Moment Magnifier (B1|Delta_b,B2|Delta_s)

 

 

 

Enter the Moment Magnification Factors required for calculating the bending strength considering the moment magnification effect in slender RC columns in which compressive axial forces and bending moments occur simultaneously.

For a frame braced against sidesway, if the Moment Magnifier is not entered, the program automatically calculates the Moment Magnifier. The Moment Magnifier is reflected in the design member forces in slender columns only. For a sway frame, the program will use the default value of 1.0.  

If the Moment Magnifier is entered manually, the Moment Magnifier will be applied to design member forces in both slender and non-slender columns.

 

 

 

From the Main Menu select Design > Common Parameter > Moment Magnifier (B1|Delta_b,B2|Delta_s).

 

 

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 Magnifier

Enter the moment magnification factors. (refer to Note 1)

B1y|Delta_by
Moment magnification factor for members subjected to vertical loads in a frame braced against sidesway for strong axis bending

If the value is not entered, the program will automatically calculate the Moment Magnifier as per the code. Moment Magnifier will be used only when Braced │Non-sway is selected in Definition of Frame.

B1z|Delta_bz
Moment magnification factor for members subjected to vertical loads in a frame braced against sidesway for weak axis bending

If the value is not entered, the program will automatically calculate the Moment Magnifier as per the code. Moment Magnifier will be used only when Braced │Non-sway is selected in Definition of Frame.

B2y|Delta_sy
Moment magnification factor for members subjected to horizontal loads in a frame unbraced against sidesway for strong axis bending [Default = 1.0]

If the value is not entered, Moment Magnifier will be 1.0. Moment Magnifier will be used only when Unbraced │Sway is selected in Definition of Frame.

B2z|Delta_sz
Moment magnification factor for members subjected to horizontal loads in a frame unbraced against sidesway for weak axis bending [Default = 1.0]

If the value is not entered, Moment Magnifier will be 1.0. Moment Magnifier will be used only when Unbraced │Sway is selected in Definition of Frame.

 : Apply the entered values to the selected members.

 : Close the entry Dialog Bar.

Note 1
When values are not entered in B1y|Delta_by and B1z|Delta_bz, the values are auto-calculated in the program.

Note 2
When values are not entered in B2y|Delta_sy and B2z|Delta_sz, B2y|Delta_sy = 1.0 and B2z|Delta_sz = 1.0 are applied. In general, the member moment magnification factors for horizontal loads can be accurately obtained by P-Delta analysis. Thus, it may be desirable to perform P-Delta analysis to obtain more accurate analysis results.

Note 3
If the values for the moment magnification factors (B1|Delta_b, B2|Delta_s) are repeatedly entered for the same member, the values will be updated to the last values entered.

Note 4
The entered moment magnification factors can be reviewed in the data table arranged in the order of element numbers. The user 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 > Moment Magnifier (B1|Delta_b, B2|Delta_s).

From the Tables tab of the Tree Menu select Design Tables > General Design > Moment Magnifier (B1|Delta_b, B2|Delta_s).