What is BIM and why should I care about it?

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By Stephen Spangler, US Army Corps of Engineers’ Engineer Research and Development Center
BIM, BIM, BIM. Building Information Modeling. Unless you have been hiding under a rock — or with respect to the design world, under your drafting desk — you have at least heard of or read about BIM technology. If you attend any of the big CAD vendor conferences, such as the BE Conference or Autodesk University, you are probably starting to notice that the number of presentations on CAD is dwindling and the number of presentations on BIM is growing. “So what,” you may be thinking, “my company is one of the foremost companies in the use of CAD technology.” This article will provide a brief explanation of what BIM technology is and why you probably should be taking an interest in it.

Stephen Spangler, US Army Corps of Engineers

What is BIM?
First off, BIM most accurately stands for Building Information Modeling. You may also see it defined as Building Information Model, but I think this is inaccurate since models are one of the many products of BIM. If I had to compare CAD technology to BIM technology, I would say BIM is to CAD, as CAD was to hand drafting. BIM represents a significant technology leap in the capturing of design information about a building or structure.

On a side note, before those people who design structures other than buildings start to tune out, BIM is not just for buildings. I work for the US Army Corps of Engineers and BIM technology has already been successfully used to model not just buildings, but civil works projects such as locks and dams. Any type of structure can be modeled in BIM. Perhaps one day BIM will be renamed as Structure Information Modeling, Facility Information Modeling or Design Information Modeling. (Well, scratch that last one, DIM is not exactly the best acronym to have tied to a technology.)

The Tao of BIM
One common misconception is that CAD is for 2D design and BIM is for 3D design. This is definitely not the case, since you can easily create 3D designs with CAD technology. The main difference between CAD and BIM all comes down to how an object perceives itself after it is placed. For instance, in CAD when you draw a wall, you may possibly draw one line then copy parallel that line a certain distance to achieve a wall with thickness. When you place windows or doors in that wall, you have to break the lines and do some clean up to create your openings. If the walls or doors have to be moved later in the design process, the wall lines have to be reconnected and a new opening has to be created. With BIM, you are dealing with objects that are simulations of building components. These objects know what they are and what their characteristics are. When you place a wall in BIM, it knows that it is a wall. It contains information about its materials, its fire rating and height (just to name a few). When you place a door object into a wall object, the opening is automatically created. If you have to move the door, the wall opening is filled in and an opening is created in the door’s new location.

BIM saves money
How often has a design in CAD seemed sound, but when it was being constructed, problems were determined resulting in costly changes? With BIM, you are truly developing a model that accurately reflects what is being constructed in the field. Interference detection analyses can be run on the model prior to construction, determining where beams run into each other or where ducts run into pipes. Wouldn’t you rather discover these problems in the design phase, rather than in the construction phase? With BIM, this is possible. Besides interference detection, BIM technology can be used for modeling, drafting, visualizing, animating, simulating, analyzing and plotting to name a few of its capabilities. One key aspect of BIM is that it allows for collaboration amongst engineers and architects on a scale that has not been possible before.

Do I have to learn something new?
Right now, you may be thinking, “Oh great! Now I have to learn something new. Guess all my CAD skills will go to waste.” This couldn’t be further from the truth. Throughout the use of BIM software, like Bentley’s TriForma, you are constantly using tools from the MicroStation set of tools. Also, after a BIM model is created, extractions are taken from the model. These extractions are used in creating model files and sheet files. Once you get to this stage where you are assembling your construction documents, your CAD skills are used 100%.

Conclusion
I realize this is only the tip of the iceberg regarding BIM. Every day, I learn more and more about this exciting and powerful technology. A year ago, I had heard of BIM, but did not realize its power. Over this past year, I have been helping the Corp of Engineers develop a strategic plan for implementing BIM technology. While CAD is still an excellent tool for design, BIM technology allows the reuse of information throughout all phases of a structure’s life cycle. BIM also allows for time and cost savings that could not be realized through CAD technology. With the current war and disaster recovery efforts the Corps of Engineers is involved in, money and resources have become more and more limited. As such, the implementation of BIM technology is no longer an option for the Corps, but a necessity.

About the author
Stephen Spangler works as a Mechanical Engineer for the CAD/GIS Technology Center at the United States Army Engineer Research and Development Center (ERDC). Mr. Spangler has been heavily involved with the development of a CADD details library and AEC CAD standard for the Department of Defense. He is currently involved in the development of a BIM road map and standard for the United States Army Corps of Engineers.

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