The δb factor is a moment amplifier to account for the P-δ effects (small P-delta, second order effects caused by displacement of the member between brace points).
The
δb factor is to be calculated for each member individually, and differs for each combination.
δb is calculated for each axis of the member:
| Eq. (4.4.2.2) |
where
|
Cm
| = | 0.6 – 0.4(M1/M2) for members with no transverse loading between supports in the plane of bending 1.0 for members with transverse loading between supports in the plane of bending
|
| N* | = | total axial load in the member (combined using the appropriate AS/NZS Load Combinations) |
|
Nomb
| = | is the "elastic critical buckling resistance for the member in the plane of bending" | Eq. (C2-5) |
|
|
I
| = | Ix or Iy, of the axis for which δb is being calculated |
| Ke | = | 1.0 |
| L | = | the unbraced length, in the axis for which δb is being calculated |
