The recent growth of mass timber buildings (MTB) in number, height, and architectural complexity represents a major opportunity for the timber construction sector, but it also introduces significant challenges to overcome, particularly regarding moisture management and long-term performance in diverse climatic conditions. In this context, this study presents 240 days of hygrothermal monitoring data of a MTB during construction, focusing on the moisture behaviour of cross-laminated timber (CLT) elements and the influence of construction practices on moisture safety. Monitoring was carried out in high-risk zones, including wall-floor joints on north and south fa & ccedil;ades and interior moisture-prone rooms. Moisture content (MC) was continuously recorded alongside daily precipitation and key construction events. During the first 100 days, characterised by mild temperatures and limited rainfall, MC values remained mostly below 20%. However, short and intense rainfall events caused rapid increases above 30%, demonstrating the high sensitivity of CLT to water exposure. As precipitation increased and temperatures decreased, drying was limited, and MC remained above 20% for prolonged periods. The premature installation of gypsum boards and bituminous membranes before roof and fa & ccedil;ade waterproofing trapped moisture, resulting in visible mould growth. The construction schedule and lack of temporary protection significantly extended water exposure, while alternative strategies, such as early roof waterproofing, temporary shelters, or targeted end-grain protection were not adopted. These results demonstrate that the growing complexity of MTBs requires an integrated moisture management plan developed prior to construction and applied throughout the construction phase. Such a plan should consider local climate, construction sequencing, protective measures, and continuous monitoring to ensure moisture-safe building practices and support the long-term performance of timber structures.

A reliable characterisation of the response of mechanical dowel-type timber connections is essential for the development of design methods. The European standard EN 26891 and the American standard ASTM D1761 provide guidelines for the experimental tests of connections made with mechanical fasteners and have been widely adopted in research practice. However, differences in loading protocols, test set-ups, boundary conditions, and displacement measurements hinder a direct comparison between experiments, making the reliability and transferability of results difficult to assess. To address this gap, the RILEM TC TPT is developing a round-robin programme to assess the reproducibility and repeatability of tests on timber connections in accordance with EN 26891 and ASTM D1761 across various laboratories. The specific objectives of this initiative are as follows: (i) identify sources of variability in testing outcomes related to equipment, operator, and procedural interpretation; (ii) quantify the influence of specimen preparation and material sourcing on the evaluation of the mechanical performance of dowelled timber joints; and (iii) provide a basis for improving standardisation in test methods and reporting across laboratories. The programme is structured in two phases: (i) centralised material supply with Laminated Veneer Lumber to minimise material variability, focusing on the influence of specimens’ assembly and test set-up, and (ii) independent and local sourcing of Glued Laminated Timber to capture local material and fabrication influences. With this, the round-robin experimental campaign aims to contribute to more reliable testing procedures and to the refinement of international design standards for timber connections.

Cross-Laminated Timber (CLT) has gained increasing attention as sustainable and efficient material for slab systems in construction. However, the lack of standardized design guidelines and comprehensive performance comparisons between different CLT-based slab solutions limits its widespread application, particularly in emerging markets with limited local expertise. This study aims to fill this gap by evaluating the structural performance and applicability of four CLT slab systems: (i) CLT slabs, (ii) CLT-concrete composite slabs, (iii) CLT-glued-laminated timber (GLT) beam ribbed slabs, and (iv) CLT-steel beam composite slabs. A comprehensive design methodology based on the Gamma method and Eurocode 5 is developed, critically applied, and its limitations discussed for each system, considering both ultimate and serviceability limit states, with special attention to vibration criteria and shear connection efficiency. The systems are compared in terms of maximum span, self-weight, thickness, and dynamic response under residential and office load categories. Results show that ribbed slab systems with timber or steel beams achieve the longest spans (up to 14 m for residential use), with lower self-weight, while CLT and CLT-concrete slabs exhibit maximum spans of 9 m with reduced thickness. Serviceability limit states, particularly vibration, were identified as the governing design constraints in most cases. This study provides a systematic comparison of CLT slab solutions, contributes to the development of reliable design tools, and identifies priorities for experimental validation, supporting the broader adoption of CLT in regions with growing timber construction sectors, such as Portugal.

The wood of Albizia glaberrima demonstrates favourable attributes for nailing, screwing, and gluing. It exhibits moderate durability and resistance to termites though it is susceptible to specific borers. A comprehensive research initiative was undertaken to increase its suitability for structural purposes. The research encompassed non-destructive and destructive testing methodologies to evaluate mechanical properties, including bending and tension characteristics, while also assessing physical properties such as density and moisture content. The results of this study unveiled that A. glaberrima possesses a relatively light density, averaging at 530 kg/m³. The dynamic elasticity module ( E din ) exhibited a range between 10,315 N/mm² and 13,662 N/mm², contingent on the specific non-destructive method employed. Bending strength ( f m ) was determined to be 63 N/mm², while tensile strength ( f t,0 ) measured at 56 N/mm². The local and global values of the elastic modules in bending ( E m,l and E m,g ) were established as 14,487 N/mm² and 10,270 N/mm², respectively, whereas the corresponding value for tension ( E t,0 ) recorded a value of 14,412 N/mm². These findings substantiate the inherent potential of Albizia glaberrima wood for structural applications.

The capacity of dowel-type timber connections is generally governed by brittle failure modes, such as splitting and row shear failures. In design standards, this is indirectly addressed through the effective number of fasteners concept. This parameter accounts for both the non-uniform load distribution and the interactions among fasteners, which can induce brittle failure before the fasteners’ capacity is fully mobilised. Although the current expressions for the effective number of fasteners in European design codes are based on tests on timber-to-timber connections, they are also applied to other configurations, such as steel-to-timber connections. The present study investigates, through numerical simulation, the validity of existing empirical expressions under various loading conditions and connection arrangements. The numerical model adopted was previously proposed and validated by the authors and is grounded in linear elastic fracture mechanics. The model validation performed herein on the original experimental dataset used to derive the empirical expressions for the effective number of fasteners further strengthens its validity. The parameters influencing the connection response across different configurations are further evaluated, including the fastener slenderness ratio and the spacing between fasteners. The findings reveal that both connection arrangement and loading direction (compression vs tension) substantially affect failure assessment and, by extension, the effective number of fasteners. Specifically, steel-to-timber and tension-loaded connections tend to fail earlier than timber-to-timber connections under compression, thereby leading to a lower effective number of fasteners. These critical factors are not adequately captured in current design equations, underscoring the need for revised approaches, supported by further experimental validation and probabilistic assessment, to improve the reliability of design expressions for the effective number of fasteners.

The sustainability of buildings and the well-being of their occupants are pivotal themes in initiating a dialogue between architecture and manufacturing. This dialogue addresses challenges such as the shortage of skilled labor and the growing demand for housing, which are mitigated through industrialization. Within a three-dimensional (3D) framework, particularly in the context of timber prefabrication, Pods enhance various interactions and qualities of interior spaces, thereby addressing issues related to building performance and construction sustainability. This study introduces the design of a series of wet units (Pods), which are assembled from prefabricated two-dimensional (2D) timber panels, enabling diverse architectural configurations without altering the construction system and components. A notable feature of this construction approach is the integration of technical spaces within the structure of the units, facilitating improved space management and the incorporation of necessary infrastructures for unit operation, thereby ensuring autonomy. Drawing inspiration from automotive industry methodologies, the project encompasses various typologies and levels of customization and adaptability, which enhance production efficiency and allow integration into different spatial contexts. By reinterpreting and adapting construction practices, this project contributes to the development of sustainable cities and communities. It promotes the use of organic materials as a construction base and enriches the industrialization process architecturally, allowing for creative freedom in architectural design and the harmonious integration of aesthetics with manufacturing.

This study generalises an upscaling modelling approach, originally proposed for connections loaded parallel to the grain, to account for in-plane multiaxial loading of connections. The main objective is to evaluate how the combination of internal forces affects the brittle response of dowelled connections. A Beam-on-Foundation model is implemented to obtain the nonlinear load-displacement behaviour of single fasteners. Such information is assigned to coupled nonlinear springs located at the connection shear planes in a multiple-fastener connection model to capture the stresses in the timber member between the fasteners. The onset of cracks along the grain direction is evaluated using the mean stress approach. The numerical model shows a strong correlation with prior experimental findings and offers an efficient method for predicting crack initiation in multiple-fastener connections. Additionally, limit curves for the interaction of normal force and bending moment are provided for an exemplary connection layout, considering different slenderness ratios and brittle and ductile failure.

In recent years, the use of timber in construction has significantly increased, driven by global decarbonization targets and advancements in engineered wood products. As a result, concerns about the durability and long-term performance of new timber buildings are becoming increasingly prominent. Monitoring wood moisture content is a critical aspect of addressing these concerns, as it directly influences wood's susceptibility to biological degradation and its physical and mechanical properties. Despite the availability of various wood moisture meters on the market, these devices are often costly or involve ongoing subscription fees, limiting their accessibility to researchers and practitioners. This study introduces an Arduino-based, low-cost wood moisture content data logger as a viable alternative. Leveraging the customizability of Arduino, an open-source platform, this device enables users to modify their measurement setups to suit specific research needs using a range of compatible sensors. The system utilizes the electrical resistance method to measure wood moisture content. The paper provides detailed information about the components used, including the Arduino board and sensors, the electronic setup, and the open-source code developed for the device. Additionally, an experimental campaign was conducted to validate the system's performance by comparing its results with those of two commercially available wood moisture meters and one digital multimeter. The validation involved monitoring wood samples with varying moisture levels under controlled conditions to evaluate accuracy and reliability. Results demonstrate that the proposed system provides comparable accuracy to commercial solutions while maintaining a fraction of the cost. This approach empowers researchers to construct their own customizable, cost-effective wood moisture content data loggers, broadening access to critical tools for wood property analysis and degradation monitoring.

For the design of robust timber buildings, it is essential to develop reliable methods to assess possible brittle failure of connections. Therefore, this paper proposes a three-step modelling approach to predict: (i) the load- displacement behaviour of individual dowels, (ii) the stress distribution in the timber matrix, and (iii) the brittle failure of the timber, in connections with laterally loaded steel dowels. The local nonlinear behaviour of single- dowel connections was determined with a Beam-on-Foundation model and subsequently assigned to nonlinear springs located at the multiple-dowel connection shear planes. The timber member and the steel plate were modelled using 3D shell elements with linear-elastic orthotropic and isotropic material properties, respectively. The interaction between dowels and shell elements was characterised by hard contact and friction. A post- processing module, based on linear elastic fracture mechanics, was implemented to evaluate potential cracks along the grain direction through the mean stress approach. The numerical model aligns well with previous experimental results and provides a novel approach for the prediction of crack initiation based on a realistic load distribution in multiple-dowel connections, while taking advantage of high computational efficiency.

Recognizing the significance of moment-resistant timber joints in the advancement of timber frames characterized by enhanced rotational stiffness, moment resistance, and ductile failure attributes, this paper proposes a comprehensive and straightforward design procedure that applies the component method to estimate the moment resistance, initial rotational stiffness, and rotational capacity of moment-resisting steel-timber joints with stiffened end-plate, steel link and bonded-in rods. Analytical predictions are compared to experimental results derived from full-scale tests of 15 joints, employing conventional transducers in conjunction with digital image correlation techniques. Distinguishing itself from prior investigations, this research examines joints with multiple bonded-in rod arrangements, specifically two and four rows. The findings indicate that the structural performance of these joints is significantly influenced by the rotational stiffness of the link, the thickness of the end plate, and the diameter of the bonded-in rods. The joints demonstrate considerable versatility, permitting design as full-strength, equal-strength, or partial-strength connection, depending on the resistance of the key components. The analytical proposition based on the component method exhibits a good predictive capability regarding joint mechanical capacity for both stiffened and unstiffened end plates with two and four bonded-in rod rows. Moreover, the moment-rotation behavior is effectively represented through a tri-linear approximation, which adeptly captures the initial stiffness and joint moment resistance.

Cross-laminated timber (CLT) presents significant potential for sustainable construction but requires further investigation under seismic conditions. This study develops a numerical model to evaluate the seismic design requirements of CLT buildings according to European (Eurocode 8) and Brazilian (NBR 15421) standards. Experimental data from a full-scale CLT building were used to validate the model. The model was then applied to assess seismic design according to standard requirements across different geographic locations, and a parametric investigation was conducted to evaluate the impact of the connector design on structural performance. The results indicate that the tested CLT building was overdesigned for all evaluated regions, and a significant reduction in displacements—up to 33%—is achieved by adjusting the quantity of the connectors. Additionally, the analysis shows limitations in NBR 15421, as it resulted in higher average lateral displacements due to insufficient consideration of energy dissipation. These findings underscore the importance of optimising connector configurations to enhance the seismic performance of CLT buildings while reducing overdesign. Additionally, properly considering energy dissipation in design standards is crucial. In particular, the Brazilian standard would benefit from a comprehensive review to better address energy dissipation, ensuring safer and more efficient seismic designs.

This study provides a preliminary mechanical characterization of minimally processed Acacia dealbata logs to assess their potential valorisation as a by-product of invasive species management. A total of 45 logs (90–143 mm diameter) from two harvest seasons groups, spring (17 logs, 2.0 m) and winter (28 logs, 2.4 m), were visually selected and evaluated for dynamic modulus of elasticity using longitudinal stress wave and transverse vibration tests. Testing was conducted in two moisture content states: air-dried (> 12%) and kiln-dried (≈ 12%). Significant differences between the two groups necessitated separate analyses and suggested a relationship between harvesting season and physical-mechanical properties. Although dynamic properties increased post-kiln drying, initial dynamic modulus of elasticity values were lower due to elevated initial moisture content. Visual characteristics exhibited weak correlations with dynamic properties, whereas high correlations were observed between adjusted dynamic modulus of elasticity values for both moisture states (r > 0,90 for longitudinal stress wave; r > 0,70 for transverse vibration). Adjusted dynamic modulus of elasticity values (18,29/14,00 GPa for longitudinal stress wave; 16,32/12,69 GPa for transverse vibration) were comparable to prior studies and support a potential classification of Acacia dealbata (mimosa) logs for structural applications.

The key objectives of both European Union and Portuguese policies are energy efficiency and carbon neutrality in the building sector. Timber construction offers unique advantages in achieving these goals, such as increased productivity through faster and more efficient building processes, using renewable resources with lower carbon emissions during production and throughout the lifecycle, and contributions to forest conservation. However, in many countries, timber construction remains underutilised due to concerns about its thermal and acoustic performance, fire safety, and limited availability of raw materials. This study addresses these challenges by evaluating the potential of various insulation materials, including polystyrenes, mineral wools, natural fibres, composites, and acoustic mats, for incorporation into prefabricated timber components. Key performance criteria included thermal insulation, sound absorption, fire reaction, environmental impact, and local availability. Among the materials analysed, glass wool, rock wool, and cork emerged as the most favourable options, offering excellent thermal and acoustic performance and presenting strong results in other key parameters. These findings underscore the potential of incorporating these materials into timber construction systems, contributing to developing sustainable and high-performance building solutions.

While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes.

A reliable determination of the embedment strength and foundation modulus of timber elements is critical for the design and safety assessment of joints in timber structures. However, the existence of various test configurations for characterising the embedding properties of large diameter steel fasteners in timber elements poses challenges in directly comparing and utilising available test data. This paper aims to provide an insight into the influence of embedment property test methods, comparing experimental results from different test setups within the guidelines of the EN 383 and ASTM D 5764-97a standards for European softwood species, Scots pine wood (Pinus sylvestris) and Norway spruce (Picea abies). In addition to the test guidelines, the thickness of the specimen and the application of the load was evaluated within the protocols. A comprehensive statistical analysis was performed to identify statistically significant differences between the groups evaluated. The results of the analysis revealed disagreement between the standards in the evaluation of the strength of the embedding, highlighting the potential bias inserted by the experimental setup and protocol. Furthermore, it was proven that the thickness of the specimens influences both the embedding strength and the foundation modulus of the wood species tested. Finally, no distinctions were observed between tensile and compressive loading within the guidelines of the EN 383 standard.