Using the Criteria - General command, the user can set parameters to control the meshing of walls and slabs in the model. The program provides several control parameters to control quality and quantity of mesh generated for walls and slabs.

Max. Distance between Nodes on Mesh Line allows the user define the maximum distance between nodes on wall edges and nodes on semirigid diaphragm edges. Note that the program may generate additional nodes closer than user entered value, but it is never allowed to be larger than that. The Geometry Tolerance is mostly used in geometry calculation as a threshold tolerance. This should not be confused with a merge (close) node tolerance (which is explained below). Examples are as follows: it is used as a tolerance to check a node is on a line or to check a point is inside a polygon, etc...

The user can generate coarse or fine mesh by usually setting Max. Distance between Nodes on Mesh Line. Usually, a coarse mesh gives conservative results since the walls and diaphragms are stiffer. A finer mesh leads to more flexible walls and diaphragms, which leads better results but it may significantly increase analysis time. A good balance should be provided before starting analysis.

Once meshing walls and semirigid diaphragms are done, the program generates a finite element model for analysis, which is basically composed of nodes and elements (columns, beams, braces and shells in walls and semirigid diaphragms). During this process, it is possible that several nodes are very close. To have a good (and valid) analytical model, these nodes are merged to a single node and elements connected to this node are adjusted accordingly. The Merge Node Tolerance is used for this purpose so that if distance between any 2 (or more) nodes are found to be smaller than the Merge Node Tolerance, then they are treated as a single node (i.e., these close nodes are merged together). Note that the node tolerance is not only used for nodes generated after meshing process, but for all nodes in a model (whether there is wall or semirigid diaphragm).

Briefly, Max. Distance between Nodes on Mesh Line, Merge Node Tolerance, and Geometry Tolerance are three main controlling parameters to generate a good mesh for analysis. Usually, Merge Node Tolerance is suggested to be larger than Geometry Tolerance.