Stairs And Louvres

PROJECT Four Seasons Centre for the Performing Arts Staircase
ARCHITECT Diamond and Schmitt Architects Inc.

The Four Seasons Centre for the Performing Arts (see CA, September 2006) in Toronto is Canada’s first purpose-built opera house that received considerable acclaim by performers and patrons when it opened in the summer of 2006. As part of the 2009 RAIC Awards of Excellence, the project received an honourable mention for its free-spanning glass stair located in the City Room, a large front lobby space.

Working from the concept of a staircase comprised almost entirely of structural glass, the architects and structural engineers developed an innovative design that has resulted in the longest-spanning glass stair constructed in the world. With a horizontal run of almost 27 metres and a rise of 8.8 metres, the 2.1-metre-wide glass stair appears to float in the lobby space. The only visible structures are two 15mm x 100mm stainless steel bars at the top and bottom of each balustrade that form the chords of the truss. The web of the truss is constructed from 12 individual glass panels measuring approximately 3,700mm x 1,550mm and constructed from three layers of 12mm low-iron glass laminated together with a 1.9mm clear plastic interlayer. Spanning delicately between the balustrades are the treads, each consisting of two layers of 15mm low-iron glass, a layer of 10mm low-iron glass, and a vertical riser constructed of two layers of 10mm low-iron glass. A sandblasted non-slip wear layer is laminated to the top of each tread to ensure both safety and privacy from below. Through the use of multiple small connections at the nodal points rather than the usual practice of a single large connection, there are no vertical support elements at the glass joints. Every piece of hardware that joins or connects pieces of the stair was individually designed and engineered as part of the design process.

Most glass stairs utilize the balustrades or pickets that are connected to a rigid structure like a floor slab to absorb vibration. In this case, the treads and risers of the stair are used to provide lateral stability and to resist vibration. Human perception of vibration can be influenced and magnified by psychological factors. Therefore, the design team felt it was important to improve upon standard acceptable limits for the glass stair. A potential large volume of traffic walking in unison combined with an uncommon building material such as glass necessitated a thorough investigation of the dynamic properties of the stair and its response to vertically and laterally induced vibrations.

A model of the City Room was developed to analyze and design each component of the stair’s supporting elements, which are mainly tension rods hung from the long-span roof truss system. The model was used to study the overall behaviour of the stair under the applied forces and to understand the response of static and dynamic loading. To minimize the concentration of stresses of the glass units, fully rigid connections were avoided.

Because of its innovative nature, the stair was peer-reviewed on two occasions, and each element was subjected to independent testing prior to finalization of the design. The construction of a full-size mock-up of a five-tread section of the stair was a significant part of the design-review process.

The innovation displayed in the design of this stair stems from the close working relationship between the architect, the structural engineer, the fabricator and the installer. Issues of safety, failure mode analysis and constructability were also discussed, analyzed and detailed at great length.

PROJECT Bluepoint Louvre Faade System
ARCHITECT Paul Raff Studio

Paul Raff Studio has designed a unique residential complex with remarkable green design strategies, earning an honourable mention in the process. Its most novel feature is a louvre faade system which was developed as an integral component of a multi-unit housing project in Phuket, Thailand. The project context required a unique response that could provide panoramic views to the ocean, privacy, minimization of solar heat gain, and maximum durability and resilience in a demanding tropical environment.

The Bluepoint Louvre Faade System forms the outermost layer of an exterior wall assembly and consists of fixed vertical louvres, providing an exterior shading solution that limits solar energy from entering the building while offering a range of innovations that optimize views to the exterior.

The louvres are made from a wood composite extrusion that is produced locally. These are supported by the two other major components of the system: steel tabs and support rails which are laser-cut, break-formed and shop-welded. The system’s use of wood-plastic composites (WPC) is a relatively new technology that is being used with increasing frequency. WPC is highly resistant to rot, can maintain dimensional stability in high humidity and temperature conditions, and is comparatively lightweight relative to traditional wood components. It is composed of wood from recovered sawdust (and other cellulose-based fibre-fillers such as peanut hulls, bamboo and straw), and waste plastics. Within current construction product markets, WPC is typically extruded in profiles to emulate traditional geometries of dimensional lumber.

Using exclusively conventional architectural construction drawings in describing this assembly would be radically inefficient, as inherent to this application are hundreds of unique site-responsive conditions requiring excessive visual description. Thus, an instruction set with unique nomenclature and graphic tables was developed as part of the project. This mode of system description eliminates additional complexity associated with language barriers and differing cultures of construction delivery.

In order to achieve the desired visual complexity of the system while minimizing the actual complexity of the construction process, the Bluepoint Louvre Faade System was developed through a parametric modelling process into a highly rationalized set of simple components where mechanical fastening techniques and conditions of anchorage to the building substructure remain straightforward, with limited site adjustment required in the field. Furthermore, web-based communications and file-sharing facilitated project collaboration across 12 time zones and three languages. The inclusion of academic and industry partners across various phases of project development also helped with communications. Finally, the utilization of CADD-linked spreadsheets streamlined the design process and eliminated redundant parts.

This project sets out to further the practice of architecture through the application of new sustainable materials, fabrication techniques, and the potential of design professionals to participate in the development of new product lines outside of the scope of traditional practice. Using readily available technologies (digital-modelling technology, web-based communications and file-sharing, web-based access to academic research, CADD-linked spreadsheets), a small Canadian architectural practice was able to deliver innovative design in a global context.