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 pile foundation, this is mostly
done using an inhouse developed spread sheet, such as Excel, that determines
the pile group required for each column – (if not using a 3rd party
foundation design software like STAAD.foundation or SAFE). The plie groups for
each column, as decided from the Excel sheet are then laid out in plan and
checked for pile-to-pile distances (between piles of adjacent pile caps) and
pile cap overlaps, in order to decide which all pile caps 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 pile layout for each column, and the pile cap, it would be useful in terms of checking beforehand as to which all pile caps doesn’t ‘dodge’ into the next if rotated by 90°; and which all columns are to be provided with combined pile caps.
This app was developed to provide the designer a quick layout of the pile foundation for some preliminary decisions as to which all columns are to be provided with combined pile caps, for example. It also checks which all piles are closer to each other than the minimum required distance and highlights them by a line connecting them
As said, since this app is presented only as a utility for the preliminary check to find pile overlaps and piles closer than allowable limits, 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 pile cap of the 3P group is drawn as a rectangle, for representative purpose only.
The program is developed with ETABS
in mind, however for other packages too, like for STAAD.Pro, too it can be utilized, as shall be explained.
How to use it:
The required pile group 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
coordinated is pasted in the PileData-V01-01.xlsm Excel file provided.
The Excel sheet then generates a set of data files. The pile plotting
application PilePlot-V01-01.exe provided then reads the data files and
outputs a script file, which can then be read into AutoCAD to get the pile
layout.
The PileData-V01-01.xlsm Excel file provided has two
sheets:
1) In the Output sheet, as
seen below, is where the pile group number (1 for single-pile or 1P, 2 for two-pile
group or 2P, 3 for three-pile-group or 3P and so on) is 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.
If any of the support points are to omitted from being provided a pile-cap, just enter 0 (zero) for the number of piles to be provided – like, for example, those support nodes which you are sure of being part of a pile-cap supporting multiple columns.
Only columns B, C and D (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 pile-cap, in degrees, are provided in Column D (marked C in red), which shall be explained in the subsequent sections. The orientation angle of the pile-cap can be 0°, 90°, -90° or any other angle, as required. The placement of the pile-cap for 0° orientation is shown by representative figures on columns H and I (marked E in red). As of now, the app is programmed only to handle pile caps for pile groups from 1P to 10P pile groups, in the arrangements as shown by the representative figures.
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 E and F (marked D in red).
The diameter of the piles is entered in cell K4 (in m) and the spacing between the piles is entered in cell L5 (in terms of the diameter of piles) – marked F in red. It is also this minimum distance between the piles that is used to check whether any of the piles from different pile caps are close to each other than what’s allowable.
Enter in cell L6 (marked G 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. 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.
Please note that the AutoCAD’s ‘OSNAP’ (Object Snap) mode must be disabled. Also 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 piles are represented by circles, and the extend of the pile caps with edges having offsets of 15cm from the edges of the piles. The 3P pile caps are shown simply by rectangles. Note that in node 4, the 2P pile group is oriented at 0°, while that at node 1 is at 90°. Similarly, the 3P pile group is oriented at 0° at node 5, 90° at node 15, and at - 90° at node 90. Similarly, 180° or any other angle can be assigned.
Note that some of the piles of nodes 16 and 5; and similarly of 12 and 11 are seen connected by straight lines. They indicate that the line connected piles are closer to each other than the distance allowed (calculated by diameter and allowable distance, entered in K4 and L5 in the Output sheet (marked F in red, in the figure). Also note that a Check.txt file will be created on running the scrip file generator which lists the piles which are closer to each other than allowable. For the above example, the Check.txt will be
Pile 2 of Node 12 ==> Pile 1 of Node 11
Pile 5 of
Node 12 ==> Pile 3 of Node 11
Pile 4 of
Node 16 ==> Pile 2 of Node 5
The following is another example output (but unlike the drawings prepared by the provided app, is void of the printed node numbers) where the 3P pile caps are rotated by 45° and -225°. One can also see the 1P, 8P, 9P and 10P pile groups.
In order to use the app, the following files are to be download: Excel sheet for data input (PileData-V01-01.xlsm) and the Pile plotter program (PilePlot-V01-01.exe) both zipped into PilePlot-V01-01.zip*. The output files of a typical small building (the first example explained above with) have also been included, zipped into PileSample.zip**.
Rahul
Leslie
rahul.leslie@gmail.com
June
2021
*https://www.dropbox.com/s/abniy61ndbbcfip/PilePlot-V01-01.zip?dl=0
**https://www.dropbox.com/s/z25kbmcrfqcmx88/PileSample.zip?dl=0
Excellent..
ReplyDelete