Structural, Civil, Architectural
Structural, Civil, Architectural
(OP)
I'm in excavation. I use CADs to program our machines via GPS. Most of the time getting cads with/without a release is not a problem. However on one job we are running into a structural engineer and architect who are claiming structural cads can't be relied upon for measurement for dimensions.
Is there a basis for this? Is there a best practices handbook or something I can point to one way or the other to help me understand? For me it makes no sense because everyone moved away from paper/pencil/drawing boards a while ago and to the preciseness of AutoCad (or similar). But now I feel like I'm going back to the drawing board. Literally. GPS/CADs can help reduce errors, reducing staking/surveying costs, and increase speed of construction. Paper won't ever be eliminated but it's as if it is playing a bigger role than necessary.
Thank you for your time.
Is there a basis for this? Is there a best practices handbook or something I can point to one way or the other to help me understand? For me it makes no sense because everyone moved away from paper/pencil/drawing boards a while ago and to the preciseness of AutoCad (or similar). But now I feel like I'm going back to the drawing board. Literally. GPS/CADs can help reduce errors, reducing staking/surveying costs, and increase speed of construction. Paper won't ever be eliminated but it's as if it is playing a bigger role than necessary.
Thank you for your time.






RE: Structural, Civil, Architectural
2. Liability, liability, liability
3. Also, many architects and engineers use "nominal" dimensions. IE, an 8" CMU wall is really 7.625", but we might draw it as 8".
4. Lastly, many engineers never enter CAD. They simply rely on printed drawings that they mark-up etc. They know what's on print, but they don't know what's their electronically.
As one last aside. I typically don't let fabricators use my drawings for shop drawings either. They need to rework the dimensions and it's a good way for them to check things out.
RE: Structural, Civil, Architectural
Agree with njlutzwe, it makes a pain in the butt checking shop drawings but at least you know that it helps spot mistakes that could have gone unnoticed by both engineers and architects.
RE: Structural, Civil, Architectural
Dave
Thaidavid
RE: Structural, Civil, Architectural
Sorry, I am paid to provide sealed construction documents. Not CAD (excluding BIM Models)
RE: Structural, Civil, Architectural
But would you build a 3D CAD model of a rebuild of an old multi-story steel structure with wood-and-drywall (or steel 2x4 and arch detailed) office interiors?
Your basic model of "where the walls are" starts off inaccurate because it wasn't built-to-drawings (exactly) in the first palce, and the settlement and movement and adjusts since then in AC, electrical, and mechanical services were never detailed in the originals: They were laid out, but fab'ed in-place.
Civil-steel details, arch details (windows, roof edges, watertight seals, repeated fittings, etc), HVAC, steel 3D CAD, and even well-dimensioned 2D CAD dwgs are essential, but they are not a CAD-CAM machinable assembly dwg. You'll need as-found field dimensions.
RE: Structural, Civil, Architectural
How about his, I have a building on my desk right now that is 1/2 conventional 1/2 specialty structure. The specialty structure is built using metric units, the conventional structure is built using imperial units (as that is the way construction is done here). Well, after going around about a bust in the specialty structures dimensions (happened during conversion) I gave up and erased all dimensions on my plans relating to their structure. So while the drawings may be off slightly, the GC is going to have to figure out what to do in the field.
RE: Structural, Civil, Architectural
As for getting GPS coordinates, you should redraw it anyway to make sure its correct.
Like stated above, some dont draw to scale, but the printed version might be correct....example, a span is 25', in cad it measures 24'-7", but the dimension was fat fingered to read 25'-0". Right on paper, wrong in CAD.
RE: Structural, Civil, Architectural
RE: Structural, Civil, Architectural
Or, they may be aware of some assumed contours or similar issues where the CAD files don't correspond to reality.
In my work, I always draw things to scale.
Unless, that is, I'm making one drawing into another drawing, and it's quicker and easier to just manually overwrite the numbers than it is to start stretching and adjusting everything.
I do see drawing files where the size of items is adjusted in model space to change the apparent size on the paper.
RE: Structural, Civil, Architectural
As for cross-checking an engineers work if the trades miss something it is also still an engineer's fault as well for not drawing it correctly in the first place. It is also a really good way to reintroduce human error into the equation when everything is having to be redrawn for estimating/construction purposes. Wrong in cad right on paper isn't really a thing. When I do take-offs for things I use measurements to scale. If I pick a line that is 24.75 but it says 25 I then have the wrong scale and my estimates are wrong and I can't use any type of earthwork program to accurately dig footings.
RE: Structural, Civil, Architectural
I Think I'll not share with you.
RE: Structural, Civil, Architectural
But if i mislabel something, i do not pawn that off on a trade. that is my fault and i hope the trade will notice it and RFI it.
RE: Structural, Civil, Architectural
Yes.