Revit Structure, Under the Hood
Fad or fiction, Building Information Modeling (BIM) and Autodesk® Revit® Structure are here to stay despite the naysaying. This article uncovers the critical path of Revit utilization and identifies key strategies, pitfalls, and methods to maximize Revit Structure use.
If you spent a great deal of money on a high-performance car would you keep it in the garage or would you open up the hood, kick the tires, and take it out for some extreme racing to see how the car handles? After a good run you may then decide that the engine needs a few tweaks or the steering may be a little stiff and needs adjustment.
So what does this have to do with Revit Structure and why did you decide to read this article? Many people believe that the greatest cost of implementing BIM is the software; this may very well be the case if you have hundreds of licenses to worry about. Actually, the largest cost of implementing the software is you, the user. Somewhere between the downtime it takes to learn, adapt, and use the software and the unproductive moments looking for answers and unforeseen changes that wreak havoc on your previous well-oiled machine, you begin to question your investment. I have heard many an argument about the economy and not being able to afford training, yet I haven’t seen one business person who can show me how that math adds up.
There are many who argue, “Why use Revit and stay with flat CAD?” I would argue that if you plan to use Revit the same way you use CAD, then you should save your money and stay in CAD. If you actually want to utilize Revit and the BIM process and strategies you must change your current design paradigm. Some call this hybrid thinking, others call it parametric thinking. If you have read Randy Deutsch’s book, BIM & Integrated Design, you may call it integrated thinking. Either way you look at it, at first you’re going to love Revit, hate Revit, suck at it, hate Revit, and eventually hold some software salesperson accountable for either your success or failure.
Symptoms of BIM / Revit Meltdown
I know we have all heard the horror stories, “So and so used Revit and it has ruined their business” claims that it doesn’t work. How is it that there are thousands globally making it work and competing at a high level? Did Autodesk pay off all of these customers? (I actually had a customer once claim this.) After a few years working for an Autodesk reseller I found a few common themes. Among the major themes, either a lack of training or self-teaching were the most common. Other areas were lack of creating metrics, over/under-modeling, and unrealistic expectations. These techniques may have worked in the past, so why don’t they work now with Revit?
The “blind leading the blind” mentality for training your co-workers was adopted from the CAD world and worked fairly well. There were very few teachers of the software and most of the learning was through the “self-taught” method. When CAD was introduced and adopted we utilized the same methods for drawing as we did drawing by hand on the board. Although there was an increase in productivity this new method of CAD didn’t change the way we designed.
Changing Education Paradigms
Many firms caught up in over/under-modeling were not trained sufficiently on the family editor and/or were trying to run while they still had no legs. At last year’s Autodesk University Design Technology Managers Conference my GURU brief hit a chord and was awarded top honors. [Insert Hyperlink http://www.therevitcoach.com/2011/01/design-technology-managers-conference.html ]. Many of the major points shared were critical insights on technology utilization and business strategic planning. One point “do not bite off more than you can chew” can be seen as a metaphor. If you were forced to eat a 12- course meal in 30 minutes, would you enjoy it or would you get sick? We didn’t utilize CAD overnight, why should we expect to use Revit the same way?
Create and outline a crawl, walk, run strategy for each software, tool, and tactic you want to deploy. Keep in mind, you will probably not be very good at using or understanding Revit at first and you will need to rely on an expert until you and your team are actually any good. This doesn’t just include the tools, but also the process. I call this nexus of talents and synergy collaborative consulting. At CAD Training Online, our Virtual Instructor-Led training is adaptable to many companies needs and provides “just in time” training, creating a great value for when you really need it.
Changing Process Paradigms
In 2009 Carl Bass, Autodesk CEO, talked about being in the “Technology Sweet Spot” where we have just overcome the impossible and impracticality of technology use and where we enter into the realm of the possible. This spot is at the critical transition where it is beginning to be expected and then eventually required. BIM and many Revit tools are currently in this technology sweet spot. As Autodesk expands the use of the Revit API we will see more BIM uses extend into construction and manufacturing.
In flat CAD we spent the majority of our time managing the changes we made between design phases. This was partially attributable to the technology, but also on the means of using CAD technology.
Revit was created to be a change management engine (Revit = Revise-it). As changes happen in the model these changes were fed back to the different views and details throughout the drawing. Some objects could maintain association to others and further improve the feedback process of design and drafting. This began to enhance our ability to provide initial analysis of a project without going to additional tools and rebuilding another model. Most firms that claim that BIM/Revit didn’t work for them only replaced Revit with CAD without changing their processes, enhancing their delivery, or changing deliverables. I often hear, “I want my drawings to look exactly the same as they did before!” Huh? We all know the definition of insanity: “Doing the same thing, expecting different results.”
Imagine if we could use that time to provide integrated analysis, validation, and alternatives?
Figure 2: Design + Analysis
We don’t need to imagine it; the technology actually enables us to do it! We can begin to get educated on these strategies, learn how to properly use the technical tools, and create a business tactic to accomplish them.
Changing Education Paradigms
We wouldn’t allow a doctor to begin using a new state-of-the-art piece of equipment unless he had worked many hours in simulated practice and had been certified by the equipment manufacturer to operate it, would we? Autodesk and its resellers and Authorized Training Centers have had to change their business paradigms to hire industry-experienced people and to train them both technically and theoretically on how the software is intended to be used and via best workflow practices.
CAD Training Online prides itself on having industry expertise; all of our consultants and educators are from industry and many are still in industry, which allows their teaching to have context and relevance.
Effective deployment approach is:
Since BIM is not “one size fits all,” it is appropriate to understand a company’s assets. Most effective consultants will not preach to their clients, but to optimize their time will use Covey’s principle to “Seek first to understand” before requesting to be “understood.” Providing a proper blend of talents, business objectives, strategies, and current deliverables will assist in outlining changes that will be required and decide when best to implement them (i.e., when, what, and how) so as not to disrupt the business.
In order to have synergy between teams, talents, and technology (T^3) we must understand how to appropriately leverage and integrate them for most effective use. It is important to understand current documentation standards, custom applications, and consultant workflow. Whether you are a structural/mechanical consultant or an architect, you must assess how you will integrate with your consultants.
Outlining a critical path and proposed strategies will be essential. You must set a big picture of what you want to accomplish, reveal obstacles and opportunities that will be best used with the technology. Drawing from Covey’s principle of self-mastery by “beginning with the end in mind,” a good plan will outline everything you hope or intend to accomplish by using BIM and will be broken down into essential phases and steps to complete. These steps should follow the SMART method: Specific, Measurable, Attainable, Realistic, and Timed.
This begins by defining who needs to be trained, in what phase, and to what level. Outline what level of detail we will model; only an experienced Revit consultant will know how to keep a good balance of modeling effort for each phase of implementation. Outline which legacy content will be converted and what will become reference material. Outline BIM strategic use and company goals. This is usually called an Implementation roadmap. This should also include hardware and software requirements, pilot project(s) selection, contract delivery model, and critical dates and milestones.
For Phase III / IV implementation, or if you are planning to deliver an IPD (Integrated Project Delivery) contract model or submit digital BIM documents, you need to begin thinking about using the AIA E202 BIM Protocol documents including the modeling matrix, or know about the AGC Consensus Docs BIM Addendum. AIA E202 defines milestones, authorized uses, and who is accountable for modeling these items. Understanding modeling LODs (Levels of Development) and MEAs (Model Element Authors) and the intended model purposes should be predefined for most efficient project execution. See modeling accountability later on in this article. As CAD Training Online’s Senior BIM Consultant, I coach many of my clients through use, integration, and understanding of risk.
Nobody becomes an expert overnight. This phase, typically referred to as implementation, should be broken up into multiple phases (crawl, walk, run, sprint). This involves learning the fundamentals, assigning implementation tasks such as content development, initial template setup, and setting up a simple project. I have had success with many large clients implementing large projects for the first phase, but would not recommend it unless you have time built into the project to overcome the learning and the efficiency curve and will be willing to invest in outside consultant content development.
When learning to crawl, it is expected there will be issues (and lots of whining). Like a baby, you must effectively crawl before you can walk. This is where most firms/users have challenges. They further compound the problem by moving on to the next phase before confirming that they are successful at walking.
After each phase of implementation there should be a wrap up meeting to confirm our established implementation metrics. Evaluate if the specific goals were accomplished. What lessons were learned? What things to avoid in the future? Establish best practices! The most important item is to confirm the success of the implementation and/or project deliverables. Don’t expect to have improved productivity at this stage, although I have seen this occasionally from very committed teams. These are usually our repeat customers.
Beyond 2D Construction Drawings
There are many beginning strategies to engage when exploring the first implementation of BIM/Revit in your office. A structural engineering firm’s use and needs of Revit will be entirely different than that of Architects or Engineers. You may have one Architect who uses Revit and the remaining few are still in flat CAD. How do you best deal with this?
Working with Architects
When collaborating with architects using “Flat” CAD, good luck! All kidding aside, you will still have an advantage when using Revit, but will be required to model some of the architect’s data. When collaborating with architects working in Revit, this is where the fun begins.
Okay, I’m being a bit sarcastic, but having a sense of humor is prerequisite of working in design, right? I have learned much about how bad some architects’ models are through my consulting with engineers, both structural and mechanical/electrical. Many of them have set bad modeling habits already, not just because they taught themselves from a book, but because they have not yet began working with a consultant. Occasionally I run into some architects who have worked with different consultants and still have bad models because their consulting engineers are afraid to point out their mistakes to them.
Isn’t this lack of communication contrary to the goals of integrated project delivery? Shared model, shared risk, shared reward. Because more eyes are looking at the model, we uncover many mistakes earlier on and are able to correct these mistakes. This helps all team members reduce risk and create better coordinated drawings.
The first step involves coming to terms with the tools. If our architect uses Revit profile edits on walls it will be very difficult to use copy/monitor walls effectively as profiles are removed. Defining who models what element is not only important, but reduces risk. It also involves how we work with an architect’s model in our structural model and also in how they use our model in theirs. Having an optimal strategy and communication plan is critical, even with BIM.
A good rule of thumb is this: walls, columns, floors, roofs, etc. that are under the ownership/accountability of the structural engineer are maintained in the structural model for edits and additions.
Figure 6: Wall sharing strategy
Architects should draw their wall finishes separate from their structure and join @ openings. Their structural walls will have a PHA (placeholder approach) designation to be used in filters to turn off when used in sheeted views.
In working views the architect’s walls will be on for joining and editing purposes (see Figure 6). As the structural engineer adds rebar, clip angles, and other structure this will be the wall shown in the architect’s view to the architect’s standards. This does two things. First, it makes it easier to simulate finishes in construction, and second, it allows differentiation of the structure and architectural model elements.
As the structural engineer you own the walls as the MEA (Model Element Author) and will show the walls you are accountable for in your printed models. Coordination views will be created to help coordinate openings and alignment of walls, openings, and location; however, these are just the placeholder walls the architect places initially in their drawing. Your model (structure only) will replace their walls.
Coordination Plans showing Architecture in grayscale and Structural in Black with metal studs shown in dashed red. Not structural (bearing or shear), but a wall not used in analysis. These walls can be filtered and shown as structural without having analytical lines used for analysis (RST 2012 new feature). These new plans can provide enhanced communication without complicated “layering” schemes or duplication of effort.
Sections, Details, and 3D Views
Traditional construction drawings for structural engineers consist of many “standard” details. Having been a drafter and detailer in a structural consulting firm I can tell you this is only standard on prototypical buildings. Most of what are considered “standard buildings” are standard components found in our model elements except that each area of a building is a little different with different rebar size and configuration or steel connections. As each building has different challenges and details we can use Revit’s dynamic detailing capabilities to tell a better story. Wall sections and details are derived directly from the model (see Figure 9). With the correct amount of detailing we can create details that are not only coordinated, but also communicate effectively. Although there will still be many standard structural details, you can take advantage of Revit’s 3D section views to illustrate big picture items and then dial into greater detail with individual details. Utilizing Revit to enhance communication will reduce RFIs and also can unify your drawings and help orient people to the project.
Modeling Complex Roof Geometry
Modeling complex forms is a fascinating topic and has been greatly enhanced since Revit 2010. Whether you are creating a conceptual mass or surface NURB (Non-Uniform Rational B-spline) you can create many free-form shapes. These shapes may not impress many of the Maya, 3ds Max Design, or Rhino users out there, but the automation with panalization tools and adaptive components has greatly enhanced the capacity to rationalize form and then drive form to custom automation.
Much of the focus of my last AUGI|AEC Edge Cover article, Summer 2010 12 Tips for Efficient Conceptual Massing [insert hyperlink /uploads/aec_edge/AAE2010Sum-lr.pdf ] was about efficient form creation. Although there is much that can be learned about form creation, how can structural engineers utilize these tools?
Structural engineers can use the massing forms to creating complex roof and ceiling structures. The first step is to create a NURB form. To do this, create an in place mass family. Lay down some points and then provide a different z elevation for each of these points. This will allow you to create a spline through points. After making some coordinate changes, select the points through which you want to make a spline and select Spline Through Points (see Figure 10).
Figure 10: Spline Through Points
If you want to edit this shape in the future and don’t want the surface to envelop the points, make the model spline a reference line. To make these splines a surface, select all of the splines (model or reference) in order and select Make Form. This should create a NURB surface. Once you have created a NURB surface you can begin to create beams and trusses associated to this form (see Figure 11).
Figure 11: Beams and Trusses on NURB forms
See more on this topic at Autodesk University 2011: “SE5489-L Tips & Tricks to model Complex Roof shapes: From Revit Architecture to Revit Structure” or contact me for further information.
Your firm’s success with Revit Structure is going to hinge on many factors. You ability to plan, educate, implement and review are critical to the successful integration of Revit Structure. Please take advantage of those who have been there before you. There is no reason to reinvent what has already been vetted by others. Please let us know when you need our help in tackling these challenges.
Jeremiah Bowles is Senior BIM Consultant at CAD Training Online, Autodesk Revit Structure SME and Adjunct Professor at ITT Tech. He has been in the AEC industry since 1992 with a diverse portfolio of experience. As an early adopter of Revit and BIM technologies he has been able to leverage his real world experience to create contextual and applicable learning. He is an innovator in CAD & BIM use and is on the forefront of extending BIM utilization into construction beyond the current methods. Jeremiah holds a B.A. in Business and is currently attaining a B.S. / M.S. in Construction Management at Pittsburg State University in Pittsburg, KS. You can follow Jeremiah on twitter @therevitcoach or email him at email@example.com .