

t p

t = t fc

c b c c

t p

t = t fc or t wc

c c

a) Short projection b) Large projection

beff beff

jd jd

EN 1993-1-8 §6.2.5



Resistance in compression of a flange T-stub :

Where:

16


eff p fcmin ; 2l b b c

eff p c fc c fcmin ; /2 min ; /2b c h h t c h t

c,fc,Rd jd eff eff F f b l

Large projectionShort projection

hc

bfc bp

hp

c

c

l eff

c c

beff

t fc

hc

bfcbp

hp

c

c

l eff

c

beff



Resistance in compression of the web T-stub :

Where:

17


c,bw,Rd jd eff eff F f b l

eff c fc2 2 0l h t c

eff wc2b c t

c

c

hc

l eff

c c

beff

t fc

t wc

c



Resistance in compression of the joint :

Where :

18


C,Rd c,fc,Rd c,bw,Rd2N F F

C,Rd jd cp cp cp cp wc 2N f h b l b t c

cp p cmin ; 2h h h c

cp p fcmin ; 2b b b c

cp c fc2 2 0l h t c

hc

bfcbp

hp

c

c

c c

t wc

t fc



Joint modelled by a T-stub (anchor bolts, base plate) in tension

Evaluation of the tensile resistance of the T-stub 6 possible failure modes :

Base plate/anchor bolts (modes 1, 2, 1-2 and 3)

Column web (mode 4) and weld

19

PINNED COLUMN BASE JOINT - RESISTANCE IN TENSION

F T,Rd

l eff

F T,Rd



Failure modes of base plate/anchor bolts

Mode 1 : Yielding of the base plate Mode 2 : Failure of anchor bolts

Mode 1-2 : Yielding of the base plate Mode 3 : Failure of anchor bolts

20


Prying

effect

No pryingeffect

F T,1,Rd

Q Q

F T,2,Rd

Q Q

F T,1-2,Rd F T,3,Rd



Mode 4 : Yielding of the column web in tension

The prying effect has an influence on the choice of failure

modes.

Failure modes 1 and 2 are not possible without prying forceand are replaced by failure mode 1-2.

21


F T,4,Rd



Prying effect and failure modes :


EN 1993-1-8 Table 6.2

Prying effect Presence of prying effect Absence of prying effect

Deformation

Condition

Resistance of

the T-stub

*

b bL L

*

b b>L L

T,1,Rd T,2,Rd

T,Rd

T,3,Rd T,4,Rd

;min

;

F F F

F F

T,1-2,Rd T,3,Rd

T,Rd

T,4,Rd

;min

F F F

F

F T,Rd

Q Q

F T,Rd



Anchor bolt elongation length :

Where:

t wa Thickness of the washerd Anchor bolt diameter


EN 1993-1-8 Table 6.2

b m p wa8 0,5L d e t t k

23

t p

em

8d Concrete

grout

base plate

k



Limit anchor bolt elongation length :

Where:

As Tensile stress area of one anchor bolt

l eff,1 Effective length :


EN 1993-1-8 Table 6.2

3

* sb 3

eff,1 p

8,8m ALl t

eff,1 eff,cp eff,nc=min ;l l l

wc w/2 /2 0,8 2m p t a

24

m

t pBase plate

aw

p/2

t wc



Effective lengths of the T-stub :

Circular mechanism Non circular mechanism


EN 1993-1-8 Table 6.6

eff,cp 2l m eff,nc 4 1,25l m e

mm ee

p

t wc

25

mm ee

Yield line



Resistance of modes 1 and 1-2:

Where:


EN 1993-1-8 Table 6.2

Failure mode Mode 1 Mode 1-2

Yielding of

the base

plate

Resistance of

the T-stub

F T,1-2,Rd

pl,1,Rd

T,1,Rd

4MF

m

2

p yp

pl,1,Rd pl,Rd eff,1 pl,Rd eff,1 eff,cp eff,nc

M0

; ; =min ;4

t f M m l m l l l

g

pl,1,Rd

T,1-2,Rd

2MF

m

F T,1,Rd

Q Q

m

26



Resistance of modes 2 and 3:

Where:

F t,Rd,anchor Resistance of one anchor bolt


EN 1993-1-8 Table 6.2

Failure mode Mode 2 Mode 3

Failure of

anchor bolts

Resistance of

the T-stub

pl,2,Rd pl,Rd eff,2 eff,2 eff,nc; = ; =min ; 1,25M m l l l n e m

pl,2,Rd t,Rd,anchor

T,2,Rd

2 2M nF

F m n

T,3,Rd t,Rd,anchor

2F F

27

F T,2,Rd

Q Q

emF t,Rd,anchor

F T,3,Rd

F t,Rd,anchor F t,Rd,anchor



Tensile resistance of anchor bolts :


28

(b) Washer plate : No bond(a) Hook : bond resistance

1. Base plate

2. Grout

3. Concrete foundation

EN 1993-1-8 §6.2.6.12



Resistance of one anchor bolt, two failure modes:

Tensile resistance of the anchor bolt section, F t,Rd

,Bond anchorage resistance, F t,bond,Rd.

Design tensile resistance of the anchor bolt section :

Where:

f ub Tensile strength of the anchor bolt

g M2 = 1,25


29

t,Rd,anchor t,Rd t,bond,Rdmin ;F F F

ub st,Rd

M2

0,9 f AF

g

EN 1993-1-8 Table 3.4

EN 1993-1-8 Table 3.1



Bond anchorage resistance of a straight bolt :

Where:

d Nominal diameter of an anchor bolt

f bd Design bond strength :If d < 32 mm :

If d ≥ 32 mm :

g c = 1,5

f yb : Yield strength of the anchor bolt.


30

t,bond,Rd b bdF dl f

F t,Bond,Rd

l b

ck

bd

C

0,36 f f

g

ck

bd

C

0,36 132

100

f d

f g

2

yb 600 /mm f N

INN COLU N AS JOIN SIS ANC IN NSION



Bond resistance of a bolt with a hook :

Check that :


31

b bdt,bond,Rd0,7

dl f F

2

yb 300 /mm f N

F t,Bond,Rd

≥5d

90°

l b

EN 1993-1-8 §6.2.6.12 (5)

PINNED COLUMN BASE JOINT RESISTANCE IN TENSION



Resistance of mode 4:

Where:

f y,wc Yield strength of the column web


Failure mode Mode 4

Yielding of the column

web in tension

Resistance of the

T-stub

F T,4,Rd

t wc

eff,t wc y,wc

T,4,Rd t,wc,RdM0

b t f F F

g

eff,t eff,1=b l 32

PINNED COLUMN BASE JOINT RESISTANCE IN TENSION



Weld resistance :

Where:

aw weld throat thickness of the web

b w correlation factor

f u nominal ultimate strength of the weaker joined partl w,wb total effective length of the web welds

Final resistance of the joint in tension :


33

u

t,w,Rd w,eff,t ww M2

/ 3 f

F l a b g

w,eff,t eff,1 w,wb=2l l l

EN 1993-1-8 Table 4.1

T,Rd T,Rd t,w,Rd t,Edmin ;N F F N

PINNED COLUMN BASE JOINT SHEAR RESISTANCE



Three ways to transmit shear force to concrete block :

Friction resistance between base plate and concrete (compression),

Shear of anchor bolts (compression/tension),

Use of shear nibs (important tension force).

34

PINNED COLUMN BASE JOINT - SHEAR RESISTANCE




Design friction resistance :

Where:

N c,Ed Compression force

C f,d Coefficient of frictionFor sand-cement mortar :

35


EN 1993-1-8 6.2.2 (6)

f,Rd f,d c,EdF C N

f,d 0,2C

Axial force N c,Ed

Shear force

V Ed<0,2×Nc,Ed

Friction




Shear resistance of an anchor bolt:

Where:

f yb Yield strength of the anchor bolt

36


EN 1993-1-8 6.2.2 (7)

bc ub svb,Rd

M2

f AF

a

g

2 2bc yb yb0,44 0,0003 and 235 N/mm 640 N/mm f f a

F vb,Rd




Shear resistance in presence of compression :

Addition of friction resistance and shear resistance of anchor bolts :

Where:

n Number of anchor bolts

37


EN 1993-1-8 6.2.2 (8)

v,Rd f,Rd vb,Rd EdF F nF V

Axial force N c,Ed

Shear force

V Ed

Friction

Shear of anchor

bolts




Shear resistance in presence of tension :

Where:

F T,Rd Tensile resistance of the T-stub in tension

38


Axial force N t,Ed

Shear force

V Ed

Shear of anchor

bolts

t,EdEd

vb,Rd T,Rd1

1,4

NV

nF F




Shear resistance of welds (in compression) :

Where:

l w,eff total effective length of the welds in the direction of sheara weld throat thickness in the direction of shear

Check of the shear resistance of welds (in tension) :

39


w,Rd vw,d w,eff EdV f a l V

uvw,d

w M2

/ 3 f f

b g

2 2

t,Ed Edw,Ed vw,d

w,eff,t w,eff

N V F f a

l l



FIXED COLUMN BASE JOINT

FIXED COLUMN BASE JOINT INTRODUCTION



Calculation of the bending resistance and initial rotational

stiffness in presence of axial force :

Initial rotational stiffness :

FIXED COLUMN BASE JOINT- INTRODUCTION

41

M j,Ed ≤M j,Rd

j,Ed

N j,Ed

M j,Rd

j,Ed

M j,Ed

S j,ini

j,Ed

j,ini

j,Ed

MS




Application of the component method :


42

beff

l eff

F C F T

M j,Ed ≤M j,Rd

j,Ed F c F T

N j,Ed

T-stub in tension : T-stub in compression :




Lever arms :

Tensile force positioned at the centre of anchor bolts,

Compression force at the centre of the column flange.

Bending moment :

Bending resistance : resistance

reach on a T-stub.

43


F C

zT zC

F T

M j,Ed

hc

t fc

j,Ed C C T TM z F z F

C C,Rd T T,RdorF F F F

FIXED COLUMN BASE JOINT BENDING RESISTANCE



Bending resistance depend on eccentricity :

Dominant tensile force : Dominant compression force :

FIXED COLUMN BASE JOINT- BENDING RESISTANCE

44

j,Ed j,Rd

N

j,Ed j,Rd

M Me

N N

2 T-stubs in compression

C N 0z e N T0 e z

2 T-stubs in tension

F T

zT zT

F T,Rd

M j,Rd

N j,Rd

F C,Rd

zC zC

F C

M j,Rd

N j,Rd





45

Dominant bending moment :

Joint composed of a tensile part and a compressive part :Resistance reaches in one these parts,

T-stub in tension critical T-stub in compression critical

N T N Core z e z

F C

zT zC

F T,Rd

M j,Rd

N j,Rd

F C,Rd

zT zC

F T

M j,Rd

N j,Rd




Resistance in compression of a flange T-stub :

Where:

46


eff p fcmin ; 2l b b c

C,Rd jd eff eff

F f b l

F C,Rd

l eff beff

p cceff fc fcmin , min ,

2 2

h hhb c t t c

g

yp

p

jd M03

f c t

f

hc

bfc bp

hp

c

c

c c

t wc

t fc

l eff

beff

EN 1993-1-8 (6.4)




Resistance of the tensile part of the joint (2 anchor bolts):

Analysis of the resistance of an equivalent T-stub :

Same calculation as for pinned column base joint:

Different effective length, l eff

Replace m by mx, e by ex in resistance of T-stub


47

F T,Rd

EN 1993-1-8 Figure 6.10




Effective lengths of the T-stub :

Circular mechanism Non circular mechanism


EN 1993-1-8 Table 6.6

48

e w

mx

ex

bp

x

eff,cp x

x

2

min

2

m

l m w

m e

x x

x x

eff,ncx x

p

4 1,25

2 0,625 /2min

2 0,625

/2

m e

m e w l

m e e

b




Loading Lever arm

z

Bending resistance M j,Rd

for a given value of eN

Dominant

compression forcez = zC + zC

N j,Ed < 0 and 0 ≤ eN ≤ +zC N j,Ed < 0 and-zC ≤ eN ≤ 0

The smaller of and

Dominant tension

forcez = zT + zT

N j,Ed > 0 and 0 ≤ eN ≤ +zT N j,Ed > 0 and -zT ≤ eN ≤ 0

The smaller of and

Dominant bendingmoment

z = zT + zC

N j,Ed 0

and eN > +zT or eN < - zT

N j,Ed ≤ 0

and eN < - zC or eN > zC

The smaller of and

M j,Ed > 0 is clockwise, N j,Ed > 0 is tension.

49


C,Rd

C N/ 1

F z

z e

j,Ed j,Rd

N

j,Ed j,Rd

M Me

N N

C,Rd

C N/ 1

F z

z e

T,Rd

T N/ 1

F z

z e

T,Rd

T N/ 1

F z

z e

C,Rd

T N/ 1

F z

z e

T,Rd

C N/ 1

F z

z e

Table 6.7

FIXED COLUMN BASE JOINT- INITIAL ROTATIONAL STIFFNESS



The column base joint can be classified rigid :

for frames where the bracing system reduces the

horizontal displacement by at least 80% :

Otherwise :

Where :

Lc : storey height of the column,

Ic : second moment of area of the column,

: slenderness of the column in which both ends are

assumed to be pinned.50

FIXED COLUMN BASE JOINT INITIAL ROTATIONAL STIFFNESS

c j,ini

c

30EIS

L

0

0 j,ini 0 c c

0 j,ini c c

- if 0,5

- if 0,5 3,93 and 72 2 1 /

- if 3,93 and 48 /

S EI L

S EI L

0

EN 1993-1-8

(2) §5.2.2.5




Otherwise the column base joint is semi-rigid :

Joint model by a rotational stiffener in the global analysis :

51


Rotational stiffener

S jS j

j j,ini j,Ed j,Rd

j,ini

j j,Rd j,Ed j,Rd

if 2 /3

if 2 /3

S S M M

SS M M M

j,Ed j,Rd(1,5 / ) ; 2,7M M




Model for the calculation of the initial rotational stiffness :

Tensile and compressive parts modelled by axial stiffener.

Initial rotational stiffness :

52


F C

zT zC

F T

M j,Ed

k T k C

j,Ed

N j,Ed

j,Ed

j,ini

j,Ed

MS

M j,Ed

j,Ed

N j,Ed




Stiffness of compressive part of the joint

Where:

l eff Effective length of the T-stub,

beff Effective width of the T-stub,E c Elastic modulus of concrete (see EN 1992-1-1),

E Elastic modulus of steel.

53


c eff eff C 13

1,275

E l bk k

E

Concrete

Flange

F C

c

Contact between flange and concrete

EN 1993-1-8 Table 6.11




Stiffness of the tensile part of the joint

Depends on the presence or absence of prying effect.

54


F T

B B

Q Q

T

F T

B B

T

Presence of prying effect :

*

b bL L*

b b>L L

Absence of prying effect :

EN 1993-1-8 Table 6.11




Stiffness of the tensile part in presence of prying effect :

k 16 : stiffness coefficient of anchor bolts in tension :

k 15 : stiffness coefficient of base plate in bending under tension :

55

T

15 16

1

1 1k

k k

s16

b

1,6A

k L

3

eff p

15 3

0,85 l t k

m

EN 1993-1-8 Table 6.11




Stiffness of the tensile part in absence of prying effect :

k 16 : stiffness coefficient of anchor bolts in tension :

k 15 : stiffness coefficient of base plate in bending under tension :

56

T

15 16

1

1 1k

k k

s16

b

2A

k L

3

eff p

15 3

0,425 l t k

m

EN 1993-1-8 Table 6.11




Rotational stiffness depend on the eccentricity :

Dominant tensile force : Dominant compression force :

57

j,Ed

N

j,Ed

Me

N

2 T-stubs in compression

C N 0z e N T0 e z

2 T-stubs in tension

F T,2

zT zT

F T,1

M j,Ed

k T k T

j,Ed

N j,Ed

F C,2

zC zC

F C,1

M j,Ed

k C k C

j,Ed

N j,Ed




58

Dominant bending moment :

Joint composed of a tensile and compressive part :

N T N Core z e z

F C

zT zC

F T

M j,Ed

k T k C

j,Ed

N j,Ed




Loading Lever arm

z

Initial rotational stiffness S j,ini

for a given value of eN

Dominant

compression forcez = zC + zC

N j,Ed < 0 and 0 ≤ eN ≤ +zC N j,Ed < 0 and-zC ≤ eN ≤ 0

Dominant tension

forcez = zT + zT

N j,Ed

> 0 and 0 ≤ eN

≤ +zT

N j,Ed

> 0 and -zT

≤ eN

≤ 0

Dominant bendingmoment

z = zT + zC

N j,Ed 0

and eN > +zT or eN < - zT

N j,Ed ≤ 0

and eN < - zC or eN > zC

M j,Ed > 0 is clockwise, N j,Ed > 0 is tension.

59

j,Ed

N

j,Ed

Me

N

2

C j,ini

2

E z k S

2

T j,ini

2

E z k S

a

2

j,ini

k

C T

1

11 1

E zS

k k a

C C T Tk

T C

kk

N

× -z ×=

+

=

z k k e

k k

e

e

Table 6.12



APPLICATION

APPLICATION – PRESENTATION OF THE EXAMPLE



Detail of the joint and the concrete block

61

Grout of 30 mm thickness

Axial force : NEd

Anchor bolts M24 class 4.6

Column : IPE 450 in S235

Base plate 48022010 in S235

Shear force V z,Ed

Axis z-z

Axis y-y

Axis x-x

Concrete class C25/30

bp=220

hp =480

d f =500mm

eb

eh

400

800

l b=400mm




Detail of the joint

62

15

225

40 40140

225

15

m e 4060,8Web weld : 4 mm

Flange weld : 6 mm

10

2 anchor bolts M24

Class 4.6

190

9,4

14,7




Load Case 1 (compression) :

Nc,Ed = 85 kN

V z,Ed = 35 kN

1-1 – Check the resistance in compression

1-2 – Check the shear resistance

Load Case 2 (tension) :

NT,Ed = 8,86 kN

V z,Ed = 17,5 kN

2-1 – Check the resistance in tension

2-2 – Check the shear resistance

63

APPLICATION – 1-1 RESISTANCE IN COMPRESSION



Concrete (C25/30) design strength :

The value of b j is equal to 2/3, as :

Coefficient a bf :

64

ckcd cc

c

cd

251 16,7 MPa

1,5

f

f

f

a g

min 1

bf h

bf p p p p

bf

= min 1+ ; 1+2 ; 1+2 ; 3max( , )

500 800 480 400 220; 1 ; 1 , 3 1,67

480 480 220

ed e

h b h ba

a

m p

p

50 mm

30 mm min 0,20,2

e bh




Foundation bearing strength :

Additional bearing width of the flange :

65

jd bf j cd

jd 1,67 2/3 16,7 18,6 MPa

f f

f

a b

yp

p

jd M03

23510 20,5 mm

3 18,6 1,0

f c t f

c

g




Geometrical parameter :

Short projection

Resistance in compression of the column base joint :

66

cp p cmin ; 2 min 480;450 2 20,5 480 mmh h h c cp p fcmin ; 2 min 220;190 2 20,5 220 mmb b b c

cp c fc2 2 450 2 14,7 2 20,5 379,6 mm 0l h t c

C,Rd jd cp cp cp cp wc2

18,6 480 220 379,6 220 9,4 2 20,5 /1000

766,6 kN

N f h b l b t c




Check of the resistance in compression:

67

C,Rd c,Ed

766,6 kN 85 kNN N

bfc =190

b c =15

t fc=

14,7

b c =15

hc = 450

20,5

l eff = 220

hp = 480

c= 20,5

beff

c

c

c

c

t wc = 9,4

APPLICATION – 1-2 SHEAR RESISTANCE (CASE 1)



Friction resistance :

Shear resistance of one anchor bolt :

Shear resistance of the joint

68

f,Rd f,d c,Ed

f,Rd 0,2 85 17 kN

F C N

F

bc ub svb,Rd

M2

vb,Rd 3

(0,44 0,0003 240) 400 35341,6 kN

1,25 10

f AF

F

a

g

v,Rd f,Rd vb,Rd

v,Rd 17 2 41,6 100,2 kNF F nF F




Shear resistance of welds :

Check of the shear resistance :

69

uw,Rd w,eff

w M2

w,eff

w,Rd

/ 3

2 450 2 14,7 2 21 757,2 mm

360/ 34 757,2/1000 629,5 kN

0,8 1,25

f V a l

l

V

b g

z,Rd v,Rd w,Rd z,Edmin ; 100,2 kN =35kNV F V V

APPLICATION – 2-1 RESISTANCE IN TENSION (CASE 2)



Length m :

Effective lengths and mechanisms :

Effective lengths of mode 1 and 2 :

70

wc w/2 /2 0,8 2

(140-9,4)= -0,8 2 4 = 60,8 mm

2

m p t a

m

eff,cp

eff,cp

=2=2× ×(60,8)=381,9 mm

l ml

40 40140

m e 4060,8

Web weld :4 mm

eff,nc

eff,nc

=4 +1,25

=4×60,8+1,25×40=293,1 mm

l m e

l

eff,1 eff,cp eff,nc

eff,2 eff,nc

min ; 293,1 mm

293,1 mm

l l l

l l




Presence of prying effect?

Limit anchor bolt elongation length :

Anchor bolt elongation length :

Prying effect develops and failure modes 1, 2, 3 and 4 will be

considered.

71

b m p wa

*

b b

8 0,5

8 24 30 10 5 0,5 22 248 mm 2382 mm

L d e t t k

L L

3* sb 3

eff,1 p

3*

b 3

8,8

8,8 60,8 3532382 mm

293,1 10

m AL

l t

L




Bending resistance of the base plate (per unit length) :

Bending resistances of the base plate

Mode 1 :

Mode 2 :

72

2

p yppl,Rd

M0

2

pl,Rd 3

4

10 2355,87kN.mm/mm

4 1,0 10

t f m

m

g

pl,1,Rd eff,1 pl,Rd 293,1 5,87 1722 kN.mmM l m

pl,2,Rd eff,2 pl,Rd 293,1 5,87 1722 kN.mmM l m




Resistance of one anchor bolt in tension

Design tensile resistance of the anchor bolt section:

Design bond strength :

73

ub st,Rd

M2

t,Rd 3

0,9

0,9 353 400101,6 kN

1,25 10

f AF

F

g

ck

bd

C

bd

0,36

0,36 251,2 MPa

1,5

f f

f

g




Design bond anchorage resistance:

Design anchor bolt resistance :

74

t,bond,Rd b bd

t,bond,Rd 24 400 1,2/1000 36,2 kNF dl f F

F t,Bond,Rd

l b = 400 mm

t,Rd,anchor t,Rd t,bond,Rdmin ; 36,2 kNF F F




Resistance in tension of the T-stub : modes 1 and 2


Form of the

mode

Resistance of

the T-stub

pl,1,Rd

T,1,Rd

T,1,Rd

4

4 1722 113,3 kN60,8

MF

m

F

75

F T,1,Rd = 113,3 kN

Q Q

m

= min ( ; 1,25 ) = min (40 ; 1,25 60,8) = 40 mmn e m

pl,2,Rd t,Rd,anchor

T,2,Rd

T,2,Rd

2 2

2 1722 40 2 36,262,9 kN60,8 40

M nF F

m n

F

F T,2,Rd=62,9kN

Q Q

emF t,Rd,anchor




Resistance in tension of the T-stub : modes 3 and 4


Form of the

mode

Resistance of

the T-stub

76

T,3,Rd t,Rd,anchor

T,3,Rd

2

2 36,2 72,4 kN

F F

F

eff,t wc y,wc

T,4,Rd

M0

T,4,Rd 3293,1 9,4 235 647,5 kN

1 10

b t f F

F

g

eff,t eff,1= = 293,1 mmb l

F T,4,Rd = 647,5 kN

t wc

F T,3,Rd=72,4 kN

F t,Rd,anchor F t,Rd,anchor




Resistance of the equivalent T-stub in tension:

Weld resistance :

Check of the resistance of the joint in tension :

77

T,Rd T,1,Rd T,2,Rd T,3,Rd T,4,Rdmin ; ; ; 62,9 kNF F F F F

T,Rd T,Rd t,w,Rd t,Edmin ; 62,9 kN 17 kNN F F N

b g

ut,w,Rd w,eff,t w

w M2

t,w,Rd

/ 3

360/ 3293,1 2 4 487 kN

0,8 1,25 1000

f F l a

F




Check of the shear resistance of bolts :

Check of the shear resistance of weld :

78

t,EdEd

vb,Rd T,Rd

17,5 8,86

0,31 11,4 2 41,6 1,4 62,9

NV

nF N

2 2

t,Ed Edvw,d

w,eff,t w,eff

2 2

1?

8,86 17,5 360/ 3

4 0,033 12 293,1 757,2 0,8 1,25

N V f a

l l



CONCLUSION

CONCLUSION



Design methods, based on EC3 and EC2, are presented to

check the resistance of pinned column base joint fordifferent internal forces (compression/tension/shear).

The bending resistance and initial rotation stiffness of rigid

column base joint are determined considering T-stubs intension and compression.

These methods are based on the component method of EN

1993-1-8. The different components are: anchor bolts intension and/or shear, bending of base plate, base plate in

compression with concrete, welds.

80



REFERENCES

REFERENCES



EN 1992-1-1 – Eurocode 2 Design of concrete structures Part 1-1:

General rules and rules for buildings

EN 1993-1-1 – Eurocode 3 Design of steel structures Part 1-1:

General rules and rules for buildings

EN 1993-1-8 – Eurocode 3 Design of steel structures – Part 1-8:

Design of joints.

Skills Baseplate En

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