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The building industry requires the development of a ductile lateral force–resisting system made of mass timber to allow mass timber to continue to grow in popularity as the primary structural building material. A timber frame with mass ply lam (MPL) beams and columns with a timber buckling-restrained brace (TBRB) was subjected to a quasi-static cyclic loading protocol defined according to the qualification procedure of conventional buckling-restrained braces (BRBs). Two of the TBRBs in this study included a carbon fiber–reinforced polymer (CFRP) wrap to help confine the two ends of the mass ply panel (MPP) casing and improve the performance of the brace. The experiments showed that the TBRB without any CFRP wrap met the requirements for qualification of conventional BRBs, and the mass timber braced frame was able to reach a drift ratio of 3.0%. The TBRB with CFRP wraps met the requirements for qualification of conventional BRBs; the confinement provided by the CFRP wraps postponed failure of the TBRB by enabling the steel core to reach a maximum strain of 3.1% in both tension and compression and the mass timber braced frame to reach a maximum drift ratio of 4.5%. [ABSTRACT FROM AUTHOR]

The increasing availability of mass timber panels has expanded the possibilities for using timber-concrete-composite (TCC) flat floors beyond the traditional TCC T-beams. While TCC floors often easily satisfy ultimate limit state requirements, their stiffness, vibration characteristics, and long-term performance are critical design considerations. This research aimed to validate the bending, vibration, and long-term performance for nine different TCC floor systems through full-size tests with a span of 5.8 m. The tested floor systems used laminated-veneer-lumber, laminated-strand lumber, and cross-laminated-timber (CLT) panels connected to a concrete slab with and without an interlayer. Three types of shear connections were employed: self-tapping screws; glued-in steel mesh; and a combination of STS and adhesive bond. First, the shear connection properties were determined via 54 small-scale push-out tests. Then, 18 floors were tested in bending and vibration shortly after fabrication, and an additional nine floors were subjected to service loading for 32 months under variable climatic conditions, after which they were subjected to bending and vibration tests. The results confirmed that the calculations based on the γ -method accurately predict the stiffness, natural frequency, and governing failure modes of TCC floors. The long-term exposure to service loading had minimal effect (within 10%) on resistance, stiffness, and natural frequency of TCC floors, except for the TCC using CLT, which showed the highest creep deflection and stiffness reduction among the tested configurations. [ABSTRACT FROM AUTHOR]

The evolution of long-span timber structures during the last centuries has been driven by technological developments that are associated with materials, joints, and manufacturing. Many extraordinary structural solutions have been developed, some of which have been very advanced in their time and have been replaced by new ones, typically because of the advent of new manufacturing methods or, at times, due to new technological innovations. This study examines the Hilding Brosenius (HB) system, which was developed in the 1940s as a versatile wooden frame solution for medium-to-long spans. The HB system is based on an I-shaped cross section where the web consists of two diagonal board layers, and the flanges are assembled from boards by nailing and gluing. This study presents and discusses the main structural components of the system from the perspective of structural mechanics, current design requirements, and manufacturing technologies. As a practical application example, the structural system will be examined in the renovation project of an HB portal frame from the 1950s. The main findings of this study are: (1) the HB system has certain features that would make it worthwhile modernizing and reusing it more widely; and (2) the HB system design principles lead to a safe and robust yet light and optimal structure. [ABSTRACT FROM AUTHOR]

Glulam timber structural linear elements often show low span-to-depth ratios. Moreover, timber is intrinsically orthotropic with very low shear moduli. These two circumstances justify the substantial contribution of shear strain to the overall deformation of linear elements. Since design specifications for timber beams commonly adopt 1D models, two such elastic models are proposed in this paper for static plane behavior, where, instead of fully orthotropic, glulam is assumed to be transversely isotropic. These models provide a good compromise between accuracy and simplicity for design proposes. A 3-field mixed formulation is generalized in order to produce two new 1D finite elements suitable for modeling transversely isotropic elastic glulam beams. To assess the accuracy of these new finite elements the results they produce are compared with those determined with a plane stress transversely isotropic 2D finite element. The included examples show that the proposed combination of transverse isotropy with a third order shear deformation model provides a suitable background to the 1D modeling of glulam beams with improved accuracy when compared to the models conventionally used in design. The paper is concluded with a parametric analysis which identifies the cases where the improved models should be used instead of simpler ones. [ABSTRACT FROM AUTHOR]

On the global warming potential (GWP) of centric loaded columns in structural engineering The advancing climate change and the change of boundary conditions regarding the planning process of buildings are influencing the building industry in its fundamental principles. A "business as usual" is irresponsible in view of the proclaimed goals of the German government regarding climate neutrality in 2045. This paper is intended as a step towards the necessary sensitization regarding a more sustainable structural design using the example of centric loaded structural columns in structural engineering. For the selected materials timber, steel and reinforced concrete the main factors influencing the GWP are discussed and compared on the basis of functional equivalence. The aim of the comparison is to determine the sensitivity of individual parameters with regard to the global warming potential (GWP) of structural columns and to support more ecological structural design. [ABSTRACT FROM AUTHOR]

This study solves the following tasks: a comparative analysis of theoretical, computer, and experimental data on the bending of experimental beams is given, the influence of various forms of reinforcement on the strength and stability of beams with a corrugated web is determined; the deformability of a beam with a corrugated web with perforations and without perforations in the elastic and elastic-plastic stage is studied. Experimental studies of models have allowed establishing the main characteristics of the load-bearing capacity, the features of the loss of stability of shelves and corrugated webs with various methods of reinforcing perforations. The given test results showed the necessity and economic feasibility of the work carried out to identify the optimal ways of reinforcing perforations, to meet the requirements of technologists for passing equipment within the construction height of the beams, reducing the consumption of steel for their reinforcement and reducing the complexity of production. The conducted mathematical modeling, laboratory tests, and the performed dispersion analysis allow the study to draw conclusions about the effectiveness of the improved BGS-3 and BGS-5 models and about the need to develop recommendations for introducing two proposed options for reinforcing the perforations of the BGS-3 and BGS-5 models. [ABSTRACT FROM AUTHOR]

Beam–column connections with corbels supporting the beams and continuity reinforcement protruding from the columns, also known as composite connections, are often used in construction as an alternative to monolithic cast-in-place connections. Since they are halfway between fully rigid and pin connections, these semirigid composite systems require more in-depth investigation, especially concerning their behavior at high temperatures and in fire. Compared with fully rigid connections, the primary advantage of semirigid systems is that they allow the use of precast beams. Unlike pin connections, semirigid systems allow a certain degree of fixity at beam ends after the in-place casting of the top of the beams. This study focused on the designs of two full-size specimens representing the region of the connection comprising the column stub, corbel, and beam extremity cast and tested in ambient conditions and under standard fire exposure to compare their performance with two monolithic specimens tested under the same conditions. The study also develops a numerical model of the connection using a finite-element discretization (ANSYS software) to conduct a sequential analysis of the thermal and static behavior of the connection. The numerical results are shown to satisfactorily fit the deflection curves, crack patterns, and actual conditions of the specimen after failure. The semirigid connection is stiff at ambient and medium temperatures but behaves as a pin connection at high temperatures. Further, the moment redistribution with a decreasing hogging moment at the beam ends and higher sagging moment at the midspan shows that semirigid beam–column connections are more vulnerable at high temperatures than monolithic connections. [ABSTRACT FROM AUTHOR]

In order to accurately use numerical analysis results to evaluate seismic performance, a quantitative relationship between the parameters of the ideal finite element model (FEM) and full-scale test model (FTM) of historic timber structures must be established. In this study, a single-story full-scale timber structure with four columns and Dou-gongs that was common during the Song dynasty of China (A.D. 960–1279) was taken as the object, and pseudo-static test (or simulation) analysis was carried out on the FTM and the corresponding FEM. The numerical model was consistent with the test model in terms of the structural deformation pattern and stress characteristics of the key nodes. The key-point loads of the skeleton curves, stiffness ratio, ductility coefficient, and stiffness relationship were quantitatively established for the two models. Accordingly, approximate formulas for the above relationships were proposed. [ABSTRACT FROM AUTHOR]

In order to explore the influence of different working conditions on the mechanical properties of dovetail joints, in this paper, the "Qing Dynasty Engineering Rules" of the Ministry of Qing Dynasty and "Wood Construction Technology of Ancient Chinese Buildings" were used as the weighing standards, using the results of wood properties tests conducted by other scholars as a reference, the numerical simulation of pseudo-static load was carried out on the dovetail joints of Qing Dynasty based on the finite element software ABAQUS. The influence of different angles outside the plane of tenon, different materials, different axial loads, and different load positions on the mechanical properties of dovetail tenon joints was investigated. The results showed that: 1) The hysteretic curves of dovetail mortise and tenon are all inverted z-shape. 2) The maximum bending moments at dovetail joints were 0.896, 0.914 kN·m and 0.979 kN·m when the lateral angles of the Fangs were 0°, 1.41° and 2.82°, respectively. When the axial load at the top of the column increases from 0 to 50 kN, the two-way maximum bending moments of dovetail joints change from 0.896 kN·m and 0.523 kN·m to 2.680 kN·m and 5.129 kN·m respectively. The two-way yield moment changed from 0.823 kN·m and 0.473 kN·m to 2.366 kN·m and 4.172 kN·m respectively. When the axial load at the top of the column increases from 50 kN to 100 kN, the changes of the two-way maximum bending moment and yield bending moment do not exceed 1%. 3) The peak viscous damping coefficients of dovetail joints corresponding to horizontal displacements of 0, 25 mm, and 50 mm applied on the beam side are 22.05%, 28.50%, and 29.38%, respectively. [ABSTRACT FROM AUTHOR]

Laser scanners are being increasingly utilized in the engineering community to collect accurate and dense 3D data on timber roof structures. Point clouds, which are produced by either scanning or photogrammetry, can be subsequently processed using specialized software to create geometric models of individual components of the roof structure manually. Manual modeling of each structural element in a computer-aided-design-based structural analysis software application is a labor-intensive and time-consuming process, whereas automatic modeling typically yields incomplete results in terms of the numbers and sizes of individual beams owing to shortcomings in data acquisition or data processing. In the context of structural assessment, full- scale modeling of each beam is mandatory for a holistic analysis of structural health. This study addresses the gap between automated roof-structure models and preliminary structural assessments through a hierarchical analysis and refinement of the geometric model. The proposed method was applied to two different roof structures, and structural assessments show that it is feasible to import and process the generated models in a structural analysis software application. The resulting structural models indicate that the workflow improves the months of time consumed by optional mistakes from manual contributions to less than a week without the uncertainties caused by human error. [ABSTRACT FROM AUTHOR]

Forestry in general and the wood supply chain in particular are facing a wide range of challenges. Digitalization seems to be able to provide a remedy, but the forest-based sector's high degree of heterogeneity and the large number of actors hampers the search for solutions – in Germany and beyond. In the presented Smart Forestry approach, we apply concepts from Forestry 4.0 to achieve intelligent and fully integrated timber harvesting. It is based on digital twins that are networked and orchestrated in an Internet of Things. First, we reengineer existing forestry processes, identify the relevant objects and messages, and specify templates for digital twins. The necessary Internet of Things technologies are selected and enhanced for use in forestry. Finally, we build first prototypes of the target system that are the basis for upcoming reference experiments in practice – from the forest owner via production in the forest and logistics to the timber buyer. [ABSTRACT FROM AUTHOR]

Optimal sensor placement for timber architecture heritage poses a significant challenge due to the unique structural types and complex monitoring purposes. In this study, a three-stage method is proposed, taking a courtyard-style heritage, built 133 years ago, as an example. First, a finite element model that accounted for the parameter randomness and initial damage was constructed using a genetic algorithm (GA) and experimental results. Second, a new weighted fitness function of logarithmic type was developed for multi-type sensors and multi-objective monitoring. Third, a novel genetic algorithm, Meta-GA, was proposed, introducing competition group mechanisms and gene libraries to improve optimal capability while maintaining computational efficiency. The Meta-GA is then compared to the other two optimization modes using seven indexes. Finally, damage detection capability was tested for the proposed three schemes at noise levels of 0%, 5%, and 10%. The results reveal that the proposed three-stage method with Meta-GA can provide the best solution. [ABSTRACT FROM AUTHOR]

A failure prediction assessment is generally required to enhance infrastructural seismic design. This study used Artificial Neural Networks (ANN) and the Finite Element Method (FEM) to predict the deflection of the concrete and timber piles. Two models were simulated in accordance with the analytical method, location, and type of seismic load applied to the pile. The removal of noise from the seismic data from the Savitzky–Golay filter was applied to improve the quality of the numerical simulation results. To assess the lateral deflection of the single pile during seismic excitation, soil-pile seismic resistance prediction is carried out. Finally, the accuracy level of the obtained non-linear pile's deflection is detected. The results show that timber and concrete piles exhibit different lateral deflection mechanisms. Removing noise from the seismic data improved the prediction of the p–y curve's quality. The deflection mechanism of the pile model depends on the soil-pile interaction and pile material. The pile type controls the allowable lateral deflection and the rigidity of the pile impact on the deflection seismic response of the pile. [ABSTRACT FROM AUTHOR]

Nowadays, hybrid structures, which combine low‐density composites with low‐cost thin‐walled metals, have shown great effect in enhancing the performance of automotive body structures, especially the energy absorber components. This study focuses on the experimental and numerical investigation of the bending energy absorption behavior of CFRP/aluminum hybrid double hat‐section beams used in the side part of the car body. In the experimental section, two types of double hat‐section beams were fabricated: aluminum and Al/CFRP. These beams were then subjected to quasi‐static three‐point bending tests. The results demonstrated that the hybrid beam exhibited superior energy absorption capabilities compared to the single beam. Subsequently, a finite element model was developed using LS‐Dyna software and was validated by comparing the experimental and numerical load–displacement results. In‐depth numerical analyses were conducted to investigate the influence of various design parameters, including CFRP‐reinforcement configuration, numbers of CFRP layers, CFRP ply‐angle, CFRP reinforced length, and aluminum/CFRP mass, on crashworthiness indicators. The numerical findings indicate that the hybrid beam with 04, 45/−45s ply‐angles exhibited better crash force efficiency (CFE) and specific energy absorption (SEA) compared to other ply‐angles, respectively. Furthermore, increasing the number of CFRP layers within the total beam's mass improved its energy absorption capacity. It was also revealed that the CFRP length on the upper and lower hats could be considered as 42.5% of the total aluminum beam length, as opposed to the full CFRP length, providing enhanced energy absorption capabilities. Highlights: Bending behavior of the Al and Al/CFRP double hat section beams.Effects of variable thickness and identical mass on the double hat section beam.Effects of variable ply angle and number of CFRP layers on the hybrid beams.Discrete effect of CFRP reinforcement configurations and inner CFRP lengths. [ABSTRACT FROM AUTHOR]

Perforated beams can bring countless benefits compared to traditional plain-webbed beams. However, steel beams with sequential web openings are more susceptible to instabilities, and special care must be taken in a design concerning the failure modes these structures can present. The study presented herein explicitly dealt with the stability behavior of perforated beams with sinusoidal openings. This type of perforated member features smooth-lined openings constructed from a single thermal cut in conventional plain-webbed steel profiles. A broad study was carried out through numerical simulation using the ABAQUS software, in which perforated profiles manufactured with S600E high-strength stainless steel were studied. The use of high-strength steels in perforated profiles is a little explored topic in the literature, despite having a significant impact on the behavior of these elements. With the study carried out, a broad overview of the stability behavior of these members was obtained, especially concerning global stability. A total of 5940 FE models were developed, considering the application of different types of loads. In these models, linear buckling analysis (LBA) and geometrically and materially nonlinear analysis with imperfections (GMNIA) were performed. The results obtained were compared with international design codes, and it was found that some codes fail to represent the behavior of members that present lateral-distortional buckling (LDB) and interactions between local and global failure modes. This behavior is a significant design concern since the studied members had high yield strength, making them more susceptible to interaction-governed failure modes than usual-yield strength members. Additionally, the study found that some design codes do not accurately represent the behavior of members loaded outside the shear center due to the destabilizing effect of loading on these structures. [ABSTRACT FROM AUTHOR]

Over recent decades, various heritage institutions have utilized a multitude of materials to reinforce the painted layers of ancient Chinese wooden architecture. In this study, we conducted a comprehensive evaluation of the properties and durability of four widely used reinforcement agents, i.e., AC33, B72, FKM, and FEVE, using a series of techniques, including contact angle tests, water vapor permeability measurements, color difference evaluations, tensile strength tests, UV–vis spectrometry, and scanning electron microscopy (SEM). The results demonstrate that the transmittance rates of the films made from these four reinforcement agents are approximately 100% in the visible light range. Among them, the B72 film exhibits the highest hydrophobicity. The AC33 film has better permeability, fair tensile strength, and is more hydrophilic. FKM film is more hydrophobic but has lower permeability and tensile strength. Overall, the FEVE film presents the best comprehensive properties, including better hydrophobicity, higher permeability, and tensile strength. This research provides data evidence to guide heritage conservators and curators in decision-making when selecting appropriate reinforcement materials in practice. [ABSTRACT FROM AUTHOR]

Recent sustainable building strategies make the right decisions to be environmentally friendly and reduce carbon emissions. In some reinforced concrete (RC) elements, fiber-reinforced polymer (FRP) bars have been proposed as an alternative to conventional steel bars. The demand for using noncorrosive and/or nonmetallic reinforcing bars in various reinforced concrete projects has increased. Although these concrete elements are lightweight, have a long lifespan, and need little maintenance, their non-ductile nature and bond with the surrounding concrete create significant challenges. Several experimental investigations have been conducted to evaluate the behavior of RC elements, even with their high cost. This study aims to assess numerically the viability of using FRP bars instead of traditional steel ones in simply supported reinforced concrete beams (RCBs) as longitudinal reinforcement (passive reinforcement). Utilizing the three-dimensional (3D) nonlinear finite element analysis (FEA) software (ABAQUS), a total of eighteen models were carried out to validate the results available in reference case studies with FRP bars. The verification of the numerical results has been verified by comparing them with the reference experimental data. Next, in order to assess the rigidity of such RCBs with FRP bars, parametric research was carried out. The numerical results proved that RCBs with FRP bars have a positive impact on enhancing load-carrying capacities. But on the other hand, the strain energy of such RCBs with CFRP bars is reduced to about 75% of the strain energy of RCBs with steel bars, which leads to low beam ductility. [ABSTRACT FROM AUTHOR]

In this study, a real plot of abandoned agricultural land overgrown with forest in Russia has been surveyed. The amount of future CO2 sequestration by this forest for the next 20 years has been calculated by means of a mathematical model. The unprofitability of the 20-years climatic reforestation project on this land has been proved, based on the current price of carbon units in Russia and China, because Russia cannot enter the European carbon units' market. To improve profitability, it was proposed to combine the reforestation with timber harvesting, charcoal, natural fertilisers and forage production. Thus, the wood cut for maintenance is used partially for sale, partially for production of charcoal and partially left as a fertiliser on the cleared stripes, where meadow plants will be replaced with alfalfa, using technologies of zero soil treatment. The economic feasibility study has been performed based on the real capital and current expenses of the combined reforestation project. The positive Net Present Value and a very high Internal Rate of Return of the joint project, calculated by the methods of financial mathematics have indicated its economic viability and attractiveness for investors. [ABSTRACT FROM AUTHOR]

On the load‐bearing behaviour of mechanical fasteners in steel‐timber‐composite floors In the context of a sustainable structural design, research on steel‐timber‐composite floors (STC) is currently being performed at the Technical University Dortmund. The performance of the ceiling system depends on the used materials and especially on the design of the composite joint. Accordingly, various joint configurations with reversible mechanical fasteners were experimentally tested at the beginning of the research. In the course of the performed push‐out tests, the advantages of wood screws (HS) installed perpendicular to the grain compared to self‐drilling metal screws (BS) and wood screws installed with an inclination angle could be detected. The vertically installed wood screws showed a comparatively high composite stiffness as well as a highly ductile failure mechanism combined with a low installation effort. Thus, in future experimental tests to determine the flexural behaviour of the STC ceiling system, vertically installed wood screws will be predominantly used for the composite joint. [ABSTRACT FROM AUTHOR]

Calculation of timber‐concrete composite ceiling connected only at a few discrete points by the force method This article demonstrates that timber‐concrete composite ceiling with discontinuously arranged connectors can be calculated using the force method with little computational effort. The calculation results match exactly when the framework‐model is applied, where the pendulum rods are always densely arranged and their tensile stiffness increases. The concept of transverse moment is introduced for calculating the unit states, and analytical solutions are derived. Through superimpositions, a good insight into the complex behavior of timber‐concrete composite ceiling is obtained. [ABSTRACT FROM AUTHOR]

The exterior beam-column joints (BCJs) in reinforced concrete (RC) structures are critical and often vulnerable elements, particularly under seismic conditions, with the potential for catastrophic structural failure. Achieving robust and ductile joint design is paramount. Although efforts have been made to establish design standards for strong and ductile joints, further research is needed, especially regarding the realization of a weak beam-strong column mechanism in moment frames. This study utilizes finite element modeling (FEM) to enhance BCJs performance by exploring various reinforcement configurations as alternatives to conventional shear stirrups in the joint area. The objective is to address the challenge of reinforcement congestion in the joint area during concrete placement, which can compromise earthquake resistance. Ten FEM models were developed for evaluation, one without additional reinforcement and nine with various reinforcement configurations. The primary focus was on assessing the effectiveness of these configurations in BCJs under monotonic loading by comparing damage–rotation curves, load–deflection curves, and damage distribution. The results show that in-plane diagonal bars outperformed their out-of-plane bars, reducing core damage by 22–37%. Among the configurations, the model with two X-shaped reinforcements, replacing conventional joint stirrups, emerged as the optimal solution. This configuration provided enhanced rotational stiffness, minimized core damage in tension and compression by about 83%, improved load-carrying capacity by 13.7%, and promoted the formation of plastic hinges away from the joint, achieving the sought-after weak beam-strong column mechanism. This research has significant implications for practical design and construction in RC structures, enhancing their resilience to seismic events and contributing to safer built environments. [ABSTRACT FROM AUTHOR]

Concerning preventive maintenance plans for heritage timber buildings, computational methods are pioneering knowledge for the implementation of new preservation approaches in heritage structure management. In this context, fuzzy logic and random forest methodologies manage both data obtained from professional experts and data obtained in situ from the buildings themselves. This kind of digital procedure can harmonize the outcomes of building assessments because slight variations in the evaluation of input parameters do not produce a significant dispersion over the model's output. Preventive conservation strategies require cooperation among qualified experts who examine multidisciplinary knowledge related to heritage properties. Thus, new digital protocols and procedures that help decision makers prioritize preventive interventions and avoid corrective actions are paramount in minimizing the irreparable loss of properties. The main aim of this research is a new approach to two computational management systems: fuzzy logic and random forest. The outcomes of this study will be useful to stakeholders who are responsible for the maintenance of heritage buildings, as this methodology reduces the probability of failure and uncertainty during decision-making. The instruments derived will establish mitigation strategies oriented toward proactive future maintenance programs for heritage timber buildings in southern Chile. [ABSTRACT FROM AUTHOR]

Introducing openings or holes into wooden structures is a common practice for providing utility services. However, this practice leads to stress concentration, resulting in a reduction in stiffness and load-carrying capacity. Therefore, understanding the effects of holes on beam properties is important for design considerations. This study investigates the mechanical behavior of a wooden beam made from juvenile Pinus elliottii containing open cylindrical holes with three different diameters: 4, 8, and 12 mm. The mechanical properties were evaluated for compression parallel to the fibers, quasi-static bending, and tension perpendicular to the fibers. Numerical simulations were conducted using a finite element (FE) model, considering the orthotropic elastic properties determined from experimental tests and elastic ratios reported in the literature. The experimental results indicated that the influence of hole diameter was not significant on the compressive properties; however, longitudinal crack failures began to form for holes with diameters of 8–12 mm. Regardless of hole size, the compressive and bending characteristics revealed that hole location did not affect the stiffness, strength, or damage mechanisms. [ABSTRACT FROM AUTHOR]

Enhancing the total factor productivity in forestry is an important part of deepening the reform of the collective forest rights system. Based on the survey data of 295 forest plots in 12 towns of Liuyang City, Hunan Province, China, the study utilized a three-stage DEA model to assess the total factor productivity of forestry at the plot level. The empirical study employs Tobit and fractional regression models to investigate the effects and differences of forestry subsidies and forestry regulatory policies on the heterogeneous total factor productivity of different types of forests. The study found that: (1) the mean value of plot-scale forestry total factor productivity is 0.127, and there are obvious differences in total factor productivity among timber forests, economic forests, and mixed forests; and (2) afforestation subsidies and nurturing subsidies significantly positively influence high-level TFP. Ecological benefit compensation positively affects high-level TFP, but is not significant at any level of TFP. Forestry regulatory policies negatively impact high-level TFP, but are not significant at any level of TFP. This paper puts forward countermeasure suggestions to improve forestry subsidy policies, optimize forestry regulatory policies, and improve forestry total factor productivity from the perspective of heterogeneous forest types. [ABSTRACT FROM AUTHOR]

Facing increasing sustainability demands, the construction industry is at a turning point where the implementation of circular economy (CE) strategies plays an essential role in driving the necessary transformation aimed at reducing the environmental impact. To facilitate this shift, structural engineering must effectively integrate circular principles into building design. With the exponential growth of research articles within this field, it is crucial to map the evolution of the research area. The objective of this study is to detail the trends with, challenges to, and research contributions, integration, and material applications of CE principles within structural engineering. Consequently, a systematic mapping of the CE within the field of structural engineering has been conducted in this study. Initially, the mapping process began with the identification of relevant keywords, followed by searches across four databases. Each resulting article was carefully screened against content criteria, culminating in 91 publications that were thoroughly evaluated. The publications were then categorized and analyzed based on attributes such as research type, circular design, materials, and applications. The results are presented through informative figures and tables. The analysis of the research indicates a predominant focus on technical solutions for structural systems, with demountable connections designed to facilitate the future reuse of materials representing more than half of the literature reviewed. A significant portion of the literature also addresses designing from reclaimed elements; these articles reflect a transformation in engineering approaches, incorporating computational design and innovative methodologies. The focus on steel as a structural material is prominent in the reviewed literature. However, there is an increasing focus on timber, which signals a definitive shift toward sustainable structural systems. Recurring challenges identified in the literature regarding the transition to a circular economy (CE) in the construction industry include the need for industry-wide adoption, precise standardization, the integration of digital tools, and the overcoming of related obstacles in policy and market acceptances. Furthermore, the literature demonstrates a significant research gap: the absence of a comprehensive digital framework enabling an effective digital circular structural design workflow. [ABSTRACT FROM AUTHOR]

Due to various factors such as aging, natural environment erosion, and man-made destruction, architectural heritage has formed various diseases and cracks, especially in pathology cracks, which are the most typical masonry–timber architectural heritages, directly affecting the structural stability of masonry–timber buildings. This paper uses artificial intelligence and architecture and other multi-disciplinary research methods, taking James Jackson Gymnasium, a famous masonry–timber architectural heritage in Wuhan, as an example, using 3D laser scanning technology to obtain disease details and crack data of architectural heritage, using a Mask R-CNN model to detect crack area, using an FCN model to identify and calculate single cracks, and finally summarizing the type, location, and characteristics of cracks, analyzing the causes of cracks, and then putting forward corresponding hierarchical restoration strategies. The research results build a set of detection and repair systems of masonry–timber architectural heritage pathology cracks, which provide a set of accurate and objective pathology cracks data for architectural heritage protection and repair, and provide a reference for architectural heritage repair. [ABSTRACT FROM AUTHOR]

Parametric Finite Element (FE) simulations were performed to investigate the ultimate flexural of different configurations of friction steel beam-to-column joints equipped with FREEDAM (free from damage) dampers. The main aim of this study was to compare the effectiveness of friction dampers featuring either single or multiple slotted holes, examining how these variations influence the behavior of the joint and the devices under seismic loads. In particular, the ultimate behavior of the connection (i.e., when the device reaches its maximum stroke) was investigated to characterize the involvement of the bolts in shear, the bearing of the plates, and the yielding of the supporting components. The analysis of bolt stress states revealed significant differences influenced by the number of bolts and slots. The FE models were calibrated against the experimental results obtained within the FREEDAM RFCS Project. These insights contribute to the design and performance evaluation of steel beam-to-column joints with FREEDAM connections, in particular the detailing of the haunch slots, laying the groundwork for future research and applications. [ABSTRACT FROM AUTHOR]

Advancing the seismic resilience of building systems is an active area of research in earthquake engineering. Ensuring safe egress in and out of buildings during extreme events, such as an earthquake, is essential to supporting this effort. To this end, understanding the seismic response of stairs facilitates the robust design of egress systems to ensure they can remain operable after an earthquake. From prior earthquake events and physical experiments, it is understood that stairs with a flight to landing fixed connection at multiple levels within a building are prone to damage. In addition, the stair system with flight to landing fixed attachments may affect the dynamic behavior of the building. To accommodate seismic inter‐story drifts, a kinematically free connection between the stairs and landing has been proposed. Herein this connection is referred to as a drift‐compatible stair connection. To investigate and aid in the design of such a connection, a unique set of shake table experiments were conducted at the University of Nevada, Reno. In this paper, an overview of these tests is presented, and a high‐fidelity finite element model of the tested stair system is used to predict the responses measured during these experiments. Developed in Abaqus, the robustness of the modeled stair unit is investigated considering a variety of contrasting connections, namely, drift‐compatible connections, fixed ends and one end fixed and the other free. Results from these numerical simulations offer guidance towards development of simplified models of multi‐level stair subsystems. Such models are needed when investigating seismic resilience of building systems across a wider range of hazard levels. Furthermore, best practices observed utilizing the models developed and evaluated herein against experimental data will be useful for subsequent analysis of larger stair tower models, such as the 10‐story stair system implemented in the NHERI Tall Wood mass timber building with post‐tensioned rocking walls, conducted in 2023 at the UC San Diego Large High‐Performance Outdoor Shake Table. [ABSTRACT FROM AUTHOR]

The flexural behavior of hybrid timber–steel encased beams comprising coniferous radiata pine (Pinus radiata) (MGP10) and Douglas fir (Pseudotsuga menziesii) (F8) timber lamellae with bonded-in steel bars is studied. The effect of cross-section depth, steel bar size, timber species/grade, and steel bar arrangements (only bottom and top-and-bottom) on the hybrid beams' stiffness, failure mode, ductility, and load-carrying capacity were investigated. The flexural capacity and stiffness of the doubly (top-and-bottom) reinforced beams are increased by 127% and 71%, respectively. However, in the singly (bottom) reinforced beams, the flexural capacity and stiffness are increased only by 41% and 25%, respectively, highlighting the important role of the compressive bars. The failure of all beams was associated with tensile flexural failure of timber, but the steel bars improved the ductility of the beams. The maximum coefficient of variation of the peak load in hybrid beams (CoV=14.3%) is lower than that of the bare timber beams (CoV=21.7%). Two analytical models were developed based on a linear and a bilinear stress–strain relationship for timber. The analytically predicted peak load and stiffness agree well (less than 13% and 12% difference) with the experimental results. [ABSTRACT FROM AUTHOR]

The mechanical properties of connection joints and the fire protection design of steel structures are crucial for ensuring structural safety. The utilization of fire-resistant steel in steel structure joints represents a novel approach to enhance fire resistance. In this study, a test on two welded–bolted hybrid connection joints between fire-resistant steel columns and beams was conducted considering both ambient and elevated temperatures. Through an analysis of the failure modes, load–vertical displacement curves, moment–rotation curves, and load–strain curves of the joints, key parameters such as the ultimate bearing capacity, ductility, and deformation capacity were determined. The test results showed that the ultimate bearing capacity of specimen Joint-2-ET at an elevated temperature is 81.14% that of specimen Joint-1-AT at an ambient temperature. While the temperature increases during fire had little effect on the initial stiffness of the joint, it significantly reduced the rotation capacity and ductility of the joint. A finite element model of the joints was developed using ABAQUS software, and its accuracy was validated by comparing the results with the experimental findings. Additionally, a parametric analysis was conducted to explore the effects of temperature and heating region on the mechanical performance of these welded–bolted hybrid connection joints. The outcomes of this research provide valuable insights for engineering applications involving welded–bolted hybrid connection joints between fire-resistant steel columns and beams. [ABSTRACT FROM AUTHOR]

Introduction. The paper discusses the advantages and features of the main existing methods of connecting wooden columns and crossbars.Materials and methods. It was proposed to increase the load-bearing capacity and reduce the deformability of joints by modifying the joints with the introduction of epoxy resin between the screw and the wood and between the overlay and the end of the wooden element to which it is attached and modifying the design of the overlays.Results. As a result, a constructive solution for connecting wooden columns and crossbars was developed, which has increased reliability compared to the studied connections and is free of their disadvantages. This result was achieved due to the presence of an adhesive layer between the screw and the wood, as well as between the overlay and the wooden element, the making of notches on the sides of the overlays attached to the wooden elements, the increased length of the screws screwed into the overlay with a groove, compared to the length of the screws screwed into an overlay with a tenon, placement of holes for screws at an angle of 90° to the surface of the overlay into which the screws are screwed.Conclusions. An urgent issue is the development of constructive solutions for connections of wooden elements, in particular the interfaces of columns and crossbars. The paper discusses the advantages and features of the main existing methods of connecting wooden columns and crossbars.