Form: Divide Selected Areas
SAP2000 allows area objects to be divided into smaller objects in the object-based model, and meshed into elements in the analysis model. Dividing the object is accomplished using the Edit menu > Edit Areas> Divide Areas command. Meshing an area object is accomplished using the Assign menu > Area > Automatic Area Mesh command.
This topic addresses dividing area objects for use in the object-based model.
Select the area objects to be divided.
Click the Edit menu > Edit Areas> Divide Areas command to access the Divide Selected Areas form.
Choose the option to specify how the object is to be divided. The Area Object Dividing or Meshing topic explains how the program works and uses illustrations to show the effects of the various options.
Note: Dividing an area object is performed on one object at a time.
Divide Area Into This Number of Objects (Quads and Triangles Only) options and Along Edge from Point 1 to 2 and Along Edge from Point 1 to 3 edit boxes. Use this option to specify that the selected object be divided into the number of objects specified using the edit box for each edge. The program adds points to the adjacent edges, at equally spaced intervals, and then automatically adds the same number of points along the opposite edges so that dividing lines can be drawn between the opposing points on the edges to create the specified number of objects.
Divide Area Into Objects of This Maximum Size (Quads and Triangles Only) and Along Edge from Point 1 to 2 and Along Edge from Point 1 to 3 edit boxes. Use this option to specify that the selected object be divided into n number of objects of the maximum length specified in the edit box for each of the adjacent edges. The program adds points along each edge at equally spaced intervals such that the length of any of the resulting divided objects does not exceed the length specified in the edit boxes. The length specified determines the number of objects to be created and thus the number of points added to each edge.
Divide Area Based On Points On Area Edges (Quads and Triangles Only), Points Determined From options. Use this option to specify that the selected object be divided based on specified lines and points. The specified lines and points must lie in the plane of the area object. The program will not extend the selected line to make it intersect an edge; the selected line must already intersect an edge of the selected object. These options may be used in combination.
Intersection of Visible Straight Grid Lines With Area Edges check box. Check this check box to specify that points be added, and thus the object divided, at the intersection of the visible straight grid lines with the edges of the selected area object. Use the View menu > Show Grid command to display grid lines.
Intersection of Selected Straight Line Objects With Area Edges check box. Check this check box to specify that points be added, and thus the object divided, at the intersection of the edge of the selected area object with a selected straight line object that has been drawn or defined to cross the selected object's edge.
Selected Point Objects On Area Edges check box. Check this check box to specify that the object be divided based on the point drawn or defined on the object's edge. Note that the point object and the area object must both be selected and lie in the same plane.
Note: If a point is being drawn on the edge of the object before using point-related options, the Draw menu > Snap To > Lines and Edges command may be helpful in placing the point accurately on the object's edge.
Divide Area Using Cookie Cut Based On Selected Straight Line Objects option. Use this option to specify that the selected object be divided based on a selected straight line object. For this option, the selected line object does not need to intersect with the edge of the selected area object. If the selected line object does not intersect with the selected object's edge or fully transect the selected area object, the program places a point on the object's edge along the projected path of the selected line object. Note that the selected line object and selected area object must lie in the same plane.
Divide Area Using Cookie Cut Based On Selected Points Objects option and Rotation of Cut Lines From Area Local Axes (Deg) edit box. Use this option to specify that the selected object be divided based on a selected point object. For this option, the selected point object does not need to lie on the edge of the selected area object. The program "draws dividing lines" that pass through the selected point to proportionately placed points on the area object's opposing edge or edges. Use the edit box to specify the rotation in degrees of the "dividing line" from the original local 1 and 2 axes of the selected area object. Positive rotations appear counterclockwise when the local 3 axis is pointing toward you.
Divide Area Using General Divide Tool Based On Selected Points and Lines option and Maximum Size of Divided Object edit box. Use this option to specify that the selected object be divided based on selected point or line objects and the maximum length for the resulting divided object, as entered in the edit box. For this option, the selected point or line object must lie within the same plane as the selected area object and lie within the selected object (i.e., the point can not lie on the edge of the object and the line can not cross the edge of the area object or have its end points on the edge of the area object). The program divides the selected object into n number of objects based on the maximum size specified in the edit box and the locations of the selected points and lines within the area object. See the Area Object Dividing or Meshing topic for more clarification.
Choose an option to specify the Local Axes for Added Points:
Make same on Edge if adjacent corners have same local axes definition check box. Use this check box to specify that the local axes definitions for new points added along the edges of an area object are the same as an adjacent area object corner point if the local axes definition for the adjacent corners are identical.
Make same on Face if all corners have same local axes definition check box. Use this check box to specify that the local axes definition for the new points on the face of the area object are set the same as a corner point of the area object if the local axes definitions for all of the corner points of the area object are identical.
Choose an option to specify Restraints and Constraints For Added Points:
Add on Edge when restraints/constraints exist at adjacent corner points (Applies if added edge point and adjacent corner points have same local axes definition) check box. Use this check box to specify that a restraint degree of freedom (or constraint) is added to new points on the edges of the area object if both adjacent corners have that degree of freedom restrained (constrained) and the local axes definitions for the adjacent corners and the new point are identical.
Add on Faces when restraints/constraints exist at all corner points (Applies if added face point and all corner points have same local axes definition) check box. Use this check box to specify that a restraint degree of freedom (or constraint) is added to new points on the face of the area object if all area object corners have that degree of freedom restrained (constrained) and the local axes definitions of all corners and the new points are identical.
Example: Use of this command is demonstrated in Problem M, Problem S, Problem U and Problem Z.
See Also