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Software Knowledge Base

 


Note ID: 000042 – Applications: SLABS4

Title: SLABS4 manual - Modelling: CAD import

Description: General overview on generating a models using CAD files, including a step by step tutorial

See Also:

Date Created: 02/05/2008

Date Modified: 02/05/2008

 


SLABS4 can read data contained in a CAD file and then convert this information into structural elements that will make up a SLABS model. Building models using CAD files is the most efficient and accurate approach, particularly when the models are large or complex.

In order to use CAD files some preparation is required prior to importing information from the file. The general requirements are listed below;

 

- The format of the CAD files can be either DWG (2006 file type or earlier) or DXF (R12 format).

- The scaling of the CAD file is automatically performed by the software at time of import. All CAD files that are imported are assumed to be drawn in ‘mm’, therefore the software will rescale the drawing by 1:1000 to result in the final scale of the imported CAD file in ‘m’.

- Columns must be either 4 sided (square or rectangles) or circular shapes. The line type in CAD does not have to be a ‘Closed polyline’ as the software can assemble single line segments into column elements.

- Walls need to be prepared as line segments (either polyline or single line elements) in CAD prior to Importing the CAD file into SLABS4.

- Slab panels need to be prepared as 3 or 4 sided closed polylines.

- Beam elements need to be prepared as line segments (either polyline or single line elements) in CAD prior to Importing the CAD file into SLABS4.

- Line loads need to be prepared as line segments (either polyline or single line elements) in CAD prior to Importing the CAD file into SLABS4.

- SLABS4 does not require a specific name to be assigned to the layers contained in the CAD file, as in previous versions of SLABS.

 

 

The functionality and automation of the importing tools have been refined in SLABS4 with the focus of making the use of CAD files more user friendly and to improve the importing efficiency

The major improvements to the CAD import in SLABS4 are summarised below;

 

- When a CAD file is imported it is automatically repositioned, ensuring the entire drawing is located in positive X and Y co-ordinates. In previous versions of SLABS the user had to ensure an appropriate position of the CAD file was set prior to importing the file.

- The CAD file is always available as a back ground image with the option of turning the visibility On and Off by selecting the ‘CAD Visibility’ icon located on the Main Task bar (as shown below).

 

Sample Screen shot – CAD visibility On/Off

 

 

- Importing from a CAD file can be done at any time by selecting the ‘Import from CAD Drawing’ icon from the Main Task Bar (as shown below).

 

Sample Screen shot – Import from CAD drawing

 

 

- While the software is in the ‘Import’ mode (ie when the ‘Import from CAD drawing’ icon has been selected) selecting a single line (or polyline) that is contained in the CAD file will display the layer name in the information Window. This will aid in identifying the layer that may contain certain elements such as columns or walls etc, as shown in the following screen shot;

 

Sample Screen shot – the name of the CAD layer displayed in the Information Window

 

 

 

- The tools that rotate the CAD drawing have been simplified by offering the user options to rotate the drawing based on a line that is contained within the CAD file. The user can select a particular line and then close to rotate the entire drawing (either clockwise or anti-clockwise) so the final position of the line that was selected is parallel to the X or Y axis. Once a line has been selected, the rotation tools are available from the Main Menu under [ CAD > Shift CAD Drawing > Rotate CAD ].

 

- All the text and hatching contained in the CAD file can be excluded at the time of import by selecting the check boxes available in the [ Settings > CAD Import / Export settings ] window.

 

 

The complete importing process (including sample screen shots and key strokes) is summarised in the following tutorial;

 

A CAD file is loaded into SLABS4 by selecting [ CAD > Load CAD Drawing ] from the Main Menu, and then selecting the appropriate file.

Once the CAD file has been successfully imported, the icons and drop down list on the Main Task bar will become available, as shown in the screen shot below;

 

Sample Screen shot – CAD tools

 

 

In the sample CAD file the columns have been created in a layer called ‘Columns Geometry’, and by selecting this layer from the drop down the columns will be the only elements displayed on screen, as shown below;

 

Sample Screen shot – Appropriate layer selected to display the columns only

 

 

To import the columns from the CAD drawing into SLABS, the ‘Import from CAD’ icon on the Main Task bar needs to be selected. Once this button is pressed the software automatically switches into select mode with the ‘net select’ option set in the Dynamic Task Bar, as shown in the sample screen shot below;

 

Sample Screen shot – Automatic ‘net select’ mode

 

Because all there are only column elements contained in the selected layer, a box that encloses all the columns can be created in order to import all the columns in one operation.

 

Sample Screen shot – Column elements in the CAD layer are selected

 

 

To convert the selected elements into structural columns, the column icon in the tools box is pressed. The software will display a confirmation window that contains the total number of elements that are to be imported, as shown below;

 

Sample Screen shot – Confirmation window displaying the total number of columns that are to be imported

 

 

Once the elements are imported the software will retain them as selected and this will allow the user to set all parameters in the Properties window. This approach will allow element such as walls (or slabs) with different thickness to be prepared in different layers in the CAD file and then imported independently.

 

The line segments that represent the walls are contained in the layer ‘Wall Import’ and when this layer is selected from the drop down list the line elements are displayed on screen along with the columns that were imported in the previous step, as shown below;

 

Sample Screen shot – Wall segments contained in the CAD drawing and the existing columns are displayed

 

 

The walls are imported following the same process as the columns outlined above, however once the ‘Import from CAD Drawing’ icon is selected and the line segments are selected (note that the software will not select the existing columns elements when the ‘import from CAD icon is pressed) the wall icon in the tool box is selected to instruct SLABS that the line segments are to be converted into wall elements. A similar confirmation box is displayed as for the columns, as shown in the following screen shot;

 

Sample Screen shot – Confirmation window displaying the total number of walls that are to be imported

 

 

As for the column elements, the imported wall is automatically kept selected by the software to allow the user to assign the appropriate parameters in the Property window.

 

The final elements that are to be imported are the slab panels. The name of the CAD layer that contains all the slab elements is ‘Slab panels’, and when this layer is selected from the drop down list the closed polylines that represent the slab panels are displayed as shown in the sample screen shot below;

 

Sample Screen shot – Closed polylines contained in the CAD drawing that represent the slab panels and the existing columns and wall

 

 

The slab panels are imported following the same process as the columns and walls outlined above, however the slab icon in the tool box is selected to instruct SLABS that the closed polylines are to be converted into slab panel elements. A similar confirmation box is displayed as for the columns and walls, as shown in the following screen shot;

 

Sample Screen shot – Confirmation window displaying the total number of slab panels that are to be imported

 

 

As for the column and wall elements, the imported slab panels are automatically kept selected by the software to allow the user to assign the appropriate parameters in the Property window.

 

A similar process is repeated in order to import beam elements and line loads into a model. The only difference being that the appropriate icon in the tool box needs to be selected in order to indicate the type of element that the CAD information is to be converted into.

 

The importing process is now complete and the user can set all the other relevant parameters such as load cases, load combination, material properties and apply the loading. Once these settings have made, the model can be meshed and analysed.