Form: Automatic Slab Mesh Options
Use the Run menu > Automatic Slab Mesh Options command to access the Automatic Slab Mesh Options form and set how the datum plane area objects in the object model are to be meshed into elements in the analysis model. The locations of columns, braces, walls, ramps, slabs, openings, beams, design strips and grid lines influence the generation of the mesh.
Use Rectangular Mesh option. Rectangular meshing is based on an initially rectangular meshing grid that is then modified to account for skewed meshing lines and, if specified, localized meshing at some points.
For the Use Rectangular Meshing Option, it is useful to define "Encompassing Area Objects" and "Mesh Groups." An Encompassing Area Object does not lie fully inside any other area object. A Mesh Group consists of an Encompassing Area Object and all of the area objects that are fully inside the Encompassing Area Object. In the special case where area objects overlap, for meshing purposes, the small area object is internally broken into sub-objects that lie inside and outside of the larger object.
The following controls exist for rectangular meshing.
Use Localized Meshing check box.
When localized meshing is not used, an initial grid is defined that has lines passing in the two mesh directions through all points in the structure. This can lead to closely spaced mesh lines and thus large meshes with many area elements.
When localized meshing is used, an initial grid is not necessarily passed through all points. Instead, it is passed through as many points as possible while keeping mesh lines at least half the specified approximate maximum mesh size apart. Then, if specified, points are merged where possible, as described in the next bullet item. Finally, localization then picks up points that were not included in the original mesh grid.
Merge Points Where Possible check box. This option is enabled only when the Use Localized Meshing check box is checked.
Merge points takes place as soon as the initial grid is defined. Points on the initial grid are moved, if possible, to align with close by points, lines, or edges of area objects. The maximum distance that a point is allowed to move is 10% of the specified approximate maximum mesh size.
Many points are not allowed to move at all. This includes points at point object locations, points that lie on line objects, and points that fall on area object edges.
None option. This option creates a mesh by doing a one-to-one conversion of area objects into elements. This option is valid only for 3- or 4-sided area objects that have straight edges. Area objects with more than 4 edges, or with curved edges, will be ignored when meshing.
Approximate Maximum Mesh Size edit box. The value shown in this edit box specifies the approximate maximum size assumed for the rectangular meshing option.
Use the View menu > Set Display Options command to show or hide mesh lines.