Recipient Organization
STATE UNIV OF NEW YORK
(N/A)
SYRACUSE,NY 13210
Performing Department
Sustainable Construction Management and Engineering
Non Technical Summary
Cross Laminated Timber was first developed as a product in the early 1990s as a collaboration between industry andresearch institutions in Austria. The system is based on creating a composite panel for construction that usesindividual boards to form wood layers and then cross laminates successive layers (typically three or five total) toprovide a dimensionally stable large (8' x 20' x 4-5") composite product that can be manufactured, shipped, anderected efficiently. These panels are used as floors, walls, and roofs in a structural system with a set of standardconnection and finishing details. This continuous structural system is typically enclosed within the thermal boundaryof structure, and can be covered or left expose.This system has been successful in Europe, and is being introduced in Canada due to a number of factors:First and foremost, it is a system that has multiple advantageous features for improving the environmental and energyperformance of buildings. As building owners recognize the need to build in a more energy-efficient manner, basicdecisions about how the thermal envelope and the structural system relate are becoming a greater focus. The use ofa sustainably produced material with relatively low energy inputs offers owners a construction system whose first costis less sensitive to increasing energy costs. The continuous nature of panel construction, and absence of thermalbridging, and the inherent R value provided by CL T provides owners with lower operational costs than competingsystems (steel and concrete) where the structural system makes detailing a continuous envelope more difficult,where the structural material provide negligible R value contribution, and where the production of the materials ismore energy intensive, in some cases by an order of magnitude. Additionally, the amount of carbon captured in thestructure (as enumerated elsewhere) is significant.The second factor contributing to the success of c.L T construction is the construction efficiency that it offers. Unlikesteel, cast-on-site concrete, concrete masonry unit (CMU) and site built light frame construction, CL T construction ispre-fabricated to provide faster on-site progress. The large panels are similar to pre-cast concrete in size andapplication, and allow for similar lifting and placing equipment to be used for their assembly. Much of the CL T marketshare in Europe has been in the low to mid-rise construction (3-8 story). In this sector CL T has provided costcompetitive solutions for building owners sensitive to time pressures.The third factor contributing to the success of the CL T construction is the use of significant amount wood in thestructure. This has provided lighter buildings with decreased foundation costs, lower seismic loading, improvedacoustic performance, and greatly increased fire resistance compared to light construction.Awarded Start Date: 11/20/13Sponsor: NYS Energy Research and Development Authority
Animal Health Component
(N/A)
Research Effort Categories
Basic
75%
Applied
(N/A)
Developmental
25%
Goals / Objectives
The major goal of this project is to characterize the structural performance of CL T panels using indigenous and under-utilized speciesand grades from the Northern Forest.
Project Methods
ANSI/APA PRG 320-2012 provides seven CLT grades. These grades include four grades that are based on MSRlumber (high grade more expensive material), and. three grades that are based on visually graded material. The V2group shown in the Table 1 (below) is a Spruce, Pine, Fir mix found in the forests of Canada.The selected NY species groups of Red Maple and Red Pine, as well as mixed cant material would be compared tothis V2 group. The National Design Specifications for Wood Construction (NOS) published values for the bendingstrength of an individual Red Maple board exceed the values for the V2 group shown in Table 1. These bendingvalues for individual boards indicate the potential for favorable results when tested in a CL T panel. Red Pine is notseparated as a species groups in the (NOS), but is grouped with Eastern Softwoods, thus CL T panel testing willindicate how Red Pine fares as a separate species.The material that is left after removing the valuable outer boards from a log is a cant. Due to the presence of defects,the cants are typically not acceptable for aesthetic applications. However, there is valuable wood fiber (White Ash forthis project) that may be appropriate for structural applications at a low cost. The third set of tests would be run oncant material.The CL T panels will be fabricated in configurations for two tests: Bending tests will be performed on panels ofapproximate 12" x 120" x 4" dimensions, Shear tests will be performed on panels of 24" xc 24" x 4" dimensions. Thestandard requires that at least 10 panel tests be performed for each test type (bending, shear) to estimate a meanvalue with 5% precision with 75% confidence. The final step in the research will involve comparing the costs for the three raw materials, and typical production costswhen using industrial equipment. With these costs and strength values, a clear understanding of the potentialopportunity for CL T production with NY species wlll be provided.