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The SMART team, a software R&D department at UK's Buro Huppold, has developed a method of integrating digital design, analysis, and construction processes. Integrated modeling proved essential for building the complex structure of the convention center for Education City, Qatar, shown here.

A SMART approach to integrated 3D analysis at Buro Happold

By Brett Duesing, Obleo Design Media

As one of the largest engineering consultancies in the world, Buro Huppold crosses continents — with 15 offices throughout Europe, the US, and the Middle East – as well as disciplines, offering its clients solutions to nearly any design, structural, and civil engineering problem.  The firm’s design CV is considerable, including such early achievements like the Pompidou Center, and the Sydney Opera House.  The firm’s size — and its sizable tasks –  has led to its own Research & Development department, which looks for new ways to solve spatial problems.

“My SMART team – Software Modeling Analysis Research Technologies – focuses on the area of very complex nonlinear geometry in modeling analysis,” says Dr. Shrikant Sharma, who leads the group out of BH’s Bath, UK office.  “We’ve developed software which expedites these analyses through our internal research in cooperation with the top UK universities.”

Outside the Box -- More complex architectural shapes  -- like Buro Happold?s elongated curves on Malmö Green house in Sweden -- brings the need for 3D tools to solve geometric problems for engineering and construction.  The SMART team, a software R&D department at BH, has developed a method of integrating digital design, analysis, and construction processes.

Outside the Box -- More complex architectural shapes, like Buro Happold?s elongated curves on Malmö Green house in Sweden, brings the need for 3D tools to solve geometric problems for engineering and construction.

Sharma’s patented software creation for BH, SMART Form, is one example of how 3D modeler can be used to model not just shapes, but to model problems.

Open Architecture

“We use a variety of tools to optimize the process of finding the most efficient structure.  We write software as we need to, and obviously use existing software when it fulfills our needs,” says Sharma.  “But sometimes existing applications can’t answer the questions we have.  Some programs are very generic and we can’t add in certain specifications.”

Part of the philosophy its software developers, McNeel & Associates, was to keep the Rhinoceros modeler an open architecture that third-party programmers could independently develop and sell plug-ins which give users access to enhanced tools for specific for different industries.  As a result, Rhinoceros itself is kept unburdened with too many features, but at the same time adaptable to diverse design specialties from aviation to architecture.

Rhino’s 3D geometries are part of the input for SMARTForm, along with the queries for the particular structural or costing problem.  The Rhino model also displays the output from the SMARTForm analysis.  SMART plug-in queries can survey the 3D model automatically, highlighting surfaces that conform to a certain extent of curvature or angle, or lie a prescribed distance from other entities.

Just as Geographic Information Systems (GIS) query relationships between points, lines, and enclosed shapes on 2D maps, SMARTForm uses topological relationships, along with differential geometry, to map out problems on a complex 3D structure.

sidra-branches-wBuilding A Tree

A recent example of SMARTForm capabilities is Buro Happold’s convention center in Education City, a new 2,500-acre campus on the outskirts of Doha, Qatar.

“Education City will have lots of extensions of foreign schools, some of which are already there, like Carnegie Mellon,” explains Sharma. “They will provide state-of-the-art education to students of the Middle East, and promote the location as an international center of education in the region.”  This massive convention center includes auditorium and committee meeting rooms for major events in Education City.  One of its exterior walls contains a 20-meter-high, 250-meter-long sculpture of a Sitra Tree – an ancient Arabian icon of learning, growth, and stability.

Making the form structurally sound is a job for Sharma and his SMART group, which modeled, analyzed, and optimized the tree sculpture and roof supports. SMART worked closely with the structural engineering team which was responsible for the detailed design and analysis of structural elements. Brian Cole, also based in Bath, led the project within SMART.

treecrosssections1The team begins with the Rhinoceros model of the architect’s free-form shape, which in the final structure will only be the tree’s outer skin. The actual loads will be carried by a substructure of steel members, which is up to the team to devise. The internal support system needs to be efficient in its use of materials and effective in its support at all points.  Because the components will be digitally manufactured off site, the system should keep the number of assembly parts to a minimum.

“We wanted the skeleton to be as close to the skin as possible simply to make sure the structure is efficient and uses the least amount of steel,” says Sharma.  “For the shape of the members, you wanted something that would be as close to a circle as possible but not have a lot of complex connectors, so we chose an octagon.  Also, we wanted the members to conform as much as possible to the center line of the branches.”

SMARTForm was used for finding the center line through the 3D model with a least-square fit formula, ensuring a uniform distance from the skin.

“The result is that we have a minimum of straight segments which are very close to the center line, while not having a lot of bend in the structure.  To make sure there’s a consistent space between the structure and the skin, the orthogonal structure actually tapers in its width as it goes from the bottom to the roof line,” Sharma explains.  “The branches also taper at a slightly different ratio.  A simple mathematical equation based on volume dictates how wide the members will be.”

Treehousing -- The trunk?s metal skin provides the form.   The load of the structure is carried by the centerline members.  BH engineers chose an octoganal shape to approach a circluar form, but which would better support angles at the joints.  Engineers also used thinner sides and hand-access holes to aid on-site assembly.

Treehousing -- The load of the structure is carried by the center-line members inside a steel skin. BH engineers chose an octagonal shape to approach a circular form, but which would better support angles at the joints. Engineers also used thinner sides and hand-access holes to aid on-site assembly.

The varying width of the octagonal steel members give a consistent support throughout the Sidra Tree without tensile warping of the thin skin of metal panels.  The geometric rationalization resulted in an efficient arrangement of solid regular structures that supports the more free-form exterior skin. It also enabled detailed design of the substructure using conventional design codes by the structural engineers.

Plug-ins to cut corners

SMARTForm analysis not only is useful in creating efficient geometry of structural systems, it can also be used to test construction alternatives that reduce cost.  constr-sidra

The outer skin of the Sitra Tree sculpture was to be thin panels made of corrosion-resistant steel.

“The client did not want glass-reinforced plastic, which would be much easier to fabricate with curvatures.  The intent was to build this fantastically complex tree structure from metal, which is a bit more problematic and expensive to construct.  With metal, cost became a significant constraint.”

The design and build team of Victor Buyck and Buro Happold found that a doubly-curved metal panel would cost up to four times to produce than one which is curved in just a single direction.

“A two-curvature panel will be very difficult to fabricate, since the bending, rolling, and stretching of the metal occur all at the same time, so there are a lot more costs associated with it.   Essentially, we wanted to maximize the number of panels that could be described as a single-curve surface, and keep the doubly-curved panels to a minimum.”

Using SMARTForm and the Rhinoceros panel scheme, Sharma’s team could quickly identify the thousands of metal panels by their topological make-up.  In the majority of occurrences, the secondary curve was only slight.  Sharma proposed a design compromise that changed the cost dramatically, while tweaking the overall shape of the Sidra tree almost imperceptibly.  The new panelization consisted of 70 percent of the panels as single-curve components, cutting about 60 percent of the cost of the skin fabrication.

“If you replace many of the original doubly-curved pieces with single-curved replacements, you can barely tell the difference,” says Sharma.  “We could construct basically the same tree-skin form with less complexity, but without loosing any of the character or smoothness of the shape.  There are points, especially at the branching joints, where you obviously need a double-curved piece.  We replaced the design driven by a curvature-based definition in SMARTForm which followed the flow lines of the tree shape.”

Digital fabrication

“Another consideration was transportation,” says Sharma.  “The entire tree was being fabricated in Malaysia. We didn’t want a lot of small pieces, and we wanted a close fit for the substructure when it was to be assembled on site. Another constraint was the assembly itself, not just initial construction but the need for a long-term access and maintenance strategy. We made the horizontal and vertical sides of the octagonal members thicker and the inclined plates thinner. Through the latter, we could more easily drill holes for manual access without losing stiffness in the design.” oct_constr

There is a reason why Sharma prefers to keep a strict mathematical control over design pre-processing. Maintaining a uniform accuracy to the infrastructure and design modifications carry on into post-processing, where the 3D data will feed into automatic CNC machining in the Malaysian fabrication shop.

The creation of the center line, the parsing of the center line, the panels, the understructure definition, the access holes – everything is programmed and generated automatically.  Every time something changes as part of the design evolution, we need to handle it consistently.  You also want to make sure you have a digital fabrication output without any manual intervention.  There are hardly any drawings of the skin panels, most all of the fabrication uses the 3D data directly to the factory machines.”

The Sitra Tree is an example of how architecture is borrowing from industrial design to take advantage of the efficiencies inherent in 3D technology.  The SMART group’s handling of the engineering ensures a high level of consistency throughout the thousands of pieces that make up the Sitra structure.  Each part is numbered and organized according to a machining and assembly schedule.  Because of the accuracy of the 3D processing and the CNC cuts, the tree is assembled with a perfect fit.

orSMART’s overall technique — using Rhinoceros as a central 3D hub which can transfer data back and forth to stand-alone tools such as ANSYS and Robot, further analyze and optimize designs through plug-ins and propriety software like SMARTForm, and schedule machining output through CNC devices  — is what Sharma calls “integrated modeling.”

“With integrated modeling,” Sharma says, “we can keep design, analysis, and fabrication essentially in one system that is truly automated.”

Learn more about SMART plug-ins for Rhino at:  www.burohappold.com/bh/srv_bld_smart_solutions.aspx.

About Buro Happold

Designers of elegant, bold, and sustainable engineering solutions for today’s built environment, Buro Happold builds for people.  With comprehensive services for any sized construction project, Buro Happold solves architectural, infrastructural, and environmental problems all over the globe.  For more information and to view past projects of Buro Happold, please visit: www.burohappold.com.


About Rhinoceros

Rhinoceros provides the tools to accurately model your designs ready for rendering, animation, drafting, engineering, analysis, and manufacturing.  Rhino can create, edit, analyze, and translate NURBS curves, surfaces, and solids in Windows, without limits on complexity, degree, or size.  Rhino gives the accuracy needed to design, prototype, engineer, analyze, and manufacture anything from an airplane to jewelry. To see the many diverse products designed with this affordable 3D tool, and to download a free evaluation version, please visit: www.rhino3D.com.

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