8 CHS Joints 2011

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Hollow sections in structural applications Course

Wardenier part 8 CHS Joints page

Wardenier Tubular Structure Course - 2011

Tubular Structures

Circular Hollow Section Joints

em. Prof.dr.ir. J. Wardenier

Delft University of Technology

National University of Singapore


Now many Applications

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Basic Types of welded Joints


Symbols used (e.g. for K Joints)d

b

h

t

e

g

01

2

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Joint parameters

0

1

d

d=

0

21

2d

dd +=

for T and X

for K-joint

0

02t

d=

0

'tgg =

00

'y

op

fANn

=

0

0

yfn =


Failure modes (basic)

Chord punching shear

Chord plastification

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Further possible failure modes (additional)

Chord shear failure

Brace effective width

Local Buckling in chord or brace


Analytical models

Ring model

Punching shear model

Shear failure of the chord

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Ring model (elastic stress distribution)

1,Ed

joint joint

N1

N1

1,Ed

joint joint

N1

N1


Ring model (assume line loads)

Be

2,5 to 3d0

11 sin

2

N

11 sin

2N

N1

N1

c1d11

1 sin2

Ne

11

B2

sinN

Be

2,5 to 3d0

11 sin

2

N

11 sin

2N

N1

N1

c1d11

1 sin2

Ne

11

B2

sinN

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Ring model (plastic hinges)

0y20p ft

4

1m =


Ring model

=

2

dc

2

d

2

sinNBm2 11011ep

1

0y20

1

0e1

sin

ft

)c1(

d/B2N

=

C0

Qf= f(n)f

1

0y20

1

01 Q

sin

ft

)c1(

cN

=

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Ring model

some effects have been neglected, e.g.:

- influence axial and shear force on mp

and

- chord stress effect


Effect chord loading (be careful different def. in codes)

Function f(n) = Qfbased on n (IIW 2009)

(In Eurocode based on n)

0,0

0,2

0,4

0,6

0,8

1,0

1,2

-1,0 -0,8 -0,6 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0

2 = 63,5

2 = 25,4

2 = 63,5

2 = 50,8

2 = 25,4

N1usin1

/

(fy0

t02Q

u)

N0/ Npl,0

N0

N2

N0p

A

A

1

N1

2N0

N2

N0p

A

A

1

N1

2

p011gap,0

2

1i

p0ii0

NcosNN

NcosNN

+=

+==

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N1sin 1 = d1t0. f(ellips )vp with vp = 0,58fy0

Assumption:

at failure about uniform

punching shear yield

stress distribution

(check by experiments)

validity !


f(ellips )


12

10y011

sin2

sin1ftd58,0N

+=

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Chord shear model

Based on yield criterion of Huber-Hencky-Von Mises

Ngap,0Ngap,0


Chord shear model

)f58,0(A2

3

fAV 0y0

0y

v0,pl

==

Npl,0 = A0 fy0 = (d0 - t0) t0 fy0

The shear load capacity is given by:

The axial load capacity is given by:

)f58,0(A2

3

fAV 0y0

0y

v0,pl

==



)f58,0(A2

3

fAV 0y0

0y

v0,pl

==


Npl,0 = A0 fy0 = (d0 - t0) t0 fy0


)f58,0(A2

3

fAV 0y0

0y

v0,pl

==


)f58,0(A2

3

fAV 0y0

0y

v0,pl

==



)f58,0(A2

3

fAV 0y0

0y

v0,pl

==


Npl,0 = A0 fy0 = (d0 - t0) t0 fy0


)f58,0(A2

3

fAV 0y0

0y

v0,pl

==


Ngap,0

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Chord shear model

0,1N

N

V

sinN2

0,pl

0,gap

2

0,pl

ii

+

2

v0y

ii

0y00,gap Af58,0

sinN

1fAN

)f58,0(A2

3

fAV 0y0

0y

v0,pl

==

Npl,0 = A0 fy0 = (d0 - t0) t0 fy0



or

2

v0y

ii

0y00,gap Af58,0

sinN

1fAN

or

0,1N

N

V

sinN2

0,pl

0,gap

2

0,pl

ii

+

2

v0y

ii

0y00,gap Af58,0

sinN

1fAN

or

Ngap,0


Experiments

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Finite element simulation

0

100

200

300

400

500

0 20 40 60 80 100

Ovalisation [mm]

Load[kN]

EX-03 - Collar, Compression

Experiment = 0.54

Numerical 2= 50.6

Calibration with experiments

(Choo/Van de Vegte)


Verification with experiments

For example:

X-joints

analysis for

IIW (2009)

0

2

4

6

8

0,0 0,2 0,4 0,6 0,8 1,0

f(N1u

)Xj

oints

+

7,01

1

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Evaluation to design rules

Analytical models

ExperimentsStrength formulae

Scatter in test results

scatter in mechanical properties

tolerances in dimensions

tolerances in fabrication

failure mode

Design strength

N1,Rd =Nk/m


Strength formulae for CHS joints(IIW 2009 = Draft ISO = CIDECT)

or

f

1

200y

Rd,1 Qsin

tf)'g(f)(f)(fN

=

or

i

2

0y0fuRdi,

sintfQQN =

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Criterion

to be checked

Axially loaded joints with CHS

Braces and Chord

Design strength:

chord plastification

Design strength:

chord punching shear

(only for di d0 2t0)

Limit states criteria IIW (2009)

i

20y0

fuRdi,sin

tfQQN =

12

101y0Rd1,

sin2

sin1tdf0,58=N

+

i

20y0

fuRdi,sin

tfQQN =

12

101y0Rd1,

sin2

sin1tdf0,58=N

+

Criterion

to be checked

Axially loaded joints with CHS

Braces and Chord

Design strength:

chord plastification

Design strength:

chord punching shear

(only for di d0 2t0)

i

20y0

fuRdi,sin

tfQQN =

12

101y0Rd1,

sin2

sin1tdf0,58=N

+


Function Qu

Notes: 1) When cos1 >, check shear

( )8.612.6Q 0.22u +=

]

)tg(1.2

1[1)8(165.1Q

0.8

0

0.31.6u

+

++=

1

N1

t1

d1

N1

d0 t0

0.15u

0.7 -1

12.6Q

+=

1

N1

t1

d1d

0 t0

2

N2

t2

d2N1

1

t1

d1g

+e

d0

N0

X joints 1)

T and Y joints

K gap joints

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Function Qf

Compression tension

T, Y, X joints C1 = 0,45 0,25 C1 = 0,20

K gap joints C1 = 0,25

Qfequations X, T and K gap joints (IIW 2009)

0,pl

0

0,pl

0

M

M

N

Nn +=( ) 1Cf |n|1Q =


Range of validity based on:

- test evidence

- validity of formulae

- limitation of failure criteria (e.g. avoid local buckling)

- deformation- deformation capacity

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Comparison Qu for T, X and K gap joints for

2=25 (IIW, 2008)

0

10

20

30

40

0 0.2 0.4 0.6 0.8 1

Qu

K gap jointg'=2

K gap jointg'=infinite

T joint

X joint

g'=g/t0

Relation Qu between joint capacities

9

Comparison Qu for T, X and K gap joints for

2=25 (IIW, 2008)

0

10

20

30

40

0 0.2 0.4 0.6 0.8 1

Qu

K gap jointg'=2

K gap jointg'=infinite

T joint

X joint

g'=g/t0

9


Overlap joints IIW (2009)

Brace effective width (1)

Chord M-N yield (2)

Brace shear (3)

brace i = overlapping member; brace j = overlapped member

di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj

brace i =overlapping member; brace j = overlapped member


di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj


(2) (2)

(1)

(3)

N0


di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj



di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj


(2) (2)

(1)

(3)


di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj


di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj



di

d0

dj

ti

t0

Ni

Nop

Nj

No

ij

4.8

4.11

4.10

4.11

4.10

tj


(2) (2)

(1)

(3)

N0

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Relation CHS vs RHS overlap Joints

IIW (2009)

- criteria for RHS overlap joints multiplied by /4

(ratio between the cross sectional areas for d=b)

- all b and h dimensions in formulae replaced by d.


Simplification

Ce in graph

i

f

iyi

0y0

e

yii

Rdi,

sin

Q

tf

tfC

fA

Neff. ==

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Design graphs for X joints

X joint efficiency

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

effciencyCX

2=10

2=15

2=20

2=30

2=40

1

f

11y

00yX

1y1

Rd,1

s in

Q

tf

tfC

fA

N

=


Design graph for T joints

T joint efficiency

0,0

0,10,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

effciencyCT

2=10

2=15

2=20

2=30

2=40

2=50

1

f

11y

00yT

1y1

Rd,1

s in

Q

tf

tfC

fA

N

=

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Design graphs for K gap joints

Compare the strength for various d0/t0 ratios and various gaps

1

f

11y

00yK

1y1

*1

sin

Q

tf

tfC

fA

N

=

K gap joint efficiency g'=2

0,00,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

effciencyCK

2=10

2=15

2=20

2=30

2=40

2=50

i

21

i

f

iyi

00yK

yii

Rd,i

d2

dd

sin

Q

tf

tfC

fA

N +

=

1

f

11y

00yK

1y1

*1

sin

Q

tf

tfC

fA

N

=

K gap joint efficiency g'=10

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

effciencyCK

2=10

2=15

2=20

2=30

2=40

2=50

i

21

i

f

iyi

00yK

yii

Rd,i

d2

dd

sin

Q

tf

tfC

fA

N +

=


Joints related to basic types (IIW 2009)

N2 N1N2 N11N2N

X

X

KK

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Joints related to basic types IIW (2009)

h1

d0

t0

N1

N1

1t1

d0

b1

t0

N1

N1

h

1

d0

1

t0

t

N1

N1

h1

d0

t 0

N1

b1

N1

1

f20y01 Qtf)(f)(f)(fN =


Multi-planar Joints

Storm Surge Barrier near Hook of Holland, The Netherlands

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Multiplanar joints

Geometrical effectGeometrical effect

Loading effectLoading effect

Effect depends on: - type of joint (T, X, K, CHS, RHS)

- type of loading (axial, b.i.p., b.o.p.)

Effect for strength, stiffness and deformation capacity


Example:XX joint of CHS

multiplanar effects

N2

= N1

N2 = 0.6 N1

N2 = 0.0

N2 = -0.6 N1

Uniplanar joint = 16.0 = 0.60

2 = 50.8

1111 / d0

N1

/(fy

o*to)2

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Moment joints

Bending in plane

Bending out of plane

In frames and Vierendeel girders

(see beam to column joints)

In principle the

same philosophy


Interaction between N, Mip and Mop

0,1M

M

M

M

N

N

Rd,i,op

Ed,i,op

2

Rd,i,ip

Ed,i,ip

Rd,i

Ed,i +

+

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Special items

Concrete filling of the chord

complete

or

only between tubulars e.g. between pile and leg ina jacket

Punching shear check


Joints with a Can

Can length for X joints L > 2d0

llcancan/d/d00

f(Nf(N))

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Semi-flattened end joints

T and X-joint:

replace d1 by d1,min.

K-joint with gap:

replace di by

0,5(di +di,min.)


Slotted Gusset Plate Joints

Exposed roof structure

of

Toronto Convention Centre

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Slotted plate joints

Lw 1,3d An

Lw

An=A

g

a)

crack

slot

GussetPlate b)

CHS

crack

CHSLw


Tee end to CHS Joints

N1,Rd = 2fy1 t1 (tw + 5tp) A1 fy1

N1,Rd

= 2fyw

tw

(t1

+ 2.5tp

+ s)

2fyw tw (t1 + 5tp)

2.51

tp

N1

d1

tw

5tp+ t

w

s s

t1

2.51

tp

N1

d1

tw

5tp+ t

w

s s

2.51

tp

N1

d1

tw

5tp+ t

w

s s

t1

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The end ofthe lectures

on

CHS joints


Documents

8 CHS Joints 2011