AISC Design Guide 13..

In Equations 4.4-2 and 4.4-3, the first term after the equal
sign represents the design shear strength per in. of thickness
of the web doubler plate on two shear planes with a
h
dc
k
dc
2 k, in.
column depth, in.
distance from outside face of column flange tothe
length equal to that of the transverse stiffener fillet welds.
web toe of the flange-to-web fillet, in.
The second term represents the design shear strength per
in. of thickness of the web doubler plate on one shear plane Alternatively, the web doubler plate and the column web
with a length equal to
the column depth. When a single can be interconnected with plug welds (see AISC Seismic
web doubler plate is used, the column web thickness must Provisions Commentary Section C9.3 and Figure C-9.2)
also
be checked using Equations 4.4-2 and 4.4-3.
and the total thickness must satisfy the above equation.
When a fillet-welded edge detail is used, the minimum
web doubler plate thickness tp
min to allow for proper
4.4.3 Connecting Web Doubler Plates to Columns Along
beveling of the plate19
to clear the column flange-to-web
the Column-Flange Edges
fillet is:
tp
min r re
ktf
re
(4.4-4)
In wind and low-seismic applications and high-seismic
applications involving Ordinary Moment Frames (OMF),
where
web doubler plates are welded along their column-flange
edges to develop the required shear strength of the web
r column flange-to-web fillet radius, which can doubler plate; that is, Vudp
as used in Equation 4.4-1.
be estimated by subtracting the flange thickness In high-seismic applications involving Special Moment
from the k-distance and rounding the result to the Frames (SMF) and Intermediate Moment Frames (IMF),
nearest 1/ 16 -in. increment, in.
web doubler plates are welded along their column-flange
re
permissible encroachment from LRFD Manual edges to develop the shear strength of the full web-
Table 9-1 (page 9-12), in. doubler-plate thickness. Either fillet welds or groove
k distance from outside face of column flange tothe
web toe of the flange-to-web fillet, in.
welds can be used; see Figure 4-13. The preferred detail is
usually the one that minimizes the amount of weld metal
t f column flange thickness, in.
required with due consideration of the associated material
In wind and low-seismic applications, to
prevent shear
preparation requirements.
buckling of the web doubler plate, the minimum thickness
It is recognized that welding in the flange-to-web fil-
t
o o o
let region of wide-flange columns carries the potential for
pmin per LRFD Specificati n Secti n F2 sh uld be:
shrinkage distortions and subsequent cracking due to
restraint
and low notch toughness (AISC, 1997b). This is
hFy
tp
min
(4.4-5)
418
primarily of concern for the groove-welded detail in Figure
4-13a. Nonetheless, fabricators may prefer that al-
Alternatively, the web doubler plate can be designed for ternative, which can be combined with good quality and
shear buckling in accordance with LRFD Specification
process control, inspection, and repair when necessary
Appendix F2.2. to
maximize efficiency. As another alternative, the detail
In high-seismic applications, to prevent shear buckling shown in AISC Seismic Provisions Commentary Figure
of the web doubler plate without the use of plug welds C-9.3c with a pair of web doubler plates placed symmetbetween
the web doubler plate and the column web, the rically away from the column web and used integrally with
minimum thickness of both the column web and web dou-
transverse stiffeners top and bottom can be used.
bler plate per AISC Seismic Provisions Section 9.3b and The use of a fillet-welded detail requires a beveled edge
LRFD Specification Section F2 should be: to clear the flange-to-web fillet radius and a web doubler
plate thickness that is at least equal to
the required bevel.
dm ts
dc 2tf
hFy
tmin
(4.4-6)
Allowing a slight plate encroachment into the flange-to-
90 418 web fillet radius, as illustrated in LRFD Manual Table 9-1
where
(page 9-12), reduces the required bevel and increases
the net section that remains after beveling. Because the
dm
moment arm between concentrated flange forces,
flange-to-web fillet region is a smooth transition, such
in.
slight encroachment does not normally affect fit-up. The
ts
transverse stiffener thickness, in.
flange-to-web fillet radius can be estimated by subtract-
dc
column depth, in.
ing the flange thickness from the k-distance and rounding
1
t f column flange thickness, in.
the result to
the nearest / 16 -in. increment.
The reduction in plate thickness due to
beveling must
19This assumes a 45-degree level.
be considered when selecting the plate thickness (Section
30
© 2003 by American Institute of Steel Construction, Inc. All rights reserved.
This publication or any part thereof must not be reproduced in any form without permission of the publisher.