Page 272 - Structural Steel Designers Handbook AISC, AASHTO, AISI, ASTM, and ASCE-07 Design Standards

Brockenbrough_Ch05.qxd 9/29/05 5:12 PM Page 5.52

CRITERIA FOR BUILDING DESIGN

5.52 CHAPTER FIVE

5.9.9 Design of Connecting Elements
Connecting elements of connections (gusset plates, splice plates, clip angles, etc.), as well as affected
elements of the members themselves (flanges or webs at member ends, etc.), must be designed for the
forces present. Design for tension, shear, block shear, and compression is treated in the following.
1. Elements in Tension. The available strength (design strength φR n and allowable strength R n /Ω)
of affected member elements and connecting elements loaded in tension is the lower of the values
for the limit states of tension yielding and tension rupture.
For tension yielding,
(5.151)
R n = A g F y
φ= 0.90 (LRFD) Ω= 1.67 (ASD)
For tension rupture of the connecting element,
(5.152)
R n = A e F u
φ= 0.75 (LRFD) Ω= 2.00 (ASD)
where A e is the effective net area, which includes the shear lag effect. (See Art. 5.3.2.) Also, for bolted
splice plates, A e must not exceed 0.85A g .

2. Elements in Shear. The available shear yield strength of affected member elements and connect-
ing elements in shear is the lower of the values for the limit states of shear yielding and shear rupture.
For shear yielding,
(5.153)
R n = 0.60A g F y
φ= 1.00 (LRFD) Ω= 1.50 (ASD)
For shear rupture,
(5.154)
R n = 0.6F u A nv
φ= 0.75 (LRFD) Ω= 2.00 (ASD)
2
2
where A nv = net area subject to shear, in (mm )
3. Elements Subjected to Block Shear. Block shear rupture is a limit state defined by one or more shear
failure paths and a perpendicular tension failure path. The available strength for this limit state is given by
(5.155)
R n = 0.6F u A nv + U bs F u A nt ≤ 0.6F y A gv + U bs F u A nt
φ= 0.75 (LRFD) Ω= 2.00 (ASD)
2
2
where A gv = gross area subject to shear, in (mm )
2
2
A nt = net area subject to tension, in (mm )
2
2
A nv = net area subject to shear, in (mm )
U bs = 1.0 where the tension stress is uniform
= 0.5 where the tension stress is nonuniform (such as from bending)
4. Elements in Compression. The available strength of connecting elements in compression is
determined for the limit states of yielding and buckling as follows.
For KL/r ≤ 25, limit state of yielding,
(5.156)
P n = F y A g
φ= 0.9 (LRFD) Ω= 1.67 (ASD)
For KL/r >25, limit state of buckling, see Art. 5.4.

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