In this study market opportunities for treated glue-laminated (glulam) products were investigated in the industrial wood sector. The main benefits of treated glulam are through-product treatment and the ability to manufacture treated products in shapes and sizes that do not fit into common treating chambers. These attributes provide for very durable and large glulam structures that are appropriate for outdoor use. For these reasons bridges, power poles, and sound abatement barriers were investigated. These are markets where wood has lost market share to or is being challenged by concrete and steel substitutes.
The vehicular bridge market was once heavy to the use of wood. Today wood accounts for only 7% of the number bridges in the US and less than 0.9% of the actual surface area of bridges in place. In interviewing municipalities in Canada it is clear that wood is not the preferred material with many wood bridges being replaced by concrete. Further, none of the municipalities contacted were planning wood bridges. However, wood bridges are still being installed. In the US 0.9% of the bridges installed by area in 2007 were wood. This is good news as wood is holding its market share. Steering clear of high volume or large bridges, local bridges are well suited for wood as they are plentiful, small in scale, and many are in disrepair. If 20% of local bridges were built with wood in Canada this would have equalled approximately $51 million in wood bridge construction in 2007.
Municipalities are much more open to the use of wood for pedestrian bridges and overpasses. Their quick construction and aesthetics are positive attributes in this application. One municipality contacted is planning multiple wood pedestrian bridges in the next five years. However, for the purpose of this market review there is little published information on pedestrian bridges.
Noise abatement barriers are a good high-volume technical fit for treated glulam. Increases in traffic and current road infrastructure improvements will lead to more demand for sound abatement in the future. This market is dominated by concrete, but at a very high price. If treated glulam can give adequate durability and sound performance properties it would be approximately 20% cheaper than concrete. The market for sound barriers in Canada could utilize up to 10 mmbf of wood per year to construct 80 km of barrier. This product can also be marketed as a high-performance acoustic fence for residential markets.
Treated glulam was also considered for utility poles. It is transmission grade poles where glulam would best fit the market as the demand is for longer poles which are more difficult to get in solid wood. This type of pole is where wood is currently being displaced by tubular steel. If glulam poles were used in 25% of the replacement transmission poles per year this could equal 8 mmbf. Light poles or standards are another market to consider. While this is a relatively low volume market glulam light standards are a premium product in European markets.
Wood frame construction in China is currently limited to 3-storey buildings, mainly due to fire risk perceptions. However, multi-storey (more than 3 storeys) wood frame buildings are gaining popularity around the globe, while providing an acceptable level of performance in...
European experience shows that Cross-Laminated Timber (CLT) can be competitive in mid-rise and high-rise buildings. Although this system has not been used to the same extent so far in North America, it can be viable wood structural solution for the shift towards sustainable densification of urban and suburban centers. For these reasons FPInnovations has undertaken a multi-disciplinary project on determining the performance of a typical CLT construction, including quantifying the seismic resistance and force modification factors for CLT buildings in Canada and the US.
In this report, a performance-based seismic design (PBSD) of a CLT building was conducted and the seismic response of the CLT building was compared to that of a wood-frame structure tested during the NEESWood project. A suitable force modification factors (R-factors) for CLT mid-rise buildings with different fasteners were recommended for seismic design in Canada and the US. The six-storey NEESWood Capstone building was redesigned as a CLT building using the PBSD procedure developed during the NEESWood project. The results from the quasi-static tests on CLT walls performed at FPInnovations were used as input information for modeling of the main load resisting elements of the structure, the CLT walls. Once the satisfactory design of the CLT mid-rise structure was established through PBSD, a force-based design was developed with varying R-factors and that design was compared to the PBSD result. In this way, suitable R-factors were calibrated so that they can yield equivalent seismic performance of the CLT building when designed using the traditional force-based design methods.
Based on the results of this study it is recommended that a value of Rd=2.5 and Ro=1.5 can be assigned for structures with symmetrical floor plans according to NBCC. In the US an R=4.5 can be used for symmetrical CLT structures designed according to ASCE7. These values can be assigned provided that the design values for CLT walls considered (and implemented in the material design standards) are similar to the values determined in this study using the kinematics model developed that includes the influence of the hold-downs in the CLT wall resistance. Design of the CLT building with those R-factors using the equivalent static procedures in the US and Canada will result in the CLT building having similar seismic performance to that of the tested wood-frame NEESWood building, which had only minor non-structural damage during a rare earthquake event.
In an attempt to prevent the spread of fire and smoke beyond the compartment in which the fire starts, regulations often require building construction such as walls and floors to exhibit varying degrees of fire resistance. Since penetrations for building service equipment and systems in wall and floor assemblies acting as fire separations are unavoidable...
Nail-Laminated Timber (NLT) and box beam are efficient and economical engineered wood products. Although NLT has been used in North America for more than a century, only in recent years it has gained renewed interests as they have been seen as the most economical panel products used in mass timber buildings. Box beams, on the other hand, are lightweight and generally possess higher strength and stiffness than comparable-sized solid timber and are more efficient than solid timber large spans and loads.
In this report, existing design provisions and their limitations for the design and construction of NLT in box beam in Canadian standards are reviewed. For NLT, there is a general lack of information related to manufacturing, design and construction to ensure consistent manufacturing and installation practices. Therefore, it is difficult to research and document with confidence the full range of performance that can be achieved with NLT. It is therefore recommended that a North American product standard and design information on structural performance, floor vibration, fire resistance, acoustic performance, and construction risk mitigation measures (e.g. moisture and fire) be developed.
In CSA 086, design methods are limited to box beams with flanges and webs bonded with glue. As the flanges and webs of a box beam can be assembled by either glue or mechanical fasteners, it is recommended that design provisions for box beam with mechanical joints be also developed. With the information in Eurocode 5 and relevant supporting research papers, it is ready to be implemented.
Across B.C. and Canada, communities are under pressure to create better-performing buildings that meet stringent code requirements while reducing construction waste. Meanwhile, consumers are demanding high-quality structures that are delivered quickly and at a reasonable price. Modern methods of construction that include prefabrication can help construction professionals create buildings that meet all these criteria.
Furthermore, prefabrication provides steady employment and is good for the economy. The market opportunities are present across Canada and in the U.S., but prefabrication is not being used to its potential due to several barriers:
Negative perception of quality
Fear of innovation
Lack of information and understanding
Unclear economic benefits
Limited industry capacity
Planning and regulatory complications
A concerted effort to address these barriers includes:
Improving products through research and development
Researching, documenting, and promoting best practices
Developing guidance documents so prefabrication is easier to incorporate
Providing national-level leadership and resources to promote innovation
Successfully implementing these recommendations will require a broad and deep national perspective, an understanding of all stages and aspects of wood construction, and the vision and skills to bring together diverse experts and stakeholders.
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