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

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