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D7.4.2.2<br />
Member Capacity<br />
This section applies only to members analysed using an elastic method of analysis. For bending about<br />
the minor principal y-axis only the in-plane requirements need to be satisfied.<br />
In-plane capacity<br />
⎛<br />
*<br />
N ⎞<br />
φM iy = φM sy ⎜1−<br />
⎟<br />
(Clause 8.4.2.2 of AS 4100)<br />
⎝ φ ⎠<br />
N cy<br />
Note: N * ≤ φN cy<br />
where<br />
φN cy is determined in accordance with Clause 6.3 for buckling about the same principal axis,<br />
with an effective length factor (k ey ) taken as 1.0 for braced and sway members, unless a<br />
lower value of (k ey ) is calculated for braced members (refer 4.6.3 of AS 4100)<br />
Alternatively, For RHS & SHS to AS 1163, which are compact as defined in Clause 5.2.3 of AS 4100, and<br />
where the form factor (k f ) determined in accordance with Clause 6.2.2 is unity, φM iy may be calculated as<br />
per Clause 8.4.2.2 of AS 4100.<br />
Where<br />
D7.4.3<br />
φM<br />
iy<br />
⎧<br />
⎪⎡<br />
⎛1+<br />
β<br />
= φMsy<br />
⎨⎢1−<br />
⎝<br />
⎜<br />
⎣⎢<br />
2<br />
⎩⎪<br />
my<br />
⎞<br />
⎠<br />
⎟<br />
⎤⎛<br />
N ⎞ β<br />
⎥ −<br />
φNcy<br />
⎦⎥<br />
⎝<br />
⎜<br />
⎠<br />
⎟ + ⎛ +<br />
1 1.<br />
18 1 ⎝<br />
⎜<br />
2<br />
3 *<br />
β m = the ratio of the smaller to the larger end bearing moment, taken as positive when the member is<br />
bent in reverse curvature for members without transverse load, or<br />
= the value determined in accordance with Clause 4.4.2.2 of AS 4100 for members with transverse<br />
load.<br />
M ry = the nominal section moment capacity about the appropriate principal axis determined in accordance<br />
with Clause 8.3 of AS 4100.<br />
Biaxial Bending and Axial Compression<br />
my<br />
3<br />
⎞<br />
⎠<br />
⎟<br />
⎛ N<br />
−<br />
⎝<br />
⎜1<br />
φN<br />
*<br />
cy<br />
⎞ ⎫<br />
⎪<br />
⎠<br />
⎟ ⎬ ≤ φM<br />
⎭⎪<br />
ry<br />
For a member subject to biaxial bending and axial compression, both the conditions defined in Sections<br />
D7.4.3.1 and D7.4.3.2 must be satisfied.<br />
D7.4.3.1 Section Capacity<br />
N * M * M *<br />
x y<br />
+ + ≤1 (Clause 8.3.4 of AS 4100)<br />
φN<br />
φM<br />
φM<br />
s<br />
sx<br />
sy<br />
Alternatively, for RHS and SHS to AS 1163, which are compact about both the x- and y- axes:<br />
where<br />
⎛ Mx<br />
⎜<br />
⎝ φM<br />
γ<br />
* *<br />
rx<br />
⎞ My<br />
⎟ + ⎛ ⎞<br />
⎠ ⎝ ⎜ φM<br />
⎟ ≤ 1<br />
⎠<br />
ry<br />
γ<br />
(Clause 8.3.4 of AS 4100)<br />
where<br />
γ = + ⎛ *<br />
1.4 ⎝ ⎜ N ⎞<br />
⎟<br />
φ ⎠<br />
≤ 20 .<br />
N s<br />
φM rx and φM ry are calculated in accordance with Clauses 8.3.2 and 8.3.3 of AS 4100<br />
DuraGal DESIGN CAPACITY TABLES<br />
DCTDHS/06<br />
D7-10 for STRUCTURAL STEEL HOLLOW SECTIONS MARCH 2002
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