22-Design of Four Bolt Extended Endplate Connection (Steel Structural Design & Prof. Shehab Mourad)

1 Prepared by Prof. Shehab Mourad – Department of Civil Eng. - KSU
Design of Four-Bolt Unstiffened Extended End-Plate Connection
Assumptions
1- Fully pretension ASTM, A325 M, or A490M bolts are used with
diameter less than 36 mm.
2- End plate material is A36
3- Only static load is permitted.
4- Recommended distance pf = db + 12 mm, fabricators prefer to use
standard dimension , usually 50 mm, which is adequate for all bolt
diameters.
5- End plate width which is effective in resisting the applied moment is
not greater than bf + 25mm.
6- The gage distance (horizontal distance) of tension bolts (g) should not
exceed the beam tension flange width (bf).
7- When the applied moment is less than the design flexural strength of
the beam, the bolts and end plate may be designed for the applied
moment only.
8- The effective length of weld to resist shear is the distance between the
mid-depth of beam to the inside face of the compression beam flange.
g ≤ bf LeLe
bf
bp
pf
pf
pf
pf
tf
tf
tw
d
Puf = Mu
(d-tf)
Puf
Mu
d-tf
Effective weld
length for shear
2bd
Le
Le

9- Minimum number of bolts at tension side is 4 and minimum number
of bolts at compression side is 2.
The required end-plate thickness (tep ) can be obtained as follows:
tep = 4 M eu
f Fy bp
Where; Fy : end-plate yield strength
f = 0.90
bp = effective end-plate width, should not exceed bf +25 mm
And, M eu = am Puf pe
4
Where;
Puf = factored beam flange force = Mu / (d-tf)
am = Ca Cb (Af/Aw)1/3
(pe/db) 1/4
Ca = constant = 1.38 for Fy = 250 MPa for both the beam and end-plate and bolts A325
(For other cases see Table 10-1 in the LRFD Connection Manual)
Cb = (bf / bp) 1/2
bf = beam flang width, mm
bp = effective end-plate width, mm not exceed bf +25 mm
Af = area of beam tension flange, mm2
Aw = area of beam web, clear of flanges, mm2
pe = effective pitch, mm = pf – (db/4) – wt
pf = distance from bolt center line to the near surface of tension flange, mm
wt = filet weld throat size, mm
db = nominal bolt diameter, mm

Example
Design a four-bolt unstiffened extended end-plate moment connection for a W 460x
74 beam to a W 360 x 147 column flange. Both materials for beam and end-plate are
A36m, Fy = 250 MPa. Use ASTM A325M bolts Fvb= 400 MPa, Fub =620 MPa with
standard holes ( m = 0.33) and 480 MPa electrodes.
Given : Factored shear force Vu = 200 kN
Factored bending moment Mu = 330 kN.m
W 460 x 74 ;
d= 457 mm bf = 190 mm, tw = 9.0mm , tf = 14.5 mm
W 360 x 147:
d= 360 mm bf = 370 mm, tw = 12.3 mm, tf = 19.8 mm, T = 286 mm
Solution:
1 - Flange force Puf
Puf = Mu = 330 x 1000 = 746 kN
(d – tf) ( 457 – 14.5 )
2- Check for bolts in tension and shear
(a) for tension use 4 bolts with diameter (db)
f Rn = f Fub x (p db
2
/4) x 4 ³ Puf
= 0.75 x 620 x (p db
2
/4) x 4 ³ 746 x 1000
db ³ 22.6 mm , use 4 bolts M 24 for tension flange
(b) Number of bolts needed for slip critical connection
f Rn = f 1.13 m [0.7 Fub (p db
2
/4) ] Nb ³ 200 x 1000
= 1.0 x 1.13 x 0.33 [ 0.7 x 620 x (p (24)2
/4) ] Nb ³ 200 x 1000
Nb = 2.733 bolt
a total of 6 bolts (4 at tension flange and 2 at compression flange)
will be sufficient to resist the shear force 200 kN as a slip critical
connection.
(c) Check bolt shear strength (6 bolts)
f Rn = f Fvb (p db
2
/4) Nb Ns
= 0.75 x 400 (p (24)2
/4) x 6 x 1 x 10-3
= 814 kN > 200 kN
O.K

3- Design of end-plate
Choose Le ³ 1.5 d ( 36mm) and bf ( 190mm) > g ³ 3d (72 mm)
choose Le = 40 mm and g = 140 mm and pf = db + 12 mm = 24 +12= 36mm
bp = 2 Le + g = 2 x 40 + 140 = 220 mm
However the effective width of plate should not exceed bf + 25 = 190 +25 = 215 mm
M eu = am Puf pe
4
Where; am = Ca Cb (Af/Aw)1/3
(pe/db) 1/4
Ca = 1.38
Cb = (bf / bp) 1/2
= (190/215) 1/2
= 0.94
Af / Aw = (190 x 14.5) / [(457-29) x 9] = 0.75
pe = pf – (db/4) – wt , assume weld size for flange = 14 mm
pe = 36 – 24/4 – (0.707 x14) = 20.1 mm
am = 1.38 x 0.94 x (0.75) 1/3
(20.1/24) 1/4
= 1.11
M eu = 1.11 x 746 x 20.1 /4 = 4177.73 kN.mm
tep = 4 M eu = 4 x 4177.73 x 1000 = 18.59 mm ® 20 mm
f Fy bp 0.90 x 250 x 215
Check shear strength of end-plate with thickness 20 mm and bp eff = 215 mm
f Rn = 2 f ( 0.6 Fy Ag)
= 2 x 0.9 x ( 0.6 x 250 x 215 x 20) x 10-3
= 1160 kN > 746 kN
O.K

4- Fillet weld design
(a) web weld size near tension bolts
determine required size of weld to develop web flexural strength near tension bolts
f Rn = f (0.6 FEx x 0.707 x w) x 2 ³ 0.9 Fy x tw
0.75 (0.6 x 480 x 0.707 x w ) x 2 ³ 0.9 x 250 x 9.0
w ³ 9.15
choose w = 10 mm fillet weld on both sides of web from the inside face of beam flange
to the center of inside bolts plus two bolt diameter (48mm)
(b) web weld size required to resist the factored shear force
Length of weld (Lw) = d/2 - tf = 457/2 – 14.5 = 214 mm
f Rn = f (0.6 FEx x 0.707 x w x Lw) x 2 ³ 200 x 1000
= 0.75 x 0.6 x 480 x 0.707 x w x 214 x 2 ³ 200 x 1000
w ³ 3.06 mm
choose weld size = 8mm (minimum size) on both sides of web below the tension bolts
(c) flange weld size
length of weld = Lw = 2 (bf +tf) -tw = 2 ( 190 + 14.5 ) – 9 = 400 mm
f Rn = f (0.6 FEx x 0.707 x w x Lw) ³ 746 x 1000
= 0.75 ( 0.6 x 480 x 0.707 x w x 400 ) ³ 746 x 1000
w ³ 12.2 mm ® 14.0 mm
Use 14 mm fillet welds surrounding the beam tension flange, welds at compression
flange may be 8 mm fillet weld (minimum size )
140 4040
190
220
36
36
36
36
14.5
14.5
9.0
457
48
40
40
w= 8 mm
w= 10 mm
w= 14 mm
End plate 609 x 220 x 20 mm
609 mm

22-Design of Four Bolt Extended Endplate Connection (Steel Structural Design & Prof. Shehab Mourad)

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22-Design of Four Bolt Extended Endplate Connection (Steel Structural Design & Prof. Shehab Mourad)