Defining BIM
Ten years ago, BIM was just a glint in the eye of some project engineer in Middle America. Now it has become the most prevalent and fast-growing engineering and construction-management design, scheduling, and coordination tool since we moved from manual drafting to using AutoCAD on a computer peripheral. Some could even say that BIM has become a household name in AEC firms worldwide. Because of this notion, and the fact that BIM is still relatively new to the global engineering and construction management process, there is no set-in-stone definition of what BIM actually is, what it entails, its limitations or boundaries, and even what the simple acronym stands for.
Because of all of this, we will try to peel back the layers of Building Information Modeling and try to define the most well-known and commonly used facets of this process. We’ll try to standardize certain aspects of it—even though it’s nearly impossible to do that from only one person’s point of view—and attempt to answer some simple questions that people who are new to BIM often have.
If you ask 10 different people who work for 10 different companies in 10 different industries “What is BIM, exactly?” you are sure to get 10 very different answers. This is because this acronym has been thrown around so loosely that the term is almost akin to 3D Modeling. This is one notion that is simply false no matter how you look at it. 3D modeling is defined exactly how it sounds: modeling a drawing in 3D. To simply extrude shapes to create a three-dimensional model does not mean that you are now utilizing BIM. This is especially true if these models are populated with “dumb” objects –3D objects that have no intelligence built into them and are neither parametric nor have any constraints or advanced details. This is the misunderstanding that I think most firms have about BIM. Just because you generate 3D models does not mean that you are taking advantage of all Building Information Modeling has to offer.
Because BIM is such a general tool and has many factors at play, some firms decide to approach the process in piecemeal fashion—using separate definitions or micro-BIM definitions. Here are a few.
1. Populating a 3D model with intelligent, parametric objects so that each contains information such as Manufacturer, Part #, size, type, gauge, voltage, and so on.
This will enable you to export all of the intelligent objects in your model into a real-time Bill of Material that reflects actual part numbers from manufacturers, types, sizes, and amounts—and will change constantly, based on how your model changes. AutoCAD® MEP is one example of a design application that allows you to do this. In the newer releases, it’s as simple as typing the command “BOM”. This saves a noticeable amount of time and effort by replacing the previous way of manually entering data to complete a BOM based on information shown in the model—over and over again—every time the model changes. By populating a model with intelligent objects, you can also globally change items easily, select only certain “types” of objects, have Navisworks Manage display every object’s part number when flying through your model, and drastically reduce file size.
2. Collision detection and coordination.
This is, by far, the most popular piece of the BIM pie that firms use across the board. No matter if you have a model that is populated with dumb 3D solids or intelligent parametric objects, you can bring each model together in a program like Autodesk® Navisworks® Manage and perform a collision detection study against each trade in your project.
Identifying each collision between trades in a virtual world before ground is broken on your project will save an endless amount of man-hours and change orders in the field due to real-world clashes between trades when installation efforts begin. These are typically identified and resolved in weekly or bi-weekly coordination meetings held by either the appointed Lead BIM Coordination (LBC) firm or the General Contractor. It is hard, these days, to find a large project that isn’t utilizing this part of BIM, and this was the first step that took us to the point we are now. Where we once stood around light tables comparing different trades’ drawings on to-scale blueprints, we can now fly through a virtual world of MEP and catch these hits before they happen in the field. This is currently the #1 reason that GCs and owners alike choose to use “BIM” on their projects.
3. Stage visualization and schedule modeling.
Another great, but lesser known feature of the BIM process is the staging aspect for the building owner. Navisworks Manage allows you to take your installation schedule and import it from Primavera or Microsoft Project directly into your model using Timeliner, a tool that runs inside Navisworks Manage, and create a “stage animation.” You will place certain trades’ objects on certain “layers” within the model that will tie into certain points of interest on the schedule.
Let’s say that steel is the first to be laid out in the field. You would select all steel in the model, assign it to an installation effort on your schedule along with the dates associated with it, and it would enter the steel into this variable. Then you do the same for framing, architectural walls, ceiling t-bar, mechanical, electrical, plumbing, and so on. Once you assign all of these pieces to the different areas and dates on your installation schedule, you will create a staging layout based on the exact dates of your schedule. You will then be able to click the beginning of your new schedule within Navisworks, click “play,” and see your virtual project be put together in an animation—showing the dates as it flies by. You can click on certain dates and see what your project will look like on that certain date. Hopefully if you click on the end-date of your project schedule, you should see a complete building.
Owners love seeing these stage animations because they can see their project’s evolution before they even lay out the construction area for demo/excavation. The best part about this facet of BIM is that since your schedule and model has to be complete anyway, it doesn’t take much more work than tying the two together to create something that looks like it took months to do.
4. Data management and Infrastructure.
The final piece that I will be touching on is the ‘collaboration’ aspect of BIM. Autodesk has come up with many solutions for this as well, one of the better ones being Buzzsaw. Buzzsaw allows all of the different subcontractors to share their drawings with one another in one centralized location, allowing subs to download the latest and greatest models from other team members to integrate into their building information model, assuring that they are looking at the newest true model available. We all don’t share a common network drive among the project team, so sometimes it isn’t as easy as clicking on a drive letter to grab another company’s files for coordination.
Another great collaboration and data management tool from Autodesk is Vault. This application allows team members to centralize their models and drawings internally as a team, allowing you to check-in and check-out drawings for others to work on and giving you more revision management capabilities. Vault, as opposed to Buzzsaw, allows for tight support, direct to the program that you use, whether it is an AutoCAD-based or Revit-based application. It will keep archives, letting you easily access historical data to check old models versus new ones. This is another great collaboration tool to be used alongside Buzzsaw.
With all of these different aspects to look at in regards to BIM, it is no wonder that the acronym is tossed around so loosely. To say that your project utilizes BIM is a generalized statement. Which part of BIM are you taking advantage of? Are you using 4D for real-time simulations? Are you using 5D for cost analysis? Are you doing trade coordination to stop change orders from occurring in the field? Because of all of these different aspects, I am sure that in the near future, BIM will become an AEC standard for all companies and trades alike to view and abide to. We will all be on the same page, and bid a project based on BIM I, BIM II, BIM III, etc. If this happens, there will be a lot less confusion in the industry and a lot more specific scopes of work when bidding jobs.
Bill Campbell lives in the San Francisco Bay Area, is an AutoCAD 2012 Certified Professional and works for a top engineering construction firm in San Jose, CA as ‘BIM Lead’. He enjoys surfing and jogging the beach with his wife and dogs, snowboarding and traveling abroad. Bill previously owned and operated a 3D BIM firm in the Detroit area. He is quite adept to customizing and tweaking AutoCAD and other Autodesk products for ease of use & functionality, and actively beta-tests Autodesk’s upcoming BIM-based software. He is currently working on standardizing BIM definitions within the AEC industry with his new project, “BIMkit”.
