Table 8-2 (continued). Nominal Strengths of Rectangular HSS-to-HSS Truss Connections Connection Type
Connection Nominal Axial Strength*
Gapped K-Connections
Limit State: Chord Wall Plastification, for all C
)
(
Pn sin = Fy t 2 9.8 eff 0.5 Qf G 0.90 (LRFD)
Hb tb
Bb Pr
(
Pn sin = 0.6Fy tB 2 + + eop
Pr
Bb
g
8 1.67 (ASD)
Limit State: Shear Yielding (Punching), when Bb < B − 2t Do not check for square branches.
Hb
tb
(K2-20)
t
H
+e B
)
(K2-21)
G 0.95 (LRFD) 8 1.58 (ASD) Limit State: Shear of Chord Sidewalls in the Gap Region. Determine PnsinR in accordance with Spec. Sect. G5. Do not check for square chords. Limit State: Local Yielding of Branch/Branches Due to Uneven Load Distribution. Do not check for square branches or if B/t s 15 Pn = Fyb t b ( 2Hb + Bb + beoi − 4t b
)
(K2-22)
G 0.95 (LRFD) 8 1.58 (ASD) F t y 10 beoi Bb Bb B t Fyb t b Limit State: Local Yielding of Branch/Branches Due to Uneven Load Distribution G 0.95 (LRFD) 8 1.58 (ASD) For 25% c Ov 50%: Ov Pn, overlapping branch Fybi t bi 2Hbi 4t bi beoi beov 50
For 50% c Ov 80%: Pn, overlapping branch = Fybi t bi 2Hbi − 4t bi + beoi + beov
Overlapped K-Connections
Hb
Bb Pr
tb
Pr j
(
Bb
i
Hb
tb
For 80% c Ov c 100%: Pn, overlapping branch = Fybi t bi 2Hbi − 4t bi + Bbi + beov
t
–e
(
H
where beoi
B
(K2-25)
)
(K2-26)
10 Fy t Bbi Bbi B t Fybi t bi
Note that the force arrows shown for overlapped K-connections may be reversed; i and j control member identification
10 Bbj t bj
(K2-24)
)
(K2-27)
Fybj t bj Bbi Bbi Fybi t bi Subscript i refers to the overlapping branch Subscript j refers to the overlapped branch ⎛ Abj Fybj ⎞ Pn, overlapped branch = Pn, overlapping branch ⎜ ⎟ ⎝ Abi Fybi ⎠ beov
(K2-23)
(K2-28)
Functions Qf 1 for chord (connecting surface) in tension U Qf = 1.3 − 0.4 ≤ 1.0 for chord (connecting surfacce) in compression, for T-, Y-, and cross-c connections U Qf = 1.3 − 0.4 ≤ 1.0 for chord (connecting surrface) in compression, for gapped K-connecttions eff where Pr and Mr are determined on the side of the joint that has the higher Pr Mr U= + , compression stress. Pr and Mr refer to required axial and flexural strength AFc SFc in the chord. Pr Pu for LRFD; Pa for ASD. Mr Mu for LRFD; Ma for ASD eff = ⎡( Bb + Hb compression branch + ( Bb + Hb tensioon branch ⎤ 4B ⎣ ⎦ 5 eop * Equation references are to the AISC Specification.
)
)
98 / HOLLOW STRUCTURAL SECTION CONNECTIONS / AISC DESIGN GUIDE 24
Spec. Sect. K2.3 (K2-10) (K2-11) (K2-12) Spec. Sect. K2.1 Spec. Sect. K2.3c