1.6.1 Actions and combination of actions
A structure and its components shall be designed for the actions and combination of actions as specified in AS/NZS 1170.0.
1.6.2 Structural analysis and design
Structural analysis and design shall be in accordance with AS/NZS 1170.0.
NOTE: Guidance on the applicability of elastic structural analysis to continuous beams and frames is given in Appendix B.
1.6.3 Design capacity
The design capacity (Rd) shall be determined by any one of the following:
(a) The nominal capacity (Ru) in accordance with Sections 2 to 7 and the capacity reduction factor (φ) given in Table 1.6 as appropriate, i.e., Rd = φRu.
(b) Testing in accordance with Clause 8.2.3.
A1
A1
(c) Where the composition or configuration of such components is such that Item (a) or (b) cannot be made in accordance with those provisions, structural performance shall be established from the design capacity or stiffness by rational engineering analysis based on appropriate theory, related testing if data is available and engineering judgement. Specifically, the design capacity shall be determined from the calculated nominal capacity by applying the following capacity reduction factors:
(i) For members ...φ = 0.80.
(ii) For connections ...φ = 0.65.
1.6.4 Earthquake design 1.6.4.1 For Australia
All structures shall be designed for the actions and combination of actions specified in AS 1170.4. If cold-formed steel members are used as the primary earthquake resistance element, then the structural response factor (Rf) shall be less than or equal to 2.0, unless specified otherwise.
1.6.4.2 For New Zealand 1.6.4.2.1 General
All structures shall be designed for the actions specified in NZS 1170.5 and combination of actions specified in AS/NZS 1170.0, subject to the limitations specified in Clauses 1.6.4.2.2 to 1.6.4.2.4.
1.6.4.2.2 Structural ductility factor
For the ultimate limit state, the structural ductility factor (μ) shall be taken as follows:
(a) For seismic-resisting systems involving an assemblage of elements acting as a single unit, μ shall be less than or equal to 1.25.
(b) For seismic-resisting systems using semi-rigid connections, μ shall be less than or equal to 1.25.
(c) Where a special study is undertaken (see Clause 1.6.4.2.3), μ may be increased but shall not be greater than 4.0.
(d) For all other earthquake-resisting systems, μ = 1.0.
For the serviceability limit state, μ = 1.0.
NOTES:
1 An example of an assemblage of elements is a braced wall panel, where the whole panel and its attachments at the top and base contribute to the earthquake resistance.
2 Earthquake resisting systems using semi-rigid connections cover frames with connections that are flexurally weaker than the members framing into the connection.
1.6.4.2.3 Special studies
Where it is demonstrated by special study that μ for a particular structural system is greater than 1.25, then—
(a) μ shall be based specifically from studies including the—
(i) structural form and configuration under consideration;
(ii) ductility of the material;
(iii) location of yielding regions of the structure;
(iv) structural damping characteristics involved in the structural system; and
(v) need to provide the structure with a small margin against collapse under the maximum considered event in accordance with NZS 1170.5.
(b) where μ greater than 1.25 is applicable to a design, then capacity design shall be used in order to protect elements of the earthquake resisting system from inelastic demands beyond their capability to dependably resist such demands; and
(c) for buildings containing one or more suspended floors, capacity design principles shall be used to suppress inelastic demand in individual column members.
1.6.4.2.4 Structural performance factor
When considering lateral stability of a whole structure, the structural performance factor (Sp) shall be taken as 1.0.
For the ultimate limit state, Sp shall be taken as follows:
(a) Where μ is less than or equal to 2.0, but not less than 1.0—
Sp = 1.3 − 0.3μ . . . 1.6.4.2.3
(b) Where μ is greater than 2.0, then Sp = 0.70.
For the serviceability limit state, Sp = 0.70.
1.6.5 Durability 1.6.5.1 General
A structure shall be designed to perform its required functions during its expected life.
Where steelwork in a structure is to be exposed to a corrosive environment, the steelwork shall be given protection against corrosion. The degree of protection shall be determined after consideration has been given to the use of the structure, its maintenance and the climatic or other local conditions.
1.6.5.2 Corrosion protection
NOTE: Corrosion protection should comply with AS/NZS 2311 and AS/NZS 2312, as appropriate. For further information, see Appendix C.
TABLE 1.6
CAPACITY REDUCTION FACTOR
Design capacity Clause reference
Capacity reduction factor
(φ)
(a) Stiffeners: 3.3.8
Transverse stiffeners (φc) 3.3.8.1 0.85
Bearing stiffeners (φw) 3.3.8.2 0.90
Shear stiffeners (φv) 3.3.8.3 0.90
(b) Members subject to axial tension (φt) 3.2.1 0.90
(c) Members subject to bending: 3.3
Section moment capacity— 3.3.2
for sections with stiffened or partially stiffened compression flanges (φb)
3.3.2 0.95
for sections with unstiffened compression flanges (φb) 3.3.2 0.90 Member moment capacity—
members subject to lateral buckling (φb) 3.3.3.2 0.90
members subject to distortional buckling (φb) 3.3.3.3 0.90 beams having one flange through-fastened to sheeting
(channels or Z-sections) (φb)
3.3.3.4 0.90
Web design—
shear (φv) 3.3.4 0.90
Bearing (φw)—
for built-up sections Table 3.3.6.2(A) 0.75–0.90
for single web channel and channel-sections Table 3.3.6.2(B) 0.75–0.90 for single web Z-sections Table 3.3.6.2(C) 0.75–0.90
for single hat sections Table 3.3.6.2(D) 0.75–0.90
for multiple web deck sections Table 3.3.6.2(E) 0.60–0.90
(d) Concentrically loaded compression members (φc) 3.4 0.85
(e) Combined axial load and bending: 3.5
Compression (φc) 3.5.1 0.85
Bending (φb)— 3.5.1
using Clause 3.3.2 0.90 or 0.95
using Clause 3.3.3.1 0.90
(f) Cylindrical tubular members: 3.6
Bending (φb) 3.6.2 0.95
Compression (φc) 3.6.3 0.85
(g) Welded connections: 5.2
Butt welds— 5.2.2
tension or compression 5.2.2.1 0.90
shear 5.2.2.2(a) 0.80
shear (base metal) 5.2.2.2(b) 0.90
(continued)
TABLE 1.6 (continued)
Design capacity Clause reference
Capacity reduction factor
(φ)
Fillet welds— 5.2.3
longitudinal loading 5.2.3.2 0.55 or 0.60
transverse loading 5.2.3.3 0.60
Arc spot welds (puddle welds)— 5.2.4
shear (welds) 5.2.4.2(a) 0.60
shear (connected part) 5.2.4.2(b) 0.50 or 0.60
shear (minimum edge distance) 5.2.4.3 0.60 or 0.70
tension 5.2.4.4 0.65
Arc seam welds— 5.2.5
shear (welds) 5.2.5.2 0.60
shear (connected part) 5.2.5.2 0.60
Flare welds— 5.2.6
transverse loading 5.2.6.2(a) 0.55
longitudinal loading 5.2.6.2(b) 0.55
Resistance welds— 5.2.7
spot welds 5.2.7(a) 0.65
(h) Bolted connections: 5.3
Tearout 5.3.2 0.60 or 0.70
Net section tension: 5.3.3
With washers— 5.3.3(a)
double shear connection 0.65
single shear connection 0.55
Without washers 5.3.3(b) 0.65
Bearing 5.3.4 0.60 or 0.65
Bolts— 5.3.5
bolt in shear 5.3.5.1 0.80
bolt in tension 5.3.5.2 0.80
(i) Screwed connections: 5.4
Screwed connections in shear— 5.4.2
tension in the connected part 5.4.2.2 0.65
tilting and hole bearing 5.4.2.3 0.5
tearout 5.4.2.4 0.60 or 0.70
Screwed connections in tension— 5.4.3
pull-out of connected parts 5.4.3.1 0.5
pull-over (pull-through) of connected parts 5.4.3.1 0.5 (continued) A1
TABLE 1.6 (continued)
Design capacity Clause reference
Capacity reduction factor
(φ)
(j) Blind riveted connections: 5.5
Riveted connections in shear— 5.5.2
tension in the connected part 5.5.2.2 0.65
tilting and hole bearing 5.5.2.3 0.50
tearout 5.5.2.4 0.60 or 0.70
(k) Rupture:
Shear rupture 5.6.1 0.75
Block shear rupture (bolted connections) 5.6.3 0.65