Open BIM Roadshow : some thoughts on collaboration with BIM

Yesterday, I went to the Open BIM Roadshow seminar, organized by Kubus (ArchiCAD dealer for The Netherlands and the Flemish part of Belgium) in collaboration with local ArchiCAD dealer FocusIT and Construsoft (Tekla dealer).

At this event, we first saw a general overview of ArchiCAD (Building Information Modeling for Architectural Design) and Tekla Structures ("BIM" for construction design). While I assume the audience of this blog to know what ArchiCAD is about, they might not be familiar with Tekla Structures. At least, I wasn't and it was good to see how this system is targeting the design of Steel and Concrete structures using similar methods as what we are used to in Architectural BIM software, such as ArchiCAD or Revit.

Tekla - Construction Modeling for engineers

In Tekla, you create a full 3D model of beams, columns, foundations, floor slabs up to the details of connections and fastenings. Everything is parametric and stays editable. While the interface is literally bursting with dialog boxes and buttons to click, it seemed to be a very efficient system in the hands of somebody who knows what they are doing. More info on the Finnish Tekla...

Tekla is not a structural analysis software, yet can integrate with most common analysis software, such as Scia Engineer, Buildsoft Diamonds, Robot Analysis and others.

In this software, you also don't draw anything in 2D. All production drawings are fully generated from the 3D model. This is not completely true for regular architectural BIM software, where many annotations, dimensions, detailing and other parts are still drawn on top of the generated plans and sections from the 3D model.


The last part of the show was the most interesting: how can you effectively collaborate between different parties using BIM software. They demonstrated this using ArchiCAD and Tekla Structures and the Open Source BIM Server from TNO.

You can basically set up your own BIM server locally with no effort, as it can be used as a standalone Java-application. Run it and point your browser to the correct address (localhost and port). If on a network, clients have to know your address first.

And now the workflow.

They started by having an architect create (or load) a model inside ArchiCAD. Instead of simply dumping everything into one gigantic IFC file, it was more efficient to prepare a part of the project to be exchanged. In this case, it was the entrance atrium, which was a glass-steel construction. Only the core structure (load-bearing walls, floors, columns and beams) were exported.

> Guideline 1 : work with subsets of a project

Then this part was exported into an IFC file and uploaded to the BIM server, running in the local network. The other party downloaded the IFC file on his local machine and used it as a reference model inside Tekla. With some (essential) communication you can synchronize project main origin and some basic information about the project.

Inside Tekla, the referenced geometry could be either used as a 3D underlay to model Tekla objects on or (using a macro) could be used to be translated into native Tekla objects. Some (but not all) information about these elements was passed on, such as the profile name (IPE200) and the main material (steel). However, to be used correctly, many other settings had to be improved.

The structural engineer could model a more appropriate version of the structure, possibly sending the model back and forth to analysis software in the run.

> Guideline 2 : use reference geometry

The Tekla model was translated into IFC format again (only a few beams and columns, not the full building) and uploaded to the BIM server as a new revision. This was loaded inside ArchiCAD using IFC Merge, possible filtering out some of the non-essential objects, such as bolts. All the model came in on separate and locked layers, without interfering with the rest of the project data in the architectural model.

The architect then revised the design, using the structural model to check correct beam profiles and sizes. And the bi-directional journey continues.

>  Guideline 3 : communicate and go back and forth, everybody staying inside his or her own native system

When the structural engineer loaded the second iteration of the IFC model, he could set up particular views to compare before and after the revision of the architect and could visualize what is new, what was removed and what was modified. However, this requires some thoughtful planning of the architect. E.g. when you want to change four columns into another type, you could adjust one, remove the others and copy the revised one over. But that would have a different meaning then revising the four columns and have them all as modified rather than as new elements. Inside ArchiCAD you might want to use the pipet and syringe to extract and inject properties from one element to the other, ensuring the internal ID stays the same (the "GUID").

> Guideline 4 : be wary of how to manage changes

This went on. When the second IFC version of the engineer was available, the architect could use the option inside ArchiCAD to visualize the model changes between IFC files, using markup coloring.

Be warned that this technology is rather new and thus the actual workflow between different parties has to be laid out thoughtfully. You have to ensure that you agree on reference positions, floor levels to respect and know where the problems areas are.

But all in all, this is what BIM is all about: using the information inside the building model to better manage and communicate about the project with different involved parties. And this is much more than merely using a 3D model to generate drawings.