BIM Tools and Parametric Modeling - Group A - Week 3

The subject of concern for this week’s blog is in regard to the BIM handbook.  This handbook is a great introduction to what BIM modeling is, what it does, and the major uses of BIM.  For my group, Chapter 2 is the main focus for this post.

The chapter first begins discussing, briefly, the history of BIM modeling.  This was quite interesting to read because it gave a foundation of how BIM started out and how it became the powerhouse program that it is today.  The most interesting part about its history was the fact that two different modeling techniques were actually competing with each other for several years before finally joining forces.  Boundary representation approach (b-rep) defined shapes as “closed, oriented set of bounded surface” while the other approach, constructive sold geometry (CSG), did not bound the shapes, but instead had the shapes correspond to algorithms and values that could be used to calculate different features of the shape, such as points, radius, or diameters.  You wouldn’t be able to tell, using modern programs, that these two were separate entities until finally coming together in current modeling software.  CSG is great for real time editing, and B-rep is good for measuring and gathering information regarding the model.

            The next section discussed how different types of software can only account for certain types of predefined objects that are used in the design process for the construction of a project.  Two tables are given, 2-1 and 2-2, which give the built in families and predefined objects for a range of programs.  These two tables illustrate an important fact: each program has its own niche that it fills.  Although all of them are used in design, each one has its own strengths that it brings to the table.  For example, Bentley Mechanical and Electrical has objects for the HVAC systems in a building, while Tekla has more objects that relate to the structural aspects of a building.  Additionally, each of these programs has complementary programs where data can be transferred easily.  When it comes to parametric design, the user can pick their poison and decide what would be the best program for design.

            One last topic that this chapter covered was how parametric design is useful in making edits much more easily in the program.  For example, if one part of a wall needed to be changed, that change can be made so that the walls and shapes around it updated accordingly.  This in turn can allow the properties and attributes to update so that all relevant information can be automatically changed so that no time is wasted manually changing these values.  This is huge step from CAD programs where these pieces of information did not have the luxury of this.

            After reading this chapter, I did learn a little more about BIM modeling.  I never really used Revit much, but this information does make Revit seem like a great tool that I should learn to use.

Source:

Eastman, C. M. (2011). BIM Handbook : A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers and Contractors. Hoboken, NJ: Wiley.

Comments:

-To Matt:

That point you brought up regarding the computational power regarding the parametric modeling is on point.  I completely overlooked that aspect of the advancements of parametric modeling.  Although that type of modeling does make it easier for properties and attributes to update, it’s still important for engineers to be careful when designing so that if a future edit is made, the program doesn’t crash due to insufficient power.

-To Steve:

You’re very lucky to work with EwingCole and have that experience using Revit for projects.  I know some companies I interviewed with were hesitant about switching over to 3D modeling but from the sounds of it, it would be a worthwhile endeavor for companies to do.

-To Esther:

I like how you touched upon the specific strengths and weaknesses between Revit and Tekla.  I was going to do something like that in my post, but you beat me to the punch.  I never used Tekla as a program before either, but it does sound quite useful for structural design.