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.
In many mass timber buildings, CLT or nail laminated timber (NLT) floors are designed with a concrete topping to improve acoustic separation, reduce vibration or act as a fire barrier. Little research has examined the fire behavior of these floor systems, but some preliminary tests involving LVL show that they may be able to meet three-hour fire resistance ratings, which could potentially open up the use of mass timber in Type I buildings, representing a large market opportunity. This project will test the behavior of composite floors under fire loading conditions considering the following parameters: shear connector type, mass timber panel types and thicknesses and concrete thicknesses. It will also test and validate an innovative fire research methodology using radiant panels.
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.
The objective of this work is to generate fire resistance data for NLT assemblies to address significant gaps in technical knowledge. This research will support designers and builders in the use of mass timber assemblies in larger and taller buildings, as well as provide scientific justification for Authorities Having Jurisdiction (AHJ) to review and accept this construction method. The intent is to demonstrate that NLT construction can meet or exceed NBCC fire safety requirements for use in buildings of mass timber construction.
The data could be used towards the inclusion of an NLT fire resistance calculation methodology into Annex B of CSA 086 - Engineering Design for Wood, which currently addresses only glue-laminated timber (GLT), structural composite lumber (SCL) and cross-laminated timber (CLT).
The objective of this work is to generate fire performance data for NLT assemblies to address gaps in technical knowledge. This project aims to study how the size of gaps between NLT boards might affect charring of an assembly and its overall fire performance. This research will support designers and builders in the use of mass timber assemblies in larger and taller buildings, by ensuring fire safe designs.
The objective of this project is to establish fundamental fire performance data for the design and specification of NLT assemblies; this project specially addresses determining FSRs for NLT. The goal of this project is to confirm that NLT, when used as a mass timber element, has a lower FSR than standard thickness SPF boards when tested individually and flatwise. The project also considers how the surface profiles, design details, and the direction of an assembly might influence flame spread. This includes the evaluation of typical architectural features, such as a 'fluted' profile.