Lateral rotation factor

The lateral rotation factor kr is based solely on the flange restraint conditions. Its value for some codes is given in the following table. The restraint codes given represent the flange restraints at each end of the segment under consideration. For example, PP represents partial restraint at both ends, while PF represents partial restraint at one end and full restraint at the other end.

End Restraints	AS3990/ AS1250	AS4100	SABS0162	NZS3404
RR	0.70	0.70	0.70	0.70
SR	0.77	0.70	0.77	0.70
FR	0.85	0.85	0.85	0.85
PR	.935	0.85	.935	0.85
LR	1.00	1.00	1.00	1.00
UR	.935	1.00	.935	1.00
SS	0.84	0.70	0.84	0.70
FS	.935	0.85	.935	0.85
PS	1.02	0.85	1.02	0.85
LS	1.00	1.00	1.00	1.00
US	1.02	1.00	1.02	1.00
FF	1.00	1.00	1.00	1.00
PF	1.10	1.00	1.10	1.00
LF	1.00	1.00	1.00	1.00
UF	1.10	1.00	1.10	1.00
PP	1.20	1.00	1.20	1.00
LP	1.00	1.00	1.00	1.00
UP	1.20	1.00	1.20	1.00
LL	1.00	1.00	1.00	1.00
UU	1.20	1.00	1.20	1.00

The values of kr in the table are taken from AS1250 clause 5.9, AS4100 table 5.6.3(3), SABS0162 clause 7.2.3, BS5950 clause 4.3.5, NZS3404 table 5.6.3(3) and AS3990 clause 5.9.

There are some specific assumptions affecting kr which you should be aware of, as follows:

AS1250, SABS0162, BS5950, HK CP2011 and AS3990 do not give specific rules for calculating kr for all combinations of flange restraints at the ends of the segment. In such cases interpolation has been used to calculate some of the values of kr given in the table.
The extra restraint condition in AS1250, SABS0162, BS5950, HK CP2011 and AS3990 which provides partial restraint against lateral rotation (about the cross section minor axis) of the critical flange is not supported in SPACE GASS.
Because it is difficult for SPACE GASS to determine whether a member is a true cantilever or not, AS1250 clause 5.9.4, SABS0162 clause 7.2.3(b), BS5950 clause 4.3.5.4/4.3.5.5, HK CP2011 clause 8..4.3 and AS3990 clause 5.9.4 have not been considered. This may cause the bending effective length for cantilevers to be underestimated and you should therefore check the bending effective length for cantilevers calculated by the AS1250, SABS0162, BS5950, HK CP2011 and AS3990 modules.

$image\ebx_-1773499217.gif$ Before accepting the bending effective length calculated by SPACE GASS, it is recommended that you verify for yourself that the values of kr given in the previous table are a suitable interpretation of the code that you are using.