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Corrosion of the rebar in reinforced concrete (RC) structures is a critical concern, compromising their reliability and long‐term operation. Carbon fibre–reinforced polymer (CFRP) tapes are widely used for strengthening RC structures due to their superior properties such as light weight, high strength and ease of application. The study aims to investigate the effectiveness of using CFRP‐bonded tapes as a flexural repair system for RC beams, considering the effect of pre‐repair damage to rebar. The experimental programme consisted of testing two unstrengthened control specimens without damage and two samples with 50% damage to the rebar, strengthened with CFRP materials. To maximize the effectiveness of CFRP materials for strengthening, a comprehensive understanding of their behaviour, particularly during the later stages of loading, is essential. The purpose of this study is to fill this gap of knowledge with the use of innovative remote monitoring techniques: submicron indicators and digital image correlation (DIC). By cross‐verifying results through two independent approaches, any potential biases or errors inherent were mitigated, leading to more robust and reliable outcomes of the experimental research. A comprehensive analysis of the obtained experimental data, also validated through theoretical calculations, has shown that the proposed repair method ensured a 95% recovery of the initial bearing capacity. Also, notable changes in the behaviour of samples were observed with increased strains and deflections compared to control samples. Remarkable possibilities of the DIC method enabled monitoring of the stress–strain state of the full‐scale samples until the destruction stage. The findings of the research are significant in the engineering application, as it deepened the understanding of CFRP strengthening techniques and can potentially broaden the use of CFRP tapes in strengthening corroded RC beams. [ABSTRACT FROM AUTHOR]

Forestry is an important component of Canada's economy with British Columbia (BC) contributing almost half to the national roundwood production. Yet, the country's timber supply and forest economy are threatened by climate change, with increased frequency and severity of natural disturbances and changes in forest productivity. Mountain pine beetle (Dendroctonus ponderosae) outbreaks are endemic in BC, but the latest climate change-driven outbreak has resulted in a cumulative loss of over half of all merchantable pine, leading to a mid-term timber supply shortage. In this study, we investigate the potential of commercial thinning and alternative planting regimes based on species diversification and assisted species migration to mitigate the anticipated decrease in timber supply in BC. We simulated the long-term effects of these management options in a case study area in interior BC, using a toolbox that combines management- and research-oriented data and models. We found that combining commercial thinning and species diversification has the best potential to mitigate future timber supply shortages in BC. We discuss the limits of this toolbox approach and identify research needs and recommendations for future studies aiming at modelling cumulative effects of management, climate change, and natural disturbances on timber supply. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of carbon fiber–reinforced polymer (CFRP) composites in strengthening RC beams for a simple span overhanging from both ends and subjected to equal concentrated forces at each end. This innovative loading configuration allows for investigating the performance of CFRP composites under pure moment within the middle span and ensuring continuity of the moment over the supports, which cannot be captured using the classical simple span with four-point loading configuration. A nonlinear finite-element analysis (NLFEA) using Abaqus software was carried out to accomplish the objectives of this study. The NLFEA models were verified initially based on independent experimental results from the literature to calibrate the NLFEA models in terms of the material constitutive models, boundary conditions, and meshing. Then 12 NLFEA models were created with different strengthening schemes of CFRP strips, varying in terms of length and number of layers, in addition to a control beam. All the evaluated RC beams were similar in terms of length and cross-sectional dimensions, material properties, and steel reinforcement. The results revealed that the developed NLFEA models can reasonably simulate the flexural behavior and failure mode of the studied RC beams, which are significantly affected by the configuration and length of the CFRP strips. The results also indicated that it is essential to extend the CFRP strips from the middle span toward the overhanging span to provide continuity and allow the CFRP strips to contribute effectively to the flexural strength. [ABSTRACT FROM AUTHOR]

Solid wood is renowned as a superior material for construction and furniture applications. However, characteristics such as dead knots, live knots, piths, and cracks are easily formed during timber's growth and processing stages. These features and defects significantly undermine the mechanical characteristics of sawn timber, rendering it unsuitable for specific applications. This study introduces BDCS-YOLO (Bilateral Defect Cutting Strategy based on You Only Look Once), an artificial intelligence bilateral sawing strategy to advance the automation of timber processing. Grounded on a dual-sided image acquisition platform, BDCS-YOLO achieves a commendable mean average feature detection precision of 0.94 when evaluated on a meticulously curated dataset comprising 450 images. Furthermore, a dual-side processing optimization module is deployed to enhance the accuracy of defect detection bounding boxes and establish refined processing coordinates. This innovative approach yields a notable 12.3% increase in the volume yield of sawn timber compared to present production, signifying a substantial leap toward efficiently utilizing solid wood resources in the lumber processing industry. [ABSTRACT FROM AUTHOR]

Structural sawn timber, sourced from softwood plantations, is widely used in lightweight timber-framed residential housing and in engineered wood products for contemporary mass timber construction. However, a significant proportion of milled timber boards are considered ‘out-of-grade’, failing to attain a structural grade under existing classifications systems due to various stiffness, strength, and/or utility-limiting features. This study investigates the potential of controlled lamination techniques to produce structurally usable laminated timber products from out-of-grade timber, using a minimal number of requisite boards. Numerical and experimental methods were employed to compare different board assignment heuristics, in terms of reducing the stiffness variability in laminated board populations. The results indicate that controlled board locations produced remarkably consistent laminated products, achieving very low variability even with a minimum lamination of only two boards. The findings of this paper suggest that controlled lamination techniques have the potential to transform low-value out-of-grade timber into a valuable resource for value-added applications, challenging the existing market perception that out-of-grade timber lacks structural usability. [ABSTRACT FROM AUTHOR]

The purpose of this work is to test the effectiveness of strengthening timber structures by means of composite bars. This article presents the results of preliminary tests carried out on solid beams made of fir wood. The test specimens, which are classified as strength class C24, had dimensions of 7 × 17 × 330 cm. Beams were reinforced with 8 mm diameter basalt fiber-reinforced polymer (BFRP) bars. The bars were glued into grooved channels along the bottom surface. Epoxy resin was used as an adhesive. The strength tests were conducted in accordance with the requirements of EN 408+A1:2012. The four-point bending scheme was adopted. The tests were conducted in the following two series: unreinforced beams (A) and beams reinforced with composites (B). Five elements were tested in each series. The reinforcement resulted in an average increase in the bending moment value of 8.41%. The deflection value at failure increased by 19.77%. The work also includes an analysis of the failure mode and a ductility analysis. Further tests should be carried out using a higher reinforcement ratio. A higher reinforcement ratio should make the presented reinforcement configuration more effective. [ABSTRACT FROM AUTHOR]

To enhance the design and research work on dynamic characteristics of high-rise laminated timber buildings, this paper carried out a modal analysis study on one of the largest laminated timber buildings in China. The finite element calculating modal analysis was carried out using SAP2000 software, and the experimental modal analysis of the building was carried out via environmental excitation. The calculating modal results and the experimental modal results showed good agreement. The calculating modal frequency values were generally lower than the experimental modal frequency values. The natural frequencies obtained by the two methods appeared in the Y-direction first-order bending mode and had values of 2.03 and 2.5 Hz, respectively. The corresponding frequencies of the first-order torsional mode were 2.82 and 3.25 Hz, respectively. The distribution of the CLT core tube along the length direction of the building has an impact on the vibration mode. The six-story part shows the second-order bending form, while the four-story section only shows the first-order bending form. The above work provides a case study and reference for the simulation and modal analysis of high-rise laminated timber buildings, demonstrating the critical role of the core tube structure in such wooden buildings. This insight contributes to a better understanding of structural performance and design considerations in similar projects. [ABSTRACT FROM AUTHOR]

The strengthening, rehabilitation and repair of wooden beams and beams made of wood-based materials are still important scientific and technical issues. This is reflected, among other things, in the number of scientific articles appearing and the involvement of research centres around the world. This is also related to society's growing belief in the importance of ecological and sustainable development. This article presents an overview of the latest work in this field and the results of our own research on strengthening solid wooden beams with carbon-fibre-reinforced polymer (CFRP) sheets. The tests were carried out on full-size solid beams with nominal dimensions of 70 × 170 × 3300 mm. A 0.333 mm thick CFRP sheet was used for reinforcement. The research analysed various reinforcement configurations and different reinforcement ratios. For the most effective solution, a 46% increase in load capacity, 35% stiffness and 249% ductility were achieved with a reinforcement ratio of 1.7%. Generally, the higher the reinforcement ratio and coverage of the surface of the wood, the higher the strengthening effectiveness. The brittle fracture of wood in the tensile zone for unreinforced beams and the ductile crushing of wood in the compressive zone for reinforced beams were obtained. The most important achievement of this work is the description of the static work of beams in previously unanalysed configurations of strengthening and the confirmation of their effectiveness. The described solutions should extend the life of existing wooden buildings and structures and increase the competitiveness of wooden-based structures. The results indicate that, from the point of view of optimizing the cost of reinforcement, it is crucial to develop cheaper ways of combining wood and composite than to verify different types of fibres. [ABSTRACT FROM AUTHOR]

This study focuses on evaluating several machine learning algorithms for the condition assessment of utility timber poles. An efficient feature extraction technique combining Hilbert Huang transform (HHT) and wavelet packet transform (WPT) is adopted from the authors' previous work and implemented to determine damage-sensitive features from vibration data related to five serviceable and eight unserviceable in-situ timber poles. Then, these features are pre-processed using correlation heat map analysis for feature selection. Principal component analysis (PCA) is adopted as the final step of pre-processing for reducing noise interference and enhancing classification accuracy. Afterwards, a feature matrix is formed, which is fed into the selected classifiers for pattern recognition. In addition, the information gain method is also implemented and compared against PCA to examine the effect of feature selection. Finally, selected classifiers are employed using those dominant features, and their performance is evaluated based on six parameters – accuracy, precision, recall, F1-score, confusion matrix and Receiver Operating Characteristic (ROC) curve. It was found that choosing the best feature set related to the health state helps to improve the performance of the pattern recognition algorithms to a great extent. [ABSTRACT FROM AUTHOR]

This scientific paper explores the use of correlation coefficients of vibration signals and machine learning algorithms for structural damage assessment in beams under moving loads. The paper discusses the challenges of maintaining structural integrity and the importance of automated, nondestructive monitoring techniques. Preprocessing techniques, such as the random decrement technique (RDT), are highlighted for improving data analysis. Machine learning algorithms are identified as valuable tools for structural damage assessment. The paper concludes by emphasizing the potential of machine learning in safeguarding critical infrastructures. The text also discusses trigger points and the vibration response of a slender beam under a moving load. An artificial neural network (ANN) is proposed as a computational model for identifying non-linear features. Experimental testing on a simulated bridge girder using accelerometers collected data to identify and locate damage in the beam. The ANN achieved high accuracy in detecting damage appearance and location, but further research is needed to improve accuracy in real-world situations. [Extracted from the article]

This paper presents a unique study on the dynamic identification of the tallest glue-laminated timber frame building in the world using forced vibration tests (FVTs) and long-term ambient vibration tests (AVTs). Because the amount of sway in service under wind has become the governing design criterion for tall timber buildings, this paper aims to provide useful information and evaluate available tools and methods for modal identification in tall glulam timber frame buildings. First, combined operational modal analysis schemes based on the variational mode decomposition with the stochastic subspace identification and the random decrement technique were adopted to identify the modal properties from nonstationary ambient data. Then, unique full-scale forced vibration tests were conducted using two different methods to excite the building: measured electrodynamic shakers excitation and unmeasured rhythmic human-induced excitation. Finally, a finite-element (FE) model of the tall glulam frame building was developed and frequency response function (FRF)–based model updating was conducted showing that the FE model was able to predict the modal behavior of the test building. The results show that natural frequencies identified from output-only techniques are in good agreement with the FVT results. Damping ratios obtained from both AVTs and FVTs exhibited amplitude-dependent behavior with a larger variation observed in the FVT results due to larger range of response amplitudes. These results have significant consequences for the design of tall timber buildings under serviceability-level loading, where damping plays an important role. The resulting damping ranges presented in this paper can serve as a useful guideline for practicing engineers in developing their prediction models of tall timber buildings under serviceability-level loading. [ABSTRACT FROM AUTHOR]

Concrete cover separation (CCS) is a common type of delamination failures that occurs at the plate end in reinforced concrete (RC) beams strengthened in flexure using fiber-reinforced polymer (FRP) materials. The effectiveness of FRP U-wrap anchorage has been demonstrated in mitigating CCS failure, resulting in increased utilization of FRP composites for strengthening purposes. The current study presents the development of a nonlinear three-dimensional finite element (FE) model using ABAQUS software in order to simulate the flexural behavior and debonding failure of FRP-strengthened RC beams end-anchored with vertical FRP U-wraps. The cohesive zone model (CZM) is used in the developed FE model to predict the debonding failure of the anchored beams, considering the influence of relevant parameters. The validation of the FE model was achieved through comparisons with experimental data from the literature, which demonstrated good agreement. A parametric study was then conducted to investigate the impact of the design parameters of FRP U-wrap on the behavior of the anchored beams. The examined parameters included the width, layout, and height of the vertical FRP U-wraps. The findings of the FE parametric study have revealed that to successfully prevent plate-end debonding, it is critical to not only use the required area of vertical FRP U-wrap but also carefully consider the U-wrap layout. The FRP U-wrap should be placed at the plate-end region covering the concrete tooth created by the shear cracks, and the U-wrap layout should consider the detailing recommended in this study. [ABSTRACT FROM AUTHOR]

Braced timber frames (BTFs) are an efficient lateral force resisting system that can effectively resist wind and earthquake loads. It is well-known that the performance of BTFs is strongly dependent on connection behavior, but clear design guidelines are not available for detailing ductile BTFs. Furthermore, conventional connections with steel fasteners can exhibit significant stiffness and strength degradation under earthquake loads and result in large residual deformations. There is a need for more resilient energy-dissipating connections for BTFs and other mass timber systems. This study investigates the behavior of dowel-type and bolted wood-steel-wood connections with superelastic nickel-titanium (NiTi) shape memory alloy (SMA) fasteners. Under bending, the SMA fasteners are able to effectively recover their original shape with negligible residual deformation, even after undergoing large deflections. The SMA connections tested in this research showed significant potential for self-centering. Post-test autopsies of the connection test specimens showed ductile deformation mechanisms and similar levels of wood crushing between the steel and SMA fasteners under cyclic loading. However, the connection displacement ductility ratios of 4.6 and 6.2 observed with SMA fasteners is not sufficient to meet the requirement for moderately ductile frames. Additional research is required to better understand and characterize the behavior of SMA connections at the component and connection levels. [ABSTRACT FROM AUTHOR]

As a typical feature of traditional Chinese timber structures, columns with floating foot joints are prone to rocking under horizontal force. The column rocking behavior plays an important role in resisting lateral loads. This paper proposes modelling strategies for the rocking behavior of traditional timber columns. The proposed model can capture the contact state of the column foot via a series of distributed axial springs and the possible sliding via a horizontal spring. It has a lower computational cost than refined finite element (FE) models and is independent of numerical calibration compared to rotational spring models. The modelling strategies were validated against refined FE models and experimental data available in the literature. The principle behavior of the approach was carefully investigated including contact stiffness, distribution modes, spring numbers, column bending effects, and computational efficiency. Results show that the effective compression height of the column foot can take the value of the column radius to determine spring stiffness. Column bending needs to be considered in the mechanical analysis of column foot joints for slender columns. The case study on the lateral stiffness of traditional timber frames confirms the applicability of the proposed model in the structural analysis of ancient timber buildings. [ABSTRACT FROM AUTHOR]

The exposed-dowel half-through tenon (EHT) joint is a common and important connection configuration in southwest China. However, deformation and looseness in the EHT joint constitute the primary causes of failure in the joint connection performance. In this study, a mechanical model of the joints under bending was established and analyzed. The geometric, physical, and equilibrium equations were constructed, the bending moment-rotation relationship was obtained, and the bending moment-rotation envelope curve and the flexural capacity were calculated. A low cycle reciprocating experiment of the EHT joint was conducted to measure the moment-rotation hysteretic curve and envelope curve of the joints. A comparison of the envelope curves calculated using the model and test curves was conducted, and the results showed that the calculation curve was in good agreement with the test curve. The ultimate bending capacity errors of the joint in the forward loading stage and reverse loading stages were 11.2 and 5.8%, respectively. A parametric analysis of the joint using the established mechanical model showed that increasing the diameter of the wooden pillar and the width of the tenon greatly improved the flexural capacity of the joints while increasing the height of the small tenon and reducing that of the joints during the reverse loading stage. These research results provided a reference for the new construction and restoration of the Drum Towers in southwest China. [ABSTRACT FROM AUTHOR]

To improve the out-of-plane stability of partially encased composite (PEC) beam webs and enhance the synergy between concrete and section steel, a new type of wavy web PEC beam was designed and fabricated. In this study, the flange thickness and shear–span ratio were varied as key parameters. Low-cycle reversed loading tests were conducted to investigate the effects of these variables on the load-bearing capacity, failure patterns, deformation capacity, hysteretic energy dissipation capacity, and stiffness degradation of the wavy web PEC beams. Numerical simulations were performed using ABAQUS CAE2023, a finite element analysis (FEA) software, under low-cycle reversed loading conditions. The applicability of the ABAQUS software CAE2023 for the corrugated web PEC beam model was validated by comparing test results with finite element analysis results. A detailed parametric analysis was then carried out using the finite element model to further investigate the mechanical properties of the wavy web PEC beams. The research findings are as follows: the wavy web PEC beams exhibited good ductility; a larger shear–span ratio led to a transition in the failure pattern from shear failure to flexural failure; varying the flange thickness significantly affected the failure location and characteristics; and reducing the flange thickness could limit the propagation of concrete cracks, thereby improving toughness and energy dissipation capacity. [ABSTRACT FROM AUTHOR]

This study developed a forest management plan model using reinforcement learning (Q-learning) to optimize both the economic and ecological functions of forests. Management objectives for national forests were established, and forest conditions were analyzed using GIS spatial data and administrative records. A 60-year forest management plan was formulated to predict timber production and management performance across different regions and time periods. Our analysis revealed that Scenario 3 (Carbon Storage Priority) demonstrated the highest economic value, starting at approximately KRW 576.2 billion in the initial period and escalating to KRW 775.7 billion over six 10-year periods, totaling 60 years. In addition to its economic performance, Scenario 3 effectively improved forest age class structure and ensured a stable timber supply, making it the most balanced approach for sustainable forest management. By focusing on carbon storage as a key management goal, this approach highlights the potential for achieving both economic and environmental benefits concurrently. These results suggest that reinforcement learning is a powerful tool for developing long-term forest management strategies that address multiple objectives, including economic viability, ecological sustainability, and resource optimization. [ABSTRACT FROM AUTHOR]

To investigate the flexural failure mode and behavior of wooden beams strengthened using aluminum (Al) plates, which were attached with self-tapping screws and structural adhesive, ten specimens were tested in bending. The experimental parameters were the thickness of the bottom Al plate, the longitudinal and transverse grain spacing of the self-tapping screws. The experimental results revealed that (1) compared with unreinforced beams, the reinforced beams exhibited ultimate load capacity and displacement ductility coefficients that were 18.4%–54.3% and 6.4%–43.1% higher, respectively; (2) for the same Al plate thickness in the tensioned area, the initial stiffness of the reinforced wooden beams increases as the longitudinal grain spacing of the screw grains decreases; (3) the plane-section assumption was satisfied by the strain in the middle section of the Al plate-reinforced wooden beam along the height; (4) the strains at the same position in the wooden beam and Al plate were similar, thus indicating that the wooden beam and Al plate behaved collectively. Furthermore, a formula was proposed for calculating the flexural capacity of an Al plate-reinforced wooden beam, thus providing a valuable reference when designing wooden beam reinforcements. [ABSTRACT FROM AUTHOR]

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Masonry aggregates have developed throughout city centres of Europe due to a centuries-long densification process that generally lacked consistent planning or engineering. Adjacent units are connected either through interlocking stones or a layer of mortar. Without interlocking stones, the connection between the units is weak, and an out of-phase response of the units can lead to separation and pounding. Modelling guidelines and code instructions are missing for modelling the interaction of such adjacent units because of scarce experimental data. Therefore, in this study an unreinforced stone masonry aggregate was tested on the bidirectional shake table with an incremental seismic protocol as a part of the SERA AIMS—Adjacent Interacting Masonry Structures project. The aggregate was constructed at half-scale with double-leaf undressed stone masonry without interlocking between the units. Floors were built with timber beams and one layer of planks, with different beam span orientation for each unit. After significant damage, one of the units was retrofitted by anchoring the timber beams to the walls to prevent out-of-plane failure and testing was continued. Significant interaction between the units was observed with specific damage mechanisms. Cracking and separation were observed at the interface in both longitudinal and transverse direction, starting at lower intensity runs and progressively increasing. Bidirectional seismic excitation affected the unit separation, with friction forces seemingly playing a role in the transverse direction. Signs of pounding at the interface were observed during higher intensity runs, together with the formation of a soft storey mechanism at the upper storey of the higher unit. The mechanism involved an out-of-plane response of the shared wall, with a horizontal crack at the height of the interaction. These findings contribute to a better understanding of the seismic behaviour of masonry aggregates. [ABSTRACT FROM AUTHOR]

This work presents the simulations of the non-linear dynamic response of a three-dimensional finite-discrete element model. The model simulates a half-scale masonry building aggregate tested on a shake table by other Authors. The aggregate is made of two un-connected building units having different heights and slightly different wall thicknesses. The floors are made of timber beams and boards. The modelling approach accounts jointly for in-plane and out-of-plane responses, which can be expected given the high flexibility of the floors, and for the separation between the two building units. The simulations are related both to the blind predictions, according to a scheduled testing sequence, and to the post-dictions according to the actual testing sequence and some model calibrations. The prediction model overestimates displacements, underestimates base shear and fairly predicts the damage pattern of comparable experimental runs. The use of the recorded shake table motion improves the accuracy of the post-diction simulations, while still delivering beam unseating. A higher Young's modulus of the blocks improves markedly the predictions. The strengthening intervention with steel angles connecting floors to walls is only approximately modelled and does not improve the outcomes of the simulations. In summary, the adopted modelling approach is capable of accounting for the pounding between the two building units, predicting the most significant damage as well as estimating approximate average of peak values of base shear and displacements, while individual time histories are less accurately estimated. [ABSTRACT FROM AUTHOR]

To measure the interfacial fracture toughness of ceramic/metal interfaces such as thermal spray coatings, a novel modified cantilever beam bending method is proposed. Finite element simulations are used to determine the energy release rate and phase angle for an interfacial crack in a bi-layered cantilever for varying modulus, thickness and beam aspect ratios. A high-throughput experimental procedure for the new test geometry is presented to extract a large number of measurements of interface fracture energy from the same sample, using digital image correlation. Interfacial fracture energies G C , determined using this method are compared for thermal spray coatings of Alumina and YSZ on steel substrates. G C of these coating-substrate combinations follow the same trend as measured from four-point bending or modified clamped beam bend techniques. Advantages and limitations of the technique in comparison to other methods in practice are discussed. [ABSTRACT FROM AUTHOR]

Cracks exist in the majority of components of ancient Chinese timber structures and have led to serious mechanical property degradation problems, threatening the safety of the whole structures and making the cracks' detection for wooden components a necessity. With the rapid development of intelligent protection technology of cultural buildings, it is important to establish a scientific identification and quantification method for cracks in wooden components to replace traditional manual detection techniques. Deep learning is precisely such an advanced technology. In this study, images of cracked wooden components were first collected from the Yingxian wooden pagoda and the crack characteristics were analyzed. A dataset for crack segmentation was established using a total of 501 images of cracked wooden components, including a training dataset of 450 images and a validation dataset of 51 images. Based on the mathematical principles of deep learning and the fully convolutional neural networks (FCNN), a deep fully convolutional neural network (d‐FCNN) model was constructed based on encoding and decoding methodology. Four model indicators, pixel accuracy (PA), average pixel accuracy (mPA), mean intersection over union (mIoU), and F1‐score were analyzed to train the model and determine the optimal model parameters, including learning rate, batch size, and epoch. It concluded that the optimal initial learning rate takes the value of 10−4, batch size of 6, and epoch of 100, achieving the average accuracy of 78.8%. Further, based on the pixel's accumulation principle, a quantitative calculation method for crack length and maximum width was proposed. Two cracked wooden columns were prepared, and crack image identification and quantification experiments were conducted to verify the correctness of the constructed d‐FCNN model and the proposed crack quantification method. The results show that the model is suitable for crack intelligence detection, identification, and quantification of cracked wooden components. [ABSTRACT FROM AUTHOR]

This study focuses on the Ecuadorian Amazon, a crucial region for forest biodiversity and conservation of native species, which faces challenges due to timber extraction. The research objective was to characterize timber harvesting during 2012 to 2021, focusing on the ten most harvested forest species in terms of volume and provincial distribution, as well as their conservation status according to the IUCN. For the methodology, data were extracted and analyzed from Ecuador's Forest Management System (SAF), focusing on timber extraction in six provinces and assessing 210 species. The results revealed that, from 2,627,659.17 m3 authorized, 2,296,238.08 m3 were harvested, representing 54.17% of the national timber harvest from native forests. Species of the Fabaceae family predominated in number and volume, with yields varying from 0.5 m3/ha in Orellana to 2.8 m3/ha in Zamora Chinchipe. Analysis of the IUCN categories showed that 67.6% (142 species) are Least Concern (LC), while 3.3% (7 species) are Vulnerable (VU), and 1% (2 species) Endangered (EN). Two species were listed as Data Deficient (DD), one as Critically Endangered (CR) and one as Near Threatened (NT). It is crucial to note that, of the 210 species analyzed, 55 species (26.2%) are not included in the IUCN database, highlighting the importance of more detailed assessments for their conservation and distribution. [ABSTRACT FROM AUTHOR]

Composite steel‐timber beams – initial ideas for structural design Since the introduction of the Green Deal and the EU Taxonomy Regulation, pressure in construction market has increased to design load‐bearing structures in addition with a view to greater sustainability. Composite beams in steel‐timber construction can contribute to this. However, reliable calculation rules for steel‐timber composite beams do not yet exist. Working Group 6 of TC11 in the European Convention for Constructional Steelwork (ECCS) deals with hybrid steel‐timber structures and this article presents initial ideas for calculation approaches for steel‐timber composite beams. The problems are tackled that, in contrast to concrete, the material timber has a significant tensile strength and the different types of shear connectors between steel and timber can also show a variety of load‐slip curves. Finally, a first comparison between the presented calculation method and a large‐scale test is presented. [ABSTRACT FROM AUTHOR]

Structural mass timber has been used more often in buildings over the last 5 years, given its potential to be a sustainable alternative. However, concerns still exist around the fire safety of mass timber structures, and current mass timber building designers must consider a variety of fire protection strategies, including but not limited to noncombustible protection and design for sacrificial char thickness. This research focuses on better understanding how prescriptive code fire protection strategies affect the sustainability goals that have partially driven mass timber use. This paper studies how decisions during early design can reduce embodied carbon (EC), the initial energy use of a structure's construction. Five structural floor system types were modeled parametrically for various levels of fire protection. System types included timber–concrete composites, cross-laminated timber (CLT)–steel hybrids, and all-timber systems. The resulting EC data analysis reveals that all-timber systems perform the best for EC when the fully protected option is used at shorter spans, when the combined approach option is used at midrange spans, and when the fully exposed timber option is used at longer spans. Across all studied systems, the shallowest possible depth occurred for the 10-ft (3.05-m) spanning CLT–steel hybrid systems at 11.5 in. (292 mm) deep for the fully protected system, and the lowest possible EC was 10.5 lb CO2 eq/ft2 (51.3 kg CO2 eq/m2) for the fully protected 10-ft (3.05 m) all-timber system. [ABSTRACT FROM AUTHOR]

HIGHLIGHTS The paper assesses the impact of China's legal restrictions on the global forest industry. Results demonstrate log and sawn timber output of high-risk countries will decrease. High-risk countries' production and export of processed wood products will increase. China's total timber imports will decline and will be replaced by domestic timber production. Increasing imports of processed Chinese timber products is beneficial for high-risk countries. Utilizing the Global Forest Products Model (GFPM), this paper analyzes the potential impacts of China's timber import legality requirement policies. Two alternative scenarios are compared with the baseline scenario: (1) China requires that imported timber must comply with the requirements of Verified Legal Compliance (VLC), (2) China imposes tighter requirements for imported timber, which must come from sustainably managed forests and meet Forest Certification (FC) requirements. The results show a decline in log production but an increase in processed wood exports to high-risk countries, suggesting a move towards more valuable wood processing. Both high- and low-risk countries are expected to see an increase in forest stocks. Welfare analysis indicates that high-risk countries will benefit from industrial upgrades, while China might face welfare losses. Nevertheless, the enforcement of legal standards for timber imports into China is likely to enhance the perceived legitimacy of the sources of domestic timber materials, thereby facilitating the re-entry of processed timber products into developed markets. This study proposes that China's timber import regulations could offer mutual advantages, aiding in the fight against illegal logging and encouraging the legal timber trade. Utilisant le Modèle global des produits forestiers (GFPM), ce papier analyse les impacts potentiels des politiques d'exigence légale dans les importations de bois en Chine. Deux scénarios alternatifs sont comparés avec ces scénarios de base: 1) la Chine requiert que le bois importé soit en accord avec les exigences légales de la Verified Legal Compliance (VLC), 2) la Chine impose une légalité plus serrée pour le bois importé, qui devrait être issu de forêts à gestion durable et respecter les canons de la Certification forestière (CF). Les résultats indiquent un déclin de la production de bois de coupe mais une croissance de l'exportation de bois transformé vers des pays à haut risque, suggérant un glissement vers une transformation du bois plus exclusive. Il est prévu que les pays à haut risque, tout comme ceux à bas risque, vont être témoins d'une croissance de leur stock forestier. Les analyses de bien-être social indiquent que les pays à haut risque vont bénéficier d'un progrès industriel, alors que la Chine pourrait connaître une diminution de son bien-être social. Toutefois, la mise en force des standards légaux pour les importations de bois en Chine va probablement renforcer la légitimité perçue des sources de matériaux de bois domestique, facilitant ainsi la réinsertion des produits de bois transformés dans les marchés développés. Cette étude avance que les régulations des importations de bois par la Chine pourraient résulter en avantages mutuels, aidant ainsi le combat contre la coupe de bois illégale et encourageant en revanche le commerce légal du bois. Utilizando el Modelo Global de Productos Forestales (MGPF), este artículo analiza las posibles repercusiones de las políticas chinas sobre requisitos de legalidad para la importación de madera. Se comparan dos escenarios alternativos con el escenario de línea de base de referencia: (1) China exige que la madera importada cumpla los requisitos de Conformidad Legal Verificada (CLV) y (2) China impone requisitos más estrictos para la madera importada, que debe proceder de bosques gestionados de forma sostenible y cumplir requisitos de Certificación Forestal (CF). Los resultados muestran un descenso de la producción de troncos rollizos, pero un aumento de las exportaciones de madera transformada a países de alto riesgo, lo que sugiere un cambio hacia una transformación de mayor valor de la madera. Se espera que tanto los países de alto como de bajo riesgo experimenten un aumento de las reservas forestales. El análisis del bienestar indica que los países de alto riesgo se beneficiarán de las mejoras industriales, mientras que China podría sufrir pérdidas de bienestar. No obstante, es probable que la aplicación de normas legales a las importaciones de madera en China aumente la percepción de legitimidad de las fuentes de productos maderables nacionales, lo que facilitaría la reintroducción de productos madereros transformados en los mercados desarrollados. Este estudio propone que la normativa china sobre importación de madera podría ofrecer ventajas mutuas, ayudando en la lucha contra la tala ilegal y fomentando el comercio legal de madera. [ABSTRACT FROM AUTHOR]

A fundamental requirement for analysing timber structures under fire is to consider the degradation of material properties with temperature. Therefore, the objective of this study is to propose a model that accounts for the variation of the thermo-physical properties, the development of char, and its evolution with temperature. This model integrates a sequential coupling of heat transfer analysis with structural response. The degradation of the material properties is accounted for through the regulatory approach recommended in Eurocode 5. The stress analysis employs an elasto-plastic model with nonlinear isotropic hardening. Implementation of the model is achieved within the Abaqus suite of finite element software using external subroutines. The model's predictions align well with experimental data, accurately reproducing both thermal and structural responses. Specifically, the model accurately predicts temperature profiles, displacements, and the depth of the charred layer, which initiates above 300 °C. Additionally, for rectangular sections, it was observed that exposure of all faces to fire results in a non-rectangular residual section. Furthermore, employing the temperature-dependent thermal property curves suggested by EC5 yields satisfactory results when predicting the fire resistance of softwood timber structures. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive three-dimensional finite element modeling and parametric analysis of composite beam-to-column joints in steel–timber composite structures. The investigation encompassed a variety of shear connector configurations, end plate designs, and bolt dimensions, aiming to elucidate their respective influences on the structural performance and behavior of these joints. Through meticulous numerical simulation, this research sought to enhance the understanding of the interactions and load transfer mechanisms within composite connections, thereby contributing to the optimization of design practices in the field of structural engineering. The load–displacement relationship for timber–steel composite joints subjected to monotonic loading was investigated using ABAQUS 6.14 software. This study systematically analyzed the effects of various parameters, including different configurations of shear connectors, end plate thicknesses, and bolt dimensions, on the overall performance of the joints. Through this comprehensive numerical analysis, the research aimed to provide deeper insights into the mechanical behavior and structural integrity of these composite connections under the applied loading conditions. A non-linear finite element model of timber was developed and verified with the results of the experiment in this study. The findings are discussed in detail, highlighting the intricate relationships between the selected parameters and their respective effects on the performance and overall stability of the composite connections. This thorough evaluation aimed to enhance the understanding of how these variables interact within the context of composite joint design and behavior. Finally, design recommendations for composite structures, such as the dimensions of the bolt, end plate thickness, and different sizes of shear connectors are provided. [ABSTRACT FROM AUTHOR]

This study investigates the utilization of 3D laser scanning, GPS, BIM and GIS technologies for safeguarding historical wooden structures. As a case study, it focuses on two historic Chinese wooden buildings, the Guanyin Pavilion and Tangwang Palace, renowned for their exceptional historical significance and intricate timber architecture. The Guanyin Pavilion was subjected to high-precision modeling and tilt monitoring, which found that certain columns had a maximum tilt angle of 0.7892°. Additionally, a general tilt tendency was seen across various structural elements. The measurements from the point cloud data exhibited an error range of ±10 mm. However, the relative errors in smaller components approached 2.5%, which necessitated regular verification through human measurements. Using GIS and BIM technology in Tangwang Palace facilitated the meticulous documentation and dynamic supervision of architectural components, encompassing historical development and present state. The maintenance records revealed persistent problems with the roof tiles and wooden beams, exposing structural vulnerabilities. During various maintenance intervals, it was observed that the roof tiles were frequently loose and separated, indicating potential flaws in the design or materials used. The application of these modern technologies enhances the effectiveness and precision of conservation efforts and provides a robust scientific foundation for the continuous monitoring and study of cultural heritage. [ABSTRACT FROM AUTHOR]

Timber–concrete hybrid structures are commonly employed in multi-story timber buildings; however, further research is necessary to fully understand the seismic performance of these structures as well as the dynamic properties of the floor. The two dynamic concerns, seismic effects and the vibration of floors in hybrid structures, are key issues, in view of which this study aimed to investigate the small-seismic-response spectra and elastic time histories in a high-rise timber hybrid building, specifically the medical technology building of Jiangsu Provincial Rehabilitation Hospital in China. The dynamic characteristics of a localized cross-laminated timber (CLT) floor were tested in situ, and the impacts of human-induced vibration were quantified. Comprehensive theoretical analysis results reveal that the basic vibration pattern of the structure was mainly translational in nature and that the period ratio, inter-story displacement angle, and shear-to-weight ratio all met the demands of the Chinese timber building design code. The experimental test results show that the vertical natural frequency of the CLT floor was about 15.96 Hz and thus met appropriate requirements with respect to natural frequency. However, peak floor acceleration was found to be high under the conditions of a single person walking quickly, a single person trotting, and multiple persons walking randomly. In light of these findings, the floor should be paved with a fine-grained concrete building surface, according to design requirements, so that its serviceability might be improved. Overall, the relevant analytical methods presented in this paper provide guidance and practical reference for the seismic analysis of timber hybrid structures, as well as vibration serviceability analysis for CLT floors. [ABSTRACT FROM AUTHOR]

With the expanding application of lightweight wooden structures in modern construction, the load-bearing capacity of ordinary triangular single-span wooden trusses limits the applicability of lightweight wooden structures. As a result, triangular multi-span wooden trusses have emerged to replace single-span wooden trusses. In practice, multi-span wooden trusses are composed of multiple single-span lightweight wooden trusses, with connections between members using metal plates, a field that has been relatively well researched. However, connections between spans are primarily made with nails in actual engineering, and there has been little research on the use of wooden pins to connect multi-span wooden trusses. To study the mechanical performance of multi-span wooden trusses connected by wooden pins, this paper innovatively combines existing equipment with a self-designed pulley assembly device to conduct a continuous static full-scale loading test on double-span wooden trusses connected by wooden pins of three different diameters. We comprehensively evaluate which type of wooden pin is more suitable for triangular multi-span wooden trusses. The results indicate that the 16 mm diameter wooden pin provides the best energy dissipation performance for connected beam trusses. The 20 mm diameter wooden pin offers the best performance stability. The 20 mm diameter wooden pin also demonstrates a good load-bearing capacity and resistance to deformation. Overall, the 20 mm diameter wooden pin exhibits the best connection performance in triangular beam trusses. [ABSTRACT FROM AUTHOR]