Our Timber Construction Talents at the Heart of Discussions during the 2nd NextGen Wood Conference 2025!
Several members of our centre took part in the 2nd edition of the NextGen Wood Conference, held in Ottawa from May 26 to 28, 2025. This major event brought together researchers, industry professionals, and policymakers to exchange on advancements in timber construction and innovations in structural connections.
Professor Alexander Salenikovich played a key role in organizing the « Timber Connections Workshop» on May 28, in collaboration with Professor Thomas Tannert (University of Northern British Columbia). This specialized workshop brought together about fifty participants from various backgrounds—academic researchers, practicing engineers, industry representatives, and graduate students—to discuss the latest advances in connections for mass timber and cross-laminated timber structures. The event provided an opportunity to assess current trends in design, mechanical performance, and connection safety, while offering a platform for exchange between research and practice. Professor Christian Dagenais also took the floor as a speaker. He presented his research on the fire performance of modern mass timber connections, which sparked great interest among participants. His presentation helped fuel discussions on regulatory issues and the challenges of safe design in the context of climate change.
Several members of our student community actively contributed to the various activities of the NextGen Wood Conference 2025, illustrating the energy and commitment of the next generation in timber construction.
- Antony Beaulieu, Luc Girompaire and Rosalie Côté gave presentations, enabling exchange with professionals during technical sessions, networking events, and debates on current issues in timber construction.
- Kiavash Gholamizoj delivered a talk and presented a scientific poster during the Timber Connections Workshop. His work, focused on cyclic testing of glulam timber connections using dowels and steel plates, drew the attention of structural engineering specialists seeking to optimize the seismic performance of timber buildings.
- Anthony Beaulieu and Félix Coulaud attended both the conference and the workshop, gaining a comprehensive view of the challenges and advances in the field.
- Meanwhile, Christopher Gagnon and Coralie Offroy actively participated in the Timber Connections Workshop, deepening their knowledge of innovative approaches to structural connections and hybrid materials, notably through experimental demonstrations and technical discussions.
This participation strengthened the ties between academic research and industry and enabled our members to establish themselves as committed contributors to the conversation on sustainable development in timber construction.
We extend our sincere thanks to the organizers and all participants for this unique opportunity for collaboration and inspiring exchange.
Some Highlighted Presentations:
- Fire Performance of Modern Mass Timber Connections
By Christian Dagenais and Monireh Aram
This presentation addressed the challenges associated with the fire performance of modern mass timber connections, highlighting the limitations of current Canadian standards and presenting preliminary results from a five-year research project conducted in collaboration with FPInnovations and Quebec’s Ministry of Natural Resources and Wildlife. - Brittle Failure of CLT Connections with Inclined STS
By Amir Einipour, Alexander Salenikovich, Jianhui Zhou, and Thomas Tannert
This study explored brittle failure modes in CLT connections using inclined self-tapping screws (STS), revealing behaviors more complex than those predicted by the CSA O86 standard and proposing a new predictive approach. - Cyclic Tests on Glulam Timber Connections with Dowels and Slotted-in Steel Plates
By Kiavash Gholamizoj and collaborators
Experimental tests were conducted to evaluate the strength, ductility, and failure modes of dowel-type connections reinforced with slotted-in steel plates, aiming to improve their design in braced glulam structures. - Stiffness of Timber Connections with Dowel-type Fasteners
By Tao Gui, Ying Hei Chui, and Alexander Salenikovich
This work compared several theoretical models to predict the stiffness of dowel-type timber connections—an essential parameter for ensuring the reliable structural behavior of timber systems. - Impact of Forestry Practices on the Carbon Footprint of Lumber Products
By Rosalie Côté, Évelyne Thiffault, and Ben Amor
This research quantified the influence of forestry practices on the biogenic carbon footprint of lumber—an essential aspect for better integrating biogenic CO₂ flows into the life cycle assessment of wood products.
Details:
« Timber connections Workshop» session
Fire Performance of Modern Mass Timber Connections (oral presentation)– Christian Dagenais, Monireh Aram
Mass timber buildings are becoming popular worldwide, with their environmental benefits becoming ever more important as the effects of climate change becoming increasingly apparent. One of the challenges of building timber structures is evaluating and properly designing for its performance in fire, with the connections between timber elements typically being seen as critical components of the structure. Recent studies have largely focused on evaluating the fire performance of connections using bolts and dowels. These types of connection can be challenging to design and are usually found in “Heavy Timber Construction” (Type IV in the US). They are not quite found in recently constructed timber structures in North America. Modern mass timber connections have seen little research attention regarding their fire performance. Modern concealed connections include, among others, proprietary connectors made of cold-formed steel, milled or extruded aluminum, as well as knife plates and bearing plates made of custom steel. In Canada, very little information is given in Annex B of CSA O86 [1] related to fire-resistance of timber connections. It essentially only requires that all metallic components should be located within the effective cross-section, thus providing some level of thermal cover. It however lacks at providing guidance on gap tolerances between the elements, char penetration (if any) and performance criteria. When designing for the American market, fire design of connections is given in the Fire Design Specification (FDS) for Wood Construction [2] and Technical Report 10 [3], both published by the American Wood Council. Guidance is given with respect to char penetration at unbonded intersections (joints), thermal separation time and maximum temperature rise criteria. When the gap between elements is greater than 3.2 mm (1/8”) and air flow through the gap is not prevented, it is assumed that the joint is fully exposed to fire. Given the conservatism of the US provisions, a few design teams, mass timber manufacturers and connectors’ suppliers conducted fire-resistance tests so that code-compliant solutions could be made available to the design community. While these tests provided code-compliant solutions to achieve from 1-hr to 2-hrs fire-resistance rating, most of them used fire stop sealant and large beams to provide sufficient wood cover to the metallic components. This result in solutions that are likely overdesigned and no longer cost-competitive against other types of construction since sustainable materials are typically more effective on cost and more sustainable by wasting less material. There is a need to develop design provisions based on first principles and applicable to modern mass timber connections, for ultimately implementing into the next edition of CSA O86. This presentation will present preliminary results of a 5-years research project led by FPInnovations in collaboration with industry partners and Ministère des ressources naturelles et de la faune du Québec. Main observations will be presented along with potential recommendations for future work. The work done is also complimentary to the CWCRN Theme 2-2A projects on connections.
Cyclic tests on glulam timber connections with dowels and slotted-in steel plates (poster) – Kiavash Gholamizoj , Alexander Salenikovich , Ying Hei Chui , David Hanna
Modern mass timber braced frames rely on ductile connections to dissipate energy effectively. However, brittle failure modes in dowel-type connections may occur before the fasteners yield, limiting ductility and energy dissipation capacity. This study addresses these challenges by conducting experimental cyclic tests on dowel connections with one or two slotted-in steel plates. Connections were designed per CSA O86 [1] and Eurocode 5 draft [2] and tested to evaluate stiffness, resistance, ductility, energy dissipation, and failure modes, as well as to compare the two design approaches.
The tested connections form part of glulam brace elements in multi-storey timber braced frames. Each joint includes 12.7 mm (1/2-in.) dowels in various configurations at one end, while the opposite end, features steel side plates with inclined self-tapping screws, overdesigned to allow for reuse across tests (Figure 1). A total of 72 tests were conducted across nine series: five configurations with single slotted-in plates and four with double plates, using 6 or 12 dowels in various spacings (Figure 2). Each series included two static tests and six one-directional cyclic tests in axial tension. The static tests are used to determine the cyclic displacement protocols based on ISO 16670 [3]. Performance parameters, derived from load-slip graphs, highlight the effects of fastener spacing and end distance on resistance and failure modes. Experimental results are compared with predictions from CSA O86 and Eurocode 5, providing insights for designing reliable connections that meet the high force demands of mass timber braced frames.
Brittle failure of clt connections with inclined STS (oral presentation) –Amir Einipour , Alexander Salenikovich , Jianhui Zhou , Thomas Tannert
The crosswise layup in ross-laminated timber (CLT) panels leads to distinct brittle failure modes compared to those observed in solid timber or glulam. CLT connections with self-tapping screws (STS) installed at an inclined angle, may fail under brittle failure modes for which the guidance in the 2024 edition of the Canadian Standard for Engineering Design in Wood (CSA O86) is limited. In a recent study at the UNBC Wood Innovation Research Lab, the brittle failure modes and load-carrying capacities of CLT connections with inclined STS were investigated, see Figure 1a. A total of 18 series with six two-sided with STS connections installed at a 45º angle were tested under uniaxial tension, encompassing a range of connection layouts that considered CLT lay-up, screw penetration length, edge distance of the connection, and screw arrangements.
All connections exhibited quasi-linear behaviour up to the maximum load and failed in a brittle manner. The observed brittle failure modes across different test series were more complex than those outlined in CSA O86, including occurrences of rolling shear and layer separation alongside the predominant plug shear, see Figure 1b. Using screws of the same length in CLT with different layups affected the load-carrying capacity due to changes in the failure plane. Connections near the panel edge showed lower capacity than those in the centre, highlighting the impact of edge distance on brittle failure. Based on these findings, a new approach for predicting brittle failure in CLT connections with inclined STS will be proposed.
« NextGen Wood Conference »
Characterizing char rate of wood under real-fire scenarios- Antony Beaulieu
The use of engineered wood in construction is increasing in popularity due to its numerous advantages. However, its combustible nature remains a significant constraint in building construction to comply with fire safety requirements provided in building codes. The existing common design methods for wood structural elements rely on a normalized time-temperature curve from CAN/ULC S-101 (Standard Methods of Fire Endurance Tests of Building Construction Materials). However, this curve does not accurately reflect real fire scenarios, as it assumes a continuously increasing temperature over time, whereas in reality, the temperature eventually decreases. This project aims to characterize the charring rate of wood exposed to real fire conditions by analyzing important factors that influence this rate, such as heat flux and oxygen concentration. The goal is to provide performance-based design data to improve knowledge of the behaviour of the charring rate of wood exposed to different parameters. To obtain these data, experimental tests will be carried out using a controlled atmosphere cone calorimeter device to evaluate various parameters and a propane furnace to simulate real fire time-temperature curves. The collected data will be compared to assess the impact of different factors on the charring rate of wood and will be used to propose a charring rate equation for real-fire scenarios in design applications. This research will help characterize the charring rate of wood to propose design data that better represents a real fire scenario in buildings.
Stiffness of timber connections with dowel-type fasteners – Tao Gui , Ying Hei Chui , Alexander Salenikovich
When designing structural timber systems, serviceability limit states (SLS) can govern the final design solutions. Deformations in mechanical timber connections play a key role in controlling common SLS, such as vibration and deflection, which are dependent on the stiffness of the connections. It is also required for ultimate limit states (ULS) design. For instance, in statically indeterminate structures where the applied design load is resisted simultaneously by more than one component, and the load distribution is governed by stiffness properties of these components. Therefore, accurate models predicting the deformation or stiffness of timber connections are required for design purposes. Early timber connection models were largely based on the theory of beam on elastic foundation (Winkler foundation) [1]. Winkler foundation model works reasonably well for strength prediction but not stiffness. This is because the Winkler theory tends to lead to an over-estimation of the deformation due to the assumption of decoupling of the foundation springs. An improved approach is necessary for connection stiffness prediction. This paper investigates the use of Multi-spring foundation [2] and Half-space foundation [3] theories to address the limitations of Winkler foundation model. Finite element models based on the three different foundation theories were developed and the predicted results are compared. It was found that the Multi-spring foundation and Half-space foundation theories provide more accurate predictions of connection stiffness for dowel-type fasteners compared to the Winkler foundation theory. However, further experimental studies are required to determine the specific application ranges of these models.
Cyclic tests on glulam timber connections with dowels and slotted-in steel plates – Kiavash Gholamizoj , Alexander Salenikovich , Ying Hei Chui , David Hanna
Modern mass timber braced frames rely on ductile connections to dissipate energy effectively. However, brittle failure modes in dowel-type connections may occur before the fasteners yield, limiting ductility and energy dissipation capacity. This study addresses these challenges by conducting experimental cyclic tests on dowel connections with one or two slotted-in steel plates. Connections were designed per CSA O86 [1] and Eurocode 5 draft [2] and tested to evaluate stiffness, resistance, ductility, energy dissipation, and failure modes, as well as to compare the two design approaches.
The tested connections form part of glulam brace elements in multi-storey timber braced frames. Each joint includes 12.7 mm (1/2-in.) dowels in various configurations at one end, while the opposite end, features steel side plates with inclined self-tapping screws, overdesigned to allow for reuse across tests (Figure 1). A total of 72 tests were conducted across nine series: five configurations with single slotted-in plates and four with double plates, using 6 or 12 dowels in various spacings (Figure 2). Each series included two static tests and six one-directional cyclic tests in axial tension. The static tests are used to determine the cyclic displacement protocols based on ISO 16670 [3]. Performance parameters, derived from load-slip graphs, highlight the effects of fastener spacing and end distance on resistance and failure modes. Experimental results are compared with predictions from CSA O86 and Eurocode 5, providing insights for designing reliable connections that meet the high force demands of mass timber braced frames.
Fire performance of modern connections in mass timber construction – Luc Girompaire, Christian Dagenais, Alexander Salenikovich
The fire performance of mass timber connections is influenced by multiple factors extensively documented in the literature [1, 2], including structural load ratio, type of fastener, diameter and number. Another critical factor is the gap size between connected elements, which can significantly affect the fire performance by increasing temperatures within joints and accelerating fastener heating [3, 4]. Like other construction materials such as steel and aluminium, timber experiences a reduction in mechanical properties as temperature rises [5–8]. Gap size also impacts the charring rate. Both U.S. [9, 10] and European [11] standards introduced a gap factor that locally increases the charring rate of timber at joints. In European standards, a gap between 2 mm and 5 mm increases the charring rate by 20% [11], while in U.S. standards, gaps exceeding 3.2 mm (1/8”) are considered fully exposed to fire [10]. Currently, Canadian standards do not account for gap size in charring rate adjustments. Therefore, further investigation is needed to assess its impact and establish clear guidelines for Canadian designers. This study aims to quantify the effect of gap size between two timber members exposed to the CAN/ULC S101 time-temperature curve on heat flux and the charring propagation within the joint. Additionally, the influence of wood grain orientation on charring rate will be examined. To this end, four joint configurations (shown in Figure 1) and four gap sizes will be tested. In the first test series, the lateral sides of the specimens will be encapsulated to ensure unidirectional charring propagation. A second test series will investigate tri-directional charring propagation.
Impact of Forestry Practices on the Carbon Footprint of Lumber Products –Rosalie Côté, Évelyne Thiffault, Ben Amor
Forest management influences the carbon balance of the forest ecosystem. Thus, forestry practices influence the biogenic carbon footprint of harvested timber. However, in current life cycle assessments for building timber, biogenic CO2 fluxes are not systematically considered. The aim of this research was to quantify the effect of forest management parameters on the biogenic carbon balance of a m3 of timber from the eastern boreal forest. Using forest management compartment units of the boreal balsam fir forest of Quebec as case studies, we created forest management scenarios that included variations in four parameters: harvest type, i.e., the proportion of clearcut vs. partial cut harvesting, harvest intensity in % area harvested yearly, harvest rotation age and proportion of harvested lumber destined to sawmilling vs. destined to other wood products. We then simulated scenarios over a 150-year period in CBM-CFS3 for the ecosystem dynamics and MoSiR for the product end-of-life to obtain average biogenic CO2 fluxes per m3 of lumber, with positive flux values indicating net carbon emissions to the atmosphere, and negative values indicating net ecosystem carbon sequestration. Our results suggest linear or non-linear relationships for each of the four parameters tested. Simulations enabled us to find threshold points for harvest type and intensity where the carbon balance becomes negative, i.e. where the m3 of lumber generates net sequestration of biogenic CO2. Quantifying the effect of forest management will enable us to improve our practices to achieve carbon neutrality, and also to better include biogenic carbon accounting in life-cycle analyses.
To learn more about the 2nd edition of the NextGen Wood Conference & Workshop 2025, click here