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The Column in Simple Construction brief is aimed at the design of pinned columns, where the dominant force in the columns is the axial load, and the moments in the column are as a result of the reaction of the beams taken to act 100mm from the web or outer face of the column flange.
Note: The Columns in Simple Construction brief does not consider the major and minor moments in the columns from the Masterframe analysis. Therefore, if the columns and beams have been modelled as continuous construction, the use of the Columns in Simple Construction brief will not be appropriate since it will effectively ignore the moments from the analysis. The software will give a note underneath the diagram stating that an Axial with Moments check should be considered rather than a Column in Simple Construction brief.
The layout of the Columns in Simple Construction screen is shown below.
The Section AutoDesign tab contains options to amend the steel member section size, to make the member a compound member (which also provides options to provide plates to the member) and to add web openings. Within the Section AutoDesign tab, there are also options to carry out an Autodesign on the selected member or on all members visible on screen.
For more detailed information on the AutoDesign area, see the Designing a Member section.
Kx-factor - effective length coefficient for the major axis compression
Ky-factor - effective length coefficient for the minor axis compression
Lambda limit - Slenderness limit. This was originally a BS 5950 check, but was dropped in later versions of the code and does not appear in the Eurocodes. However, it was opted to maintain this input in the steel design.
FL/UL - the ratio between the factored loads (FL) and unfactored loads (UL). This is used in the British Standard design as part of the check to ensure that Mc = Py*S <= 1.2 py. This check is not used in the EC design so the FL/UL factor is not required.
The selfweight and loads eccentricity inputs allow for the shifting of the loads from above the column and the position of the reactions from the incoming beams to be modified in order to modify the nominal moments on the column section.
Tp - toe plate thickness. Modifies the position of the beam reaction about the column minor axis to account for a plate between the toes of the column flanges.
ex1 upper - modifies the position of the beam reaction at the top of the column height about the major axis. When zero the software defaults to half the column section plus 100mm
ex2 upper - modifies the position of the beam reaction at the top of the column height about the major axis. When zero the software defaults to half the column section plus 100mm
ey1 upper - modifies the position of the beam reaction at the top of the column height about the minor axis. When zero the software defaults to half the column web (for an I-section) plus 100mm. For closed sections, the software will use half the section width plus 100mm
ey2 upper - modifies the position of the beam reaction at the top of the column height about the minor axis. When zero the software defaults to half the column web (for an I-section) plus 100mm. For closed sections, the software will use half the section width plus 100mm
ex1 lower - modifies the position of the beam reaction at the bottom of the column height about the major axis. When zero the software defaults to half the column section plus 100mm
ex2 lower - modifies the position of the beam reaction at the bottom of the column height about the major axis. When zero the software defaults to half the column section plus 100mm
ey1 lower - modifies the position of the beam reaction at the bottom of the column height about the minor axis. When zero the software defaults to half the column web (for an I-section) plus 100mm. For closed sections, the software will use half the section width plus 100mm
ey2 lower - modifies the position of the beam reaction at the bottom of the column height about the minor axis. When zero the software defaults to half the column web (for an I-section) plus 100mm. For closed sections, the software will use half the section width plus 100mm
The off-centre eccentricity inputs allow for the shifting of the beam eccentricity out of the line of the column section axes. This allows for the modelling of beams connecting off the centre line of the column. The diagrams at the top of the calculation pane update automatically to assist in inputting the desired values.
cy1 Upper - off centre eccentricity for beam reaction Fx1, at the top of the column. A value of zero means the beam is aligned to the centreline of the column section.
cy2 Upper - off centre eccentricity for beam reaction Fx2, at the top of the column. A value of zero means the beam is aligned to the centreline of the column section.
cx1 Upper - off centre eccentricity for beam reaction Fy1, at the top of the column. A value of zero means the beam is aligned to the centreline of the column section.
cx2 Upper - off centre eccentricity for beam reaction Fy2, at the top of the column. A value of zero means the beam is aligned to the centreline of the column section.
cy1 Lower - off centre eccentricity for beam reaction Fx1, at the bottom of the column. A value of zero means the beam is aligned to the centreline of the column section.
cy2 Lower - off centre eccentricity for beam reaction Fx2, at the bottom of the column. A value of zero means the beam is aligned to the centreline of the column section.
cx1 Lower - off centre eccentricity for beam reaction Fy1, at the bottom of the column. A value of zero means the beam is aligned to the centreline of the column section.
cx2 Lower - off centre eccentricity for beam reaction Fy2, at the bottom of the column. A value of zero means the beam is aligned to the centreline of the column section.