Footing layout plotter for AutoCAD
In many of the structural design offices dealing with buildings, it is common practice to model and analyse the structure in an FE package like STAAD.Pro or ETABS and then extract the support reactions to design the foundation. In case of foundations, this is mostly done using an inhouse developed spread sheet, such as Excel, that determines the footing size required for each column – (if not using a 3rd party foundation design software like STAAD.foundation or SAFE). The footing sizes for each column, as decided from the Excel sheet are then laid out in plan and checked for footing overlaps and inter footing gaps in order to decide which all footings are to be merged.
This layout is usually done using a package like AutoCAD, which is time consuming. If an application could have been developed that could read the Excel sheets and draw an AutoCAD file, showing the columns, the footing layout for each column, it would be useful in terms of checking beforehand as to which all footing doesn’t ‘dodge’ into the next and which all columns are to be provided with combined footings.
This app was developed to provide the designer a quick layout of the shallow foundation for some preliminary decisions as to which all columns are to be provided with combined footings, for example.
As said, since this app is presented only as a utility for the preliminary check to find footing overlaps, the sizes of the columns are not considered (and are drawn with a uniform 400X400 mm size), nor are the offsets of columns, even if they are suitably offsetted in the ETABS file (drawn with centre of the pile cap located at the location of the support point node).
The program is developed with ETABS in mind, however for other packages too, like for STAAD.Pro, it can be utilized, as shall be explained.
The app is very similar to the Pile Layout Plotter uploaded earlier (https://rahulleslie.blogspot.com/p/layout-plotter-in-many-of-structural.html).
How to use it:
The required footing size for each column
base (identified by the support node number) if calculated by the designer’s
own program or spread sheet. This data, along with the list of nodal coordinats
is pasted in the foot-Plot-050621.xlsm Excel file provided. The Excel
sheet then generates a set of data files. The footing plotter application footPlot-050621.exe
provided then reads the data files and outputs a script file, which can then be
read into AutoCAD to get the footing layout.
The foot-Plot-050621.xlsm Excel file provided has two sheets:
1) In the Output sheet, as
seen below, is where the footing sizes are entered against each support node
number (which is supposedly prepared in another program or spread sheet and
then pasted here). During the pasting of data, if from another Excel
file, it might have the Excel sheet cells here lose their colour seen in
picture below, but that is okay, and no way affects its working.
Only columns B, C, D and E (marked A, B and C in red) are actually read by the program, and that too, only from 4th row onwards. The orientation of the footings, in degrees, are provided in Column D (marked C in red), which shall be explained in the subsequent sections. The orientation angle of the footing can be 0°, 90° or any other angle, as required.
Corresponding the node numbers in column B, the X and Y coordinates are looked up from the table of nodal coordinates in the JtCoord sheet (the contents of which we’ll soon come to), and filled up automatically in columns F and G (marked D in red).
Enter in cell L6 (marked E in red), the name of the script file to be generated by the app. It may be same as that of the ETABS model file. The name of the file generated will be the name entered, but with the extension “.SCR”
2) In the JtCoord sheet, as seen below, is where the coordinates of the nodes are provided. The format of the sheet much matches the format of the joint coordinates output of ETABS (but omitting the unique ID column – so before pasting them from the ETABS output, delete the unique ID column).
Here, only columns B, C and D (marked A and B in red) are actually read by the program, and that too, only from 4th row onwards. It is not required that all the nodes in the ETABS file need to be listed here, but only the support nodes (which are usually the Base level nodes for most buildings).
Please note that with the values to be listed in the column B (marked A in red), with some of the ETABS models, the node numbers may be named with a hyphen, like for example, 10-2, 11-7, etc. Since this would mess up with the app, these – probably the hyphen and the number that follows – has to be removed before pasting it on to the excel sheet – both Data as well as JtCoord sheets. All coordinate values are to be provided in metres.
In case the app is to be used with STAAD.Pro, the coordinates have to be flipped: In place of X-coordinate (for column C), provide the X-coordinate of STAAD; in place of Y-coordinate (for column D), provide the negated Z-coordinate of STAAD; and in place of Z-coordinate (for column E), provide Y-coordinate of STAAD. For example, if the coordinate of a support node in STAAD is (4.5, 3.9, 2), for this sheet, convert it to (4.5, -2, 3.9). In a nutshell, the coordinate system followed here is same as that of ETABS, which is as shown below. So whichever analysis package – be it Midas/Gen, RISA-3D, or whatever – is being used, rearrange the coordinates of the support nodes as necessary. And all coordinate values are to be provided in metres.
Once these data are entered into the sheets Output sheet and the JtCoord sheet, the data files to generate the AutoCAD script file can be generated on pressing the “Write” button in the Output sheet. In order to generate the script file, the program footPlot-050621.exe needs to be run. This script file can then be read into a new AutoCAD via its ‘Tools à Run Script…’. The procedure for generating the script file is depicted below.
Please note that the AutoCAD’s ‘OSNAP’ (Object Snap) mode must be disabled before runnung the script. Also please note that, on running the script, do a ‘zoom all’ in order to see the created pile layout drawing, which would otherwise usually appear in with a very miniscule size.
The following is an example of such
a drawing created:
In the AutoCAD drawing, one can see the columns shown representatively by a square with a diagonal cross, and with the number of the support node written to the top right of it. The footings are represented by rectangles, and with the size of the footing written to the top left of it. A rectangular footing of 1.8X2.2 is being provided for column at node 3, and square footings of different sizes are being provided for other columns. Note that in node 9, the footing is oriented at 45° only for demonstration. Similarly, any angle can be assigned.
It can be visually noted that the footings at nodes 12 and 11; 17 and 6; and 16 and 5 are overlapping. Also, the width of the gap between footings at nodes 3 and 4 can be measured in AutoCAD.
In order to use the app, the following files are to be download: Excel sheet for data input (foot-Plot-050621.xlsm) and the Pile plotter program (footPlot-050621.exe) both zipped into footPlot-050621.zip*. The output files of a typical building have also been included, zipped into FootSample.zip**.
Rahul
Leslie
rahul.leslie@gmail.com
June
2021
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