AISC Design Guide 13..

For a pair of full-depth transverse stiffeners, the thickness joint penetration groove welds with fillet-weld reinforce-
required for shear strength is: ment, or complete-joint-penetration groove welds. When
using double-sided fillet welds, the weld size required is:
( Rust) 1
( Rust)
2
ts
(4.3-5)
09 . 06 . Fyst( l 2 clip) 2
09 .Fystt s 0943 . Fystts
wmin
0. 75(1. 5 0. 6 F F
EXX) 2 EXX
where (4.3-6)
Rust
required strength of the transverse stiffener (see
Section 4.2.1), kips; the subscripts 1 and 2 in
where
Equation 4.3-5 indicate the forces at each end Fyst
transverse stiffener specified minimum yield
of the transverse stiffener
strength, ksi
Fyst
transverse stiffener specified minimum yield ts
transverse stiffener thickness, in.
strength, ksi
FEXX
welding electrode specified minimum
l transverse stiffener length, in.
strength, ksi
clip transverse stiffener corner clip dimension, in.
In Equation 4.3-5, ( Rust) 1 and ( Rust) 2 can add, as for lateral
moments, or subtract, as for gravity moments. The
The 1.5 factor in the denominator
of the second term in
Equation 4.3-6 is the weld strength increase factor for the
90-degree angle of loading determined from LRFD Specmost
critical case for transverse stiffener thickness will ification Appendix J2.4.
usually result for the case wherein they add.
When the transverse stiffener is required for a compres-
In high-seismic applications, the thickness of each sive flange force only (due to local web yielding, web
transverse stiffener should be consistent with that used crippling, or compression buckling of the web), it must
in the tested assemblies. To date, most qualifying cyclic either bear on or be welded tothe column flange todevelop
tests have utilized transverse stiffeners of thickness equal the force transmitted tothe transverse stiffener. For proper
to that of the beam flange or flange plate to meet the rec- force transfer in bearing, Rust
must be equal toor less than
ommendation of FEMA (1995).
16
Rn
as given in LRFD Specification Section J8(a). From
this section, it can be derived that, for a pair of transverse
4.3.3 Length of Transverse Stiffeners stiffeners, the width bsand thickness tsof each of the transverse
When full-depth transverse stiffeners are used, the length
stiffeners must be such that:
is selected for the distance between the column flanges, 0. 370Rust
with due consideration
of column cross-sectional toler-
ances and the welded joint that is tobe used. When partial-
( bs
clip) ts
Fyst
(4.3-7)
depth transverse stiffeners are used, the length is selected Alternatively, when using double-sided fillet welds, the
to
minimize the transverse stiffener thickness and, more weld size required is:
importantly, the size of double-sided fillet weld that is required
for the connection of the transverse stiffener to
the
Rust
wmin
column web; see Sections 4.3.2 and 4.3.5. Note that the 0. 75(1. 5 0. 6 FEXX)( bs
clip)(2) 2
minimum length for partial-depth transverse stiffeners is
(4.3-8)
one-half the column depth.
0. 524Rust
FEXX( bs
clip)
4.3.4 Connecting Transverse Stiffeners
to Column Flanges
where
In wind and low-seismic applications, when the transverse clip transverse stiffener corner clip dimension, in.
stiffener is required for a tensile flange force (due to local
Rust
transverse stiffener required strength (see Sec-
web yielding or local flange bending), it must be welded
tion 4.2.1), kips
to develop the strength of the welded portion of the transksi
Fyst
transverse stiffener specified minimum yield,
verse stiffener. As illustrated in Figure 4-8, this can be
done with double-sided fillet welds, double-sided partialstrength,
FEXX
welding electrode specified minimum
ksi
16Subsequent research (El Tawil et al., 1998) indicates that transverse
stiffness with thickness equal toor greater than 60 percent of the beam
flange or flange-plate thickness can provide for the required cross-
sectional stiffness when a beam is moment-connected to one column
flange only.
The 1.5 factor in the denominator
of the second term in
Equation 4.3-8 is the weld strength increase factor for the
90-degree angle of loading determined from LRFD Specification
Appendix J2.4.
24
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