Contents Next Previous

Using the Wizard to Generate a Grid

It is possible to generate a model node-by-node and element-by-element but this would be a lengthy and laborious process.  Therefore, the Geometry|Generate Grid function has been included to assist with the rapid generation of finite element geometries.

The key components of this box are:

The Preview Window

This shows the impact of the number entered in the following text boxes:

No. X Elements 

Defines the number of finite elements along the x-axis.

X-Spacing

Defines the length of each element on the x-axis (usually in metres).

No. Y Elements 

Defines the number of finite elements along the y-axis.

Y-Spacing

Defines the length of each element on the y-axis (usually in metres).

Beams every ? X Elements

Defines how many slab elements to have between each beam element.  It is assumed that beams are placed on all of the leftmost (x=0) and bottommost (y=0) slab elements.  If this is not to be the case, they can be deleted at the next stage.

With X Shear Connectors 

Defines whether the beams on the x-axis are to be connected to the slab by shear connectors.  If this is not ticked, it is assumed that the slab elements and beam elements share nodes thereby simulating "full" composite action between the beam and slab.

With Y Shear Connectors 

As above, but for beams on the y-axis.

The "instant preview" shown on the dialogue box is scaled correctly so that you can visualise the grid of elements fairly accurately.  When allocating element spacings it should be remembered that:

• Slab elements always perform best when their aspect ratio is reasonably "square".  Vulcan's slab elements have given accurate results in validation studies at aspect ratios up to 4:1, but it is generally preferable to use aspect ratios of not more than 2:1, at least until some experience has been gained.

• Denser element grids give more accurate results, but in highly non-linear analysis there can be a high penalty in terms of run -time.  While there is no substitute for the experience that can be gained by doing comparative studies with different element densities, the arrangement shown below represents a normal compromise giving good accuracy in deflection behaviour.