Project contact is Jianhui Zhou at the University of Northern British Columbia
Building acoustics has been identified as one of the key subjects for the success of mass timber in the multi-storey building markets. The project will investigate the acoustical performance of mass timber panels produced in British Columbia. The apparent sound transmission class (ASTC) and impact insulation class (AIIC) of bare mass timber elements as wall and/ or floor elements will be measured through a lab mock-up. It is expected that a database of the sound insulation performance of British Columbia mass timber products will be developed with guidance on optimal acoustical treatments to achieve different levels of performance.
This project studied the feasibility and performance of a mass timber wall system based on
Nail Laminated Timber (NLT) for floor/wall applications, in order to quantify the effects
of various design parameters. Thirteen 2.4 m × 2.4 m shear walls were manufactured and
tested in this phase. Together with another five specimens tested before, a total eighteen
shear wall specimens and ten configurations were investigated. The design variables
included fastener type, sheathing thickness, number of sheathings, sheathing material,
nailing pattern, wall opening, and lumber orientation. The NLT walls were made of SprucePine-Fir (SPF) No. 2 2×4 (38 mm × 89 mm) lumber and Oriented Strand Lumber (OSB)
or plywood sheathing. They were tested under monotonic and reverse-cyclic loading
protocols, in accordance with ASTM E564-06 (2018) and ASTM E2126-19, respectively.
Compared to traditional wood stud walls, the best performing NLT based shear wall had
2.5 times the peak load and 2 times the stiffness at 0.5-1.5% drift, while retaining high
ductility. The advantage of these NLT-based wall was even greater under reverse-cyclic
loading due to the internal energy dissipation of NLT.
The wall with ring nails had higher stiffness than the one with smooth nails. But the
performance of ring nails deteriorated drastically under reverse-cyclic loading, leading to
a considerably lower capacity. Changing the sheathing thickness from 11 mm to 15 mm
improved the strength by 6% while having the same initial stiffness. Adding one more face
of sheathing increased the peak load and stiffness by at least 50%. The wall was also very
ductile as the load dropped less than 10% when the lateral displacement exceeded 150 mm.
The difference created by sheathing material was not significant if they were of the same
thickness. Reducing the nailing spacing by half led to a 40% increasing in the peak load
and stiffness. Having an opening of 25% of the area at the center, the lateral capacity and
stiffness reached 75% or more of the full wall.
A simplified method to estimate the lateral resistance of this mass timber wall system was
proposed. The estimate was close to the tested capacity and was on the conservative side.
Recommendations for design and manufacturing the system were also presented.
Overall moisture management during construction has become increasingly important due to the increase in building height and area, which potentially prolongs the exposure to inclement weather, and the overall increase in speed of construction, which may not allow adequate time for drying to occur. This report provides guidelines and relevant information about on-site moisture management practices that can be adapted to suit a range of wood construction projects...