2.5.2 Design Procedure 2;Thin End-Plate and Larger Diameter Bolts: The following procedure results in a design with a rela-tively thin end-plate and larger diameter bolts.. For flush end
Trang 1Revision and Errata List, March 1, 2003 AISC Design Guide 16: Flush and Extended Multiple-Row Moment End-Plate Connections The following editorial corrections have been made in the First Printing, 2002 To facilitate the incorporation of these corrections, this booklet has been constructed using copies
of the revised pages, with corrections noted The user may find it convenient in some cases to hand-write a correction;
in others, a cut-and-paste approach may be more efficient
Trang 22.5.2 Design Procedure 2;
Thin End-Plate and Larger Diameter Bolts:
The following procedure results in a design with a
rela-tively thin end-plate and larger diameter bolts The design
is governed by either the yielding of the end-plate or bolt
rupture when prying action is included, requiring "thin"
plate behavior The "summary tables" refer to Tables 3-2
through 3-5 for the flush end-plate connections and
Ta-bles 4-2 through 4-6 for the extended end-plate
connec-tions The design steps are:
1.) Determine the required plate thickness,
(2-9)
Note: This equation is derived from equating to
given in the "summary tables" as follows:
(2-10)
2.) Select a trial bolt diameter, and calculate the
maximum prying force
For flush end-plate connections and for the interior
bolts of extended end-plate connections, calculate
as follows:
Note that for flush connections Also, the last
term in the numerator of Equation 2-14 represents the
contribution of bolt shank bending in Figure
2-1)
For extended connections, also calculate based
on the outer bolts as follows:
If the radical in either expression for (Equations 2-11 and 2-15) is negative, combined flexural and shear yielding of the end-plate is the controlling limit state and the end-plate is not adequate for the speci-fied moment
3.) Calculate the connection design strength for the limit state of bolt rupture with prying action as follows:
For a flush connection:
(2-15)
(2-16)
(2-17)
(2-18) For an extended connection:
(2-19) where,
distance from the Centerline of each tension bolt row to the center of the compression flange (Note: For rows that do not exist in a connection, that distance d is taken as zero), specified pretension in Table J3.7 of AISC ASD or Table J3.1 of AISC LRFD (also re-produced in Table 2-1 of this Guide)
(2-11)
(2-12)
(2-13)
(2-14)
Rev.
3/1/03
Rev.
3/1/03
³·²
Rev 3/1/03
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Trang 3Comparison of Results for the Two Design Procedures
Design Procedure 1
End-Plate: A572 Gr 50 material
tp = 9/16 in
db = 5/8 in
Design Procedure 2
End-Plate: A572 Gr 50 material
tp = 1/2 in
db = 3/4 in
As expected, Design Procedure 1 results in a thicker
end-plate and smaller diameter bolts than Design
Procedure 2 Either design is acceptable Note: A
check of the design strength of the two designs using
the procedure outlined in Appendix B yields the
fol-lowing:
Design Procedure 1: Mn = 1987 k-in (Thick plate
behavior controlled by bolt rupture no prying
ac-tion)
behavior controlled by end-plate yielding)
4.2.2 Four-Bolt Extended Ítiffened Moment
End-Plate Connection (Table 4-3)
In this four-bolt stiffened example, the required factored
moment of 1,750 k-in and connection geometry of the
four-bolt extended unstiffened connection of Example
4.2.1 is used so that the required end-plate thickness and
bolt diameter can be compared As before, the end-plate
material is A572 Gr 50, the bolts are snug-tightened
A325, and the connection is used in rigid frame
construc-tion as assumed in the frame analysis Both LRFD design
procedures are illustrated
Geometric Design Data
bp = bf = 8 in
tf = 3/8 in
g = 3 in
pf,i = 1 3/4 in
pf,o = 2 1/2 in
pext = 5 in
h = 24 in
Calculate:
r = 1.0 for extended connections
d0 = 24+2.5-(0.375/2) = 26.3125 in
h0 = 26.5 in
d1 = 24-0.375-1.75-(0.375/2) = 21.6875 in
h1 = 21.875 in
de = 5-2.5 = 2.5 in
Design Procedure 1 (Thick End-Plate and Smaller Diameter Bolts):
1.) Solve for the required bolt diameter assuming no pry-ing action,
in 59 0
688 21 313 26 90 75 0
1750 2 2
,
n t
u reqd
M d
Use db = 5/8 in
2.) Solve for the required end-plate thickness, tp,reqd,
in
45 2 0 3 0 8 2
1 2
Case 1 governs
pf,i = 1.75 in s use pf,i = 1.75 in
o f 0 i 1
o f
0 i 1 p
p s h s p h g
p s
h s p h
b Y
, ,
, ,
2
1 1 1 1 2
5
21 45
21 5 26 45
21 75
11 875 21
2.0 8
in 1 320
5 2 45 2 5 26 45 2 75 1 875 21 0 3 2
k 6 27 4 / 90 625 0 4
2F d
p
ext
p
1
d d
0
p
t
1 w
t g
h
s
f, o
f, i
p tf
h h0
p
b
Rev.
3/1/03
Trang 4k 9 10 ) 5 2 / 75 1 ( 6 15 ) /
i
o F p p
F
2 2
2
3
max,o wt
F F
a
t
w
Q
k 39
8
5625 0 19 3 9 10 3 50 47
1 5625 0 19
3.) Calculate the connection design strength for the limit
state of bolt rupture with prying action,
k 8 39 4 / 90 75 0 4
2F
d
Pt b t
) d d d )(d (T
) d )(d (T ) d )(d Q
(P
)d
(P
M
3 2 1 0 b
2 0 b 3 1 max,i t
3 2 1 b 0 max,o t 2 b
3 1 max,i t 0 max,o t
q
2
2
2
2
max
k 9 27 8 39 7 0 7
0 t
b P
Use Tb = 28 k
in k 5539 ) 688 28
188 31 688 33 313 38 )(
28 ( 2
75
0
in k 5878 )]
188 31 313 38 )(
28 ( 2
) 688 28 688 33 )(
18 8 8 39 ( 2
[
75
0
in k 5735
)]
688 28 188 31 688 33 )(
28 ( 2
313 38 ) 39 8 8 39 ( 2
[
75
0
in k 6074 ] 188 31 ) 28 ( 2
688 28 688 33 18 8 8 39 2
313 38 39 8 8 39 2
75
0
4.) Check that Mq > Mu If necessary, adjust the bolt
di-ameter until Mq is greater than Mu
4600 6074
q
3/4 in dia is ok
Note: A check (not shown) of 5/8 in bolt confirms
that 3/4 in is required
Comparison of Results for the Two Design Procedures Design Procedure 1
End-Plate: A572 Gr 50 material
tp = 5/8 in
db = ë/8 in
Design Procedure 2 End-Plate: A572 Gr 50 material
tp = 9/16 in
db = 3/4 in
As expected, Design Procedure 1 results in a thicker end-plate and smaller diameter bolts than Design Procedure 2 Either design is acceptable Note: A check of the design strength of the two designs using the procedure outlined in Appendix B yields the fol-lowing:
Design Procedure 1: Mn = 5460 k-in (Thick plate behavior controlled by bolt rupture no prying ac-tion)
Design Procedure 2: Mn = 5415 k-in (Thin plate behavior controlled by end-plate yielding)
4.2.5 Multiple Row Extended Stiffened 1/3 Moment End-Plate Connection (Table 4-6)
The required end-plate thickness and bolt diameter for an end-plate connection with the geometry shown below and
a required factored moment of 4,600 k-in is to be deter-mined The end-plate material is A572 Gr 50 and the bolts are fully tightenedA325, and the connection is used in rigid frame construction as assumed in the frame analysis Both LRFD design procedures are illustrated
Geometric Design Data
bp = bf = 8 in
tf = 3/8 in
g = 3 in
db = 3/4 in
p
pb
d
p t
pf, ib
pf, oe
bp
f s
s 3
h
h1
h0 h
0 d 1 d 3 d
d2 p t
ext p
Rev 3/1/03