BIM Handbook Chapter 2

The first time that I heard BIM is on my second year of college. At that time, I just know this is a tool that can be applied on building industry in the future. This week, I read the Chapter 2 of BIM handbook and understand more about BIM.

According to the United States National Building Information Modeling Standard (NBIMS V1-P1), A BIM is a digital representation of physical and functional characteristics of a facility. As such it serves as a shared knowledge resource for information about a facility forming a reliable basis for decisions during its lifecycle from inception onward. . At early time, there are two forms of solid modeling, one is boundary representation approach (B - rep) and the other is constructive solid geometry (CSG).Then this two method merged to one that become the precursor of modern parametric modeling. The current generation of BIM tools all grew out of the object - based parametric modeling capabilities developed for mechanical systems design. You can define a model family or element class and the shape and assembly geometry in a parametric modeler automatically adjusts to changes in context. Like the example of wall quote in the handbook (page 30-32).So, BIM tools are object – based parametric models with a predefined set of object families and a number of Web sites make additional object families available for downloading and use. Besides, user can define custom parametric object families by using a sketch tool module.

There are lots of differences between the specially - developed parametric modeling tools used in BIM and those used in other industries. First, buildings are composed of a very large number of simple parts. Second, there is a broad set of standard practices and codes that can be readily adapted and embedded to define object behaviors. Third, BIM needs to explicitly represent the space enclosed by building elements. In the second part of this chapter, author mainly discussed the versatility of different BIM software and compared their advantages and disadvantages (Revit and Bentley).You can see it in Wang Chunyi’s post.

In order to evaluate whether a project is a BIM, you can use a BIM Capability Maturity Model (CMM) provided by NBIMS. This method analyzes the completeness of 11 key targets to get the maturity of BIM application. These targets include Data Richness, Lifecycle Views, Change Management or ITIL Maturity Assessment, Roles or Disciplines, Business Process, Timeliness/ Response, Delivery Method, Graphical Information, Spatial Capability, Information Accuracy and Interoperability/IFC Support. For further information you can see NBIMS V1-P1 chapter 4.1-4.2.

Source:United States National Building Information Modeling Standard