Steel Designers Manual - TheBestFriend.org

This material is copyright - all rights reserved. Reproduced under licence from The Steel Construction Institute on 12/2/2007
To buy a hardcopy version of this document call 01344 872775 or go to http://shop.steelbiz.org/
Steel Designers' Manual - 6th Edition (2003)
The equivalent effective length Le given below is based on the information given
in References 7, 8 and 9 and is only valid for c/Lb < 0.15 and dc/D < 0.2, where Lb
is the length of the beam and dc is the depth of the notch. All the other symbols are
defined above. Beams with notches outside these limits should be checked as tee
sections or stiffened.
cK K
L L
L
K K
2
Ê 2 + 2 2 ˆ
e = bÁ1+
˜
Ë
b ¯
0
= (for values of K0
refer to [1])
lb
uvLb
lb
=
r
y
( )
u, v and ry are for I-beam sections and are defined in BS 5950: Part 1.
The web angle cleat can become cumbersome when used to connect unequal sized
beams. In this case it is necessary to notch the bottom flange of the smaller beam
to prevent fouling of the bolts. Alternatively the cleat of the larger beam could be
extended and the bolts placed below the bottom of the smaller beam.
The essential detailing requirements for double angle web cleat connections are
given in Fig. 26.14 and Table 26.6 gives the recommended design procedure.
26.2.5.2 Flexible end-plates
1
Simple connections 741
This type of connection is shown in Fig. 26.15. Like the double angle cleat connection,
the top flange of the supported beam is notched to allow it to fit to the web of
the supporting beam.
If both beams are of a similar depth both flanges are notched. In either case, if
the length of the notches exceed the limits given in section 26.2.5.1, the unrestrained
web and beam must be checked for lateral torsional bucking. In practice the endplate
is often detailed to extend to the full depth of the notched beam and welded
to the bottom flange.This makes the connection relatively stiffer than a partial depth
end-plate but provided the end-plate is relatively thin and the bolt cross centres
are large, the end-plate retains sufficient flexibility to be classified as a simple
connection.
If the supporting beam is free to twist there will be adequate rotational capacity
even with a thick end-plate. In the cases where the supporting beam is not free to
twist, for example in a double sided connection, the rotational capacity must be provided
by the connection itself. In such cases thick, full depth end-plates may lead to
overstressing of the bolts and welds. Both partial and full depth end-plates derive
their flexibility from the use of relatively thin end-plates combined with large bolt