Fuction
- Enter the Equivalent Moment correction Factor, which is an adjustment factor for the Moment magnification factor, required during the calculation of the bending strength or the combined stress ratio of beam-column members in which axial forces and bending moments occur simultaneously. It is a factor relating the actual moment diagram to an equivalent uniform moment diagram.
Call
From main menu, select [Design] tab > [Design Input Data] > [Design Parameters] > [Moment Factor(Cm)]
Input
First, select the members in the model and enter the following:
Option
Select Add/Replace or Delete.
Add/Replace : Add the newly entered values or update the previously entered values.
Delete : Delete the entered values. Data entry is not required when deleting.
Moment Factor
Enter the equivalent moment correction factors.
Cmy
Equivalent moment correction factor applied to the unbraced length portion of a member bent about its strong axis (refer to (1))
Cmz
Equivalent moment correction factor applied to the unbraced length portion of a member bent about its weak axis (refer to (1))
Calculate by Program
When this item is selected, the equivalent moment correction factors for both strong and weak axes are auto-calculated in the program. (refer to (2)).
: Apply the entered values to the selected members.
: Close the entry Dialog Bar.
(1)
Enter the values between 0.4-1.0 for Cmy (Cmz). For members where the values have not been entered, the following values are applied to the members' strong and weak axes:
Beam or Girder member: Cm = 1.0
Column member: Cm = 0.85
(2)
When the values for Cm are auto-calculated in the program, bending moments at both ends of the unbraced portion of the member, which is subjected to an axial compression force, are used. The factors are calculated for each member's strong and weak axes.
Cm = 0.6 - 0.4 (M1/M2)
(3)
If the equivalent moment correction factors (Cm) are repeatedly entered for the same member, the values will be updated to the last values entered.
(4)
The entered equivalent moment correction factors can be reviewed in the Data Table arranged in the order of element numbers. You may Modify/Add and Delete items in the data table.
Access the data table following the procedure below.
From the Main Menu select Design > General Design Parameter > General Design Tables > Equivalent Moment correction Factor (Cm).
From the Tables tab of the Tree Menu select Design Tables > General Design > Equivalent Moment correction Factor (Cm).