ISO 14346:2013
(Main)Static design procedure for welded hollow-section joints — Recommendations
Static design procedure for welded hollow-section joints — Recommendations
ISO 14346:2013 gives guidelines for the design and analysis of welded uniplanar and multiplanar joints in lattice structures composed of circular (CHS), square (SHS) or rectangular (RHS) hollow sections, and of uniplanar joints in lattice structures composed of combinations of hollow sections with open sections under static loading. ISO 14346:2013 is applicable to CHS or RHS Y-, X- and K-joints and their multiplanar equivalents, gusset plate to CHS or RHS joints, open-section and RHS to CHS joints, and hollow-section to open-section joints.
Procédure statique de conception des joints soudés à section creuse — Recommandations
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 14346
First edition
2013-03-15
Static design procedure for
welded hollow-section joints —
Recommendations
Procédure statique de conception des joints soudés à section creuse —
Recommandations
Reference number
©
ISO 2013
© ISO 2013
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Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 2
5 Requirements . 5
6 Materials .12
7 Joint types .13
8 Joint classification .19
9 Limit states design .23
10 Partial load and safety factors for loads and resistances .24
11 Static design procedures .24
11.1 General .24
11.2 Design member forces .24
11.3 Design resistance .24
11.4 Design criteria .25
12 Design member forces .25
12.1 Analysis methods .25
12.2 Design member forces .26
13 Design criteria .26
13.1 Failure modes .26
13.2 Uniplanar joints .26
13.3 Uniplanar overlap joints with a CHS, RHS, I- or H-section chord .28
13.4 Special uniplanar joints .29
13.5 Multiplanar joints .30
14 Design resistance of uniplanar CHS braces to CHS chord joints.30
14.1 Design axial resistance .30
14.2 Design moment resistance.31
15 Design resistance of uniplanar gusset plates, I- or H-section braces or RHS braces to CHS
chord joints .32
16 Design resistance of multiplanar joints with CHS chord .33
17 Design resistance of uniplanar RHS braces or CHS braces to RHS chord joints .34
17.1 Design axial resistance .34
17.2 Design moment resistance.36
18 Design resistance of uniplanar SHS or CHS braces to SHS chord joints .37
18.1 Design axial resistance .37
18.2 Design moment resistance.38
19 Design resistance of uniplanar gusset plate to RHS joints .38
20 Design resistance of multiplanar joints with RHS chord .39
21 Design resistance of uniplanar CHS or RHS braces to I- or H-section chord joints .40
21.1 Design axial resistance .40
21.2 Design moment resistance.42
22 Design resistance of uniplanar overlap joints with a CHS, RHS, I- or H-section chord .42
Annex A (informative) Quality requirements for hollow sections .46
Annex B (informative) Weld details .48
Annex C (informative) Partial safety factors on static strength .50
Bibliography .52
iv © ISO 2013 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14346 was prepared by the International Institute of Welding, which has been approved as an
international standardizing body in the field of welding by the ISO Council.
Requests for official interpretations of any aspect of this International Standard should be directed to
the ISO Central Secretariat, who will forward them to the IIW Secretariat for an official response.
INTERNATIONAL STANDARD ISO 14346:2013(E)
Static design procedure for welded hollow-section joints —
Recommendations
1 Scope
This International Standard gives guidelines for the design and analysis of welded uniplanar and
multiplanar joints in lattice structures composed of circular (CHS), square (SHS) or rectangular (RHS)
hollow sections, and of uniplanar joints in lattice structures composed of combinations of hollow sections
with open sections under static loading. This International Standard is applicable to CHS or RHS Y-, X-
and K-joints and their multiplanar equivalents, gusset plate to CHS or RHS joints, open-section and RHS
to CHS joints, and hollow-section to open-section joints.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 630 (all parts), Structural steels
ISO 14347, Fatigue — Design procedure for welded hollow-section joints — Recommendations
ISO/TR 25901, Welding and related processes — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14347, ISO/TR 25901, and the
following apply.
3.1
chord face failure
chord plastification
plastic failure of the chord face or plastic failure of the chord cross-section
3.2
chord punching shear
crack initiation in a hollow-section chord wall leading to rupture of a brace member from the chord member
3.3
chord side wall failure
chord web failure
yielding, crushing or instability (crippling or buckling of the chord side wall or chord web) under the
relevant brace member
3.4
cross-section classification
identification of the extent to which the resistance (to axial compression or bending moment) and
rotation capacity of a cross-section are limited by its local buckling resistance
Note 1 to entry: For example, four classes are given in Eurocode 3 (see EN 1993-1-1) together with three limits on
diameter-to-thickness ratio for CHS or width-to-thickness ratio for RHS.
3.5
joint configuration
type or layout of the joint or joints in a zone within which the axes of two or more interconnected
members or elements intersect
3.6
local chord member yielding
local buckling of the chord connecting face in an overlapped joint
3.7
local yielding of overlapping brace
local yielding of overlapping plate
local yielding of brace
local yielding of plate
cracking in the weld or in a brace member, or local buckling of a brace member with reduced effective width
3.8
multiplanar joint
in a lattice structure, a joint connecting members situated in more than one plane
3.9
structural properties of a joint
resistance to forces and moments in the connected members, deformation and/or rotation capacity
3.10
uniplanar joint
in a lattice structure, a joint connecting members situated in a single plane
4 Symbols and abbreviated terms
A cross-sectional area of member i (i = 0, 1, 2)
i
A shear area of a chord member
s
b effective width of a plate or RHS brace member
e
b effective width of an overlapping RHS brace member at the chord connection
ei
b effective width of an overlapped RHS brace member at the chord connection
ej
b effective width of an overlapping RHS brace member at the overlapped brace connection
e,ov
b effective width for punching shear
e,p
b overall out-of-plane width of a plate or RHS or I- or H-member i (i = 0, 1, 2)
i
b effective width for the web of an I- or H-section, or RHS side wall
w
C coefficient used in the chord stress function Q as shown in Tables 2, 4, 6, and 9
1 f
c coefficient defined in Table 13
c coefficient for effective shear area
s
d effective width of a CHS brace member
e
d effective width of an overlapping CHS brace member at the chord connection
ei
d effective width of an overlapped CHS brace member at the chord connection
ej
2 © ISO 2013 – All rights reserved
d effective width of an overlapping CHS brace member at the overlapped brace connection
e,ov
d overall diameter of CHS member i (i = 0, 1, 2)
i
d depth of the web of an I- or H-section chord member (d = h −2t −2r)
w w 0 0
e noding eccentricity of a joint, shown in Figure 1 h), with a positive value of e representing an
offset from the chord centreline towards the outside of the truss
F axial force in a brace member
ax
*
design resistance for the axial force in a chord member at the gap location
F
gap,0
F design value of the axial force in a chord member at the gap location
gap,0
* design resistance of the joint, expressed in terms of the axial force in member i (i = 1, 2)
F
i
F design value of the axial force in member i (i = 0, 1, 2)
i
F axial yield capacity of a chord member
pl,0
* design resistance for the shear force of the brace to chord connection in an overlapped joint
F
s
F design value of the shear force in a chord member at the gap location
s,gap,0
F shear yield capacity of a chord member
s,pl,0
F design value of the shear force in a chord member
s,0
g gap between the brace members in a K- or N-joint, defined in Figure 1 h)
g transverse gap in KK-joints, defined in Figure 1 n)
t
h overall in-plane depth of a plate or RHS or I- or H-section member i (i = 0, 1, 2)
i
h distance between the centres of gravity of the effective parts of the brace (beam) as shown in
z
Table 12
i integer subscript used to designate a member of a joint:
0 denotes a chord member;
1, 2 denote the brace members.
In joints with two brace members, 1 normally denotes the compression brace and 2 the tension
brace. For a single brace, i = 1 whether it is subject to compression or tension. For an overlap
type joint, i is the integer subscript to designate the overlapping brace
j integer subscript used to designate the overlapped brace member in overlap type joints
k factor defined in Table 3
b
ℓ effective perimeter for local yielding of the (overlapping) brace
b,eff.
ℓ effective perimeter for chord punching shear
p,eff.
M design value of the moment in member i (i = 0, 1, 2)
i
*
design resistance of the joint, expressed in terms of the in-plane moment in member i (i = 1, 2)
M
ip,i
M design value of the in-plane moment in member i (i = 1, 2)
ip,i
*
design resistance of the joint, expressed in terms of the out-of-plane moment in member i (i = 1,
M
op,i
2)
M design value of the out-of-plane moment in member i (i = 1, 2)
op,i
M plastic moment capacity of a chord member
pl,0
n factor to account for chord stress in Q function (see applicable table)
f
q
O =×100%
O overlap ratio, expressed as a percentage
v
v
p
O overlap limit for brace shear check
v, limit
p length of the projected contact area of the overlapping brace member onto the face of the chord,
in the absence of the overlapped brace member, in a K- or N-joint, defined in Figure 1 i)
Q chord stress function as defined in Tables 2, 4, 6, and 9
f
Q function in the design resistance equation as defined in Tables 2, 3, 4, 6, 7, and 8
u
Q function in the design resistance equation for brace bending as defined in Table 4
ub
q length of overlap, measured at the face of the chord, between one brace member toe and the
position of the other projected brace member toe, in a K- or N-joint, defined in Figure 1 i)
r fillet radius of an I- or H-section
r external corner radius of an RHS
o
t wall thickness
t wall thickness (for CHS or RHS) or flange thickness (for I- or H-section) of member i (i = 0, 1, 2)
i
t web thickness of an I- or H-section
w
W elastic section modulus of member i (i = 0, 1, 2)
el,i
W plastic section modulus of member i (i = 0, 1, 2)
pl,i
α factor used in the expression of A in Tables 6 and 11
s
β ratio of the mean diameter or width of the brace members, to that of the chord
d d b
1 1 1
β = or or
for T, Y- and X-joints
d b b
0 0 0
dd++bb bb++hh+
12 12 12 12
β = or or
for K- and N-joints
22d b 4b
0 0 0
b
β =
for plate to CHS
d
4 © ISO 2013 – All rights reserved
b
β =
for plate to RHS
b
d b
0 0
γ = or
γ ratio of the chord width or diameter to twice the chord thickness
22t t
0 0
γ partial load factor on applied loading
F
γ partial safety factor on joint resistance
M
h h
1 1
η= or
η ratio of the brace member depth to the chord diameter or width
d b
0 0
θ included angle between brace member i and the chord (i = 1, 2)
i
λ slenderness
µ multiplanar factor defined in Tables 5 and 10
σ design stress for chord side wall failure
k
σ ultimate tensile stress
u
σ yield stress
y
σ yield stress of member i (i = 0, 1, 2)
yi
ϕ angle between the planes in a multiplanar joint defined in Figures 1 j) to o), or resistance factor
χ reduction factor for (column) buckling
CHS circular hollow section
RHS rectangular hollow section
SHS square hollow section
5 Requirements
The following conditions are requirements for hollow-section joints.
— Steel grades shall be according to Clause 6.
— Hollow-section joint types shall be according to Clause 7.
— The nominal wall thickness of hollow sections shall be limited to a minimum of 1,5 mm.
— For hollow-section chords with a wall thickness greater than 25 mm, the steel shall meet adequate
through thickness properties as specified in ISO 630.
— The ends of members that meet at a joint shall be prepared in such a way that their cross-
sectional shape is not modified. Flattened end joints and cropped end joints are not covered in this
International Standard.
— Where brace members are welded to a chord member, the included angle between brace and chord
(θ ) should be at least 30°. This is to ensure that proper welds can be made. For angles less than 30°,
i
confirmation that sound welds can be made should be obtained from the fabricator.
— In gap-type joints, to ensure that there is adequate clearance to form satisfactory welds, the gap between
adjacent brace members shall not be less than the sum of the brace member thicknesses (t + t ).
1 2
— In overlap-type joints, the overlap shall be large enough to ensure that the interconnection of the
brace members is sufficient for adequate shear transfer from one brace to the other. In any case, the
overlap ratio (defined in Clause 4) shall be at least 25 %.
— Where overlapping brace members are of different widths, the narrower member shall overlap the
wider.
— Where overlapping brace members with the same width have different thicknesses and/or different
strength grades, the member with the lowest t σ -value shall overlap the other member.
i yi
— In gap and overlap K-joints, the noding eccentricity, e, shown in Figure 1 h) and i), produces a primary
bending moment which requires consideration when designing truss members.
— In gap and overlap K-joints, restrictions are placed on the noding eccentricity, e, shown in Figure 1 h)
and i). Within the specified limits (e ≤ 0,25d or e ≤ 0,25h ), the bending moment due to this
0 0
eccentricity is taken into account, for its effect on joint resistance, in the Q term (a function to
f
account for chord stress at the connection face). If the noding eccentricty, e, exceeds the limits in the
previous sentence, the effect of the resulting bending moment on the joint resistance shall be taken
into account by distributing part of the total eccentricity moment to the brace members. (In such
cases, the joint resistance shall then be determined by checking the interaction of brace axial load
and brace bending moment.)
— For joints with one (or both) chord end(s) not connected to other members, the chord shall be
extended from the centre of the joint over a length of 3,5d or 3,5b or the end(s) shall be welded to
0 0
a cap plate with a thickness of at least 1,5t or 10 mm.
a) T-joint
6 © ISO 2013 – All rights reserved
b) Y-joint
c) X-joint
d) Y-joint (CHS chord) with brace in-plane bending
e) Y-joint (CHS chord) with brace out-of-plane bending
f) Y-joint (RHS chord) with brace in-plane bending
8 © ISO 2013 – All rights reserved
g) Y-joint (RHS chord) with brace out-of-plane bending
h) gap K-joint
i) overlap K-joint
j) CHS TT-joint
k) RHS TT-joint
10 © ISO 2013 – All rights reserved
l) CHS XX-joint
m) RHS XX-joint
n) CHS gap KK-joint
o) RHS gap KK-joint
Key
0 chord
1 compression brace
2 tension brace
i overlapping brace
j overlapped brace
Figure 1 — Joints between hollow sections
6 Materials
This International Standard is valid for both hot-finished (hot-formed) and cold-formed steel hollow
sections. The manufactured hollow sections shall comply with the applicable national manufacturing
specification for structural hollow sections. The nominal yield stress of hot-finished hollow sections and
the nominal yield stress of the cold-formed hollow sections shall not exceed 460 N/mm (MPa). Further
criteria are given in 11.3. These nominal yield stresses pertain to the finished product, at the stipulated
test locations.
12 © ISO 2013 – All rights reserved
7 Joint types
The joints covered in this International Standard consist of:
— CHS or RHS as used in uniplanar trusses or girders, such as Y- (with T- a special case thereof), X-
and K- (with N- a special case thereof) joints (examples of which are given in Figure 1) and their
multiplanar equivalents;
— gusset plate to CHS or RHS joints (examples of which are given in Figure 2);
— open-section and RHS to CHS joints (examples of which are given in Figure 3);
— hollow-section to open-section joints (examples of which are given in Figure 4).
Geometric parameters for various joints are defined in Figures 1 to 4. Recommended weld details for
hollow-section joints are given in Annex B.
a) T-joint — transverse plate to CHS
b) X-joint — transverse plate to CHS
c) T-joint — longitudinal plate to CHS
d) X-joint — longitudinal plate to CHS
e) T-joint — transverse plate to RHS
14 © ISO 2013 – All rights reserved
f) X-joint — transverse plate to RHS
g) T-joint — longitudinal plate to RHS
h) X-joint — longitudinal plate to RHS
i) T-joint — longitudinal through plate to RHS
Figure 2 — Joints between gusset plates and CHS or RHS chords
a) T-joint
b) X-joint
16 © ISO 2013 – All rights reserved
c) T-joint
d) X-joint
Figure 3 — Joints between open section or RHS braces and CHS chords
a) Y-joint
b) gap K-joint
c) overlap K-joint
18 © ISO 2013 – All rights reserved
d) T-joint subject to in-plane bending
Key
0 I- or H-section chord
1 RHS brace (beam)
Figure 4 — Joints between CHS or RHS braces and open-section chords
8 Joint classification
Hollow-section planar truss joints consist of one or more brace members that are directly welded to a
continuous chord that passes through the joint. The classification of hollow-section truss-type joints as
K- (which includes N-), Y- (which includes T-) or X-joints is based on the method of force transfer in the
joint, not on the physical appearance of the joint. The joint types can be defined as follows.
a) When the force component normal to the chord in a brace member (F sinθ) is equilibrated by beam
ax
shear in the chord member, the joint is classified as a T-joint when the brace is perpendicular to the
chord, otherwise it is classified as a Y-joint.
b) When the force component normal to the chord in a brace member (F sinθ) is essentially equilibrated
ax
(within 20 %) by loads in other brace member(s) on the same side of the joint, the joint is classified
as a K-joint. The relevant gap is, in principle, between the primary brace members whose loads
equilibrate. An N-joint is to be considered as a type of K-joint with one brace at 90°.
c) When the force component normal to the chord (F sinθ) is transmitted through the chord member
ax
and is equilibrated by brace member(s) on the opposite side, the joint is classified as an X-joint.
Examples of such classification are shown in Figure 5.
When brace members transmit part of their load as K-joints and part of their load as T-, Y-, or X-joints,
the adequacy of each brace needs to be determined by linear interaction of the proportion of the brace
load involved in each type of load transfer. One K-joint, in Figure 5 b), illustrates that the brace force
components normal to the chord member may differ by as much as 20 % and still be deemed to exhibit
K-joint behaviour. This is to accommodate slight variations in brace member forces along a typical truss,
caused by a series of panel point loads. The N-joint in Figure 5 c), however, has a ratio of brace force
components normal to the chord member of 2:1. That particular joint needs to be analysed as both a
“pure” K-joint (with balanced brace forces) and an X-joint (because the remainder of the diagonal brace
load is being transferred through the joint), as shown in Figure 6. For the diagonal tension brace in that
particular joint, one would need to check that:
05,,F 05F
ax ax
+≤10,
**
F F
K X
where
* is the resistance of a K-joint;
F
K
*
is the resistance of an X-joint.
F
X
a)
b)
20 © ISO 2013 – All rights reserved
c)
d)
e)
f)
g)
h)
22 © ISO 2013 – All rights reserved
i)
Figure 5 — Examples of hollow-section joint classification
Figure 6 — Checking of an N-joint with unbalanced brace member loads
9 Limit states design
The design methodology used herein is a limit states design (LSD) procedure, also called a load and
resistance factor design (LRFD) procedure. All loads are considered to be factored loads and the factored
load effect must not exceed the design resistance, where the design resistance is based on an ultimate
limit state (or states) corresponding to the maximum load carrying capacity or the load at a maximum
deformation limit.
NOTE In the analyses for the determination of the design strengths, the assumed mean values and coefficients
of variation for the dimensional, geometric and mechanical properties are listed in Table 1.
Table 1 — Mean values and coefficients of variation for the dimensional, geometric and
mechanical properties
Coefficient of
Parameter (actual measured/specified nominal ratio) Mean value Effect
variation
CHS or RHS thickness, t 1,0 0,05 Important
i
CHS diameter, d , or RHS width, b , or depth, h 1,0 0,005 Negligible
i i i
Angle, θ 1,0 1° Negligible
i
Relative gap, g’ = g/t 1,0 0,06 Important
Relative chord stress parameter, n 1,0 0,05 Important
Yield stress, σ 1,18 0,075 Important
y
Mean values or tolerances considerably deviating from these values can affect the resulting design value.
10 Partial load and safety factors for loads and resistances
10.1 The partial load factors for applied loading, for the ultimate (γ ) limit state, shall be taken from the
F
relevant building code or specification being used.
10.2 Partial safety factors (γ ) or resistance factors (ϕ) for hollow-section joints have already been
M
incorporated into the design resistance formulae given in Clauses 14 to 22. For informational purposes,
the partial safety factors used in the various joint resistance formulae are given in Table C.1.
11 Static design procedures
11.1 General
The static design procedures can be summarized as the following three steps:
a) Step one: determine the design member forces in the brace(s) and chord;
b) Step two: determine the design resistance of the joint;
c) Step three: apply design criteria to assess if the joint resistance is sufficient.
11.2 Design member forces
The design member forces shall be determined using Clause 12.
11.3 Design resistance
The design resistance for various types of joints is given in Clauses 14 to 22, where the partial safety
factors listed in Table C.1 have already been incorporated. For material with a nominal yield stress (σ )
y
exceeding 355 N/mm , the joint resistances specified in this International Standard shall be multiplied
by 0,9. In addition, if the nominal yield stress exceeds 0,8 of the nominal ultimate stress (σ ) then the
u
design yield stress shall be taken as 0,8σ .
u
24 © ISO 2013 – All rights reserved
11.4 Design criteria
The design member forces determined in 11.2 shall not exceed the design resistance given in 11.3 as
appropriate. The design criteria are given in Clause 13.
12 Design member forces
12.1 Analysis methods
12.1.1 For welded hollow-section structures, design member forces require determination by analysis
of the complete structure, in which nodal eccentricity of the member centrelines at the joint is taken
into account.
12.1.2 Simplified analysis methods are acceptable for triangulated trusses or lattice girders with
eccentricities e ≤ 0,25d or e ≤ 0,25h for gap and overlap K-joints; these are as follows.
0 0
a) Pin-jointed analysis. Moments due to eccentricity need to be taken into account for the design of chords.
b) Continuous chords with pin-ended braces. Axial forces and bending moments in the members can
be determined using a structural analysis assuming a continuous chord and pin-ended braces (see
Figure 7). This produces axial forces in the braces, and both axial forces and bending moments in
the chord. This modelling assumption is particularly appropriate for loads on the chord members
which are away from the node points or panel points.
12.1.3 Rigid frame analysis shall be used for two- or three-dimensional Vierendeel girders.
12.1.4 Other rational analysis procedures consistent with the joint stiffnesses may be used.
Key
a noding condition for most overlap connections
b extremely stiff members
c noding condition for most gap connections
d pin
Figure 7 — Possible frame modelling assumption
12.2 Design member forces
The following design member forces can be determined from 12.1:
F design axial force in the chord (i = 0) or in the brace (i = 1, 2);
i
F design shear force in the chord;
s,0
M design in-plane moment in the brace (i = 1, 2);
ip,i
M design out-of-plane moment in the brace (i = 1, 2);
op,i
M design moment in the chord.
13 Design criteria
13.1 Failure modes
The design resistance of joints mentioned in 11.3 shall be based on the following failure modes as applicable:
a) chord face failure or chord plastification;
b) chord side wall failure (or chord web failure);
c) chord shear;
i) chord punching shear;
j) local yielding of (overlapping) brace (or plate);
f) local chord member yielding;
g) brace shear.
These failure mode descriptions are used in Tables 2 to 15, which list design resistances. Weld failure
shall be avoided.
13.2 Uniplanar joints
13.2.1 General
For joint types described in Clauses 14, 15, 17, 18, 19, 21 and 22, the following design criteria apply.
a) For joints within the range of validity given in Tables 2 to 15, only failure modes listed in the resistance
tables need to be considered. The design resistance of a joint shall be taken as the minimum value
for these criteria.
b) For joints outside the range of validity mentioned in a), all criteria given in 13.1 shall be considered.
shall not exceed
c) In joints with the brace member(s) subject only to axial forces, the design axial force F
i
*
the design axial resistance of the welded joint F , expressed as an axial force in the brace member.
i
13.2.2 Uniplanar joints with CHS chord
The following design criteria apply:
a) for overlap joints, see 13.3;
b) for special uniplanar joints with braces on both sides of the chord, see 13.4;
26 © ISO 2013 – All rights reserved
c) In joints with the brace member(s) subjected to combined bending and axial forces, apply the following:
M M
F
ip,i op,i
i
+ +≤10,
* **
F M M
i ip,i op,i
where
F , M , and M are member forces determined in Clause 12;
i ip,i op,i
* * * are design resistances determined in Clauses 14 and 15.
F , M and M
i ip,i op,i
13.2.3 Uniplanar joints with RHS chord
The following design criteria apply:
a) for overlap joints, see13.3;
b) for special uniplanar joints with braces on both sides of the chord, see 13.4;
c) for welded T-, Y-, X-, and gap K-joints between SHS or CHS brace members and SHS chord members
only, where the geometry of the joints is within the range of validity given in Table 6 and also
satisfies the additional conditions given in Table 8, the only consideration is chord plastification;
d) in joints with the brace member(s) subjected to a combination of bending and axial forces, the
following design criterion applies:
M M
F
ip,i op,i
i
++ ≤10,
** *
F M M
i ip,i op,i
where
F , M , and M are member forces determined in Clause 12;
i ip,i op,i
* * * are design resistances determined in Clauses 17 and 18.
F , M and M
i ip,i op,i
13.2.4 Uniplanar joints with CHS or RHS brace to I- or H-section chord
The following design criteria apply:
a) for overlap joints, see 13.3;
b) in joints with the brace member(s) subjected to a combination of in-plane bending and axial forces,
the following applies:
M
F
ip,i
i
+≤10,
**
F M
i ip,i
where
F and M are member forces determined in Clause 12;
i ip,i
* * are design resistances determined in Clause 21.
F and M
i ip,i
13.3 Uniplanar overlap joints with a CHS, RHS, I- or H-section chord
Requirements are:
a) the design axial forces in overlap joints shall not exceed the design axial resistances given in
Tables 13 and 14;
b) the local yielding of the overlapping brace criterion and the local chord yielding criterion in Table 13
always apply;
c) the brace shear criterion in Table 14 should only be checked if O > O :
v v,limit
O = 60 % if the hidden seam of the overlapped brace is not welded,
v,limit
O = 80 % if the hidden seam of the overlapped brace is welded.
v,limit
For overlap joints with h < b and/or h < b , the brace shear criterion shall always be checked.
i i j j
28 © ISO 2013 – All rights reserved
13.4 Special uniplanar joints
The design resistance of several types of special uniplanar joints shown in Figure 8 a) to d), which are
not dealt with in 13.2 and 13.3, can be directly related to that of the basic types (i.e. X and K).
a) b)
c) d)
Figure 8 — Special types of uniplanar joints
The following criteria apply:
* *
a) in the joint in Figure 8 a), FF≤ , in which F is the design resistance of an X-joint given in Table 2
11 1
or Table 6;
* *
b) in the joint in Figure 8 b), FFsinsθθ+≤in F sinθ , in which F is the design resistance of an
1i12 2 i i
* * *
X-joint given in Table 2 or Table 6, where F sinθ is the larger of F sinθ and F sinθ ;
i i 11 22
* * * *
c) in the joint in Figure 8 c), FF≤ and FF≤ , in which F and F are the design resistances of a
11 22 1 2
K-joint, given in Table 2 or Table 6 — the force in the chord is the total chord force;
* * * *
d) in the joint in Figure 8 d), FF≤ and FF≤ , in which F and F are the design resistances of a
11 22 1 2
K-joint, given in Table 2 or Table 6.
Further, the following chord shear criteria apply at section 1-1 in Figure 8 d).
For CHS gap joints:
F F
gap,0 s,gap,0
+ ≤10,
F F
pl,0 s,pl,0
in which F is the design value of the axial force in the chord, F is the design value of the shear
gap,0 s,gap,0
force in the chord, both at the gap location. F is the axial yield capacity of the chord, i.e. FA= σ ,
pl,0
pl,0 0 y0
2A
and F is the shear yield capacity of the chord, i.e. F =05, 8σ
s,pl,0
s,pl,0 y0
π
For gap joints with an RHS chord or an I- or H-section chord:
F
s,gap,0
*
FF≤=05,(8σσAFand ≤=FA −+AA) σ 1−
s,gap,0s,pl,0y00sgap,0 gap,0s y0 s yy0
F
s,pl,0
in which A is given in Table 6 for RHS chord joints, and Table 11 for I- or H-section chord joints.
s
13.5 Multiplanar joints
13.5.1 Multiplanar joints with CHS chord
For multiplanar joints with CHS chord, as described in Clause 16, the following design criteria apply.
In each relevant plane of a multiplanar joint, the design criteria given in 13.2.1 and 13.2.2 shall be
satisfied using the design resistance with the multiplanar factors given in Table 5.
13.5.2 Multiplanar joints with RHS chord
For multiplanar joints with RHS chord, as described in Clause 20, the following design criteria apply.
In each relevant plane of a multiplanar joint, the design criteria given in 13.2.1 and 13.2.3 shall be
satisfied using the design resistance with the multiplanar factors given in Table 10.
14 Design resistance of uniplanar CHS braces to CHS chord joints
14.1 Design axial resistance
The design axial resistance of uniplanar CHS to CHS joints shall be determined using Table 2.
30 © ISO 2013 – All rights reserved
Table 2 — Design axial resistance of uniplanar CHS braces to CHS chord joints
Limit state Axially loaded joints with CHS braces and chord
σ t
y0 0
*
Chord plastification
FQ= Q
i uf
sinθ
i
Chord punching shear 1+ sinθ
* i
Fd= 05, 8σ π t
iiy0 0
(for dd≤−2t ) 2
i 00
2 sin θ
i
Function Q
u
T- and Y-joints
20,2
Q =+26,,16 8βγ
()
u
See Figure 1 a) and Figure 1 b)
a
X-joints
1+β
01, 5
See Figure 1 c) Q =26, γ
u
10− ,7β
Gap K-joints
16,,03
See Figure 1 h)
Q =+16, 51 81βγ +
()
u
08,
12,(+ gt/)
0
Function Q
f
F M
C
1 n=+ in connecting face
Qn=−()1
f
F M
pl,0 pl,0
Chord compression stress (n < 0) Chord tension stress (n ≥ 0)
T-, Y- and
C = 0,45 − 0,25β
X-joints
C = 0,20
Gap K-joints C = 0,25
Range of validity
02,,≤≤dd/ 10 ed/ ≤02, 5 gt≥+t
i 0 0
General
σσ≤ andσσ≤08,
yyi 0 yu
θ ≥°30
i
b
class 1 or 2 anddt/ ≤50 (for X-joints: dt/ ≤40 )
Compression 00
CHS chord
dt/ ≤50 (for X-joints: dt/ ≤40 )
00 00
Tension
class 1 or 2 anddt/ ≤50
Compression
ii
CHS braces
dt/ ≤50
Tension
ii
a
For X-joints with cosθβ> , the chord should also be checked for shear failure.
b [4]
Examples of cross-section classification can be found in Eurocode 3 (see EN 1993-1-1:2005, 5.5).
14.2 Design moment resistance
The design moment resistance of uniplanar CHS to CHS joints shall be determined using Table 3.
Table 3 — Design moment resistance of uniplanar CHS braces to CHS chord joints
Limit state Joints with CHS braces and chord
σ t
y0 0
*
Chord plastification
MQ= Q d
1 uf 1
sinθ
k
* 2 b
Md=05, 8σ t
11y0 0
sinθ
Chord punching shear
Brace in-plane bending Brace out-of-plane bending
(for dd≤−2t )
10 0
13+ sinθ 3+sinθ
1 1
k = k =
b b
4sinθ 4sinθ
1 1
Function Q
u
Brace in-plane bending Brace out-of-plane bending
See Figure 1 f) See Figure 1 g)
1+β
01, 5
05,
Q =13, γ
T-, Y-, X- and gap K-joints Q =43, βγ
u
u
10− ,7β
Function Q Same as in Table 2
f
Range of validity Same as in Table 2
15 Design resistance of uniplanar gusset plates, I- or H-section braces
...
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