Page 59 - Handbook of Structural Steel Connection Design and Details

Design of Connections for Axial, Moment, and Shear Forces

44 Chapter Two

Since tearout through the edge of the brace web is the critical
condition and results in a capacity greater than the shear
strength of the bolt, the full bearing capacity of the bolt can
be developed. However, since the connection is to be designed
as slip critical, the slip resistance will govern.
(2) Block shear rupture:
A (2 6 6) 0.525 2 39.9 in 2
gv
A 39.9 6.5 1.25 0.525 2 31.4 in 2
nv
A 3 .54 1 1.25 0.525 2.88 in 2
nt
Shear yielding 39.9 0.6 50 1200 kips
Shear fracture 31.4 0.6 65 1220 kips
Tension fracture 2.88 65 187 kips
Since shear yielding is less than shear fracture, the failure
mode is shear yielding and tension fracture; thus, the design
block shear strength is

R 0.75(1200 187) 1040 kips > 855 kips, ok
bs
c. Gusset checks:
(1) Bearing and tearout: The bearing strength per bolt is

r 0.75 2.4 1.125 0.75 58 88.1 kips
p
The bolt tearout capacity of the edge bolts at the gusset is
r 0.75 1.2 (2 0.594) 0.75 58 55.0 kips
p
Again the bolt shear governs.
(2) Block shear rupture: These calculations are similar to those for
the brace.
A 29.0 0.75 2 43.5 in 2
gv
A (29.0 6.5 1.25) 0.75 2 31.3 in 2
nv
A (6.5 1.0 1.25) 0.75 3.94 in 2
nt
R 0.75 [F A min {0.6 F A , 0.6 F A }]
bs u nt y gv u nv
0.75 [58 3.94 min {0.6 36 43.5,
0.6 58 31.3}]
0.75 [229 min {940, 1090}]
876 kips > 855 kips ok
(3) Whitmore section: Since the brace load can be compression, this
check is used to check for gusset buckling. Figure 2.2 shows the
“Whitmore section” length, which is normally l (27 tan 30)
w
2 6.5 37.7 in, but the section passes out of the gusset and into
the beam web at its upper side. Because of the fillet weld of the

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