BIM -An Experience

When Halcrow Yolles adopted Building Information Modeling (BIM) in 2002, the full potential of the technology and the resulting implications for in-house design processes were not understood as well as they are today. However, it was obvious that this type of modeling greatly helped designers meet a growing demand to manage projects with complex geometric arrangements.

The advantages of modeling complex geometry in BIM extend beyond coordinating the input of different consultants on a project. The process can also increase the palette of engineering solutions that can be developed. Foster + Partners’ Leslie Dan’s School of Pharmacy at the University of Toronto, for example, contains an 18-metre tall entrance space featuring two mildly distorted hemispherical pods elegantly suspended over the lobby. The pods contain auditorium seating.

Traditional engineering framing solutions to these not- quite egg-shaped elements would likely have gravitated towards one of two solutions: radial ribs (like the wedges of a cut orange) or transverse ribs (like slices of a baguette). While either of these options would form an adequate structure, both would have resulted in curved elements with a constantly changing radius of curvature, driving up the complexity and cost of fabrication.

Using BIM, the engineers realized that by offsetting the framing off vertical to follow the geometry more closely, the framing could be fabricated using constant curvature elements. Beyond being a more economic construction, the new framing arrangement developed through BIM closely matched the panelization of the finishes, eliminating the need for significant infill steelwork to support the cladding.

These early trials revealed that BIM technology not only greatly assists the manipulation of projects with challenging topographical relationships but also enables more meaningful solutions to be developed. However the deliverables of this time were quite traditional –consisting of 2D drawings (albeit with a higher degree of sophistication) and associated specifications.

A new approach to project deliverables was used on the Art Gallery of Ontario’s recent transformation by Gehry architects. It was divided into two main structural packages; the main building and the feature elements (the Stair, the Walker Court feature stair, and the Dundas Façade). For the feature elements, the contract documents consisted of three components:

1. 2D drawings and specifications

2. 3D Master Model (wire frame)

3. 3D Information Model

The Master Model contained all the dimensioning and dimensional information and, combined with the drawings and specifications, formed the basis of the contract. The Information Model contained 3D extruded shapes of all the structural framing. This model was to be used as a reference only and did not govern the contract.

In the interim

It may be that we are passing through an interim stage on the way to the industry accepting full 3D model information as the basis for the contract. If the design process operates virtually in 3D, and construction is by its very nature 3D, then procurement becomes increasingly isolated as the only part of the workflow that remains in 2D.

Ideally, if the project team’s energy is dedicated to creating a full BIM-based model, then the model should be leveraged to serve not only in producing quality deliverables (3D

or 2D), but also as the basis of all analytical and design processes. Realizing this potential, however, may require change to permeate through companies’ internal processes, organizational structures, and even the business model for a project.

Not unexpectedly perhaps, Halcrow Yolles’ first project that was fully delivered in BIM, an auditorium project with ShoP architects at Site 26 in New York City, was a learning experience. Through a formula of dedication, stubbornness, great skill and a pinch of luck, the project was delivered successfully. But following this, and building on “lessons learned,” the company committed itself to a process of customizing the software to best suit our wants, developing or adapting official standards and processes, and rolling out a training program for all our drafting staff and, more recently, our engineering staff.

With BIM we tend to see an erosion of the traditional division of drafting and engineering roles, and the emergence of a combined “modeler” role. Successful modeling, however, requires both contractual accuracy and analytical accuracy, so modeling specialists with a background in either drafting or engineering are highly valued.

Effect on fee structures

Having made some progress along the learning curve towards fully leveraging BIM, Halcrow Yolles is on track to having all of its projects in BIM by the end of 2009. Areas of focus for the BIM implementation team include looking at developing smart modeling objects that respond to their environment (a footing that resizes to suit the load in the column bearing on it, or a foundation wall that adjusts with thickness with a change in height). The team is also looking at streamlining the data exchange between the BIM model and analytical software, and exploring the potential to modify our fee structures to reflect that BIM requires consultants to shift their work effort to earlier phases in the design process.

While companies can achieve greater in-house efficiencies by streamlining their processes and their customization work, by far and away the major gains of BIM can be found in interfacing with other members of the design and construction team when all parties are working on a common platform. Achieving these efficiencies requires the buy-in from the whole of the industry. It is generally agreed that the U. S. industry is two years ahead of Canada in the adoption of BIM. Should the Canadian industry be happy to remain as followers delivering the competitive edge to our southern neighbours? Or should we work together to adapt industry best practice in order to leverage and drive the potential of current technology?

Jonathan Hendricks is a principal with Halcrow Yolles, international consulting engineers based in Toronto.

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With BIM we tend to see an erosion of the traditional division of drafting and engineering roles, and the emergence of a combined “modeler” role.