TBC Macros and Extensions

I had a guy ask me for an easier way to put Dead Load Deflections into his elevations for bridge beams. So theoretically you would select a line, calculate a spacing either by interval or dividing it by an equal number of spaces, extract the elevation from a selected surface, then apply a parabola to the elevations based upon the maximum deflection at the center of the line. Is there an easy way to do this already? I used to do it all in excel. You would also need a way to apply different percentages of deflection depending on where you are in the construction process. 25% deflection, 50% etc..

Help a brother out.

Shea

Excel is the way to go. I have a spread sheet for that.

Hi Alberto,

Up to what length can you apply your spreadsheet? I wouldn't mind getting a copy of that? pawel<at>hpsurveys.com.au

Thank you in advance.

Pawel

I'm not sure I understand your question.  There's no mathematical limit.  There's a cell limit but excel ranges are big beyond what a bridge will require.  I could get you a copy yes.  I do not know that we are working in the same units. 

I was doing this in Excel/ Symphony 25 years ago. I want something new! Anybody else build bridges anymore? Is this why they are so bumpy? Nobody knows about deflections? Just stirring it up....

Shea

#bringbackterramodel

Firstly, there is no difference between parabola and circle for typical deck spans and deflection values.

I apply my formulas as follows:

• correction = 0% * D at 0/4 * L
• correction = 75% * D at 1/4 * L
• correction = 100% * D at 2/4 * L
• correction = 75% * D at 3/4 * L
• correction = 0% * D at 4/4 * L

where:

D - deflection / hog

L - length of the span / girder

So zero correction above bearing pads and max correction in the centre.

Works just fine for small 20-30m long spans with deflections in 20-30mm range.

Terramodel ( #bringbackterramodel ) had a great command to do it "GC87":

Create an elevation DTM from another elevation DTM and a difference DTM.
Select and existing surface DTM layer, a depth layer and the DTM layer for the new elevations.

Unfortunately TBC does not provide functionality like that.

I would recommend the following:

• create lines along bridge centreline with vertices at the interval = 1/4 of the span
• drape those lines onto design bridge deck surface
• export lines as points (chainage, offset, elevation)
• correct elevations manually in excel as per the formula above
• import back csv and create new surface out of it.

Cheers,

Hi Marian,

My understanding is that Terramodel is still around, so it doesn't need to be brought back ;-)

But if you must use TBC, TMLs (yes, I too cringed that they piggybacked on the original acronym) can maybe help bridge the gap (no pun intended, but it works).

I replied to Shea's post below, but was curious about the Terramodel command you mentioned.

How does the Terramodel command help with Shea's workflow?

Do you still have to use the Excel spreadsheet to create the difference elevations, and then you import the spreadsheet as a difference surface, and then you run the command that takes the original surface + difference surface to create a new surface?

Just curious,

Quan

Revenant Solutions | Trimble Community
Independent TML Development - Build. Share. Grow.

I do a lot of this work as well and I agree with you, I would love to see a new way to do it within TBC instead of excel.

Hi Shea,

I don't build bridges, but I build TMLs...

So I've noted your post for pondering later... anyone doing stuff with an Excel spreadsheet jumps out as an opportunity for automation...

Is the goal to create points below the existing linework?  Or to create a new surface from the new points?  Or to create new lines from the new points, that go into a new surface?

I could see this getting complex quickly - but perhaps automating part of the process can at least get you away from spreadsheets...

You might try posting in the HCE forums.  Besides hitting a larger user-base, I know Alan Sharp is on there a lot and might be able to re-direct you or add it to Rockpile's todo-list.

Quan

Revenant Solutions | Trimble Community
Independent TML Development - Build. Share. Grow.