Creating custom subassembly (trench) with variable depth and fixed wall height

[Anonymous]

Good Afternoon,

I'm in the process of reviewing some training manuals to try and find this answer, but I am completely new to creating custom subassemblies. I have worked with profiles and basic road coordidors in the past, however nothing custom. We are working to try and learn to create custom assemblies to improve modeling and material takeoffs/bidding for our clients.

I am trying to create a concrete trench with a retaining wall on one side (the is above the grating height) and a tie on the opposite that will project a line to connect to a feature line (or other geometry point with a fixed elevation) - see attached sketch.

My main design issue is the relationship between the profile and top of wall. The top of wall (P1) and top of grading (P2/P5) are fixed elevations (which are shown on the sketch). The depth of the trench (P3/P3) vary along the profile (slopes down into a sump). I'm not sure how to create this relationship because the built in sub assemblies assume the trench is a fixed depth and therefore the top of the wall is xx' above the bottom of the tench always (as opposed to being a varying in order to meet a fixed elevation).

Also, P6 needs to project a line/slope to the right to meet a fixed existing elevation. I can represent the fixed elevation as a feature line, or whatever object is required to allow it to project and tie to it.

Any help or suggestions would be appreciate! Thanks!

[KMercier_C3D]

Have you put any of this into Subassembly Composer yet? Once you set up all your desired Input Parameters and Targets and start building it you may end up answering your own question or you will see the specific spot that you are having difficulty with. On the sketch provided it all seems pretty straight forward.  

[Anonymous]

I have not. I have been trying to find as much introductory information as I can. The only real tutorial I have is the Pinnacle Training Series my employer subscribes to. I haven't found any examples yet though detailing the two "unique" relationships I need to provide - i.e. the fixed top of grating elevation vs. varying trench depth along the profile.

[KMercier_C3D]

Fixed top elevation: Make Input Parameter (double) of this defined elevation value. When you need a point at this elevation, define the point's Delta Y using the input parameter variable and any of the previous point's elevation (ex. elevation of point P1 is P1.elev)

Varying depth based on a profile: Make a Target Parameter (elevation) and then when you are defining the point use any of the types that allow you to use a Elevation Target drop down.

[Todd_Rogers]

Your best bet for use of the subassembly composer is YouTube, or Autodesk University On-Demand.

[Anonymous]

Ok, I am just getting started with this but this is where I am at.

Right now I just input a -1 value for L2 and L4 in order to link them to something so there was some sort of graphic. How would I go about setting up my required inputs? P1 (and P11) is a fixed elevation (578.83 in this case but will vary in future uses) and P2 (and P5 and P6) are a fixed elevation (577.50 in this case but will vary in future uses). P3 (and P4) will vary based on the profile provided for the coordidor/final assembly (itll have a negative slope to a sump area essentially) but follow the profile drawn. So essentially L2 and L4 are going to be different every step of the profile based on the difference in the profile elevation at that point and the fixed elevation of the top of the grating.

This means that L7 will be a variable as well based on the profile - P3 Elevation along profile (minus) 0.83' base (minus) 2.00' footer and that depth relationship will also hold true for all of the other underground points for the footer/base of the trench.

I want to add a P12 which will be a tie in point for the slope going into the trench. This point will be depending on whatever the existing elevation is on the far right side. With that being said I can make that existing feature anything I need to in order to get this to tie in (i.e. I can draw a feature line if needed).

Also, what would be the idea origin point? Right now P1 is the origin, but I'm not sure that makes sense for this application, ideally I would like the Center of the trench to be the original such that the profile of the trench can be drawn in the center of the trench.

Thanks again, I really appreciate all of the help!

[KMercier_C3D]

Your "origin" is where the subassembly will connect to the assembly, make sure you set this point correctly. From  your description it sounds like your P3 should actually be your origin?

If L2 and L4 will always be equal you can use the variable P2.Y in defining your P5.Y to set them at the same elevation or your delta Y as L2.length. 

For P12 you will want to go to the Target Parameters tab and define the appropriate targets. Likely an offset and a surface.  

[Anonymous]

Thanks again.

I created my target parameters (bottom of trench and tie in point). But, the question is, how do I create that relationship in my model, i.e. how do I tell P3 and P4 to follow whatever the BottomofTrench target elevation is and how do I tell the Link from P6 to P12 to connect to whatever the elevation along the profile for the tie in point is?

I also then need to set the relationship for top of grate and top of wall based on fixed elevations, the only thing I seem to have found is a distance relationship from other points that the user can enter, but not a fixed elevation the use can enter to set those points. Or, perhaps I need to set a target polyine/profile/feature line for top of grate and top of wall, in which case, how do I define those relationships to a target? I'm even ok just setting the top of grate elevation and then having the user enter a wall heigh above grating value for the assembly as well.

[KMercier_C3D]

Which point connects to your assembly/corridor/alignment? (this point automatically has elevation information from the profile)

An elevation target is an additional profile separate from the profile that is already being used by the corridor. You will likely also want a surface target to reference the existing grade at any offset from your alignment and not just at the profile of the alignment.

[Anonymous]

P3 can connect to the profile for the bottom of the trench, or I would be ok with creating a mid point between P3 and P4 to connect to the bottom of the trench.

[KMercier_C3D]

Then P3 needs to be the first point you define and it needs to be located at the "origin". 

[doni49 · Accepted solution]

My understanding of your problem is that you want to have a certain point get placed at a specific elevation -- not just a certain distance above or below other points in the sub assembly -- correct?  SAC doesn't provide a direct method of doing this.  The distances you specify are relative to other points in the subassembly.

BUT.....  You can still get around this.

The ORIGIN is always at the baseline/profile elevation (this makes it easy to use this point as the crown).  Baseline.elevation will give you the elevation of this point per the corridor profile.

So if you have an input parameter called "TargetElev", you can give a Y distance for your point of TargetElev  - Baseline.Elevation.  So if your target elevation is 518 and the corridor profile is at 522, then the point will be set 4 ft above the profile elevation (which is 522).  If TargetElev is 510 and the corridor profile is 518, then the point will be set 8 ft below the corridor profile.

Now you just need to tell it how far in the horizontal to go.

[Anonymous]

Ok, again I appreciate the help trying to work through this.

I am going to go ahead and kinda redraw this part now that I have a little bit better understanding of what is going on. I want the Origin of my part (that follows the defined profile) to be the Centerline of the Trench, so I will make this P1 in my new drawing, from there I will go 1/2 the width of the trench in each direction to define the bottom of the trench.

From what I can gather (and correct me if i'm wrong), I need to set up an Aux Point (say AP1) and target that point to an elevation based on a target point I define, which in this case is going to be the Elevation of the Grating. So in the drawing, I can either draw an elevated polyline or a featureline to represent this paremeter. I will change the top of wall point to a user entered value for distance to top of wall from top of grating (say 1.0 ft default).

In order to get my tie point, I will need to setup a target paremeter for elevation again and an Aux Point (say AP2) and have this target paremeter also be set to a polyine or feature line in the actual drawing such that a sloped line is crated from the edge of the ledge on the trench to the existing tie in elevation.

As I get closer to a final product here, I also have a few more questions.

1. Is there a list of default point and line codes available? In terms of modeling, I am only interested in seeing the top of the wall (P11/P12), the bottom of the trench (P3/P4), and the top of the ledge (P5/P6). Everything else would really be considered hidden.

2. For the shape parameters, can those be used to calculate volumes? For example, can the volume of concrete used be determined from a shape (S1) of the wall? Could I also define an arbitrary shape from the bottom of trench to the top of grating (or even 1" below the grating) to determine the volume of the trench (S2)?

Thanks,

-Kyle

[Anonymous]

That seems like a pretty viable solution as well and elimates the need for an extra feature line for the top of the wall or top of grating. I will need two such inputs: TargetElevWall and TargetElevGrate in which the "baseline.elevation" elevation is subtracted from to determine the Y distance for that Point. 

The only thing I need to do to make this work correctly is set my origin point at 0,0 (or somewhere along the bottom of the trench) I believe.

I presume I can also reference this "baseline.elevation" for depths as well? I.e. the footing of the wall will extend 8" (thickeness of bottom of trench concrete) + 2 feet into the ground.

In terms of setting the origin - would I be best creating an additonal point in the center of my trench and offseting 1/2 the width in each direction, or simply using the corner of the trench as the basepoint but within that point, adding the offset value of (-1/2)TrenchWidth?

Finally, are the extra steps shown in the Autodesk University examples worth it? I.e. they put in steps that verify positive values for everyrthing and that every input perameter has a value assigned to it.

Sorry for the revision to my last post, but I had some time to reread everything and think it out a little bit more at home this evening. 🙂

[KMercier_C3D · Accepted solution]

You can query the elevation of any point, not just the baseline. The elevation of P1 is P1.elevation

Here are some other API functions available for points and links (both normal as well as auxiliary):

Points and Auxiliary Points Class

P1.X	Horizontal distance from point P1 to Origin
P1.Y	Vertical distance from point P1 to Origin
P1.Offset	Horizontal distance from point P1 to assembly baseline
P1.Elevation	Elevation of point P1 relative to 0
P1.DistanceTo(“P2”)	Distance from point P1 to point P2 (Always positive)
P1.SlopeTo(“P2”)	Slope from point P1 to point P2 (Upward = positive, Downward = Negative)
P1.IsValid	Point P1 assigned and valid to use (True/False)
P1.DistanceToSurface(SurfaceTarget)	Vertical distance from point P1 to SurfaceTarget (point above = positive, point below = negative)

 

Links and Auxiliary Links Class

L1.Slope	Slope of link L1
L1.Length	Length of link L1 (Always positive)
L1.Xlength	Horizontal distance between start to end of link L1 (Always positive)
L1.Ylength	Vertical distance between start to end of link L1 (Always positive)
L1.StartPoint	A point located at the start of link L1 (Can be used in API Functions for P1 Class)
L1.EndPoint	A point located at the end of link L1 (Can be used in API Functions for P1 Class)
L1.MaxY	Maximum Y elevation from a link’s points
L1.MinY	Get the minimum Y elevation from a link’s points
L1.MaxInterceptY(slope)	Apply the highest intercept of a given link’s points to the start of another link
L1.MinInterceptY(slope)	Apply the lowest intercept of a given link’s points to the start of another link
L1.LinearRegressionSlope	Slope calculated as a linear regression on the points in a link to find the best fit slope between all of them
L1.LinearRegressionInterceptY	The Y value of the linear regression link
L1.IsValid	Link L1 is assigned and valid to use (True/False)
L1.HasIntersection(“L2”) L1.HasIntersection(“L2”, true, true)	L1 and L2 have an intersection, second input is a Boolean defining whether to extend L1 with default of false, third input is a boolean defining whether to extend L2 with default of false (True/False)

[KMercier_C3D]

As far as the extra steps to make sure that input variables are positive, it is really not needed in most cases as long as you are keeping the subassembly for your own use. It is more just to make the file "idiot proof" to prevent something wacky from happening once it is out of your hands. The only parameters that I would urge to make sure are the correct positive or negative are potentially slopes. 

[Anonymous]

Thanks for that information! I just found your AU 2012 Presentation that I watched this morning, as well as the handout from it. I am going through it right now and think I finally have a decent grasp on this. The next step will be to get it into C3D to get it to do what I want it to do - in terms of learning the line/point codes and other functionality.

Thanks again!

In terms of my tie point - I want to tie to an existing feature line (or some sort of grading feature) that has a variable distance and elevation along my trench. Is there any way to accomplish this? I see that I can create a Aux Points at a traget elevation, but that scenario wants me to use a specific offset distand every time. How would I allow both to be variables that depend on that specific location?

[Todd_Rogers]

I propose that admin create a Subassembly Composer sub under the Civil 3D forum.

[doni49]

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@Anonymous wrote:

Thanks for that information! I just found your AU 2012 Presentation that I watched this morning, as well as the handout from it. I am going through it right now and think I finally have a decent grasp on this. The next step will be to get it into C3D to get it to do what I want it to do - in terms of learning the line/point codes and other functionality.

Thanks again!

In terms of my tie point - I want to tie to an existing feature line (or some sort of grading feature) that has a variable distance and elevation along my trench. Is there any way to accomplish this? I see that I can create a Aux Points at a traget elevation, but that scenario wants me to use a specific offset distand every time. How would I allow both to be variables that depend on that specific location?

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I wrote up a short SAC how-to sheet that you might find helpful. It was originally intended for my co-workers. But since that time, I've posted it here too.  I think it does a decent job of explaining how the codes/points/links all relate to each other.

http://forums.autodesk.com/t5/autocad-civil-3d-general/sub-assembly-composer-getting-started/m-p/530...

[doni49]

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kdersch wrote: 

1. Is there a list of default point and line codes available? In terms of modeling, I am only interested in seeing the top of the wall (P11/P12), the bottom of the trench (P3/P4), and the top of the ledge (P5/P6). Everything else would really be considered hidden.

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In that case, I'd suggest naming the points/links you want to have included in the surface with a code of "Top".  If you use this SA with OOTB SAs, the other once also use top for the "exposed" points (non-hidden).