BIM Part Two : BIM for Ease of Construction
Visual scheduling may be useful for presenting the general sequence of building construction to an owner during a preconstruction meeting. In visual scheduling, you assign a model item to a schedule task and create an animation of the construction sequence.
For the Wallingford project, we were able to get 3D .dwg files from our mechanical design/build subcontractor that were linked into the overall Navisworks model. We then ran the clash detective in Navisworks to look for any conflicts between structural beams and HVAC ductwork. Our results yielded 9 conflicts that we brought up in a subsequent MEP meeting with our mechanical design/build subcontractor and the architect. From our discussion we developed an RFI that we sent out to the structural engineer. Shortly afterwards, we received a response and resolved the issue!
A common issue for most projects is the way in which the existing streetscape meets elements along the building property line, such as garage ramps. Using the civil drawings, we generated line work in AutoCad and exported into Revit, where topography was added to the model. The model was exported as a .nwc file and linked to the overall project file in Navisworks.
We used the same process and SS drawings to build an accurate shoring model and appended it to the overall project file. Both of these exercises allowed us to confirm whether there would be any serious conflicts.
Additionally, modeling on a small scale can be very useful in figuring out a tricky detail, such as steel detailing. If Revit and AutoCad are not available, Sketchup may also be used for modeling. With Sketchup it is possible to easily incorporate wall and floor assemblies into your steel detailing. This helps to eliminate the possibility of human error when doing your calculations. Once the walls are laid out, steel members can be laid out per the plan details accurately and dimensions can be shown with Sketchup's dimension functions. Also, once a model has been created it can be revised and the dimensions will be corrected automatically. Furthermore a 3D model can be copied and modified for a similar steel configuration to expedite the detailing process.
The free version of Sketchup will open .dwg or .dxf 3D model files exported from Revit. The model will open in Sketchup but will no longer have properties assigned to any modeled items. Certain items, such as walls, floors, roofs and doors will automatically be separated into layers. All finishes and materials will no longer be visible, but if you don't have Revit, this can allow you to alter the existing model. Also, you don't need to model in Revit in order to use Navisworks; Navisworks can open most other 3D file formats, including Sketchup!
Tune in next issue for more on the BIM process and it's benefits to the project owner.