The Canadian Museum for Human Rights exemplifies the best of design excellence, and demonstrates what can be accomplished when concrete and steel material are married together to create a truly one-of-a kind structure.
There are many stories surrounding the development and construction of this Museum, located in Winnipeg, Man. but for the purpose of this article we will focus on the concrete and the design components used to achieve the end construction goals.
Construction started in 2009 and is expected to be complete this year with an estimated budget of $351 million.
One of the very first challenges in the construction phase was the translation of initial design concepts into separate structural components for rational modeling and design. The process of Building Information Modeling (BIM) was used to design, integrate and coordinate these structural components with the overall building and other design disciplines. BIM allows all the parties access to the design to interact with the same digital files, allowing for three-dimensional modeling, which translates right down to fabrication. BIM is relatively new to construction design, so for this project it was developed from a combination of various software models. Different consultants were also at different levels of expertise with BIM, but came together to mould the different materials and interactions of the building.
According to the structural design team, one of the successes of the BIM process for this project was that it provided opportunities to push the limits of the software to model the special curves and slopes of the building. The modeling involved analysis of the separate structural elements tied together that would eventually form this unique structure. Complex design analysis and lack of building code direction required the structural design firm to develop their own rational analysis and design process appropriate to this complex building for some of the interactions of the structural floors and other elements.
One of the key concrete design elements is the foundation. The building is supported by 141 concrete caissons beneath the heavily loaded column and wall elements. The caissons were drilled into limestone for stability and steel liners were inserted into them and filled with concrete via tremie placement methods. This was required to minimize the impact of flowing groundwater through the expansive clays above the limestone. Over 400 precast piles were driven below the lighter retaining walls and slab—a suspended slab was used due to the expansive clays. There are three building cores consisting of reinforced concrete walls that house the stairs, elevators and service risers that provide lateral stability to wind forces; in addition to supporting the steel superstructure.
One of the really unique structural design features, referred to as the “roots”, are projecting vertical and sloping concrete walls that support sloping concrete framed and structural steel framed roofs to form four roots at the base of the building. Some of these root walls are up to 23 degrees from the vertical. The geometry of the walls required a complex forming system and approach, which was achieved successfully by the contractor.
Another unconventional set of concrete walls that have been constructed start at the back of the roots and extend into the atrium, which is called the Hall of Hope. These are three 50-metre tall, architecturally designed, coloured concrete walls. There are openings randomly placed on these walls to accommodate circulation ramps for a swiss cheese effect. The expectations for these walls’ architectural finish were high, as they would be exposed to the public. Formwork leakage was closely controlled and cleaning methods were applied to maintain the look after exposure to the elements and construction runoff, in order to achieve the required finish look.
In several of the structural and non-structural concrete wall sections, a philosophical approach was taken to give an architectural effect referred to as “shaggy” concrete. Shaggy concrete can be described as a coloured concrete that leaves a look similar to a sedimentary rock finish. The structural design team worked closely with the architect and the contractor to achieve this creative architectural finish.
The interaction of the structural steel and concrete elements required special consideration in many areas. One of the features used in the design were concrete corbels to provide supporting points for the larger, more heavily loaded structural steel elements. The contractor had many challenges managing the construction elements of both concrete and steel.
This article has barely scraped the surface of the complexity of the design and construction challenges that have been met and addressed throughout the process. Pictures are worth a thousand words and a visit to the Canadian Museum of Human Rights will amaze and give you greater insight into one of the most creative buildings in Canada.
This article was contributed by the Manitoba Ready Mixed Concrete Association and the Principal Structural Design team of of Yolles, A CH2M Hill Company. Send comments to editor@on-sitemag.com
