Lecture 13 – Bolted Connections (cont.)

chirmmercifulUrban and Civil

Nov 25, 2013 (3 years and 11 months ago)

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Lecture 13 - Page 1 of 5
Lecture 13 – Bolted Connections (cont.)

In the previous lecture, we looked at general strength considerations of bolted
connections. In this lecture we will look at a typical all-bolted beam-to-girder
shear connection to see practical bolted connection considerations.
















where: Cope = cut distance of beam flange necessary to clear girder
flange and “K” distance, usually 1½”, 2” or 3”

K = distance between top of flange to edge of start of flat web
= from beam properties AISC Part 1

L
ev
= required minimum vertical edge distance in direction of load
= from AISC Table J3.4 p. 16.1-107

S = bolt center-to-center spacing from AISC J3.3 p. 16.1-106
= 2⅔ times nominal bolt diameter (minimum)
= 3 times bolt diameter (preferred)
= 3” (typical for bolts up to 1” diameter)


Co
p
e
L
e
v
S
S
K
Angle gage “g” from AISC p. 1-46
= L
eh

Connection angles
Beam
Girder
Lecture 13 - Page 2 of 5
Example (LRFD)
GIVEN
: A W16x40 A992 steel beam “A” frames into a W18x55 A992 steel girder
“B”. The applied floor Service DL = 80 PSF and the applied floor Service LL =
100 PSF. Use ¾” diameter A325-X bolts with standard bolt holes and double-
angle A36 L3x3x¼ connection angles. The beam is coped at top flange only.
REQUIRED
: Design the all-bolted beam-to-girder connection and provide a
summary sketch.














Step 1 – Determine factored beam end reaction
:

w
u
= 1.2[6’(80 PSF) + 40 PLF] + 1.6[6’(100 PSF)]
= 1584 PLF
= 1.6 KLF

Beam end reaction =
2
Lw
u


=
2
)"0'30(6.1

KLF


= 24 KIPS

W18x55 Girder “B”
W16x40 Beam “A”
4 @ 6’-0” = 24’-0”
30’-0”
Beam weight
Lecture 13 - Page 3 of 5
Step 2 – Use AISC Table 10-1 “All-Bolted Double-Angle Connections”, p. 10-22
:

These tables incorporate all design considerations for typical all-
bolted double-angle connections.

W16x40
Beam
¾” Bolts
See Step 3
See Step 5
See Step 5
See Step 7
See Step 8
See Step 9
Lecture 13 - Page 4 of 5
Step 3 – Check Bolt and Angle Design Strength
:

From Table above,

ASTM A325

Thread Cond. = X

Angle thickness = ¼”


Step 4 – Determine minimum required cope
:

The minimum required vertical edge distance must be greater than
the “K” distance for either the girder or the beam.

W18x55 girder “K
det
” = 1
"
16
5
from AISC p. 1-18

W16x40 beam “K
det
” = 1
"
16
3
from AISC p. 1-20


Step 5 – Determine vertical edge distance, L
ev
:


For compactness, use L
ev
= 1¼” (See Table J3.4 p. 16.1-107)

Step 6 – Determine angle gage for L3x3x¼ = L
eh
:


From AISC p. 1-46 → g
1
= L
eh
= 1¾”

Step 7 – Check Beam Web Design Strength
:

From Table above,

Hole Type = STD

L
eh
= 1¾”

L
ev
= 1¼”


The web thickness, t
w
of a W16x40 = 0.305” from AISC p. 1-20

W16x40 web design strength = 0.305”(200 KIPS/inch)
= 61 KIPS > 24 KIPS → OK
Bolt and angle design strength =
76.4 KIPS > 24 KIPS
Use cope = 1½”
Beam web design strength = 200 KIPS
per inch thickness
Lecture 13 - Page 5 of 5
Step 8 – Check girder Support Design Strength
:

From Table above,

Support Design Strength per Inch Thickness = 526 KIPS

The web thickness, t
w
of a W18x55 = 0.390” from AISC p. 1-18

W18x55 web design strength = 0.390”(526 KIPS/inch)
= 205 KIPS > 24 KIPS → OK

Step 9 – Determine bolt spacing S
:

Preferred bolt spacing S = 3 x bolt diameter
= 3(¾”)
= 2¼”

Use S = 3” from Table above > 2¼” → OK

Step 10 – Draw summary sketch of connection design
:
























1¼”
Co
p
e = 1½”
L
e
v
= 1¼”
S = 3”
S = 3”
Angle gage = 1¾”
2 - L 3x3x¼ x 8½” long A36
connection angles with 9 - ¾”
A325-X bolts in STD holes
W16x40 Beam
W18x55
Girder