SN017 (NCCI - Shear Resistance of a Fin Plate Connection)

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NC

NCCI

CI: Shea

: Shear resi

r resistance of a fin pl

stance of a fin pl ate

ate con

con necti

nection

on

This NCCI provides rules for the

This NCCI provides rules for the determination of shear resistance of a "Simple Joint"determination of shear resistance of a "Simple Joint" using a fin plate connection for Beam/Colu

using a fin plate connection for Beam/Column and Beam/Beam connecmn and Beam/Beam connections. tions. The rulesThe rules apply to a bolted c

apply to a bolted connection loaded onnection loaded in shear and uin shear and using non-preloadesing non-preloaded bolts (i.e. Categord bolts (i.e. Categoryy A: Bearing type b

A: Bearing type bolted connection). Tolted connection). This NCCI covers his NCCI covers the rules for the the rules for the fin plate, thefin plate, the supported bea

supported beam and the suppm and the supporting column or borting column or beam. The rules meam. The rules may be used to ay be used to evaluate theevaluate the overall shear r

overall shear resistance of the cesistance of the connection, for aonnection, for all the possible modell the possible modes of failure, bases of failure, based ond on the rules in EN 199

the rules in EN 1993-1-8 for determining 3-1-8 for determining the resistances the resistances of individual componof individual components of theents of the connection.

connection.

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1. Design model

Fin plate connections may be considered as “simple joints” according to EN1993-1-1 §5.1.2 (1) and (2) and EN1993-1-8 §5.1.1 (1), (2) and (3). For further information about simple connections see SN020. Thus the effects of joint behaviour need not be taken into account in the analysis of the frame.

However, for the design of the connection itself, the effective line of transfer of vertical shear, i.e. where zero moment is assumed to exist, depends on the flexibility of the supporting

element. In practice, most supports are neither fully rigid nor entirely flexible. Therefore it is safe to design both the bolts and the welds for shear force and moment. Hence, two design models are used, one (to design the bolt group) where the line of transfer is at the face of the supporting element and one (to design the weld) where the line of transfer is at the centreline of the bolt group. The two models are shown in Figure 1.1.

1 3 1 3 1

4

2 2 2

For weld For bolt group For weld For bolt group For weld For bolt group Assumed lines of shear

transfer

Assumed lines of shear transfer

Key. 1. Fin plate

2. Supported beam 3. Supporting column 4. Supporting beam

Figure 1.1 Fin plate connection subject to vertical shear force

The shear resistance and mode of failure of the connection is the value and mode that has the lowest resistance of all the possible modes of failure. For rules for each of the modes of failure, refer to Table 1.1 given below.

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Table 1.1 Shear resistance of fin plate connection

Mode of failure Section number

Bolts in shear VRd,1 3

Fin plate in bearing VRd,2 4

Fin plate in shear (gross section) VRd,3 5

Fin plate in shear (net section) VRd,4 6

Fin plate in shear (block shear) VRd,5 7

Fin plate in bending VRd,6 8

Fin plate in buckling (LTB) VRd,7 9

Beam web in bearing VRd,8 10

Beam web in shear (gross section) VRd,9 11

Beam web in shear (net section) VRd,10 12

Beam web in shear (block shear) VRd,11 13

Supporting column web or supporting beam web (punching shear) VRd,12 14

2. Parameters

2,b p 1,b 1 1 1 1 2 2,b p 1,b 1 1 1 1 2 2 2 2 e e h e p p e e z h e e e e p p e p z a a = 1 = 2 n n g_h g_h e h h_e g g v v b_p bp

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a Throat thickness of fillet weld Av,net Net shear area of the fin plate

d 0 Diameter of hole

e1 Longitudinal end distance (fin plate)

e1,b Longitudinal end distance (to the edge of the beam or to the edge of a notch)

e2 Transverse end distance (fin plate)

e2,b Transverse end distance (beam web)

f ub Ultimate tensile strength of the bolts

f u,b1 Ultimate tensile strength of the supported beam

f u,b2 Ultimate tensile strength of the supporting beam

f u,c Ultimate tensile strength of the supporting column

f u,p Ultimate tensile strength of the fin plate

f y,b1 Yield strength of the supported beam

f y,b2 Yield strength of the supporting beam

f y,c Yield strength of the supporting column

f y,p Yield strength of the fin plate

gh Horizontal gap between the supporting element and supported beam

gv Vertical gap between the top of beam flange and top of fin plate

h b Depth of the supported beam

he Distance between the bottom of the fin plate and the bottom of the supported beam.

h p Height of the fin plate

I Inertia of the bolt group

n Total number of bolts (i.e. n1 × n2)

n1 Number of horizontal rows of bolts

n2 Number of vertical lines of bolts

p1 Longitudinal bolt pitch

p2 Transverse bolt pitch

r Fillet radius of the supported beam t p Thickness of the fin plate

t w,b1 Thickness of supported beam web

t w,b2 Thickness of supporting beam web

t w,c Thickness of column web

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3. Bolts in shear

(

1

) ( )

2 2 Rd v, Rd,1 n n F n V β α

+

=

The shear resistance of a single bolt, F v,Rd is given in Table 3.4 of EN1993-1-8 as:

M2 ub v Rd v, γ α f A F

=

For a single vertical line of bolts ( n2 = 1, n = n1)

0

=

α

(

1

)

₁ 6 p n n z

+

=

β

For two vertical lines of bolts ( n2 = 2, n = 2 n1)

I p z 2 2

=

α

(

1

)

2 1 1

₋

=

n I p z β where:

(

)

2 1 2 1 1 2 2 1 ₁ 6 1 2 p n n p n I

=

+

−

4. Fin plate in bearing

1 2 hor Rd, b, 2 ver Rd, b, Rd,2

⎟

⎠

⎞

⎜

⎝

⎛

+

⎟

⎠

⎞

⎜

⎝

⎛ +

=

F n F n n V β α

Where α , β and n are as defined in section 3 above.

The bearing resistance of a single bolt, F b,Rd is given in Table 3.4 of EN1993-1-8 as:

M2 u b 1 Rd b, γ α f d t k F

=

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M2 p p u, b 1 ver Rd, b, γ α f d t k F

=

where:

⎟

⎠

⎞

⎜

⎝

⎛

−

=

; 10 4 1 3 3 min p u, ub o 1 o 1 b , f f ; d p ; d e α

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

min 28 17 14 17; 25 o 2 o 2 1 , , d p , ; , d e , k

Similarly horizontal bearing resistance of a single bolt on the fin plate, F b,Rd,hor is:

M2 p p u, b 1 hor Rd, b, γ α f d t k F

=

where:

⎟

⎠

⎞

⎜

⎝

⎛

−

=

; 10 4 1 3 3 min p u, ub o 2 o 2 b , f f ; d p ; d e α

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

min 28 17 14 17; 25 o 1 o 1 1 , , d p , ; , d e , k

5. Fin plate in shear (gross section)

M0 p y, p p Rd,3 3 27 1 γ f t h V

,

=

Note: The coefficient 1,27 takes into account the reduction of the shear resistance, due to the presence of bending moment, see reference (1) (section 6.3.3). For further explanation, see:

Development of a European process for the design of simple structural joint in steel frames (in French), by RENKIN Sandra, Diploma work, University of Liege, June 2003.

6. Fin plate in shear (net secti on)

M2 p u, net v, Rd,4 3 γ f A V

=

where: 0 1 p p net v, t h n d A

=

−

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7. Fin plate in shear (block shear)

V Rd,5 = V eff,2,Rd From § 3.10.2 (3) of EN1993-1-8 M0 nv p y, M2 nt p u, Rd eff,2, 3 1 5 0 γ γ A f A f V

=

,

+

where:

Ant is the net area subjected to tension

for a single vertical line of bolts (i.e. n2 = 1)

⎟

⎠

⎞

⎜

⎝

⎛ −

=

2 0 2 p nt d e t A

for two vertical lines of bolts (i.e. n2 = 2)

⎟

⎠

⎞

⎜

⎝

⎛

₊

₋

=

2 3 0 2 2 p nt d e p t A

Anv is the net area subjected to shear

= t p (h p – e1 – (n1 – 0,5) d 0)

8. Fin plate in bending

If h p

≥

2,73 z then: V Rd,6 =

∞

else: M0 p y, el Rd,6 γ f z W V

=

Where: 6 2 p p el h t W

=

9. Fin plate in buckli ng (LTB)

M0 el Rd,7 γ σ z W V

=

where:

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6 2 p p el h t W

=

) (N/mm 81 235 2 2 p

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

×

=

z t σ

Note: Lateral torsional buckling (LTB) is due to compression stresses which may develop in the lower part of the fin plate under the action of the bending moment.

10. Beam web in bearing

1 2 hor Rd, b, 2 ver Rd, b, Rd,8

⎟

⎠

⎞

⎜

⎝

⎛

+

⎟

⎠

⎞

⎜

⎝

⎛ +

=

F n F n n V β α

Where α , β and n are as defined in section 3 above.

The bearing resistance of a single bolt, F b,Rd is given in Table 3.4 of EN1993-1-8 as:

M2 u b 1 Rd b, γ α f d t k F

=

Therefore vertical bearing resistance of a single bolt on the supported beam web, F b,Rd,ver is:

M2 b1 w, b1 u, b 1 ver Rd, b,

γ

α

f d t k F

=

where:

⎟

⎠

⎞

⎜

⎝

⎛

−

=

; ; 1,0 4 1 d 3 min b1 u, ub o 1 b f f p α

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

1,7; 2,5 d 4 . 1 ; 7 , 1 d e 8 , 2 min o 2 o , 2 1 p k b

Similarly horizontal bearing resistance of a single bolt on the supported beam web, F b,Rd,hor is:

M2 b1 w, b1 u, b 1 hor Rd, b, γ F

=

k α f d t where:

⎟

⎠

⎞

⎜

⎝

⎛

−

=

; 10 4 1 3 3 min b1 u, ub o 2 o b 2 b , f f ; d p ; d e_, α

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⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

1,7; 2,5 d 4 , 1 min o 1 1 p k

11. Beam web in shear (gross section)

From § 6.2.6 (2) of EN1993-1-1 M0 b1 y, b v, Rd pl, Rd,9 3 γ f A V V

=

12. Beam web in shear (net secti on)

M2 b1 u, net b, v, Rd,10 3 γ f A V

=

where: b1 w, 0 1 b v, net b, v, A n d t A

=

−

13. Beam web in shear (block shear)

Rd eff,2, Rd,11 V V

=

From § 3.10.2 (3) of EN1993-1-8 M0 nv b1 y, M2 nt b1 u, Rd eff,2, 3 1 5 , 0 γ γ A f A f V

=

+

where:

Ant is the net area subjected to tension

for a single vertical line of bolts (i.e. n2 = 1)

⎟

⎠

⎞

⎜

⎝

⎛

₋

=

2 0 b 2, b1 w, nt d e t A

for two vertical lines of bolts (i.e. n2 = 2)

⎟

⎠

⎞

⎜

⎝

⎛

₊

₋

=

2 3 0 b 2, 2 b2 w, nt d e p t A

Anv is the net area subjected to shear

( ) (

₁ ₁ ₁

)

₀ b 1, b1 w, e n 1 p n 0,5 d t

+

−

=

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14. Supporting colum n web or

supporting beam web (punchi ng shear)

If fin plate is connected to supporting column web or supporting beam web

z f h t V 6 u 2 p w Rd,12

=

where:

t w is thickness of supporting column web or beam web, t w,c or t w,b2

f u is ultimate tensile strength of supporting column or supporting beam, f u,c or f u,b2

15. Weld design

Provide full strength double fillet welds. The welds are considered as end fillet welds. The size of the weld throat “a” complies with the following requirement:

p

46 , 0 t

a

≥

for S235 fin plate

p

48 , 0 t

a

≥

for S275 fin plate

s a p t 1 2 f,c w,c w,b2 t , t , t

Key: 1. Fin plate

2. Supporting element a: weld throat

s: leg length

Figure 15.1 Fillet weld, throat and leg length

p

55 , 0 t

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16. Ductility requirements

To ensure adequate ductility, the following requirements must be satisfied

•

V _Rd

<

min V _Rd,1; V _Rd,7 and

•

If V _Rd

=

V _Rd,3; V _Rd,4; V _Rd,5; V _Rd,6; V _Rd,9; V _Rd,10 orV _Rd,11 then

(

Rd,2 Rd,8

)

Rd,1 min V ; V V

>

17. Rotation requirement

To ensure adequate rotation capacity, requirements (1) and (2) or requirement (3) given below must be satisfied. (1) h_p

≤

d _b₁ Where r t h d _b₁

=

_b

−

2 _f,_b1

−

2 (2) φ _available

>

φ _required Where:

The “required rotation”, φ required , varies according to the structural system and loading. For

example, for a simply supported beam (length L and second moment of area I ) subject to a uniformly distributed load (

γ

Gg+

γ

Qq) at ULS:

3 Q G required 24 ) ( EI L q g γ γ φ

=

+

•

If

(

)

2 e p 2 h 2

_⎠

⎟⎟

⎞

⎜⎜

⎝

⎛

+

−

>

z g h h z , then:

∞

=

available

φ

•

Else:

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(

)

⎟

⎠

⎞

⎜

⎝

⎛

+

−

⎟

⎠

⎞

⎜

⎝

⎛

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+

−

=

e p h 2 e p 2 h available 2 arctan 2 arcsin h h g z h h g z z φ

(3) Provide details as given in SN016 for the initial design of fin plate connections or provide standard details as given in reference (2).

18. Limits of application

This NCCI applies to one or two vertical lines of bolts (i.e. n2=1 or n2=2) using non-preloaded

bolts for Category A: Bearing type bolted connection in accordance with EN1993-1-8 §3.4.1.

19. Background

The rules in this NCCI are based on:

(1) European recommendations for the design of simple joints in steel structures

- Document prepared under the supervision of ECCS TC10 by: J.P. Jaspart, S. Renkin and M.L. Guillaume - First draft, September 2003.

(2) Joints in Steel Construction – Simple Connections (P212). The Steel Construction Institute and The British Constructional Association Ltd., 2002.