Structural Analysis

[ctc]

I don't know of any way that Revit can do this, yet, so can anyone recommend a program that will assist me in performing basic structural design for residential architecture up to three stories in height including wood framing, steel beam and column, masonry, and concrete foundations and footings?

[Wes Macaulay]

The operative word being YET. :wink:

[sjsl]

Strucalc.com

[gregcashen]

The operative word being YET. :wink:

I would be very surprised to see Revit ever be able to do this sort of analysis. There are only a very small handful of programs that can even come close and none of them can do it all in one package that I know of. There are programs like STAAD, ROBOT, ETABS which can do many of them, but usually through plugins that don't speak directly to one another. Enercalc is by far my favorite calcpad type analysis tool, but I don't see it being linked to a CAD program...EVER.

Take a look at Woodworks. If Revit were ever to integrate a residential timber framing program, Woodworks would be a good choice. It has a way to go before it truly is interoperable (even within its own 3 modules...shear, connections, sizer), but if there were a way to make it work with Revit, it would be slick. THe interface is already similar enough.

[Scott D Davis]

Here's the guy to talk to:

Product manager for the structural part of Revit. Contact me at nicolas.mangon@autodesk.com (nicolas.mangon@autodesk.com)

[gregcashen]

Let me be clear that I am not saying that there will or will not be any specific Structural functionality in upcoming versions of Revit. I think we all have a pretty good idea of what they are working on. But I don't think that it is likely that there will ever be a tool that will handle residential type structural analysis of this sort. The reason is...comlicated...there is certainly a ton of programs out there that do steel, concrete or timber analysis. But for the most part, these are either FEA (Finite Element Analysis) or MA (Matrix Analysis) tools. FEA is good for concrete slabs, steels plate structures, any of Gehry's work, etc. Matrix Analysis is easier to code (could be done in Excel even) and is used in a lot of the lower end Steel design/analysis tools. The problem is, residential structures are not designed this way. For a steel frame, there are certain discrete steps which are taken in a specific order. It is pretty easy to come up with a consistent workflow to handle most of the elements in a steel building design. Same goes for concrete. Put steel and concrete together and it gets a little more complicated, but tools like STAAD, ROBOT, ETABS can handle it pretty easily. The reason is that the stiffness of elements is pretty easy to determine and the resulting load contributions are pretty straightforward. if you have a column that is twice as stiff as the the other one in a 2-column frame, it will effectively take twice the load. In residential framing, the distribution of loads to shearwalls, braced panels, portal frames, cantilever columns, masonry/concrete piers and horizontal diaphragms (floors, roofs) is less straightforward. There are not a lot of tools that know how to simultaneously handle concrete, steel, timber, masonry...

Even woodworks doesn't do everything quite right. For instance, if I want to model a house to analyze, but there are some steel portal frames in there, it doesn't handle them at all. So I have to approximate. Essentially, I have to build a conceptual model which is different from the actual structure, in order to account for the steel frame as a point of fixity. Then design the steel frame separately. I would not want to have to model the Revit model both accurately for CDs and then again conceptually for analysis. If there was a way to export the 3D model into another program to do this analysis, that would be great, and it is entirely feasible...with steel, concrete, timber, etc. But with residential, there is no existing program to export to that reliably handles this kind of work.

However...since most of this stuff can be done with a spreadsheet, it is possible that one day we could have access to the relevant fields in the db that would allow us to determine the entire building load, the direction of the loading in floors, roofs, etc., the distance from wall to wall, etc and then create a schedule with formulas that does a lot of the analysis for me. Right now it is not possible.

Talk to Nicolas and tell him what you would like to see. He is a great guy and is very open to intelligent suggestions. As such, he ignores most of mine ;)

[Wes Macaulay]

Hey Greg - do you so some structural analysis? Stress and tributary loads and such?

I've also had confirmation that Revit will be doing some structural analysis soon. Who knows to what degree...

[gregcashen]

Wes, I do all structural analysis in my office for the most part. I don't use Revit for it, but I do run schedules on the weights of walls, floors and roofs to get diaphragm loads for lateral analysis. It would be awfully nice to be able to add soem more calculations to the formulas and get the actual diaphragm shears, shearwall loads, etc. It wouldn't take too much more intelligence in Revit, just more exposure to the location and size properties of these elements.

I do know that they are hard at work on the structural features in Revit, but I don't know that it will be 7.0, 8.0 or what. I also don't know that Revit itself will have any built-in analysis capabilities. I find it unlikely. That is why I would prefer to have more access to the location and size properties of roofs, floors, walls, etc. Also, I would like to be able to determine, maybe via SQL statements, all the walls that are attached to diaphragm x. That way I could link shearwalls to diaphragms in a schedule and then follow loads to the foundation. I guess the factory could hard code these features in, but I think the time is better spent on a SQL interface that disallows table drops and other dangerous commands but lets me create reports based on my own criteria. Basically, give me the ability to create any kind of JOIN on the db and make it an "ad-hoc" type schedule. Sort of like a Multi-category Schedule, but with infinitely more power.

G