Search Results (195)

The post-tensioned cross-laminated timber (CLT) rocking wall is a recently developed resilient CLT lateral force-resisting system with a self-centering feature. The structural responses of the systems with different designs need to be determined and evaluated efficiently to promote the development and standardization of industrial applications. This study developed a computationally efficient, component-assembled numerical model for post-tensioned cross-laminated timber (PT CLT) rocking walls that captures decompression, post-tension self-centering, and energy dissipation within a framework. The single wall model was assembled using nonlinear zero-length springs for the compression at the CLT bottom, truss bar element for the PT tendon, and elastic shell element for the CLT panel deformation. The energy dissipation device, the UFP, was modeled with nonlinear one-dimensional springs between the wall panels in the coupled wall model. The wall models were separately calibrated considering the wall designs of single-panel walls and coupled walls. Both single and coupled wall models predicted the initial stiffness, decompression, yielding, post-yield stiffness, and reloading/unloading stiffness. The residual drift and nonlinear unloading captured with the PT model were also validated with the test data. A two-story platform structure model was established based on the NHERI Tallwood project, assembled with the coupled wall model and CLT slab in shell elements and columns in Euler beam elements. With recorded ground acceleration signals from the test, the platform structure’s peak story displacement and inter-story drift were simulated with less than 30% differences for most cases. Unlike existing detailed contact-based models, the proposed approach balances local damage fidelity and computational efficiency. The validated model provides a framework for evaluating PT CLT wall design parameters considering their influence on full structures. Full article

The construction sector’s drive for sustainability has increased the use of Cross-Laminated Timber (CLT), yet its structural reliability is governed by the integrity of the adhesive bond line. This study evaluates the influence of three one-component polyurethane (PUR) formulations (R1, R2, R3) on the adhesion performance of maritime pine CLT. To isolate adhesive-related effects, lamellas were mechanically classified by modulus of elasticity (MOE) and randomly allocated within stiffness classes. Adhesive characterization through ABES, FTIR, and DSC revealed that R3 exhibited slower cure kinetics (t₀ = 5482 s) but higher thermal stability. Mechanical testing showed that all formulations developed structurally effective dry bonds with shear strengths exceeding 7.1 MPa, with R3 achieving significantly higher dry shear and interlaminar strength. However, 24 h water immersion caused a catastrophic strength reduction exceeding 95% across all formulations, shifting the failure mode from the wood substrate to the adhesive layer. DSC analysis identified glass transition temperatures between 28 °C and 32 °C, which are consistent with the potential for moisture-induced plasticization near service temperatures. These results indicate that while slower-curing formulations like R3 enhance bond quality in dense softwoods due to improved interphase formation, all evaluated PUR systems showed significant vulnerability to saturated conditions, suggesting that adequate moisture protection is essential for maritime pine CLT applications. Full article

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. Full article

Screw withdrawal force is a key mechanical property related to the load-bearing capacity and reliability of mechanically fastened timber structures. This study investigates the screw withdrawal performance of cross-laminated timber (CLT) manufactured from spruce, beech, and poplar, including both homogeneous and hybrid layups. The selected species represent materials with different densities and regional availability in Hungary. A one-component polyurethane adhesive was used for panel manufacturing. Screw withdrawal force was determined using two methods: a universal testing machine (UTM) and a manual portable device (MPD). The highest withdrawal forces were observed in beech-based configurations, while the lowest values were measured for spruce. Poplar-based configurations demonstrated intermediate but competitive performance, exceeding the reference spruce values. Statistical evaluation confirmed a significant effect of layup configuration on withdrawal resistance. The MPD measurements were on average approximately 9% higher than UTM results, indicating a consistent and quantifiable inter-method difference. The results demonstrate that hybrid CLT configurations can be optimized by combining species of different densities and that portable testing methods provide reliable estimates of withdrawal performance. These findings contribute to the understanding of connection behavior in hybrid CLT and support the practical application of semi-destructive testing methods for in-situ assessment. Full article

This study presents a data-driven and explainable artificial intelligence (XAI) framework for quantitatively analyzing research trends in the seismic performance of timber structures. Unlike conventional bibliometric approaches based on descriptive statistics, the framework integrates large-scale literature mining, natural language processing, topic modeling, network analysis, and SHAP-based machine learning to enable structural and temporal interpretation. A dataset of 248 journal articles from OpenAlex was processed through a unified pipeline, including domain-specific filtering, text preprocessing, and temporal balancing. Topic modeling identified eight research themes spanning traditional component-level mechanics and emerging areas such as cross-laminated timber (CLT), hybrid systems, and performance-based design. Network analysis revealed a highly interconnected structure centered on key concepts such as shear walls, connections, stiffness, and cyclic behavior. SHAP-based analysis further showed that research evolution follows a layered and cumulative pattern rather than simple topic replacement: classical themes remain foundational, while newer concepts such as CLT and structural capacity have become increasingly influential. The proposed framework provides a reproducible and scalable method for quantitatively mapping research structures and temporal dynamics in timber seismic engineering. Full article

Glued-laminated timber (GLT) and cross-laminated timber (CLT) panels are increasingly used as exposed structural elements in representative buildings. These structures are often part of public-use areas, which require the application of restrictive fire-safety measures without significantly affecting the color of exposed wooden surfaces during the service life of these building elements. The effect of fire-retardant treatments on the color of Scots pine (Pinus sylvestris L.) wood was evaluated using five impregnation agents with different active substances. Changes in gloss and color characteristics—lightness (L*), green-red coordinate (a*), and blue-and-yellow coordinate (b*)—were measured sequentially directly after impregnation, after exposure to variable humidity conditions and after exposure to UV radiation. The total color difference (ΔE*) ranged from 2.82 to 17.76 after impregnation and increased to 6.31–20.71 after aging, indicating a risk of aesthetic deterioration of fire-retardant-treated wood surfaces under typical service conditions for timber structures in representative buildings. The most pronounced color changes were observed for the fire retardant containing potassium and copper compounds (FR4) and the combination of 2-aminoethanol with boric acid (FR5). Full article

This work proposes a design-oriented numerical modelling approach for predicting the seismic response of multi-storey Cross-Laminated Timber (CLT) buildings. The model is based on a phenomenological approach and is capable of accurately replicating the seismic behaviour of multi-storey CLT wall systems by means of a properly calibrated equivalent wall stiffness, taking into account both connections and panel deformability. An extensive set of multi-parametric linear analyses is performed to calibrate the wall equivalent stiffness by varying significant design parameters such as: CLT wall geometry, connection pattern, seismic mass and level of seismic intensity. An ad hoc iterative procedure is developed in order to calibrate the wall equivalent stiffness in terms of significant design parameters (e.g., principal elastic period, internal forces in the connection elements and inter-storey drifts). The aim of the procedure was to minimise the error between the results obtained with the proposed phenomenological model and those obtained with refined numerical models. The latter were designed to accurately reproduce the actual response of the CLT systems analysed. The results of the multi-parametric analyses are discussed and summarised in a design abacus that allows a direct implementation of the proposed phenomenological model and, therefore, a simple and efficient seismic analysis for CLT buildings. Full article

Because of concentrated connection damage, the impact of sequential hazards on CLT shear wall systems is much more severe than that on traditional concrete and steel structures considering ductile component behaviors. The present paper evaluated the dynamic response of CLT wall structures in wind-only and sequential seismic–wind scenarios and compared the structural dynamic responses and damage levels of different CLT wall systems. The structural models were established separately based on an SOM benchmark structure, a SOFIE project three-story CLT shear wall structure, and a PT CLT wall platform structure from the NHERI Tall Wood project. The equivalent fluctuating wind load was calculated with the ASCE 7 average wind speed, the reference ESDU wind profile, calibrated wind pressure distribution, and simulated fluctuation from the NatHaz Online Wind Simulator. The sequential load was applied to the structural models in the order of seismic excitation, resting time, and then dynamic wind load. The dynamic responses of different CLT wall structures were compared among loading scenarios with increasing seismic and wind intensities. The wind-excited peak story displacement and acceleration for both CLT structures were significantly magnified in the sequential seismic–wind scenarios compared with the wind-only scenarios. The simulation results indicated that the sequential seismic–wind scenarios caused significant acceleration in damaged connections for the conventional CLT shear wall structure. The PT CLT wall structure had minor displacement and acceleration, which were linear to the wind loading factors. For the conventional CLT shear wall structure, the magnification of the acceleration was found to have a strong correlation with the natural frequencies of the damaged structure. This study demonstrated that the wind responses of the PT wall structures were in a safe range after the seismic event, and conventional CLT wall structures need to be re-evaluated under sequential scenarios for structural resilience assessment. Full article

Mass timber elements such as glued laminated timber (Glulam) and cross-laminated timber (CLT) have become increasingly prominent in sustainable construction due to their structural efficiency and reduced environmental impact. However, fire performance remains a critical consideration for structural safety. This paper presents a comparative assessment of experimentally measured and code-predicted fire performance parameters for Glulam and CLT, including charring rate, effective charring depth, zero-strength layer (ZSL) thickness, and residual mechanical properties. The evaluation covers major international fire design standards: Eurocode 5 (EC5), the Australian Standard (AS/NZS 1720.4), the Swedish Handbook (Swedish), American Wood Council (AWC TR10), and the Canadian Standard (CSA O86). Across all Glulam datasets, charring rate predictions agreed with tests within approximately ±20%, while AS/NZS 1720.4 consistently over predicted charring and effective char depth by around 40%. In contrast, CLT demonstrates greater variability, primarily due to adhesive degradation, delamination, and lamella orientation, which influence heat transfer and post-fire capacity. CLT data exhibited higher scatter, with effective charring depth showing standard deviations of approximately 30 to 40%, ZSL thickness averaging about 2.5 times the typical 7 mm assumption, and residual stiffness commonly reducing to around 20 to 25% of initial values after standard fire exposure. Overall, findings suggest that current standards adequately address Glulam performance but require refinement to capture the complex fire response of CLT. Continued experimental research and targeted code development, particularly within the Australian Standard, are essential to improve reliability and confidence in performance-based fire design for mass timber structures. Full article

The increasing use of engineered timber in modern architecture raises critical concerns about fire safety, particularly when combustible linings are exposed within compartments. Classical compartment fire framework, largely derived from non-combustible enclosures, may not adequately capture the dynamics introduced by materials such as cross-laminated timber (CLT). This study investigates how combustible linings influence the fluid dynamic fields of compartment fires derived from the thermal field using CFD simulations informed by experimental data. A series of configurations, from inert to fully lined compartments, were analysed to isolate the effect of burning boundaries. Results show a progressive intensification of fire conditions with additional combustible surfaces: upper-layer temperatures approach 900 °C, smoke layers thicken, and stratification becomes more pronounced. Velocity fields are similarly affected, with peak inflow and outflow velocities doubling compared to the inert case and new vortical structures emerging near burning walls. These findings highlight that exposed CLT significantly amplifies radiative and convective heat feedback, modifying both temperature distributions and flow patterns in ways not captured by the traditional framework based on the inverse opening factor. This underscores the need for performance-based fire design approaches integrating both thermal and fluid dynamic perspectives, ensuring safe implementation of timber in modern construction. Full article

To meet the development needs of high-rise timber structures, current cross-laminated timber (CLT) shear walls typically feature a single-layer thickness of 35 mm with more than three laminations in the stack. However, such thickness easily leads to resource waste in small-scale residential buildings, while increasing transportation and hoisting costs, which is not conducive to the prefabrication and lightweight development of timber structures. To adapt to the development trend of China’s timber structure market towards public buildings such as cultural and tourism projects and small-scale residential buildings including new rural housing renovation, this study focuses on thin CLT shear walls with an overall thickness of 48 mm (16 mm per layer) and conducts research on their lateral load-bearing performance. Monotonic lateral static load tests and finite element (FE) simulations were carried out on thin CLT shear walls without openings, with different opening areas, and with the same opening area but different positions. A corresponding FE model was established and validated, with a focus on analyzing the influence of opening parameters on the shear performance of the walls. The research results show that wall openings significantly reduce the bearing capacity and shear stiffness of the walls: compared with the wall without openings, the ultimate load and shear stiffness of the walls with openings decrease by 20.4–28.6% and 36.3–42.3%, respectively. Among them, increasing the opening height has a more obvious weakening effect on the bearing capacity; for the same opening area, a wider opening results in a more significant decrease in stiffness. The FE model exhibits reliable accuracy, with the error between the experimental and simulation results in the elastic stage controlled within 10%, and the influence of the under-wall support on the shear stiffness is relatively small. Opening parameters have a prominent impact on the stiffness of the wall in the elastic stage, and the influence of the opening position is more critical—the smaller the distance from the opening to the top of the wall, the more obvious the decrease in overall stiffness. Full article

Cross-laminated bamboo (CLB) has gained increasing attention as an emerging structural material combining high mechanical performance with remarkable sustainability potential. This comprehensive review summarizes and critically discusses the main advances and trends in CLB research, drawing on experimental, analytical, and numerical approaches reported in the literature. The review highlights that the mechanical performance of CLB depends on panel architecture, bamboo product type, and adhesive systems. Reported experimental results indicate that CLB panels can achieve competitive or higher mechanical performance than selected cross-laminated timber (CLT) configurations made from specific wood species, particularly in bending, compression, tension, and rolling shear. At the same time, the literature reveals variability associated with manufacturing parameters, adhesive types, and lamella orientation, which affects the comparability of results and highlights current challenges for standardization. Structural applications investigated include floor and wall panels, beams, and rocking walls, especially for seismic-resilient building systems. Despite growing experimental evidence, most investigations remain limited to laboratory-scale elements, with modelling simplifications that constrain predictive accuracy. This review identifies the main challenges and research opportunities towards industrial scalability, standardized testing procedures, and design models adapted to the specific behavior of CLB, paving the way for its consolidation as a reliable and sustainable construction material. Full article

This paper proposes the use of cross-laminated timber (CLT) panels in conjunction with back-to-back cold-formed steel (CFS) channel or angle sections in combination with laminated veneer lumber (LVL) beam, for composite CFS-timber beams. Under a hogging and sagging moment, part of the CLT panel will act compositely with CFS-LVL in order to resist compression, while the lower part of CFS-LVL web will be in tension. Whilst shear lag effects have been well-researched for concrete-steel composite beams, there has been little research on this for CLT panels working with CFS-LVL sections. In this paper, the finite element method (FEM) is used to determine the effective flange width (FFW) for CFS-timber beams. In conclusion, the obtained result has shown that the EFW increases with any changes that lead to an increase in the ratio of the transverse layer’s depth to the longitudinal layer’s depth. Moreover, combinations of CFS sections with LVL have significantly resulted in the depth-of-beam decrease. Full article

The application of volumetric modular construction using Cross-Laminated Timber (CLT) has emerged as a sustainable and efficient alternative to traditional building methods, especially in residential and mid-rise structures. However, the widespread adoption of this technology remains limited due to the lack of standardized inter-modular connection systems. This paper presents a comprehensive state-of-the-art review of inter-modular connections used in volumetric CLT modular buildings. This review aims to evaluate the inter-modular connections by developing performance objectives and identifying gaps in knowledge of volumetric CLT inter-modular connections. It begins with an overview of global CLT modular construction trends, highlighting geographic distribution, structural demands, and environmental hazards such as seismic and wind exposure. Seven representative connection systems were identified from the literature and assessed using a multi-criteria framework comprising structural performance, manufacturing feasibility, on-site construction efficiency, and experimental and numerical evaluation. Each connection was scored according to defined evaluation metrics, and the results were provided to identify key strengths and limitations. The top-performing systems demonstrated superior resilience, modular adaptability, and validation through experimental testing and simulation. The paper identified critical research gaps, including limited performance data available for seismic applications, challenges in disassembly and reuse specifications, and the need for adaptable, damage-tolerant systems to enhance building structural performance. These findings provide a reference evaluation methodology for future development of inter-modular connections, to expand the applicability of volumetric CLT modular construction in moderate and high seismic and wind hazard regions. Full article

This study presents an integrated intervention strategy for the adaptive reuse of vernacular architecture in a state of ruin, focusing on the fortified village of Moya (Cuenca, Spain). The proposal is framed within a rural revitalization program aimed at educational and cultural tourism uses, with the goal of reactivating abandoned built fabric through the incorporation of new functions that generate social value and contribute to territorial development. The proposed methodology combines archival research, digital documentation, material characterization, and a constructive solution based on the insertion of a reversible, structurally autonomous timber volume within the existing stone masonry. Through material characterization, a differentiated consolidation protocol is developed to stabilize the ruins while maintaining historical legibility. The new architectural volume, built with prefabricated cross-laminated timber (CLT) and insulated with locally sourced expanded cork, is designed to meet contemporary standards of energy efficiency, reversibility, and environmental responsibility, while remaining fully independent from the original structure. The intervention offers a replicable model for sustainable rural regeneration, balancing conservation ethics with functional adaptation. Future lines of research include the dynamic simulation of the energy performance of the inserted dwelling, with the aim of assessing its contribution to climate neutrality and net-zero emissions targets. Full article