B2: Rebecca Lynch (Group A)

As a student who has only used a BIM software once in one of the introduction CAEE classes, chapter two was both overwhelming in the uses and explanations of the BIM applications and tools as well as intriguing in that I never knew the full potential of BIM. As mentioned by Laura Worley and Gary Reiff, there are predefined base building objects that can be inserted into the model, either through definitions in the system or external online sources. In addition, the benefits of BIM in the ability to set parameters that allow objects to update as the design progresses, rather than needing to manually change everything with CAD programs is incredible. In my co-ops, we use AutoCAD for all of our drawings and deal with mostly residential and smaller commercial buildings. Even with only having four stories and only working in 2-D, the tedious nature of having to change every drawing and all of the walls associated with one change can be frustrating.

In order to allow for these easy updates later as design progresses modelling ability, care must be taken to first define the rules and parameters. The parameters can either be a location relative to another object, or rules that can be checked as the design develops to ensure that new changes. This would be helpful in ensuring that changes in one section do not cause other sections and objects to violate codes or minimum requirements desired. An additional benefit that is unique to BIM is the modelling of the design space that, with the addition of labeling of object properties, allows for environmental conditioning applications. The properties can be used to assign occupancy and equipment performance needs to a space; thermal control and loads to zones for structural and HVAC designs; and materials and quality specifications to an object for purchasing. As with parameters, the better defined the model is in its properties, the more accurate the BIM tools will be in the calculation of loads and necessary materials for different systems.

With the accuracy of the parameters and properties, BIM is becoming increasingly used in fabrication and construction. The ability to define object as layers with parametric layout of nested elements, such as studs allows for generation of detailed framing and cut lumber schedule that is a more accurate measurement of materials needed. Similarly, in large scale structures, each floor has similar framing and structural layout. To simplify the model, systems such as, structural or electrical, can be modelled as objects that have defined rules in order to determine the layout of the components. In addition, connection designs can be completed based on loads applied and the connecting members. These will greatly decrease the time needed to model any size buildings and determine the materials needed, as well as reduce the waste generated from ordering too many materials.

As mentioned, the more parameters and properties assigned to the BIM, the more accurate the model. However, large projects can cause storage problems as larger buildings require more objects, and even small buildings with many properties and objects modeled can use too much data for storage and propagation of updates. For this reason, there must be a balance between modelling enough objects and, assigning only the important parameters and properties, so that the model is as accurate as possible without the use of too much data too reduce the speed and efficiency of the program. For large projects where a lot of data is necessary, the lack of storage capacity can be fixed with the use of multiple files in which updates in one file affect the others, but not many BIM tools have this function yet. An additional problem that the author discussed was the need to choose a BIM platform that works best for your application because each platform has its own strengths and weaknesses. An option that the author recommended to increase the functionality of the BIM model was to use external spreadsheets to define parameters. This allows for the changing between systems in order to use each for its unique strengths so you can use the best program for any given task.

References:

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. 18 Jan. 2016.

Comments:
Gary Reiff
Laura Worley