D14.C.6.7 Member Strength and Stability
Class 1 and Class 2 I-Shaped Sections
Members required to resist both bending moments and an axial compressive force shall be proportioned so that:
where= | ||
= | ||
= |
The capacity of the member shall be examined for:
-
cross-sectional strength (members in braced frames only), with β = 0.6, in which case:
- Cr is as define din Cl. 13.3 with the value of λ = 0.
- Mr is as defined in Cl. 13.5 (for the appropriate class of section), and
- U1x and U1y are as defined in 13.8.4 but not less than 1.0, and
-
overall member strength, in which case:
- Cr is as define din Cl. 13.3 with the value of K = 1, except that for strong-axis bending,
- Cr = Crx (see aslo 10.3.2),
- Mr is as defined in Cl. 13.5 (for the appropriate class of section), and
- U1x and U1y are as defined in 13.8.4 for members in braced frames, and
- U1x and U1y are taken as 1.0 for members in unbraced frames, and
-
lateral torsional bucking strength, when applicable, in which case:
- Cr is as define din Cl. 13.3, and is based on weak-axis or torsional-flexural buckling (see also 10.3.3),
- Mrx is as defined in 13.6 (for the appropriate class of section),
- Mry is as defined in 13.5 (for the appropriate class of section),
- U1x and U1y are as defined in 13.8.4 for members in braced frames, and
- U1x is as defined in 13.8.4 but not less than 1.0, for members in braced frames, and
- U1y is as defined in 13.8.4 for members in braced frames
There parameters SSY and SSZ are used to indicate the sidesway in the local Y and Z axes, respectively.
In addition, the member shall meet the following criteria:
where= |
All Other Sections
Members required to resist both bending moments and an axial compressive force shall be proportioned so that:
where all terms are as defined in 13.8.2
The capacity of the member shall be examined for the following cases in a parallel manner to that in 13.8.2:
- cross-sectional strength (members in braced frames and tapered members only),
- overall member strength, and
- lateral-torsional buckling strength.
Section Values of U1
In lieu of a more detailed analysis, the value of U1 for the axis under consideration, accounting for the second-order effects due to the deformation of a member between its ends, shall be taken as:
where= | ||
= |