Building large-sized glazing into timber walls has significantly grown over the last years, however when combined, the structural behaviour of both elements can be rather complicated. This is one of the major reasons for this investigation. In order to design energy-efficient timber-frame buildings with enlarged fixed glazing, it is of primary...
Project contact is Henry Quesada at Virginia Polytechnic Institute and State University
This project is a multistate industry-university collaboration between SmartLam, the Northeastern Lumber Manufacturers Association (NELMA), the American Plywood Association (APA), IKD Architectures, Virginia Tech, and Purdue University to advance the utilization of hardwood lumber for the fabrication of Cross- Laminated Timber (CLT). This new proposal builds upon a previous Wood Innovation project. The collaboration among the organizations proposes to: 1) apply the shear analogy method to hardwood species listed in the National Design Standards (NDS) supplement to assure these species are feasible for the construction of structural CLT panels, 2) create a custom grade CLT layup made of yellow poplar (Liriodendron tulipifera) lumber and get its approval by the Engineered Wood Association (APA), 3) train the hardwood industry in the Midwest and in the Southeast on the application of hardwood structural lumber grading rules, and 4) perform mechanical testing on the hardwood CLT panels used in the Conversation Plinth project by IKD Architectures in Columbus, IN. In 2012 Virginia Tech conducted the first experimental tests on hardwood CLT panels. Results indicated that bonding, strength, and stiffness of yellow poplar CLT panels matched or were superior to some of the softwood CLT layups in the APA standard. Similar results were also obtained by independent testing conducted by the American Hardwood Export Council (AHEC) in 2018. However, further investigation by Virginia Tech found that the main limitations for the use of yellow poplar and other low value hardwood species in CTL panels are 1) lack of experimental data on other hardwood species used in CLT panels, 2) lack of supply of structurally graded hardwood lumber, and 3) acceptance and validation of hardwood CLT panels by the APA standard. Overcoming these limitations is critical for the hardwood lumber industry in order to gain access to the CLT market. Currently, the annual production of CLT panels in the US is about 35,000 m3 but it is expected that in 10 years production will be close to 2 million m3 per year. The outcomes of this project are to increase the utilization of low-value hardwood species from national and private forests and to increase economic development in rural areas in the hardwood regions of the US.
In Australia CLT has a big potential but has to be imported from overseas to date for quite high prices. Milling of Pinus Radiata using optimised sawing patterns for yield and consecutive mechanical grading lead to a substantial amount of boards, which cannot be used for structural purposes directly. Therefore it should be economically interesting to produce CLT using this resource. The authors performed a considerable amount of mechanical tests using various setups and optimised layups in order to investigate the mechanical properties of Pinus Radiata CLT using non-structural boards. The results showed that depending on the layup of the CLT the used resource leads to a product that performs similarly to the ones on the market in Europe