Standardised Structural Connections
fourth edition � 2020
Compiled by:
P.W. Key
Australian Steel Institute
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INTRODUCTION
1.3
Connection behaviour
AS 4100 allows for three forms of construction which relate to the behaviour of connections. It
then requires that the design of the connections be such that the structure is capable of resisting
all design actions, calculated by assuming that the connections are appropriate to the form of
construction of the structure or structural part. The design of the connections is to be consistent
with the form of construction assumed.
The three forms of construction are:
Rigid construction-For rigid construction, the connections are assumed to have sufficient
rigidity to hold the original angles between the members unchanged. The joint deformations
must be such that they have no significant influence on the distribution of the action effects
nor on the overall deformation of the frame.
Semi-rigid construction-For semi-rigid construction, the connections may not have sufficient
rigidity to hold the original angles between the members unchanged but are required to
have the capacity to furnish dependable and known degree of flexural restraint. The
relationship between the degree of flexural restraint and the level of the load effects is
required to be established by methods based on test results.
Simple construction-For simple construction, the connections at the ends of members are
assumed not to develop bending moments. Connections between members in simple
construction must be capable of deforming to provide the required rotation at the connection
and are required to not develop a level of restraining bending moment which adversely
affects any part of the structure. The rotation capacity of the connection must be provided
by the detailing of the connection and must have been demonstrated experimentally. The
connection is then required to be considered as subject to reaction shear forces acting at
an eccentricity appropriate to the connection detailing.
The connections presented in Sections 3 and 4 are classified into rigid, semi-rigid or simple.
It is important to understand that the type of connection (rigid, semi-rigid, simple) is a function of
the particular connection arrangement and has a direct influence on the assumed connection
behaviour implemented by the engineer for structural analysis and design. It is therefore important
to ensure that connections are detailed to reflect the arrangements provided in subsequent
sections of this publication and to check the limits of validity documented for each connection
type.
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3.
Bolt holes are 2 mm larger than the nominal bolt diameter. Slotted or oversize holes are not
used because AS 4100 requires the use of either bolting category 8.8/TF or 8.8/TB under
the provisions of AS 4100 (Ref. 4). This connection uses 8.8/S category.
4.
In connections to column webs, the beam flange may also need to be coped (removed) to
allow the connection to be effected.
5.
Fabrication of this type of connection requires close control in cutting the beam to length
and adequate consideration must be given to squaring the beam ends such that both end
plates are parallel and the effect of beam camber does not result in out-of-square end plates
which makes erection and field fit-up difficult.
6.
The use of this connection for two-sided beam-to-beam connections should be considered
carefully. Installation of bolts in the end plates can cause difficulties in this case. When
unequal sized beams are used, special coping of the bottom flange of the smaller beams
may be required to prevent it fouling the bolts. Angles may be provided as erection seats
under the bottom flange (refer Figure 3.9).
7.
Since the end plate is intended to behave flexibly, damage of the end plate during transport
is not normally of concern and may be rectified on site.
8.
The fillet weld should not be continued across the top and bottom of the plate. Undercutting
of the supported beam web during fabrication (Figure 3.10) is to be avoided if the weld is
to comply with AS 1554, Part 1 (Ref. 8).
9.
Thinner end plates may bow due to weld shrinkage during cooling. The moderate curvature
usually involved should not be a problem as the bolts will pull the plate towards the
supporting member as the bolts are snug tightened (Figure 3.10). To reduce distortion a
minimum plate thickness of 10 mm is recommended.
10 .
The connection has little facility for site adjustment during erection. In a run of beams, a
slightly shorter beam may be detailed and supplied with packs of varying thickness in order
to take up any accumulation of fit-up tolerances.
11.
For coped beams, the top of the end plate and the bottom of the top flange cope cut should
coincide.
12.
Check end plate component width to ensure that it will fit between fillets of column section
when connecting to column web.
op bolt/bolts used fa<
rectlon purposes only
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Erection landing seat
{such as an angle)
FIGURE 3.9 ERECTION AIDS
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,/S"pported beam web
Distortion or bowing
or end plate
End plate • original position
FIGURE 3.10 UNDERCUTTING OF WEB AND DISTORTION OF END PLATE DUE TO WELD
3.3.5 Detailing limitations
The following detailing limitations are consistent with the validity limits for the design models described
in Refs 1 and 2. Detailing outside of these limits should be specifically checked with the engineer.
The detailing limitations are more general than the specific component dimensions defined in the
standard connection details.
Weld
Fillet weld to both sides of supported member web
6 mm or 8 mm fillet weld, category SP
Bolts
M20 or M24 bolts
8.8/S bolting category
Minimum 1 row, maximum 9 rows of bolts
Bolt gauge s9 = range of 9-14 x plate thickness (fi)
max. 140 for 10 thick plate
min. 90 for 10 thick plate
Plate
(Figure 3.11)
10 mm thick
Grade 250 plate or Grade 300 flat bar
Minimum depth di
Edge distances (minimum)
(dt = bolt diameter)
Hole diameters
:2: 0.5 x supported member depth, d
1.5dr
vertically
horizontally
1.5dr
22 mm for M20
26 mm for M24
Positioned as close as possible/practical to top flange or at cope
extremities
Maximum depth di
(Figure 3.12)
(Figure 3.12)
Controlled by clearance requirements
Supported member
Grades 300/350
Recommended end plate sizes
Up to 460UB supported member
Deeper than 460UB supported members
*
150 x 10 plate (s9 = 90)
200 x 10 plate (s9 =
140)
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SWC Coped Beam
Uncoped Baam
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DWC Copt;1d Beam
FIGURE 3.11 GENERALISED CONNECTION GEOMETRY
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3.4.3 Detailed configuration
The detailed configuration of the connection indicating typical standardised connection components
is illustrated in Figure 3.14.
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g2
Sgt
'd
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s,,
s .,
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s ,,
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20
of bolts
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s,
n' ITYWS'
of bolls
(b) AlTERNATIVE 'B'
Double line of bolts to supported member web
(ii) ALTERNATIVE 'A'
Single line of bolls to supported membef web
2,¾J + lwb
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'n'rows
of bolts
ol bolts
S
g3
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lwt,
t
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(d) OPTION2
Double angle cleat
{c) OPTION l
Single angle cleat
FIGURE 3.14 ANGLE CLEAT CONNECTION STANDARDISED CONFIGURATION
Standardised parameters for angle cleat connection (refer Figure 3.14):
a = 100mm
=
70mm
Sp=
70 mm
Sg1
*
Sg2
Generally
For beam depth 'D' s 200 mm deep
= 65mm
For ALTERNATIVE 'A'
=
For ALTERNATIVE 'B'
55mm
= 70mm
Sg3 =
65mm
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Ommnominal
4 mm design
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FIGURE 3.25 GENERALISED CONNECTION GEOMETRY
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16.
17.
When diagonal shear stiffeners are used, it is recommended that any horizontal stiffeners
be fillet welded to the column flange adjacent to the diagonal stiffener location, and then
the diagonal stiffener if fillet welded at its ends can be welded in the manner shown in
Figure 3.36(b)). Fillet welding to the web along the stiffener length is required in accordance
with Notes 13 and 14 depending on whether the diagonal stiffener is in tension or
compression.
Where web doubler plates are used in lieu of shear stiffeners to strengthen the column web,
these should be butt welded to the column flange in the manner shown in Figure 3.36(c)
and fillet welded all around the other two edges. Fillet weld leg length should be the same
as the doubler plate thickness.
Horizontal stiffener
(a)
(b)
Fillet weld not possible to plate
edge due to access problem
(c)
FIGURE 3.36 STIFFENER DETAILING
..
..
Bolt Clearances:
18
Bolt clearances are a major detailing issue with this connection because of the need to get
either a hand wrench and socket or impact wrench into the connection in order to tension
the bolts for 8.8/TB category.
Section 7.7 of Design Guide 1 (Ref. 7) provides the dimensions of wrenches for installing
bolts. The worst case scenario is that impact wrenches are to be used in which case the
clearance required is a maximum. In general, dimension A in Figure 3.37 should be 65 mm
to accommodate all wrench options for M24 bolts, and 55 mm for M20 bolts (Ref. 7).
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