B2: BIM Handbook Chapter 2

Parametric Modeling and BIM Tools

Parametric modeling has changed the way the building industry works. It has been transformed from a drawing-based and handcraft technology to digitally readable models that can be exported to other applications if needed. Parametric modeling is mainly used as a separate modeling tool. It is used as a tool in design because it has the ability to extract geometric and property information from a building model and import it to other applications to be analyzed. Some issues that traditional hand-drawing systems have had were also resolved. These include reduction in drawing errors and elimination of design errors based on spatial interferences.

In traditional 3D CAD, every aspect of an element's geometry must be edited manually by the users. In BIM Design Tools, the shape and assemble geometry automatically adjusts to change sin context and to high-level user controls. This means that if you want to add a door or a window, you would have to manually delete the lines of the wall when using CAD. In Revit, for example, the wall lines are automatically replaced by the door and its components.

Ilana Ritvalsky also talked about the uses of BIM softwares outside the Architectural design phase. I agree that they can slo be used in the structural design and fabrication stages. Although they are not currently being used by a lot of companies in these purposes, I think that there is a very promising future that awaits BIM in these fields.

The graph from Chapter 5 that Jonathan Plotkin presented is quite interesting. It just proves that using BIM really helps companies utilize their time better by making it easier to create construction documents. This will give the architects/engineers more time to spend on the actual design itself.

An interesting attribute of some BIM Tools was discussed by J Schwakoff in his blog. This is the "part of" relationship known as aggregation. This is the ability to model nested assemblies. I like that he talked about the possibility of reducing the amount of material needed because speculations were made in advance.

BIM Tools
BIM Tools are most useful in Architectural Design. One thing that the authors emphasized in Section 2.3.2 is that buying a software package is not like buying anything else. When buying a software, "a purchaser is buying into both the current product and its future evolutions". In addition, a support system also comes with the purchase. This section continues by enumerating some of the most prominent BIM tools in the industry today. I like that the systems' strengths and weaknesses were discussed. These  BIM Tools are as follows:

• Revit
• well-designed and user-friendly
• broad set of object libraries that support a multi-use interface
• slows down for projects larger than about 220MB
• limitations on parametric rules dealing with angles
• does not support complex curved surfaces

• Bentley Systems
• broad range of building modeling tools
• supports modeling with complex curved surfaces
• provides scalable support for large projects
• hard to learn and navigate
• less extensive object libraries
• weaknesses in the integration of its various applications

• ArchiCAD
• intuitive interface so relatively easy to use
• large object libraries
• only strong BIM product currently available for Macs
• limitations in its parametric modeling capabilities

• Digital Project
• very powerful and complete parametric modeling capabilities
• directly model large complex assemblies
• relies on 3D parametric modeling for most kinds of detailing
• steep learning curve
• complex user interface
• high initial cost
• limited object libraries
• drawing capabilities for architectural use are not well developed

• AutoCAD-based applications
• consistent to AutoCAD interface so easy to use
• limited interface to other applications
• scaling problems
• not parametric modelers that allow non-programers to define object rules and constraints

• Tekla Structures
• versatile ability to model structures that incorporate all structural materials and detailing
• support very large models and concurrent operations on the same project with multiple simultaneous users
• supports compilation of complex parametric libraries with little to no programming
• its full functionality is quite complex to learn and fully utilize
• parametric component requires sophisticated operators with high level skills
• not able to import complex multi-curved surfaces from outside applications
• relatively expensive

• DProfiler
• primarily feasibility studies before actual design begins
• its ability to generate quick economic assessments on a project plan is unique
• not a general purpose BIM tool
• single purpose is economic evaluation

Based on what I have learned about these BIM tools, I am able to put myself in a situation to choose which one I would use if I were to start a company in the building industry. I would personally choose to use Bentley Systems. Although it has a complex interface, the broad range of building modeling tools eliminates the need to use another system. It is also capable enough to model complex shapes and surfaces which will definitely make it easier to model.

Reference:

Eastman, Charles M. BIM Handbook: A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers And Contractors.Hoboken, NJ: Wiley, 2011. eBook Collection (EBSCOhost). Web. 19 Jan 2015.