Piling ECC Computation Tutorial

 

Define the Pile Grid Layout

 

We have been given the following Grid Layout where piles are to be placed.

 

 

In this type of work, sometimes you actually wish to calculate and store the 'grid' itself, and other times you are only interested in the grid as a positioning tool for your piles.

 

Here we will cover both scenarios.

 

1. You wish to store the grid points.

 

You can use the normal Cogo routines contained in Ezicad to calculate these points.

 

To achieve this particular grid, open a new job called Piletut.

 

You need one point to start from, so select Points > Add and 'click in a point'. Enter Coordinates of 100,100 in the absence of any real 'ground coordinates'. (you can easily move the grid later when the site coordinates are established.)

 

The quickest method of establishing such an irregular grid is to calculate the points along the 'longest' grid line first, and then use one of the 'offset routines’ to calculate the rest automatically.

 

Select Cogo > Bearing and Distance.

 

You are calculating from point 1, on a bearing of 90 for a distance of 3.15 to establish point 2.

 

Next, change the distance to 6, and enter 2 in the 'Multiple' field towards the bottom of the 'Bear & Dist' window to indicate you wish to calculate 2 points each 6 metres apart along the line. Press Apply and you will see Points 3 and 4 appear.

 

Now change the distance to 3.15 and press Apply to store the next 2 points.

 

Again change the distance to 6 and press Apply to store points 7 and 8

 

Now change the distance to 3.15 and Apply for points 9 and 10

 

Once more change the distance to 6 and Apply.

 

Now change your distance to 3.15, and change the Multiple field to 1 before you press Apply to calculate the last point, which should be 13.

Choose Cancel to close down the Bearing and Distance window.

 

Select Strings > Add. Use a String Id of g1 and then type in 1.13 for the definition of the points in the string. Select Finish

Select Cogo > Road >Autoroad to see the following screen.

 

Point to the string and you will see its name filled in.

 

Leave Alignment selected.

 

Select Store Strings.

 

Then enter offsets of 6.56, 6.45 and 6.56 again in columns 1,2 and 3 respectively.

 

Select OK and the screen should now appear similar to that seen below

 

All the relevant point have been calculated, and the 'lines' drawn along the major axes.

 

If you wish to be able to print/plot the grid you can now add in additional 'strings' between points 1 & 40, 2 & 41 etc.

 

If you do choose to add the strings, you may wish to use Id's of A, B, C,D, etc for each of the strings you create for later identification purposes.

 

Use Grids for Location Only

 

If you only wish to use the 'Grids' as a means of locating the pile points, and do not need to store the grid points, you can go directly to the Piling routines.

 

Select Cogo > Piling > Pile Grids and you will see the following screen.

 

The grid section will allow you to specify both regular and irregular grids.

 

For both regular and irregular grids you need to specify the origin of each axis, which is often the same, but does not need to be.

 

You also need to specify the bearing of that axis. The two axes may be at right angles to one another, or they may be at any other angle required by the aesthetic desires of the architect.

 

A 'regular' grid is where all of the grids are equally spaced. For example, you might have 6 grids at 10 metre spacing. This is easily entered by placing 10 in the spacing and 6 in the number field.

 

An Irregular Grid occurs when the space between the grids is not uniform. You will see how it is entered in the example below.

 

In this case you have an irregular grid, and in the absence of site coordinates at the present we will start with an Origin for both axes of 100 East and 100 North.

 

Axis 1 is the 'long' axis, and we will assign it to a bearing of 90 degrees i.e. it runs east to west.

 

We now specify the grid spacing.

 

Here we have one at 3.15, followed by 2 grids at 6 metre centres, then 2 grids at 3.15 metre centres etc.

 

Position your cursor in the "Spacing" field and type in; 1*3.15,2*6,2*3.15,2*6,2*2.15,2*6,1*3.15.

 

You will see the entry scrolls as you enter it in.

 

The Label for this Axis will be A. This indicates that the grids along this axis will be A,B,C,D,E etc. If you have more than 26 grids on the axis, it will use label AA for the 27th grid, AB for the 28th and so on.

 

For an Irregular Grid, the 'Number' field is ignored, as the entire grid is specified in the Spacing Field.

 

Now we come to Axis 2.

 

From the grid diagram you see that starts at the same location as Axis 1 and the Grid numbers increase in a southerly direction.

 

Enter an origin of 100,100 and a bearing of 180 degrees.

 

Here the spacing is 1*6.56,1*6.45,1*6.56.

 

The label for this axis is 1, meaning the grids will be numbered 1,2,3,4 etc.

 

Once you have finished, select the OK button.

 

You will see a grid has been drawn in a dashed line. You may need to Zoom a window to get it to fill the screen.

 

 

Defining a Piling Structure.

 

A Pile Structure is a ‘standard’ layout of piles, which you are likely to use a number of times.

Creating and Storing Structures.

 

Before you actually start on the Structure side of things, you need to enter or calculate the points that make up the pile structure using the standard entry or Cogo facilities.  You do this in the normal course of a job as if the points and structure were only to be used once.

When all the points have been calculated, you then need to add a string or strings to ‘draw’ the outline of the proposed structure.

Once the item has been created the first time, you then need to follow the 3 steps listed below.

 

1. - You use the Select Strings option to select the string or strings that define the structure.

2. - Use Select Points to select the insertion point of the structure.   NB this Insertion point may or may not be actually in the string defining the structure depending on the circumstances of your individual structure.

3. - Pull, down the Cogo menu, select the Piling option, and then select Define a Pile Structure. You will be asked to specify the name of the structure and you can enter any name up to 8 characters in length to identify the current structure.

 

While it is not intended to teach you how to use Cogo within this tutorial, we will 'calculate' the two pile layouts (structures) needed for this job, and below is the 'broad brush' details of one way it can be done.

 

One is a Square with a side of 0.75 metres.

 

The other is a Triangle with a base of 0.625 metres and sides of 0.813.

 

1. The 'Square Pile'.

 

You may either do this in the current job, or use a new job if you prefer.

 

Here I will do it 'off in the corner' of the current job.

 

Use Points > Add to add in Point number 2. with coordinates of 100,120.

 

Use Cogo > Bearing & Distance.

 

From 2 at 0 degrees for 0.75 to 3

From 3 at 90 degrees for 0.75 to 4

From 4 at 180 degrees for 0.75 to 5

From 5 at 315 degrees for 0.53 to point 6 which s the 'centre' of the pile structure.

 

Next use Strings > Add with an ID of SQ075 and enter 2.5,2 to form a 'closed string' around the square then Finish

 

Use Strings > Select > Single String Selection and select the SQ075 String you have just entered.

 

Use Points > Select > Single Selection and select Point 6.

 

Choose Cogo > Piling > Define Pile Structure.

 

When the window appears give it a name of SQ075 and then choose OK.

 

You now have a "Pile Structure" stored for the square pile cap.

 

Choose Points > Add and add point 7 with coordinates of 105,120

 

Choose Cogo > Bearing and Distance from 7 at 90 degrees for 0.625 to point 8.

 

Choose Cogo > Intersect Bearing & Distance > 2 Distance Intersection.

 

From 7 - Distance of 0.831

From 8 - distance of 0.831

 

You will see two circles appear and their two intersections are the two possible solutions. Click on the lower one and Point 9 will appear.

 

Choose Cogo > Bearing & Distance from 9 at 0 degrees for 0.385 to 10 which is the 'centre point' of this group.

 

Choose Strings > Add with an ID of TRI and specify Points 7,8,9,7 and then finish.

 

Select String TRI and Point 10.

 

Choose Cogo > Piling > Define Pile Structure.

 

When the window appears give it a name of TRI and then choose OK.

 

You now have a "Pile Structure" stored for the triangular pile cap.

 

Now it is time to specify where these pile structures are to be placed.

 

Defining Pile Location

 

You can define the location of the piles by either interactively ‘snapping’ a pile structure onto a grid intersection, or by filling in a table using the Pile Location Table option.

 

The drawing below shows the design locations of the piles.

 

 

Snapping to Grid.

 

When you select this option you will be presented with a Pop-Up window requesting the name of the structure to be inserted.

 

You can either type in the name, or use the Pull Down facility to choose from the list of defined structures.

 

In this case, if you wish to insert some of the triangular caps, select "TRI' as the structure, and leave the other parameters as they are.

 

When you choose OK, you will see there is a triangle attached to your cursor, so move the cursor to be over the grid intersection A1 and select it. You will see a Triangle drawn on the screen.

 

Pick OK, and then position it over grid B1

 

This “Insert a Pile Structure will remain active and continue to reappear with the last structure you used. You can either select another structure, or, just click OK to insert the same structure again.

 

When you have finished inserting the individual structures, you can select the ‘Cancel’ button to end the routine.

 

Repeat for A2 and B2.

 

You will notice that the triangle is "turned around' on grids A3, A4, B3 B4.

 

You can easily achieve this by using a rotation of 270 instead of the default 90 when you insert the piles on these grids.

 

We could continue on with this method, but you can see from your pile layout sketch that grids C1 to K4 inclusive all have the square grid layout, so it is more efficient to use the Table to place all of these.

 

Using the Table to Locate the Piles.

 

Choose  Cogo > Piling > Pile Location Table.

 

When the window appears you need to type in the name of each of the structures you wish to apply.

 

Start with SQ075, use offsets of 0 and 0 and apply it to Grids C1~K4.

 

You may also wish to apply structure TRI to grids L1~M2.

 

Note there is no facility to rotate a structure in the table, so if you wish to use the table to place the four remaining structures you would need to define another triangular structure ‘pointing north ’ instead of the original one pointing south.

 

If you know what you are doing you should be able to select an existing triangle and rotate it about the grid, then use that to create the structure.

 

Alternately, you may choose to go back to the simple method of locating individual pile caps to place the last four.

 

Whatever you choose, the aim of the exercise is to have all the design pile caps placed and stored.

 

When you do, the screen should appear as seen at right.

 

Importing the Field Data

At this stage you need to get the surveyed data from the field where your party has located the ‘as built location of each of these ‘pile points’.

 

In normal jobs this might come directly from your data collector, or a ‘stadia’ survey.

 

It is important to remember that the filed points must be stored in the same job as the design points, and as such, it is essential that you plan the ‘starting point number’ of  the field points so that they occupy a different range of point numbers to the ones you used for the design points.

 

This data has been supplied in a job called ‘db.pilesurvey’ , and you should open it now.

You will find that a range of points numbered from 500 onwards are shown as seen in the screen adjacent.

You should use Points > Select > Select All followed by Points > Copy to copy all these points to the clipboard.

 

Then make job Piletut active again, and use Points > Paste to paste the field points into the same job as the design location.

 

Now you need to specify which points the program should consider as “design points”, i.e. where the pile is meant to be, and which points are ‘surveyed points’ i.e. where the pile actually is in the field.

 

Specify Design and Field Points

 

Select Cogo > Piling > Calculate Displacement.

 

Concentrate your attention on the two bottom lines on the table called Design Points and Surveyed Points.

 

You need to set the Design points from a minimum of 1 to a maximum of 400, and the surveyed Points from a minimum of 500 to a maximum of 1000 as seen in the screen below.

 

Obtain a Displacement Report

Once you have specified the relevant point ranges, the quickest method of determining the compliance, or otherwise, of the job is to obtain a Report.

 

Select Cogo > Piling > Piling Report.

 

You will be asked to specify the Tolerance allowed.

 

Since placing piles in the ground can never be a precise science, you will normally be given a ‘tolerance’ by which a point can be displaced from its design location before it is considered a ‘problem’.

 

In this job the Allowable Tolerance is 85 millimetres in any direction from the design location, so enter a value of 85 and then press OK.

 

Soon word/wordpad will appear with a report with a format similar to that below. You should use the options available under File in the relevant word processor to save this document with a relevant name.

 

If you wish you can also use the word processor to change the formatting and fonts etc of the report.

 

JOB NAME: D:\tktay\Pile\piletut

Date:  20/09/2001

Piling Report   Tolerance =    85

Grid Ref  Pile Pt    DispX      DispY      VarX       VarY

__________________________________________

A1          2         -62         -64        

A1          3         -0          -0         

A1          4         -5          -61        

B1          5         -72         22         

B1          6         -84         -6         

B1          7         -87         -29         2          

A2          8         84          9           

A2          9         113         -20         28         

A2          10        53          9          

B2          11        -74         -4         

B2          12        145         -10         60         

B2          13        125         88          40          3          

A3          14        -8          29         

A3          15        8           6          

A3          16        9           -27        

B3          17        -86         131         1           46 

If you take a look at the various columns, you will see that the two right hand columns are the ones that can be used to quickly see which piles are in a position that is outside the design tolerance.

 

Obviously this is also a quick check to ensure that there is no major discrepancy in the coordinate systems used in the field and the office, and if there is more that a few points which have values appearing in the right hand columns you need to have a close look at the data before proceeding.

 

If, as should be the case at the moment, there are only a few locations where the points have fallen outside the tolerance, you will need to discuss this with the structural engineer to determine whether this is a problem or not.

 

Most often the engineer will request a plan showing the graphical representation of the direction and distance of the displacements.

 

Displacement Drawing.

 

When you are ready to create the displacement drawing you need to choose the required symbol and size to be used.

 

Select Cogo > Piling > Define Displacement Symbols.

 

This time concentrate on the area of the screen titled Piling Symbols.

 

First you need to select that option by ‘ticking the box’.

 

Next you can choose from the four different symbols available. Basically the symbol can show either a displacement vector, or the x and y components of that displacement, and the values can be drawn if required.

 

To the right you can set the length of the ‘arms’ of the symbols, as well as a scale and an offset from the actual point.

 

You need to be aware at this stage that these values work together with the Plot scale you set under plot Parameters., and you will need to ‘experiment by trial and error’ to get the values which best suit the  particular combination of paper size and orientation  in your printer/plotter, or the size of the monitor you are using is you wish to examine it on screen.

Once you set the Symbol you require, and close down the parameter table, you may find your job ‘overrun’ with arrows and numbers.

 

Don’t worry yet.

 

Use File > Plot Parameters to access the following screen.

Set the Plot scale to the value required and , if you wish to export the displacement Drawing to a CAD package you need to set the File Name you wish to use for that drawing.

 

Once you return to the screen you should see a better-behaved set of arrows similar to those below.

 

If you do not, you will need to go back to Piling Displacement Symbols, and alter either the size, or scale, or both until you get the display you wish.

 

From this point you can either print/plot the drawing, or use File > Export DWG to send it into a CAD Drawing.

 

Note that when you export to CAD, the displacement symbol is stored as a ‘block’ to allow you to easily move it around in the drawing to avoid any overwriting which might occur.