Theme 1 – Structural and Serviceability Performance
Theme 1 consists of four projects which in turn are divided into sub-projects focusing on extensive simulation and testing of timber structural components. The key outcomes from these four projects are:
1. A series of improved/refined structural analysis methods for selected systems
2. Innovative structural systems
3. Advanced structural design procedures;
4. Improved serviceability design of assemblies. The key outcome of this research will be new knowledge that can be used by researchers, designers, and the industry to ensure that next-generation timber buildings are structurally safe and serviceable.
Project T1-1 – Refined Structural Analysis and Design of Timber Systems
There are six sub-projects within Project T1-1 which are intended to develop improved methods of analysis and design guidelines for existing and new systems including seismic performance of mass timber (MT) shear wall and braced timber frames, mass timber plate systems under in-plane and out-of-plane loads, natural periods of vibration of wood buildings and stiffness properties of timber connections.
Sub-project T1-1-A – Seismic performance of balloon MT walls and cores
PI: Dr. Tony Yang, University of British Columbia
HQP: Amir Ghahremani, Benjamin Ernewein
There are currently no design guidelines for balloon MT walls as a system in CSA O86 (CSA 2019) and the NBCC (NRC 2020), and this regulatory gap inhibits the implementation of such systems. The main objective of this research project is to quantify the system performance, and to develop the technical information necessary for the wide-accepted design, of individual balloon MT walls and cores in mid-rise and high-rise buildings. Specifically, design guidelines for such systems will be developed and force modification factors will be derived for future implementation of the system in the NBCC.
Sub-project T1-1-B – Seismic performance of innovative braced timber frames
PI: Alexander Salenikovich, Laval University
HPp: Kiavash Gholamizoj
Braced timber frames (BTFs) are one of the most efficient structural systems in terms of lateral load resistance. The main objective of this sub-project is to generate technical information related to the performance of different types of innovative BTFs for mass timber and hybrid construction. Based on modelling and analysis, innovative braced frame system suitable for high-performance (low damage) and self-centering capability (Gauron et al. 2015) will be developed.
Sub-project T1-1-C – Performance of MT flat-plate systems under out-of-plane loading
PI: Thomas Tannert, University of Northern British Columbia
HQP: Houma’s Ganjali
A preferred floor design in CLT structures is a flat-plate system where the CLT panels rest directly on walls or columns without a beam framing system. This sub-project will investigate the structural performance of flat-plate floor systems in mass timber construction. Design guidelines for such a floor system in mass timber construction will be developed.
Sub-project T1-1-D – In-plane performance of mass timber diaphragms
PI: Jeffery Erochko, Carleton University
HQP: Peter Berghuis
There has been limited research into their behaviour in MT panel floor diaphragms (D’Arsenzo et al. 2019), and no design guidelines currently exist. The main goal of this sub-project is to develop guidelines for the design of MT diaphragms that take into consideration their flexibility and the flow of forces through the diaphragm to the lateral force resisting system (LFRS) underneath. The design of panel-to-panel shear connections, collector elements, chord reinforcements, and connections to boundary elements will also be covered in the guidelines to be developed.
Sub-project T1-1-E – Estimation of building periods and accelerations due to wind and seismic loads
PI: Ghasan Doudak, University of Ottawa
The NBCC (NRC 2020) provides an empirical formula to estimate the natural periods of buildings based on its building height, but it has not been calibrated to timber buildings (Hafeez et al. 2018). The main goal of this sub-project is to develop a database of in-situ measurements of natural frequencies and Next Generation Wood Construction Page 10 of 34 Chui, Y. H. (18138) internal damping of timber buildings. This database will form the basis to derive appropriate predictive models.
Sub-project T1-1-F – Stiffness properties of timber connections
PI: Ying Hei Chui, University of Alberta
HQP: Tao Gui
Stiffness properties are required for both serviceability limit state and ultimate limit state designs, and it is critical that reliable stiffness properties of common timber connections be provided to designers so that competitive, serviceable, and safe structural timber systems can be designed and constructed. Moreover, given that timber connections are often the main source of energy dissipation and deformation of timber systems, reliable connection stiffness information is a pre-requisite for adoption of advanced seismic and performance-based design methodologies. This sub-project aims to develop reliable predictive models for the stiffness properties of connections with threaded and smooth shank fasteners.
Project T1-2 – Innovative Wood Structural Systems
Three innovative timber structural systems will be further investigated in the following sub-projects.
Sub-project T1-2-A – Performance of Wood-frame Buildings on Podiums
PI: Dr. Matiyas Bezabeh, McGill University
This project aims to create seismic design guidelines for wood-frame on podium buildings (WFPBs). These mid-rise structures combine concrete podiums with wooden upper stories. The existing seismic design methods are limited in addressing vertical irregularities, impacting structural performance. The study will assess current criteria, develop new empirical standards, and establish a comprehensive design guide. It involves archetype development, numerical modeling, ground motion selection, performance assessment, and collaboration with experts. The project will train a graduate student and work closely with industry partners and external advisors, contributing to Canada’s sustainable construction goals and informing building codes.
Sub-project T1-2-B – Innovative high-capacity shear walls for wood-frame buildings
PI: Lina Zhou, University of Victoria
HQP: Ruite Qiang
Novel construction practices, such as large openings, longer spans, and concrete toppings, have created additional demand for lateral load resistance in light wood frame buildings. This has made it difficult for designers to use existing design solutions for the construction of mid-rise wood frame buildings in moderate and high seismic zones. To remedy this issue, a high-capacity shear wall system with multiple ows of nails along the sheathing panel edges will be developed. The results of this sub-project will support future code implementation of these high-capacity shear walls.
Sub-project T1-2-C – Resilient timber buildings – structural performance
PI: Solomon Tesfamariam, University of British Columbia
There is a growing need to develop more resilient and better-performing timber seismic force resisting systems (SFRS) that can be used in high-rise buildings. This sub-project aims to develop an aesthetically appealing SFRS that meets structural and architectural requirements while also sustaining limited post-earthquake damage. To this end, innovative MT systems with rocking CLT core (Wu and Yang 2017), glulam exoskeleton, and innovative energy dissipation connectors will be developed, along with a resilience-based design framework. This sub-project will provide design engineers with a new timber SFRS that is highly resilient and that can be implemented in high-rise structures.
Project T1-3 – Advanced Structural Design Methods
Within this project, advanced structural design methods that are expected to be implemented in future edition of design standards and building codes will be investigated.
Sub-project T1-2-A – Performance of wood-frame Sub-project T1-3-A – Reliability-based design of MT components and systemson podiums
PI: Frank Lam, University of British Columbia
Reliability-based design procedures in CSA O86 (CSA 2019) are based on single member analysis for sawn lumber (Foschi et al. 1990) and glulam column (Lam and Oh 2018). Research on reliability analysis on connection and system behaviour of MT structures is almost non-existent. In this study, a framework to quantify the performance of MT structures will be developed. The research outcomes will form the basic framework needed to quantify the level of safety for a given MT system using the applied design method. This information can be benchmarked against safety levels of known systems to guide future changes in CSA O86.
Sub-project T1-3-B – Performance-based design of wood-based systems
PI: Cristiano Loss, University of British Columbia
HQP: Aly Al Samouly
Next Generation Wood Construction Page 11 of 34 Chui, Y. H. (18138) Performance-based seismic design (PBSD) guidelines for new and existing buildings have evolved over the last two decades and PBSD procedures for wood systems to-date have focused primarily on wood-frame construction up to six-storeys (Pang et al. 2010, Pang and Rosowski 2007, van de Lindt et al. 2010). This sub-project aims to develop innovative design strategies and reliable procedures for PBSD of larger and taller MT buildings that could be used to support the potential implementation of PBSD method in NBCC for wood-based systems.
Project T1-4 – Serviceability Performance of Timber Systems
The focus of this project will be on two serviceability issues, floor vibration and acoustics, that have a large impact on consumer acceptance of MT buildings.
Sub-project T1-4-A – Development of generalized vibration serviceability design method for MT floors
PI: Janhui Zhou, University of Northern British Columbia
The current vibration serviceability design method in CSA O86 (CSA 2019) is based on indirect performance criteria that correlate the performance of the floor with its subjective rating scores based on a large database of wood joisted floors (Hu et al. 2001). However, this simple and reliable design method is limited to traditional wood floor systems. Since timber floor construction has become more complex with a wide range of available engineered wood products, design engineers and product producers are advocating for a generalized floor vibration design method that can be used for a broad range of timber floor systems and configurations. The development of such a design method is the goal of this sub-project.
Sub-project T1-4-B – Acoustic design of MT assemblies
PI: Sylvain Ménard, University of Quebec at Chicoutimi
The basic acoustic property required for room acoustic design is the absorption coefficient of the construction materials. However, no such information is available for the materials and assemblies used in MT buildings (Zhou et al. 2019), and acoustic performance information is even missing for some of the solutions currently in use. To address these information gaps, this sub-project will establish a database of the acoustic performance properties of various construction materials that could be used in wood buildings. The database, which will be developed based on a literature survey, and laboratory and field testing, ultimately will support acoustic design and material selection toward providing satisfactory acoustic performance in wood buildings.