Integration Between Autodesk Revit Structure andaucache.autodesk.com/au2011/sessions/4676/class... · Integration Between Autodesk Revit Structure and Analysis ... concrete walls

Integration Between Autodesk Revit Structure and Analysis Mary Beth Hamilton, EI, LEED AP BD+C - Clark Nexsen Architecture and Engineering- Raleigh, NC

SE4676: Establishing a link between your analytical software and your structural modeling software is very beneficial for both the engineer and drafter/designer. This class focuses on the bidirectional link between Revit Structure and Bentley® RAM Structural System. This class will introduce the link and go over some of the basics of the workflow. We will focus extensively on techniques and lessons learned from a structural engineer's perspective.

Learning Objectives At the end of this class, you will be able to:

• Explain the importance of linking 3D structural analytical models with 3D drafting models

• Perform basic integration between Autodesk Revit Structure 2012 and Bentley RAM Structural System V8i.

• Describe techniques and lessons learned to promote a smoother transition between your two models.

• Answer the questions “What do I abandon in my Revit and/or analytical models?” and “When do I abandon my link?”

About the Speaker

Mary Beth Hamilton is a structural engineering intern (EI) in Clark Nexsen’s Raleigh Office. She has been with Clark Nexsen, a Norfolk, Virginia, based company for three years. Mary Beth has a civil engineering degree from North Carolina State University. She has been using Autodesk® AutoCAD® and Revit® for three to four years now. Most of her efforts are concentrated on using Revit to its full potential as a tool to help make the engineer and designer’s life a little easier; whether it be interdisciplinary or intradisciplinary. Mary Beth focuses a lot of her time on integrating structural analytical modeling software with Autodesk Revit. She has experience with analytical modeling in Bentley® RAM, Autodesk Robot™, Risa 3D, and CSC Fastrak. She has taught many internal webinars on the topic of integration between these modeling software and Revit. You can contacted her at [email protected].

Integration Between Autodesk Revit Structure and Analysis

2 Mary Beth Hamilton [email protected]

Summary: Items Covered in Handout 1. Importance/benefits of a link between your 3D structural analytical model and your 3D BIM

model. 2. Introduction to link between Autodesk Revit Structure (Revit) and Bentley RAM Structural

System V8i (RAM). 3. Target workflow for bidirectional link between Revit and RAM. 4. Recommended workflow for bidirectional link between Revit and RAM with lessons learned

incorporated. 5. Additional Lessons Learned. 6. Additional Resources.

1. Importance/benefits of a link between your 3D structural analytical model and your 3D BIM model.

There are many benefits when you link your 3D structural analytical model with your 3D BIM model regardless of what software you use. The two main benefits are reduction in time and errors.

Reduction in Time: It takes a lot less time to create one model versus two models. There will always be elements that are modeled easier in one software over the other; but usually you will only have to model each member once in either one location or the other. Amendments will also be easier to manage without duplicating efforts because you can eliminate tedious redlining.

Reduction in Errors: By having your models linked, there is easier collaboration between engineer and designer; creating fewer errors. Additionally, there will be less interpretation errors. If the engineer or the designer has a complex design change, it will be easier to visualize without misinterpretations if models are linked.

2. Introduction to link between Autodesk Revit Structure (Revit) and Bentley RAM Structural System V8i (RAM).

Bentley has developed a bidirectional link between their software RAM Structural System V8i (RAM) and Autodesk Revit Structure (Revit). This link can be downloaded from their website (http://www.bentley.com/en-US/Promo/Structural+Team/RSS+Revit.htm). Also on their website you can find a user guide, some tutorials, some best practices, and some tips and tricks. Links to these items can be found in the additional resources section.

Currently in my office I am using RAM version 14.04.02 and Revit 2012. The most updated link is version 3.6.0.1. The information in this handout corresponds with the aforementioned versions of the software and the link. According to Bentley, a new version of the link will be available in the next few weeks. So be sure to check Bentley’s website for updates; with each new release comes more capabilities and a smoother transition between RAM and Revit.

The RAM environment is divided into modules. In my office, we have licenses to all the modules shown in the following screen shot (regardless of the color of the module’s status). My knowledge of the link is limited to these modules. I have spent the most time investigating the link with steel structures but I have basic knowledge of the link applicable to concrete elements.

http://www.bentley.com/en-US/Promo/Structural+Team/RSS+Revit.htm�



This handout is written with the assumption that the reader has basic knowledge of both RAM and Revit; most importantly that the reader understands how to model members in both programs.



3. Target workflow for bidirectional link between Revit and RAM.

The ultimate goal for this bidirectional link is to be able to create a model in either Revit or RAM and have it transition smoothly from one software to the other by utilizing the link. To then have the capability to modify your model in either location and still maintain the link without losing elements or creating errors.

The target or ideal workflow would be like the flow chart below. This example starts in Revit but similarly you would have the capability to complete the same tasks if started in RAM.

1. Create all linked elements (including beams, columns, grids,

foundations, slabs, and joists).

2. Designate elements as either gravity or lateral.

3.Add Loading in modeler.

4. Run data check in modeler with no errors.

5. Run through modules with no errors.

6. Import model with no errors and all elements visually

displayed as desired.

7. Make changes/ modifications to

members. 8. Run data check in

modeler with no errors.

9. Make additional changes/ modifications

to members.

10. Run through modules with no errors. . . .

REPEAT steps 6-10 above until models are complete

and accurate.

Revit RAM

Export

Export

Import

Import



4. Recommended workflow for bidirectional link between Revit and RAM with lessons learned incorporated.

In reality, the link has not reached the point in development that such a smooth transition/workflow is obtainable. Our office has been working with the link now for about 2 years. There has been definite progress with the development of the link but, there is, and will always be, room for improvement.

The workflow that follows is what I have developed that seems to work the best for our company for an initial link. I have incorporated all of the lessons learned along the way.

Draft Grid Lines, Levels, Beams, Slabs and Columns

• Starting your model in Revit is more accurate in regards to precision. Revit uses fractions where RAM uses decimal.

• Do not model foundations, concrete walls or braces where applicable; these work better when created in RAM.

• For beams to export accurately to RAM the levels in Revit need to be set to the top of steel elevation. This means graphically in Revit to be accurate the slabs must be raised from the level the thickness of the slab (i.e: composite deck raised 5-3/4” from level so that it appears to bear on beams).

Designate Lateral Columns and Beams

• The location for this setting has changed in Revit 2012, this setting is located under the analyze tab analytic adjustment. You must have all analytical model categories turned on in visibility graphics. Set “Analyze As” to “Lateral” in properties dialog.

Create Revit model from template.

Revit RAM

Note: I have tried every other option, including the z-level offset for the beams, which just moves the physical beam in Revit while keeping the analytical endpoints the same. Your beams create “unsupported” errors in RAM and create issues when adding braces.



Create Building Area Worksets and Selection Sets

• Create a workset that only contains elements that are involved with the link. There are many detailing items and items analyzed outside of RAM that do not need to be linked and might potentially create errors. If you are creating multiple RAM models for different areas of the building, possibly caused by an expansion joint, you would need to utilize multiple worksets.

• When worksets are utilized you will need to select all grid lines for the entire building and select all elements in the workset or building area workset desired and export to RAM only selected members. Selecting all grid lines helps each section to import/export in the correct location. For the selection process you can create a selection set that contains elements to be linked and the grid lines.

Before Export, Check Mapping

• Make sure that steel and concrete members are mapped to correct library locations. If the locations are not found the text will be red in the mapping dialog.

• Decks are tricky. When exporting for the first time the export creates the RAM file so you can’t use the Map to RSS option. You have to create each mapping manually. The “Deck Type Label” and all the properties must match those of RAM exactly for it to recognize the existence of the deck and the correct deck. If your model has already been created you can use the Map to RSS option which is found in the mapping editor in the edit drop down when in the deck tab.

Complete Building

Workset = Building Area A Workset = Building Area B

Revit RAM



Open RAM Model that was Generated by Revit. Things to Check in Modeler Include:

• Cantilevers: RAM and Revit do not communicate these well. These need to be checked every time. Bentley has developed a worksheet about modeling cantilevers in Revit. This is available on their Wiki page (address in additional resources section). These instructions involve modeling the cantilever as a separate beam and adjusting the “Moment Connection Start/End” for both beams. You will also have to insure the “Structural Usage” and “Analyze As” is set the same for both members. Even after following these steps cantilevers don’t always translate well. It is better to be safe and check them.

• Fixities: Just because you labeled members as lateral and/or prescribed fixities, fixities do not go between models (believe me, I’ve tried). The link has defaults for specific members. This must be checked every time you export to RAM. Usually once you set beams and brace fixities in RAM they remain the same; column fixities are the tricky ones. For columns all fixities are maintained once set in RAM except the base support which always defaults to fixed/fixed/fixed ever time your export to RAM.

• If you had levels in Revit that are not needed in RAM make sure to delete these in “Story” and “Layout Type.” Also verify in “Story” that your levels from Revit were linked in the correct order.

• Verify slabs/decks were mapped correctly and appear as desired. Check orientation.

• When you export to RAM some modules might have a green light. This is by default; it does not mean the new changes have been checked in the modules, this is a quirk of the link.

Revit RAM

Export Model to RAM

• This will create the RAM File (.rss). Make sure to coordinate file name and location.

• Make sure to look at export dialog and note any errors.

Stories not imported in correct order.



Elements to Model in RAM Modeler Include:

• Braces: These are modeled in RAM first because RAM is picky regarding the endpoints of braces in relation to the beams and columns. If modeled in Revit it is almost impossible to connect to the correct location. When modeled in Revit the braces tend to delete automatically once you run the datacheck in RAM with the error “detached from Node” or “not attached to frame member.” According to Bentley, braces in RAM are associated with the top story in which they frame. They say that to add your braces in Revit you should set the “Reference Level” for the brace to the story at the top end of the brace. I have not been successful doing this so I always add them in RAM so that when they are exported to Revit they have the required endpoints.

• Foundations: Easier to be modeled in RAM first. But will still go through link if modeled in Revit.

• Walls: Easier to model in RAM first. • Columns and Beams can be modified and

added. Note that Beams added in RAM import into Revit with joist as their structural usage for some reason. Edit in Revit as necessary.

All other elements (loads, brace points, size restrictions, etc.) and modules (steel, concrete, frame, etc.) proceed as usual

within RAM.

Revit RAM

The GRIDS should not be moved within RAM. If a grid needs to be moved, move it in Revit and re-export model to RAM. This goes back to the precision issue, fraction

versus decimal.



Revit RAM

Before Importing Model

• If you added any members that have a decimal in the title in RAM, i.e. L2.5x2.5x1/2 you will have to edit the member name within Revit. When going from RAM to Revit, RAM looks for the exact name. These names do not match because Revit uses fractions in the name. The name must be modified in Revit.

• Properties in Revit must also be modified for double angles (2L), all double angles import in with 0” spacing between angles because that is the name that matches exactly. RAM does not include spacing between angles as part of the member name. If you want a different spacing you will have to edit the member properties.

• If you did not make any modifications to the slab/deck boundary and type, I would recommend not updating the slab. To accomplish this just uncheck update slab box. (Note: Updating openings is still a good thing; openings can be added in either RAM or Revit.)

• If you decide to update slab it will come in at level elevation and will have to be moved up if your level elevations are as described above.

• If you have an expansion joint and choose to update your slab when importing one section of the building the slab on the other section will delete.

• Even though you have mapped the Revit libraries and RAM has an assigned place to look for newly added members, if the size it is looking for is not loaded into the model already, you will get an error (i.e., if you changed a member to a W24x68 within RAM and you have not used that size in Revit, you will have to load it into the model prior to importing to not get an error).

This information is not part of RAM naming. All

2L3.5x3.5x5/16 regardless of spacing are imported as

“2L3.5x3.5x5/16.”



Revit RAM

Import RAM Model into Revit

• When importing be sure that under the “Collaborate” tab you have the correct “Active Workset” chosen.

• Make sure to watch dialog box and note if there are any errors.

Things to Check in Revit once Model Imported

• Cantilevers. Need to always be checked as aforementioned.

• Make sure to check your slab. If your slab was updated, make sure it was updated correctly and didn’t delete another slab. If slab was not updated make sure to make any desired changes/updates.

• Braces can sometimes be problematic. The important part is no matter how they look once imported to Revit do not move the analytical end points or you will lose them in RAM on your next export. There are work-arounds if they do not look right in Revit. In our office we will mask the linked braces with a non-analyzed brace that is visually correct for other disciplines to see and to show in your brace frame elevations. Different import problems I have had include: braces attaching to the bottom of footings, and braces attaching to top of slab.

• If you import reactions or stud counts for beams make sure they come in correctly with your tags. You might have to edit your beam tags. There is a check box in the import dialog for the type of brackets you desire; however, if you neglect to check the box “Enclose In Brackets” you still get them. Sometimes lateral beams have stud counts that come in that are incorrect because you once ran them as gravity in RAM.



5. Additional Lessons Learned

The following are some other lessons learned that I couldn’t find a place for in the initial link flow chart. Some of these items are things I discovered while reading some tips and tricks on Bentley’s website.

• We usually link our model 5-10 times. We usually stop using the link once our design gets to about 50%. Past this point it is very time consuming to link your models. It also requires someone who is very knowledgeable in both Revit and RAM.

• Brace points can be added within RAM. But if a beam moves while in Revit and is export to RAM in a new location the brace points will not move with it. You will have to check these manually.

• Unbraced length for braces is maintained through link. • If your base elevation is not 0,0 there is a supposedly a new feature in the Link that allows

you to define an offset for the Revit model. When the model is exported to RAM it is created at the 0,0,0 origin. But when imported back from RAM the offset is used to locate the model in Revit. One of my co-workers has been working with this feature and what he has determined is that if you have a Revit model located a certain height above 0,0,0 you will need to put that value in as a positive number in the “Offset” tab of the “Export Settings” when you export to RAM. When importing the same model back to Revit you will not need to edit the “Offset” values, just leave them set to 0,0,0.

• You can run tools in Revit Structure to verify analytical model before you export to RAM which might help with some errors.

• Continuous footings cannot be imported from RAM because they are not supported in Revit.

Revit RAM

From here on out it becomes tricky. If you continue to have the models linked

you need to make sure that you aren’t making changes in both your Revit model and your RAM Model. Typically what we do is have the Designer work on all things that aren’t modeled in RAM. These items can be set as not to Analyze

and not put on the worksets/selection sets for RAM export. Designer would let the Engineer know if something comes up that involves altering a RAM

integrated element. The Engineer can continue to work on their design in RAM and either do redlines for changes in Revit or have the Designer re-import the

model from RAM. You can just import specific items if necessary. At this point it just takes the Engineer and Designer being conscious of how, where, and what is modeled. It requires coordination and there is a learning curve. At some point

you will have to let your link go because it will be too time consuming to maintain.



• Pile cap footings are not exported to RAM. • When you import your RAM model into Revit your isolated foundations will import named as

Length x Width x Thickness, in inches. This is not how you label your isolated foundations typically. Because of this I usually either not update my foundations through the link once I renamed them, or I let me link go prior to creating a foundation schedule.

• Wall openings are not transferred for lateral walls. • You can now model multistory columns in Revit and they remain multistory when you update

the model from RAM. If you start in RAM they are always imported as story to story • Moment connections within RAM generating moment symbols within Revit. • Only rectangular concrete beams are supported with the link. • Walls can also be modeled first in Revit. They will export to RAM but for some reason I can’t

get them to look right when I model them first in Revit. I can get the link to distinguish gravity versus lateral walls created in Revit; “bearing walls” export as gravity and “structural combined walls” export as lateral.

• Point loads and line loads can go through the link, however, surface loads cannot. • Curved beams are not exported to RAM. • If you have an isolated footing that is not centered under the column. This does not translate

to RAM or back to Revit. • Due to differences in how data for castellated and cellular beams is stored (with the family

symbol data in Revit, with the beam in RAM) sizes are not updated in Revit after performing a design in RAM.

6. Additional Resources.

RAM Revit Link Wiki Page on Bentley’s website: http://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/ram-structural-system-revit-link.aspx

RAM/Revit FAQs on Bentley’s website: ftp://ftp2.bentley.com/dist/collateral/Web/QA_log_Answered_questions_final.pdf

Download RAM to Revit Link: http://www.bentley.com/en-US/Promo/Structural+Team/RSS+Revit.htm

http://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/ram-structural-system-revit-link.aspx�

http://communities.bentley.com/products/structural/structural_analysis___design/w/structural_analysis_and_design__wiki/ram-structural-system-revit-link.aspx�

ftp://ftp2.bentley.com/dist/collateral/Web/QA_log_Answered_questions_final.pdf�

http://www.bentley.com/en-US/Promo/Structural+Team/RSS+Revit.htm�

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Integration Between Autodesk Revit Structure andaucache.autodesk.com/au2011/sessions/4676/class... · Integration Between Autodesk Revit Structure and Analysis ... concrete walls