Integrated math and drawing from practice

As a specialist in building and construction advice, Borreman Constructie Adviesbureau supervises the structural design of houses, apartments and utility buildings such as industrial halls, office buildings, sheds and store premises. Because things often change or need more attention during construction, the consultancy's guidance is not limited to the design phase. Thinking, working and constructing from practice, the best solution is always sought during the implementation phase, together with the client, architect and contractor.

Borreman Constructie Adviesbureau has been active since 2006 and currently has 6 employees responsible for structural analysis and drawing. The decision to offer services in the field of integrated calculation and drawing was inspired by the enormous opportunities that working around a central BIM model offers to everyone involved in the construction process.

A visual inspection of the wire model in Tekla Structures allows to correct missing or incorrect connections of the reference lines, and to build a correctly working mathematical model.

An integrated approach where everyone wins
In the integrated approach adopted by Borreman Constructie Adviesbureau, BuildSoft BIM Expert plays a crucial role. BIM Expert is a unique software that allows the exchange of model information between structural calculation software and BIM applications. Thanks to BIM Expert plugins for Diamonds, PowerConnect and Tekla Structures, Borreman Constructie Adviesbureau was able to take the step to integrated calculation and drawing, seamlessly linking their trusted calculation software with Tekla Structures.

"An integrated approach around a BIM model simplifies the design process and saves a lot of time and money," Edwin Borreman clarifies. "Architect, structural engineer and contractor no longer work in isolation on separate plans and drawings. Instead, we use Tekla Structures to build a BIM model based on the IFC file we receive from the architect. We then use BuildSoft BIM Expert to link this BIM model with Diamonds (our 3D calculation software) and PowerConnect (the software we use to calculate steel connections). The structural adjustments suggested by the calculation can then be effortlessly translated into adjustments in the BIM model. Once we have completed the structural design in this way, we share this model with the contractor via an IFC file. This makes it a lot easier for that contractor to make the execution plans. Moreover, we can do the technical checks of those execution plans faster and easier afterwards." Of course, such an integrated approach changes the design process for the worse, he believes. "In doing so, more time is invested in building and sharing a BIM model, but that extra time is more than recouped afterwards."

During the conversion of the Tekla Structures analysis model to a Diamonds calculation model, the BuildSoft BIM Expert performs the necessary checks, and profiles and materials are matched.

A complete overview thanks to the BIM model
"To illustrate the benefits of integrated calculation and drawing as clearly as possible, I think it would be good to explain our way of working by means of a concrete project," Jaap Wim explains.
Riphagen, project engineer at Borreman Constructie Adviesbureau. "A project that lends itself perfectly to this is the expansion of an existing industrial hall and accompanying offices for Van Dijk Transport from Kampen. Very specifically, I want to talk about the new office section that was planned above the existing offices. This additional floor could not be supported by the existing structure, because it was not designed for that purpose.  Therefore, the steel structure of the new office section had to be constructed separately from the existing structure."

In Borreman Constructie Adviesbureau's round-trip BIM workflow, the BuildSoft BIM Expert takes care of synchronizing the Diamonds computational model with the Tekla Structures BIM model and incorporates the necessary modifications from the computational model into the BIM model.

"In a first step, we built a BIM model with Tekla Structures, and we did so based on an IFC file provided by the architect," he says. "This BIM model included the entire structure, both the existing industrial hall and offices and the new structures to be built. The great advantage of this model was that it provided an overall view of the entire project, making it much easier to discuss different variants with the client and arrive at the best design for the steel structure of the new office section. Once the client had agreed to that design, we started working from the BIM model to further elaborate and detail the steel structure based on structural calculations with Diamonds."

Translating BIM smartly into a structural analysis model
"Integrated calculation and drawing becomes all the easier the more you consistently use good methodology," Riphagen said. "We ourselves always perform a series of model checks with Tekla Structures before using BuildSoft BIM Expert to exchange model information with our Diamonds calculation software. We do this on the entire model or on a part of it. After all, in Tekla Structures you can perfectly select a part of the full BIM model and build an integrated analytical model for that part."

"As always in this project, our checks began with a visual inspection of the wire model of the new steel structure to be built. Such a wire model visualizes the bars of the steel structure (beams, columns, tie rods, etc.) based on reference lines defined in the 3D model. In order to build a working analytical model at all, all reference lines in the ends must be aligned. A visual inspection of the wire model allows us to quickly detect and correct missing or incorrect connections."

Reference lines play a crucial role in an integrated computational and drawing approach, precisely because profile adjustments are always interpreted relative to these fixed lines.    

Riphagen: "Take the example of the beams supporting a bearing floor in the new office building. We record the reference line of each beam in the top surface of that beam. If it later turns out from the calculations that the height of one or more beams must be adjusted in the calculation model, the reference lines ensure that those adjustments in height are correctly translated into the drawing model: the top surface of each beam remains unchanged, while the bottom surface becomes higher or lower. Proper definition of the reference lines thus ensures that all adjustments in the analytical model are correctly interpreted in the BIM model in terms of execution. On the other hand, reference lines ensure that the BIM model is translated intelligently into a structural analysis model, taking into account the eccentricity between the center line and the reference line of each bar in the model."

In Borreman Constructie Adviesbureau's round-trip BIM workflow, the BuildSoft BIM Expert also incorporates the detailing of the steel connections (as calculated with PowerConnect) into the BIM model.

A round-trip BIM workflow
"In a next step, we then inspected the Tekla Structures analysis model of the new office building," Riphagen continued. "In doing so, we completed the wire model with information relevant to the structural analysis. For example, we indicated where beams are pivotally connected, which rods are part of the wind bracing (and should be considered tensile rods computationally) or where the fixed supports of the structure can be found. Once the Tekla Structures analysis model was finished, we used the BuildSoft BIM Expert to convert that model into a Diamonds calculation model. At that stage, by the way, the BIM Expert also performed the necessary checks, comparing and matching, for example, the profiles and materials from the Tekla Structures analysis model with the profiles and materials available in the
Diamond's profile and materials libraries."

"From this point on, we could completely connect to our classical way of calculating with Diamonds. In a first step, we further supplemented the Diamonds calculation model with the permanent loads, wind loads, snow loads, ... and generated the norm-compliant load combinations. After an initial 3D calculation and the corresponding norm checks, we started working out the necessary adjustments in the calculation model, in order to arrive at a structural design in which the strength and stability of all bars (beams, columns, tie rods, ...) meet the norm requirements."

"As the final step in our round-trip BIM workflow, we used the BuildSoft BIM Expert synchronized the Diamonds computational model with the BIM model. In doing so, the BIM Expert reported any geometric changes to existing bars relative to the original BIM model, asking whether or not we wanted to automatically carry those changes into Tekla Structures. Tekla Structures recognized any newly added bars and updates in terms of sections, materials and bar orientation. That's quite a flexible way of working that saved us a lot of time."

'More integrated computing and drawing is almost impossible
"But this is not where this story of integrated calculation and drawing stopped," Riphagen emphasizes. "For example, in the steel structure of the new office building there are some moment resistant portals whose nodes we detailed with PowerConnect. We did that by selecting a moment-resisting node in the Diamonds calculation model, after which PowerConnect could perform the detailed calculations based on the node forces from the Diamonds calculation model. That way, it was not only possible to dimension the steel connections (and detail end plates, stiffeners, welds, bolts, ...), but we could also immediately calculate the rotational stiffness diagram of those connections. Just because each calculation with PowerConnect was started from the Diamonds model, the stiffness of the corresponding node could be automatically adjusted in Diamonds based on the calculated rotational stiffness diagram. Each such adjustment naturally required a new 3D calculation with Diamonds, and in each case the favorable redistribution of bending moments in the portals was confirmed very nicely. The beauty of it all was that, thanks to BuildSoft BIM Expert, it was also possible to take the detailing of the nodes (as calculated by PowerConnect) into the Tekla Structures BIM model. Tekla Structures automatically recognizes those calculated nodes as components. Such components are smart tools used to connect parts in the model, automating tasks and objects so that they are treated as a single unit by Tekla Structures and can be adjusted particularly quickly. I can hardly imagine a more integrated way of calculating and drawing. So at the end, we had an extremely complete and accurate BIM model, completely consistent with the structural analysis model. The information in that model was ideally suited for sharing with the contractor, who used it as a basis for further guaranteeing the execution plans."

New opportunities To cooperate more closely
"Integrated calculation and drawing with Tekla Structures, BIM Expert, Diamonds and PowerConnect is very powerful," concludes Edwin Borreman. "Above all, it offers us as a structural consultancy new opportunities to work more closely with all those involved in the construction process. Precisely because we work from a BIM model, we are involved in that process earlier, and together with the architect we can help give direction to the structural design. Moreover, thanks to the integrated approach, the BIM model contains a wealth of accurate information that can be shared with the contractor. Material quantities follow unambiguously from the structural calculation, which greatly simplifies costing. Execution plans can be created more quickly. As I mentioned earlier, with this integrated approach, although more time is invested in building and sharing a BIM model, that extra time is more than recouped afterwards. For the client, that primarily means a better and more cost-effective result, in less time." 

More about BIM Expert: http://www.buildsoft.eu/nl/product/bim-expert

More on Diamonds: http://www.buildsoft.eu/nl/product/diamonds

More about PowerConnect: http://www.buildsoft.eu/nl/product/powerconnect

Tekla and Tekla Structures are registered trademarks of Trimble Solutions Corporation.

Text | Luc Meulewaeter (The Write Mind)  Image | Buildsoft
Featured image: The BIM model provides a total overview of the entire project, making it much easier to clearly inform the client about the design for the steel structure of the new office section.