Problems re-importing an analytical model

[Tom Weir]

Hi all,
We exported a Revit model to ETABS for analysis. We then did a Save As to save as an EDB file type. The engineer then worked on the EDB file. Unfortunately when we tried to re-import the EDB file it could not be done.

Then we thought maybe we could export the EDB file to an EXR exchange file so that we could read that back into Revit. No Luck....we go the message:

<"Etabs model was modified after import from revit, it cannot be exported back to Revit">

Are we missing something? It's not clear what the rules are for the import and export. The Help menu has nothing.

ANybody have any idea?

Thanks,

Tom Weir
Los Angeles









"Etabs model was modified after import from revit, it cannot be exported back to Revit"

[kmarsh]

Tom,
I was under the impression that, once exported, you could analyze a model and re-import any member size changes but that's all. If you add members or move them around, it can no longer re-import. What exactly did the engineer do while working in the file? I'd suggest a test where you export, run the analysis and redesign the member sizes and then try a re-import with no other modifications to the model while in the analysis package. (I assume that this might also apply to loads etc... you might have to put all that stuff in with Revit)

I'm kind of basing this on the fact that you cannot create a model in Etabs or Risa and then import into Revit, it must come from revit. So, granted that, I extrapolated the rest.

This is certainly a topic that i'm curious about (being an engineer) but I haven't actually tested it yet.

-ken

[david_peterson]

Hold the phone here.
I guess I'm not even on the same planet. I haven't played with RS2 yet, but we did just buy it. It was my understanding that the only rule you had to follow was to start in revit to create the link. (ie place a column in a RS drawing and export) After that I thought you could do anything you wanted to in the Risa or e-tabs or now RAM. Load all the structural family in RS and re-import the model and accept all the changes. If this is not the case and everything but the calcs have to be done in RS, I guess my copy might be collecting some dust for a while. We had a hard enough time getting them to switch from R14 to 2002. Now they can't do any modeling, or loading in the programs they are used to using. I hope someone can explain this whole import/export thing a little better.

[kmarsh]

David,
Please be sure to take my comments with the grain of salt they came with. I have not tested any of what I said, such that I can draw any actual conclusions. I was only suggesting a possible cause for Tom's inability to re-import a model from Etabs. I could be completely, 100% wrong.
I am, however, still very interested in the outcome of this discussion for obviously personal reasons as we are seriously considering buying a copy or 4.

-ken

[kmarsh]

Here are the results of my preliminary test:
in RS2
draw 4 grids,
add 6 columns and 4- W12x26 beams.
Export to Risa3d:
change one member size to 30x108 and add 3 beams (one 12x26 and 2-30x108s)
Re-import to Revit:
See results below: 3d pic of Risa before re-import and 3d pic in RS2 after re-import.

It looks like the 3 added beams were non-existent in the re-imported RS2 model...

perhaps more test results when I get a few more minutes.
-ken

[David Haynes]

If a size of beam or column is changed in ETABS, then those new sizes must exist in REVIT Structure prior to the reimport.

Use Load Family to bring them in before reimporting from ETABS into REVIT Structure.

Hope this helps.

[kmarsh]

David,

Yes, that is the expected behavior and was verified by my example. (notice that the original W12x26 changed to W30x108 in Risa3d came back into Revit as the W30x108.) So that works. However, in the example, I was not able to add any members to the dataset and re-import.

I'll try just moving things, without adding info, next.

[kmarsh]

Here are the results of example 2:
In Revit:
1. draw 4 column grids
2. add 4-W10x49 columns and 5-W12x26 beams
3. Load W30x108 family
Export to RISA3D:
1. Change one member size to W30x108
2. Move middle beam. (not the one with size change)
Re-import to RS2:
1. Beam size change worked (of course)
2. Beam move did not.

Now I'm wondering if changing the size of the beam that moved would change the size back in revit... OK, changing the size of the moved beam, does translate back to Revit but Revit still does not reflect the move.

On one hand, this behavior could be beneficial to the engineer who might need to line some things up in the analytical model but still want the sized to translate and not move in Revit. However, it also means that engineers will need to do most of their work in RS. (Personally, I don't understand why engineers wouldn't WANT to work in RS. In order to move to BIM, we have to get out of the "engineers engineer and drafters draft" the lines MUST blur to take full advantage of BIM)

I also added some loads in RISA3d which did not translate back... Interesting, however that there were pre-defined load cases when I got to RISA3d (ostensibly exported from RS...)

Has anybody else been doing any experimenting?
-ken

[Tom Weir]

Hi,
Thanks for your interest in this subject and for taking the time to experiment with it. There does not seem to be any documentation to explain what is going on....I am going to ask the Revit Structural Product Manager to help us flesh this out. Not being an engineer I am a bit over my head here. But as you were saying we engineers and draftspersons need to break our old habits and work more closely in RS.

I also thought (and have been told) that you could make one column in RS, export to ETABS (or whatever), and create members there. Now we seem to be finding severe limitations on that.

Let's see what more we can find out from the developers.

Tom Weir
Los Angeles

[kmarsh]

Agreed. This may also be a limitation of the particular package to which you (we) are exporting. My understanding is that the amount of information returned is in some ways dependent on the 3rd party. For instance, Etabs returns more information per member than Risa 3d does. Things like end reactions etc. So, this may be more an issue of what features the 3rd party vendor took advantage of. There also may be some time-travel type paradoxes in re-importing new or changed info from an analysis package: lost or broken relationships, and that kind of thing. I haven't thought through that far enough to determine if it makes any sense but just wanted to throw it out there.

[david_peterson]

That seems to be part of the "It dose everything" "Problem" with Revit. While I love the concept, and it may not take long to find limits of 1 3rd party app, I haven't heard any one of my engineers say they only use 1 app.

We use Ram, Safe, E-tabs, Risa, and a few others. Our engineers like to use different apps for different systems in the building.

Here's yet another question. When RS says it works with Risa, is it just Risa 3d or will it work with Risa floor? Will it work with Ram, or the whole suite of Ram products.

The more I play with it, the more I wonder about the limitations of the product and how I may have been suckered in to the RS world by a Sales pitch. I want to see this product work (mainly because we've already paid for it) but I'm thinking that we will still have to check the 3rd party model against the RS model, which goes against the whole concept. Which brings me to my next point.

What happens if you get a hick-up with RS and you re-import the model, the member sizes don't change, you send out the drawings with wrong sizes on it because you took the "link" at it's word. When you realize it, the shops have been approved and now you have to eat the steel, or worse yet, it gets put up, constructed, commissioned, and collapses a year later. Dose Adesk pick up the tab? I didn't think so. At least in the 2d world you knew you had to check everything twice against the model. This kind of leaves me with a false sense of security. Sorry to go off on a rant, but I feel like what we bought and what we were sold are 2 different programs, and we got the wrong one.

[Tom Weir]

Hi,

We use Ram, Safe, E-tabs, Risa, and a few others. Our engineers like to use different apps for different systems in the buildingBut still the idea that you would only make one model in RS for use in all of those other programs, rather than re-building the model for each app. would seem to have genuine appeal for the engineer.

We need to keep seeing more apps. get on-board...

As for the validity of the re-imported data, hopefully experience spanning many projects will start with lots of checking at first, until one is satisfied that the integrity of the data is maintained during the import\export process.

Tom Weir
Los Angeles

[kmarsh]

To answer some of your questions David;
Risa3d (as far as I know) only offers a link to Risa3d but is working on a RisaFloor link. Here is Risa3d's statement about what features the link currently supports: http://www.risatech.com/partner/download/RISA-3DRevitStructureLink.pdf
Take a minute to read through that, it should answer some questions about what features are supported and which way (direction). For instance, it does indicate that only member size changes are mapped back into RS (as shown by experiment).

Basically (as I understand it) each 3rd party developer is responsible for making use of the information exposed by Revit Structure through the API (application program interface). This is information pertaining to grid locations, member locations and sizes, and other RS model information like loads etc. The 3rd party developers now have to take that information and programmatically create the analytical model in their software. The 3rd party can then send back a certain amount of information (this may be limited by the 3rd party functionality OR by the amount of information exposed for modification through the API by the Revit folks.) Additionally, Revit API provides a method for 3rd party developers to supply additional information about each member (enveloped end moments or max reactions etc). This is another area where each 3rd party is on their own to supply as much or as little information as they see fit. I do know that Revit is encouraging 3rd party development in this area of unique information returned from analysis to RS so I would expect to see this blossom in time.

You mentioned the apparent "need" to check the analytical model against the revit model: Like Tom said, this is probably a good idea anyway for a while, until a level of personal confidence is reached. To some degree, if you can get your engineers to start working with RS by showing them that it is not a "drafting" package but a BIM package, they really can do most or all of their analytical modeling with RS. There are obviously some features (moving loads, or spectral response loading, maybe others?) that are unique to an analysis package and need to be added in the 3rd party software. However, you wouldn't expect to have that info come back into RS. It really is a paradigm shift for both drafters/designers and engineers: to make full use of RS, we must progress toward a more flowing interaction between drafters and engineers, because you are both working on the same model.

If your salesman "sold" you that the engineers just keep on doing everything like "business as usual", then yes, you were sold a "bill of goods". The engineers need to evolve (can't believe I have to say this... we engineers are SUPPOSED to be technically savvy, into high-tech, forward thinking... but apparently, on the average, we're not. *hangs head dejectedly* perhaps, more likely, we were just dense enough to not switch to a finance major during any of the 5 calculus classes we suffered through)

So, what i'm getting to is simply that less "work" should be done in the analysis packages and more done in RS. Let the 3rd party stuff do the analysis, analyze the deflected shapes, check the unity's, prepare your analysis reports etc. but do the rest of the stuff (moving stuff around, adding members, loads and changing end releases) in RS, then enjoy the fact that all the sizes came out of your analysis package and updated automatically in RS and all your drawings are coordinated!!!! No more "so, Mr. Engineer, did you want the steel beam size you showed on the plan or on the elevation? Because we priced the smaller one.... ;)

Anyway, I'm looking forward to RS, I haven't yet been able to convince my old school purse-string-holders to go for it yet, but i'm working on 'em.

[david_peterson]

I think it'd be great to never need to draw a plan again, and let the EOR make his/her own mistakes and I stick to the detailing. If those darn Architects and MEP people could figure out how much room a W24 beam takes up, I wouldn't need to even think out this. :-P

[Tom Weir]

Hi,
I have been seeing things evolve in my office for two years. At first we just started modeling in the original Revit package (5.1 through 7.0). Of course, there was no analytical link then. The engineers were not very involved in the production of the physical models then. But they started seeing that BIM and modeling could produce a more accurate and coordinated set of construction documents.

But now that RS2 is out and the analytical link has been established I see they are taking more notice. It is a "paradigm shift" in workflow, and in a busy office not an easy thing to do.

On one job I am doing the engineers wanted to use the analytical model to compare to what they had done in SAP and ETABS independantly. Since the Revit analytical model was already there it was easy to accomplish. And I think that will help them feel more comfortable with the process.

On another job with a complicated column layout they had me write the analytical model to an ETABS file, then they exported that model to SAP. It saved them a great deal of time. Word is getting out...

I just bought 2 network floating licenses for the engineers to use so they can now be more involved in the Revit model building process.

I also am starting training sessions for engineers with the idea of concentrating on the integration link issues. I also want them to at least be able to open the Revit model file, zoom and pan, view the 3D model, spin it around. Before long I expect they will want to work in Revit and save their changes. One good example is the graphical column schedule. To update column sizes throughout the project, the engineer can simply open the schedule, highlight the column, change the column size as needed, and bingo... he is done. No mark-ups for the draftsperson, no checking the mark-ups afterwards.

That's how I am trying to involve engineers and segue to the new workflow environment, and trying to break down the old way of ...engineers on this side.....draftspersons on thiat side.....attitude.

Tom Weir
Los Angeles

[kmarsh]

The really fun part (to me) is just that: the way RS allows worksets, you can break up the work-flow any way you like. You manage the plans as much or as little as you collectively decide and break up the worksets thusly.

For instance, (as i understand it) you could manage the member locations etc. and the engineers can have the loadings and member end releases to play with (in which case, they still get to make their own mistakes like before) or you could actually let the engineers build the model and you manage the sheet set and do all the detailing (nice that your sections will be auto-coordinated to the cuts on the plans... ;) In our situation, the engineers do more of the framing and are ultimately and solely responsible for the content of the drawings no matter who worked on it, so a more flexible flow happens around here between drafts-people and engineers working in the drawings. (we're also small enough that this works very easily. Much bigger and it would obviously start to break-down)

Anyhow, I'm very excited about RS and hope that you'll brush the dust off of your copy and take a stab or 3 at it; the bumps in the road are only bumps. As I've said before, I've thoroughly reviewed Tekla Structures and CSC's 3D+ as well as RS and as far as I'm concerned, RS is the package that is, by far, most geared to getting the work of structural engineering done. Note that I didn't say structural drafting; I mean the business of structural engineering in total. In the final analysis, I think we'll find that RS will beat Autocad + Separate analysis/design packages without question; it's just not easy to see around the learning curve.

Please also believe that I share your concern for the safety of the buildings that "we" design and construct. I can only see RS as an improvement to the process. As it stands now, we have a better chance of missing the transfer of a member size from RAM or RISA onto the Acad drawing now, than with RS. In fact, I committed exactly this error several years ago and, luckily, the wet-weight of the concrete exposed the one beam that was missed. If the model and the drawings had been auto-linked, we would've had a reduced possibility for human error. I'm not suggesting that we trust these things blindly, far from it; but I believe that we should take advantage of every tool available to help us create a safe and fully coordinated set of drawings.

Best Wishes!
-ken

[emile.kfouri]

Thank you so much to Ken, Tom et al for all your comments and feedback. Some very important issues have been brought up about the link with analysis tools. Revit Structure was designed from the ground up to play nice with everyone. (DWG, ADT, DGN, RVT, and all the analysis and design tools that you have on your desktop). In most cases what you see as far as the link to analysis tools are the proof of concept that our partners originally implemented. They are all working very hard to take advantage of all the available API capabilities in R2. We are also working very hard to make sure that by the time R3 comes out the partners will have everything they need to support the workflow that their users demand. If you want to see a specific program linked to Revit Structure or you want to see a specific workflow supported, please relay that to the analysis and design software providers and post it on AUGI for us all to talk about. Also contact them to find out what the supported capabilities are of each program. They vary buy product and company.

In short what you see now is simply the first pass by our partners and us. Tom put it quite well when he explained how the engineers are starting to be interested in Revit Structure as they learn more about what it offers. Autodesk and our partners are also constantly talking to our users to see what they need and how we can continue to improve the program and help address their needs.

You have a great opportunity to influence how these analysis and design tools will work with Revit Structure.

Emile
Revit Structure – Product Design Lead

[gkite]

Hi,
I have been seeing things evolve in my office for two years. At first we just started modeling in the original Revit package (5.1 through 7.0). Of course, there was no analytical link then. The engineers were not very involved in the production of the physical models then. But they started seeing that BIM and modeling could produce a more accurate and coordinated set of construction documents.

But now that RS2 is out and the analytical link has been established I see they are taking more notice. It is a "paradigm shift" in workflow, and in a busy office not an easy thing to do.This is encouraging as we are just now beginning to involve our engineering staff into our leap into RS and they certainly have some concerns. It does however appear that the more we expose our staff to the benfits of collaborating our workflow within the same model, the more obvious the advantages become.

I am also anxious for the analysis software partners to complete (or at least refine) their work on the links to RS as I see that being the largest selling point to our engineering staff. I understand when Emile explains that what we have seen thus far is a first pass but the ability to transfer the data from the RS model to the analysis software and then back again (and again, and again) is critical in my being able to implement RS companywide.

[David Sammons]

...So, what i'm getting to is simply that less "work" should be done in the analysis
packages and more done in RS...

I just started my first 'real' project where I will have a chance to use RS and the interface with ETABS. The project is a four story steel frame building and I plan to do as much of the modeling in RS and then export to ETABS for the analysis and design.

I will keep this thread informed on how this goes. Hopefully, I can have most of this done in time to share at AU.

[Paul Andersen]

This is an excellent thread. Thanks for getting this one started Tom and to all who have contributed thus far. Over the past 8-10 years our firm has been utilizing several software packages with our primary goal being an integrated analytical model and construction document set. We've had mixed results to this point with most schemes either completely breaking down or becoming too cumbersome to use somewhere after the initial design development and into the early construction document phases of a project.

Revit and RS has caught our eye for several reasons. At the technician level we see the power of the parametric engine. We can be confident that the construction documents are fully coordinated and are able to show views and information that wasn't possible before. On the engineering side we immediately saw that the RS Team was on the right track for integration with a wide variety of analytical software packages. We are currently in the process of transitioning our entire technician staff to RS. The engineers are starting to see the power of Revit and are becoming more interested.

In discussions that we have had with our reseller, analytical software developers, and the RS Team it is our understanding that the RS Team has provided the API and is willing to work with any analytical software developer on a link. Thus, the ball is in the analytical software developers court to make these links happen and during this linking process will probably spur some changes to RS. The analytical software developers are primarily responsible for how much of their software works with RS and what features they are going to take advantage of. I think it is ultimately going to be up to the early adopters of RS to help shape the capabilities of these links. We need to be proactive with our analytical software developers and let them know that we not only want a link with RS but help them understand the work flow and features that we are interested in. When we first started asking some of our favorite analytical software developers about a link to RS one didn't even know it existed and two others were aware but waiting to see if RS was for real.

It is important to note that the analytical software developers have to put some significant effort into making these links work and be productive. Some even have to hire new staff specifically to develop and test this link as their current staff is too busy making changes and updates to their core software. Therefore, they need to know that the users of their software are on Revit Structure and that the link to RS is very important to us. Otherwise the link remains a side project for them rather than the priority I think we all want it to be.

[Tom Weir]

Hi,
One of my main concerns though is that we have to sell the idea to our engineers and yet the software is still barely out of beta. As I understand it ETABS 9 is required, and yet is still in BETA.
It's somewhat like the chicken and the egg: which comes first? Will the software developers spend the money to develop the link before the engineering community gets on board? Will the engineering community get on board before the software companies have developed the links? I am sure there is some tipping point. As Emile says we need to make sure the software developers are aware that we want and need their help.
Do we (or can we) know anything about other software vendors currently developing the API for their software, like RAM?

Tom Weir
Los Angeles

[David Sammons]

I do not know about RAM but I frequently remind CSI about the importance of linking ETABS, as well as SAP2000, to RS since we predominantly use CSI's software.

Although ETABS V9 is still a beta version, it is my understanding that the release for V9 will be sometime within the next 30 days. In the meantime, we are using ETABS V9 beta for the RS link and verifying the results with ETABS V8.5.4.

[Paul Andersen]

I agree. The major hold up for us fully implementing RS is not only that a link exist but that it be of production quality and with the software packages that we prefer namely RAM, and Visual Analysis. We do not need all of the bells and whistles which will come in time but we do need the design tools that our engineers prefer and are fully trained on to be able to communicate construction document specific changes to RS with confidence. I know this is just a matter of time but some realistic deadlines of what packages with what functionality will be available in the near future would go a long way with regards to our deployment strategy of RS firm wide. To say that RISA links with RS is not enough and is somewhat misleading as RS does communicate with RISA3D but currently not with RISA Floor which is what we would primarily need for several projects. These deadlines would probably need to come from RAM, ETABS, RISA and the like since they are doing the bulk of the development. I will post to this thread with any deadlines that I can confirm from a valid source.

[emile.kfouri]

Hi all,

I thought you may be interested in the RAM to Revit Structure link press release.

http://www.ramint.com/news/05-09-27.jsp

Emile

[Terry Jordan]

We've already signed up to be beta testers for the Revit to RAM link. I was lead to believe that the link had already been released and it would be only a matter of time before we received it. Then I was perusing RAM's website one day and came across the same page as Emile.

Does anyone else share their 3D models with fabricators? We've been doing it for a couple of years and it has worked out quite well. We've been able to shave weeks off of project schedules. Of course, coordination between the construction documents and the analysis model have been somewhat of a headache. RS should cure that, but I can't help but think how much better it would be if we could just send the fabricator our RS model. The building model, not the analysis model. It would be so much more accurate and more complete and it seems like it would be possible.

Hopefully the developers at SDS/2, Tekla, etc. will see the value in creating such a link.

[Tom Weir]

Thanks Emile. That's great news about RAM...

Tom

[Terry Jordan]

I just spoke with Doug Evans with Design Data (SDS/2) and he told me that they have no intention of developing a link to RS. He reminded me that SDS/2 is already CIS/2 compatible and that it is in Autodesk's court to make RS CIS/2 compatible. That makes a great deal of sense.

So I guess the question is; when will RS be able to export to CIS/2 format, if ever?

[James.Lupton]

We do a lot of our work for contractors where we build the BIM on their behalf from the design information coming from other engineers.

We have been using Xsteel since 1997 and over the years we have saved a lot of time by taking a lot of the geometry of a structural model directly from the SDNF file.

CIS/2 gives a better capability in terms of information transfer however in addition to RS export to SDNF and CIS/2 I would like to see import options for these 2 standards.

Tekla's Xsteel can read both format's

On the subject of passing the model on to the fabricator I can also report that this model has a value. One of our contractor clients recently negotiated a £10,000 reduction in the fabricators tender as a result of passing on the model for the structure.

This was a reasonable size project however it makes the point that there is added value in providing a BIM.

We typically use as a guide a value of £10 - £15 per tonne depending on the complexity of the job and we always insist that the fabricator signs an acceptance of responsibility for the model before passing it on.

[rita.wong]

I work in a structural engineering firm and I am evaluating Revit Structure. I have some questions related to analytical modelling in Revit.

Is there a way to graphically see member releases in Revit (without clicking into the member's properties)?

Does the link to Etabs work for Revit Release 2? I had established the link for Release 1 previously, but after installing R2 and revising the paths in the Revit INI file editor to the new folder for Revit 2, nothing happens when I click "Send Model to Etabs".

By the way, for metric steel member sizes, is there a way to change the designation to match the Canadian designations (using whole numbers for the member weight)?

[Paul Andersen]

With regards to the member size designations, I would recommend that you check out this thread.

[rita.wong]

Thanks, Paul for the suggestion. I have managed to re-establish the link between Revit R2 and Etabs.

This leads to my next question. I presume that most contributors to this discussion group are based in the US, so it may not be a concern.

I built my Revit model with metric steel sizes, but when I export to Etabs (defaulted to start with imperial sizes), many members are not recognized, and some members were not brought in at all. Other than re-assigning all members as imperial sizes in Revit, is there another way around this?

I tried creating a template .edb file in Etabs and chose this .edb when starting Etabs from Revit, but it caused a run-time error.

I also tried exporting the Revit model as an EXR file. After selecting the .edb template file on start-up, I imported the EXR file into Etabs, but still the sizes were not recognized, and actually, none of the members were brought in. Any suggestions?

I'm also interested in your previous discussion about the flow of the Revit model. For those firms who have implemented Revit, what is the flow path in your firm? (model started by drafters --> engineers --> drafters, or engineers --> drafters) We're considering the implementation of a BIM software, so I would appreciate it if you wouldn't mind sharing your advice/experience.

Thanks.

[mvicentelo]

Rita it's an old post, i work with metric units and all it's running ok., see post :
---------------------------------------------------------
.EXR file

I hope this can help to others RS/ETABS users. After install Etabs V9 and Revit Structure you need install CSIxRevit plugin, this plugin enable on RS "External Tools" in Tools menu, to send RS model to Etabs and update Model from Etabs, this task create files with extension .EXR, and then you can Import from Etabs an RS model to perform detailed structural.
--------------------------------------------------------------


regards

Milton Vicentelo

[rita.wong]

Milton,

After exporting as .EXR from Revit, what do you select when starting Etabs? Does your Etabs program start with metric sizes in the frame sections library (mine starts with imperial sizes as a default)?

These are the steps I took after starting Etabs:
1. Use New Model - choose .edb
2. I chose an .edb file where there is only a simple grid defined, and metric steel sizes have been defined (from CISC.pro).

But Etabs still does not recognize the metric steel members from Revit, and the model is not brought in.

Is there a way to change the defaults in the Etabs program?

Thanks,
Rita

[rita.wong]

Hello all,

A few of you have mentioned that you are using Revit and Etabs v9 on some projects. Have engineers encountered any problems with load distribution in Etabs (for example, loads not being transferred properly from secondary beams to main girders)? I've tried using area loads (floor area defined as slab or deck in Etabs) and line loads, but I got the same errors with each method.

CSI has informed me that there's a bug with the import of slabs from Revit, and that this has been corrected in Etabs v9 beta H. But some engineers must have used this product prior to v9 beta F (my current version)?

Any advice/input would be greatly appreciated!