For several years, Decision Aids has been addressing knowledge and technology transfer gaps in the design and construction sector that have had negative consequences for the image of wood. Since June 2000 we have been operating a public web site, together with the Canadian Wood Council, as a primary mechanism for conveying information to the building industry on wood durability. The web site’s popularity is growing, with October 2002 a record month for visits (3,748). In 2002/2003, we added substantial new material to the site, we brought the French side fully up-to-date, and we reconfigured the site’s appearance and structure. In 2002/2003, we also continued to develop our participation in building science academic development at UBC and BCIT. This kind of involvement with the universities that are teaching tomorrow’s building designers and consultants has become the preferred route for Decision Aids to meet its mandate for filling current knowledge gaps in durability. In particular, we have stayed closely aligned with BCIT in its pursuit of funding for the development of an outdoor test facility for building envelope assemblies. Such a facility will be an important tool for filling information gaps regarding best practice design with wood in rainy climates.
This report summarises the findings in a project directed at determining what is known about the fire performance of connections between heavy timber members.
In Canada, where a 45 minute fire-resistance rating is required, the NBCC lists minimum dimensions of solid sawn or glulam columns (loaded in compression), beams (loaded in bending) and trusses (bottom chord loaded in tension) which achieve the rating. Methods for designing connections between solid sawn or glulam members that preserve the 45-minute rating are also provided. Where a one-hour fire resistance rating is required, the NBCC provides equations to calculate the dimensions of glulam columns (loaded in compression) and beams (loaded in bending) which achieve the rating. However, no guidance is given for designing glulam members loaded in tension and no guidance is given on connections between glulam members that preserve the one-hour rating. Furthermore, no guidance is provided for designing solid sawn members (or their connections) when loaded in compression, bending or tension.
In the U.S.A., the minimum cross-sectional dimensions of glulam and solid-sawn timber beams and columns that achieve a 1-hour rating can be calculated from the same simple formulae provided in NBCC. As an alternative, a more advanced mechanics-based method can be used to calculate minimum cross-sectional dimensions of glulam and solid-sawn timber loaded in bending, compression and tension. Where a 1-hour fire-resistance rating is required, connectors and fasteners must be protected from fire exposure by wood, fire-rated gypsum board, or any coating approved for the required fire-resistance time. This approach does not account for any inherent fire resistance of the connection but rather requires it be protected by wood, fire-rated gypsum board or a coating that can provide the entire 1-hour rating.
In Europe, guidance is provided on how to design wooden structures and their connections to achieve fire resistance ratings up to one hour. Extensive guidance is given for connections consisting of two structural members spliced together with side plates of wood or steel and held together with dowel-type fasteners (nails, bolts, dowels and screws). Unprotected wood-to-wood connections of this sort, designed in compliance with ambient (non-fire) design standards, have an inherent fire resistance rating of at least 15 minutes. The fire-resistance rating can be increased to 30 minutes or even 60 minutes by the application of wood, wood-based or gypsum board panels with thickness calculated using simple formulas. As an alternative, a fire-resistance rating up to 60 minutes can be achieved using connections with internal steel plates.
There is currently no guidance provided to designers in Canada on how to design a connection between heavy timber members that can ensure a 1-hour rating. As this seems inappropriate, it is strongly recommended that Canadian building code committees be approached and requested to adopt either the approach taken in the USA or the one in Europe.
The wood products industry wants to expand its market share in non-residential buildings. This is a challenging goal because building codes exhibit a bias against the use of wood products, particularly in the construction of non-residential buildings. The move towards adoption of performance-based building codes offers the promise of eliminating such biases. However, in order to be prepared for the introduction of performance-based codes, architects, engineers and building code officials have pointed out the need for engineering tools to assess the fire performance of buildings.
This five-year project was initiated to develop fire-safety design tools for non-residential wood-frame buildings, and to foster development and delivery of educational programs to train students and practitioners in performance-based fire-safety design. In order to achieve these goals an NSERC Industrial Research Chair in Fire Safety Engineering was established at Carleton University in March of 2001. This report summarises the progress towards these goals made by the Chair in the first two years of his tenure.
This project was launched to support a NSERC grant proposal under the Collaborative Research and Development program (CRD) in 2001, together with universities and other institutes, including UNB, McGill, Concordia, UWO, NCSU, the ICLR, CSIRO of Australia, and the CWC, with Forintek being the main industry sponsor. On October 22, 2002, a formal notification on the success of the grant application was received.
Three (3) test structures are planned for monitoring wind loads, including an industrial shed located at Forintek’s Eastern Laboratory in Québec City. The shed is being instrumented with pressure sensors and deformation measuring devices to measure wind loads and the structural response. Two (2) sections of the wall and roof have been instrumented. This included four (4) studs and two (2) roof wood I-joists. The idea is to collect limited data on wind loads and structural response as a learning exercise, before detailed study of purpose built test structures. Two (2) new test structures are planned to be built in Montreal (at McGill’s Macdonald campus).
In order to study the response of structural subsystems to lateral loads and compare that with predictions from Finite Elements models, shear wall tests were carried out at Forintek. Eight (8) wall configurations were tested with and without openings. Such tests provided valuable information on the behaviour of wall panels to lateral forces. Moreover, good agreement was found between model predictions and the experimental results. Proto-type load cells capable of measuring forces in three dimensions have been developed at the University of New Brunswick. The load cell will eventually be used to measure forces transferred at the interface between the walls and foundations or roof and walls. Considerable efforts have been made in the development of the instrumentation systems and connection details for the planned test structures (2 and 3). Forintek has established contacts with the wood industry in order to secure the construction materials needed for building the new test structures.
Work is continuing on the instrumentation of Forintek’s shed and the monitoring process will start soon. Structural and architectural plans for the new structures and details of instrumentation are being finalized.
In order to maintain the competitive advantage in existing and new markets situated in seismic and high wind zones such as the Pacific Rim and the southeastern U.S., it is proposed to study deflections in walls, floor and roof assemblies. The proposed project will also be very useful in: a) setting deflection criteria as will be demanded by performance-based codes, and b) responding to the inevitable transition to displacement-based seismic design.
Non-residential building construction in North America is a vast market for wood-based products in structural and non-structural applications. For a variety of reasons, this market is currently dominated by steel, concrete and masonry structures. Promotional efforts by the forest products industry are making positive effects in convincing specifiers to use wood-based systems in some non-residential applications. Platform-frame wood construction is the most common wood-based structural system that is currently dominating the low-rise residential market in North America. With slight modifications, this system is also well suited for use in single-storey box-type non-residential buildings with heights up to 10.7 meters (35 feet). Incremental research contributions are needed if such tall wood-frame walls are to make serious inroads into the non-residential construction market.
This project provides a literature survey on the topic of tall wood-frame walls. It identifies the important issues related to the design and performance of tall walls used in construction of single-storey non-residential box-type buildings. In addition, it gives an overview on the marketing aspects of use of tall walls in non-residential applications, as well as information on the concrete tilt-up, masonry and steel structural systems as main competitors for the market share. The results of this project will be used as a basis for planning of the future research activities in the field of tall wood-frame walls.