If the structural section you require is not contained in the Sections Library, and is not one of the standard shapes supported by Multiframe, you can define the section by specifying all the key cross section properties. Although you may find it easier to use the Section Maker application to create and install your section, this section describes how you can add a section by simply typing in the key sectional properties.
§ Choose Add Section from the Sections submenu under the Edit menu
A dialog box will appear with a list of group names, a table of section properties, a field for the section's name and a list of icons to indicate the sections shape.
§ Type in a name for the section
§ Choose the name of the group you wish to store the member in from the Group pop-up menu
§ Fill in the fields in the table with appropriate values using the down arrow key to move from field to field
§ Choose the shape of the custom section from the shape pop-up menu
If your section does not have one of the shapes shown in the list, leave the Unknown section options selected.
§ Click on the OK button
Note that it is not necessary to fill in all the fields if you do not wish to use the variables later in the CalcSheet. However, the following fields must be filled in:
|
Mass/Weight |
Mass per unit length (if using Self Weight) |
|
A |
Cross sectional area |
|
Ix |
moment of inertia about the major(x-x) axis |
|
Iy |
moment of inertia about the minor (y-y) axis |
|
J |
Torsion constant |
|
E |
Young's Modulus |
|
G |
Shear Modulus |
If you which to view stresses on your members, you should also fill in the following fields
|
Sxt (Zxt) |
Elastic section modulus about x at top side of section |
|
Sxb (Zxb) |
Elastic section modulus about x at bottom side of section |
|
Syl (Zyl) |
Elastic section modulus about y at left side of section |
|
Syr (Zyr) |
Elastic section modulus about y at right side of section |
If you wish to view rendered shapes of your section, you should also fill in the following fields
|
D |
Depth of section |
|
B |
Breadth (width) of section |
|
tf |
Flange thickness |
|
tw |
Web thickness |
If you wish to carry out analysis taking into account deflection due to shear effects, you should also fill in the following fields
|
Asx |
Shear area in x direction |
|
Asy |
Shear area in y direction |
Be careful to ensure that the units of the values you enter match those of the fields shown in the table on screen.
Only the groups in the library that are not locked, will be shown in the list of groups. If you wish to store the section in the library and have it available for use in other structures, store the section in one of the groups other than the group named Frame. Sections stored in the Frame group will be stored with the structure and will not appear in the list unless you are using this structure. You will probably find it convenient to store most of your sections in the Frame group to avoid cluttering up your library with sections that are only used in one or two structures.
Note
Each time Multiframe starts up, it will look for the default section library c:\program files\multiframe\sectionslibrary.slb file. Any changes to the sections library will automatically be saved to this file.