Engineered Wood Products Research Articles

Wood you believe it? Electric vehicles and engineered wood from an environmental perspective

In the transition to a circular bioeconomy, engineered wood products can help achieve environmental policy targets. Wood has been used as a raw material for various industries for centuries and the automotive industry could utilize wood as a structural component in vehicles. This study investigates the environmental performance of a battery compartment for electric vehicles that relies on engineered wood as a structural component. In a life cycle assessment, the wood hybrid battery compartment was compared to an industry standard over its whole life cycle with two differing end-of-life scenarios. The results indicate that the wood hybrid battery compartment creates substantially less impact over its whole life cycle. The biggest potential for impact savings is identified in the resource extraction- and production phase. In the use phase, the lightweight battery compartment also generates less environmental impact since the use of engineered wood leads to a more lightweight vehicle overall. A material reutilization of engineered wood components in the end-of-life phase further reduces the environmental impact of the wood hybrid battery compartment. The results of this study indicate that the manufacturing of wood engineered structural components for electric vehicles is beneficial from an environmental perspective.

Shear performance of single-layer unidirectional strand board (USB): modified testing methods

ABSTRACT Timber construction has gained significant attention as a sustainable solution to meet the increasing demand driven by population growth. However, climate-induced hazards like forest fires, coupled with the scarcity of high-quality round timber raw materials, pose challenges to the production of traditional engineered wood products. Therefore, strand-based materials like unidirectional strand board (USB) have been developed to address these challenges, by utilizing low-quality wood resources. Shear properties are vital for USB's use in wall and slab elements facing lateral loads. However, the variety of direct and indirect shear methods complicates the determination of reliable results. This study evaluates the shear performance of single-layer USB using modified panel and planar shear tests, with comparisons drawn to oriented strand board (OSB/4). Both modified methods effectively characterized material’s directional variability, with vertical or orthogonal shearing dominating the failure modes. The findings confirmed the orthotropic behavior of USB, with higher shear properties in the processing direction compared to the transversal direction. In addition, USB demonstrated comparable shear performance to OSB/4 in the panel and planar tests in the processing direction. Future research should investigate other mechanical and physical properties, as well as the suitable shear methods for multi-layer USBs to account for mass timber.

Mass Timber as a Tool to Sustainable Construction: a Review

Objective: This study aims to assess the sustainability of mass timber products as structural elements, to determine whether their use contributes to sustainable building practices. Theoretical Framework: This paper was developed based on a systematic literature review of mass timber construction publications worldwide, considering works that present results based on empirical data. Method: The systematic literature review was conducted adopting the ProKnow-C method in the Web of Science database due to its extensive coverage of studies in technology and natural sciences. Only peer-reviewed journal articles were selected, while conference papers, extended abstracts, and book chapters were excluded. The research was limited to works published since 2015. At last, 29 articles were selected for discussion. Results and Discussion: The results highlight the growing interest in the sustainability of engineered wood products. Studies show a lower initial environmental impact compared to traditional materials, but few address the circularity potential, particularly recycling and reuse. The lack of standardized methodology hinders the assessment of social and economic benefits, often based on the perceptions of users and stakeholders. Research Implications: This work contributes to identifying gaps in mass timber research. Additionally, as a bibliometric survey, it provides an overview of the state of the art on the topic, serving as support for future researchers. Value: This study contributes to the dissemination and analysis of knowledge about the sustainability of mass timber structures. The significance of this work lies in the novelty of using this material globally, presenting it as a viable alternative to mitigate the environmental impacts of the construction industry.

Analytical approaches for sampling and assessing volatile organic compounds emitted from engineered wood products

Analytical approaches for sampling and assessing volatile organic compounds emitted from engineered wood products

Structure Effects on Mechanical Properties of a Novel Engineered Wood Product: Cross-Laminated-Thick Veneers Based on Infinite Splicing Technology

With increasing global concern over carbon emissions in the construction industry, cross-laminated-thick veneer (CLTV) has emerged as an innovative green building material with significant potential to promote the achievement of “dual-carbon” goals. This study developed a groove and tenon splicing technique for thick veneers, enabling infinite splicing of the length direction and the preparation of a large-size CLTV measuring 12 m (length) × 3.25 m (width) × 105 mm (thickness). The mechanical properties of CLTV were studied in relation to splice position, assembly pattern of grain directions, and layer combinations. The results showed that increasing the number of // layers (// or ⊥ indicates grain direction of layer parallel or perpendicular to the length direction of CLTV) and using high-level layers significantly improved the compressive strength and reduced the coefficient of variation of CLTV. In terms of bending properties, reasonable splice distribution, placing // layers away from the neutral axis, and elevating layer level dramatically enhanced CLTV performance. Furthermore, the study revealed the synergistic effect among these design elements. The effects of layer level and the number of // layers on mechanical properties varied depending on splice arrangement and assembly pattern of grain directions, highlighting the importance of efficient structural design and raw material selection. This study addresses the limitations of traditional cross-laminated timber in raw material selection and production efficiency. Through structural innovation, it offers a solution for physical design and performance regulation, enabling the application of larger CLTV in wood structures and presenting new ideas for using fast-growing wood to reduce construction emissions.

Adhesive free Melaleuca rhaphiophylla (Swamp Paperbark) bark as an engineered wood product

Adhesive free Melaleuca rhaphiophylla (Swamp Paperbark) bark as an engineered wood product

Whole-Building Life-Cycle Assessment in the Built Environment: A Ten- and Six-Story Shake-Table Test Building Case Study

Abstract The utilization of mass timber engineered wood products has increased for new buildings aiming to reduce environmental impacts. Whole-building life-cycle assessment (WBLCA) has been used to quantify the environmental impacts for a building’s lifespan. While mechanisms for calculating the cradle-to-grave impacts of a single building are well established, there are few examples of WBLCA applied for buildings in their first and second life that can be used to inform perspectives and pathways related to the circular economy and lead to informed decision making. This work presents a case study WBLCA to examine the effect of overlapping system boundaries and alternative end-of-life pathways for a building structure in its first and second life. This case study analyzed a ten-story mass timber shake-table specimen that was partially deconstructed and reused as a six-story shake-table building structure. Environmental impacts were analyzed in terms of global warming potential (GWP) calculated as the sum of fossil carbon, biogenic carbon, and avoided impacts. When examining reuse and landfill pathway alternatives using current standards and practices, results show that reusing material causes a positive GWP trend in the first system boundary and negative GWP trend in the second boundary. These results could indicate that it is not advantageous to reuse the ten-story building structure, running against principles of waste hierarchy, although the interpretation should be considered with caution. Future analyses could be improved by considering additional criteria such as demand on forest stocks, economic incentives, and even social impacts for a more complete representation of sustainability.

Dynamic and quasi-static evaluation of stiffness properties of CLT: longitudinal MoE and effective rolling shear modulus

Cross-Laminated Timber (CLT) is an engineered wood product composed of solid layers of glued sawn timber. In this study, essential material stiffness parameters for CLT made from Norway spruce and Scots pine are evaluated. Specifically, the longitudinal modulus of elasticity (MoE) for longitudinally oriented layers and the effective rolling shear modulus for transversely oriented layers are the focus. By combining finite element (FE) analysis with four-point, out-of-plane bending tests using digital image correlation (DIC), a robust assessment of the effective rolling shear modulus of CLT layers is achieved. Additionally, eigenvalue analysis, applied to an FE model, along with resonance frequencies obtained from dynamic excitation of CLT, enables stable and simultaneous assessment of the dynamic longitudinal MoE and effective rolling shear modulus. Notably, while the dynamic MoE of longitudinal CLT layers is only 4% higher than the quasi-static local MoE, the dynamic effective rolling shear modulus of CLT layers is 40% higher than the quasi-static effective rolling shear modulus. This finding indicates a tangible viscoelastic behavior of wood concerning rolling shear.

X Ray Based Laboratory Testing Methodology for Panel Products against Termite Resistance

A host of new eco- friendly preservatives and treatments for protection of panel products are being developed. Engineered wood products require extra caution while testing with termites, due to high moisture conditions during field tests, a composite panel may subject to delamination making it difficult for a proper rating and determination of damage due to termite activity. This work focuses on development of a laboratory testing method for plywood and blockboard resistance against termite species Heterotermes indicola and Coptotermes heimi. The termite species preferability test was done in order to find out the most palletable wood species. Pinus sp and Mangifera sp. were found to be the most palletable wood species and were taken as control. Determination of maximum vigorous activity of both the termite species were done by monitoring wood consumption and survival, and it was found that Heterotermes indicola showed highest survival at population density of 0.004 g/ml, whereas Coptotermes heimi showed highest survival at population density of 0.0008 g/ml. A non-destructive and quantitative approach of X-Ray analysis was adopted for result evaluation for more quantifiable result than traditional visual observation. Based upon the results obtained, a termite testing methodology was developed for wood based panel products such as plywood and block board.

Effect of crack defects on interlaminar shear properties of cross-laminated timber (CLT)

ABSTRACT Cross-laminated timber (CLT) has become one of the most popular engineering wood products in construction because of its excellent physical and mechanical properties. In this study, the short-span three-point bending test combined with acoustic emission test was used to study the effect of cracks on the inter-layer shear properties and fracture path of CLT. Crack length and crack location was used as influencing factors. Macro and micro failure patterns are analysed. The results show that the crack length had significant effects on the interlaminar shear strength and the initial failure load. The load-strain curve and acoustic emission location fracture paths were characterised by a rolling-shear failure stage, an instability stage, and a tensile failure stage of the tensile-side outer layer of the CLT. With the increase of crack length, the initial-failure load and inter-layer-shear strength were reduced due to the variations of crack-initiation location and crack-propagation path. The research of this study has certain guiding significance for the safe use of CLT in practical engineering.

Physical and Mechanical Properties of Hardwoods Cross-Laminated Timber

Abstract Cross-laminated timber (CLT), a type of engineered wood product, is becoming widespread in the construction sector, especially for large commercial buildings. The increased demand for CLT is due its perceived benefits over conventional building materials. To effectively utilize the numerous benefits of this modern building material, there is need to ascertain its reliability as a structural material without affecting its serviceability. Thus, the objectives of this study were to evaluate both the physical and mechanical properties of CLT and to compare the mechanical properties of CLT manufactured with hardwood of low-grade lumber and industrially made softwood CLT. Hardwood species used to manufacture CLT panels were red oak (Quercus spp.), yellow poplar (Liriodendron spp.), and sweetgum (Liquidambar spp.). Commercially manufactured southern pine CLT panels were used as control. The evaluation of density was done at a moisture content of 12 percent. All specimens were mechanically tested in accordance with ASTM D198 to determine the modulus of elasticity (MOE) and modulus of rupture (MOR). The range of values for both MOE and MOR found in this study are not significantly different from values reported in a previous study. Of the hardwood samples tested, 95 percent had MOE greater than minimum allowable MOE of 1.2 × 106 psi (8,274 MPa) specified for softwood CLT by the American National Standards Institute/The Engineered Wood Association performance-rated CLT. Thus, the average MOE values observed for all the CLT species can be used as a basis for design values in the construction industry for hardwood species.

A Fast-Calibrated Computational Fluid Dynamic Model for Timber–Concrete Composite Ventilated Façades

Timber–concrete composite (TCC) systems join the positive aspects of engineered wood products (good seismftaic behaviour, low thermal conductivity, environmental sustainability, good behaviour under fire if appropriately designed) with those of concrete (high thermal inertia, durability, excellent fire resistance). TCC facades are typically composed of an internal insulated timber-frame wall and an external concrete slab, separated by a ventilated air cavity. However, there is very limited knowledge concerning the performance of TCC facades, especially concerning their thermal behaviour. The present paper deals with the development and optimization of a 2D Computational Fluid Dynamic (CFD) model for the analysis of TCC ventilated façades’ thermal behaviour. The model is calibrated and validated against experimental data collected during the annual monitoring of a real TCC ventilated envelope in the north of Italy. Also, a new solver algorithm is developed to significantly speed up the simulation (i.e., 45 times faster simulation at an error below 3.5 °C compared to a typical CFD solver). The final model can be used for the time-efficient analysis (simulation time of approximately 23 min for a full day in real-time) and the optimization of the thermal performance of TCC ventilated facades, as well as other ventilated facades with external massive cladding. Our simulation strategy partially avoids the expensive and time-consuming construction of mock-ups, or the use of comparably slow (conventional) CFD solvers that are less suitable for optimization studies.

Shear performance of glued and screwed timber-steel composite connections for composite timber-steel beams

Mid- to high-rise mass timber buildings gained popularity in the last decade. Yet, engineered wood products (EWPs) used to erect these buildings have structural limitations. EWPs present brittle failure modes, particularly in bending, shear and tension, and have a low modulus of elasticity resulting in shorted spans and deeper beams relative to those in the steel and reinforced concrete counterparts. Timber-steel hybrid beams represent a potential sustainable solution to overcome these limitations by taking advantages of the high strength, stiffness and ductility of steel, and the high capacity to weight ratio of timber. However, for this solution to be structurally performant, it is essential to create effective composite action between the two materials. This study therefore compares the structural efficiency of various bonding techniques between the steel and the timber materials. Two sets of assembly solutions, representing four connection types, were proposed and experimentally investigated: (1) connecting an embedded steel plate into the timber elements by using either polyurethane (PUR) structural adhesive with two manufacturing variations or 14 G×75 mm heavy duty screws, and (2) connecting a steel plate on the surface of the timber element using either PUR structural adhesive with self-tapping M4×40 mm screws or only self-tapping screws. Softwood Laminated Veneer Lumbers (LVL) and Grade 350 steel plates were used in the experimental tests. All bonding techniques were tested in shear. The shear capacity, the slip stiffness and the failure mode were evaluated. Additionally, the efficiency of the proposed manufacturing solutions was quantified by analytically evaluate the effective bending stiffness of a timber-steel composite beam manufactured with different bonding techniques being investigated. Results indicated that the glued connections allowed a significantly more efficient composite action, with failure occurring in the timber instead of at the composite interface and near-full composite action was reached, than the screwed connections. To achieve high composite action with the screwed solutions, a large number of screws was needed which may incur high manufacturing costs.

Board assignment heuristics for nail laminated out-of-grade timber

ABSTRACT 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.

A systematic literature review of life cycle sustainability assessment of mass timber in the construction industry toward circular economy

AbstractLife cycle analysis has been used to evaluate the environmental impacts and economic costs of a range of engineered timber structural materials as well as other materials such as steel and concrete over the last two decades. This study presents a bibliometric analysis and systematic critical review by investigating the life cycle sustainability assessment (LCSA) of engineered timber products. LCSA is comprised of three main pillars namely, environment, cost, and social impact. The study compares alternative engineering wood products used in building structures such as columns, beams and wall surfaces. The geographical distribution, main sources of research, co-occurrence of keywords were analyzed for 93 peer-reviewed articles and conferences. The United States was the most productive country, contributing almost 23 documents. Australia was next with 12 publications. Most studies compared the LCA and LCC of alternative Mass timber products and concrete or steel. Most studies evaluated cross laminated timber (62%), followed by glued laminated timber (17%), and laminated veneer lumber (9%). A comparison of the economic and environmental aspects indicated that the social aspect are less considered. The review showed that the global warming potential of manufactring1 M3 of cross laminated timber is about 155.6–158.6 kg CO2eq. The majority of the publications reviewed focused on LCA whilst others focussed on the LCC of Mass timber. No research on social life cycle assessment has been conducted as yet. A framework is suggested for future research to identify the best alternative for engineering wood.

Cold temperature effects on the impact behaviour of glued-laminated timber beams

Cold temperature effects on the impact behaviour of glued-laminated timber beams

Performance Assessment of Wood-Based Composite Materials Subjected to High Temperatures

This paper is based on research placed within the broader framework of the growing environmental impact requirements of building materials. Given this context, wood-based composite materials have emerged as a promising and innovative solution for structural elements. The current work aims to define a system for testing the mechanical behavior of glued laminated timber elements when exposed to high temperatures, in the neighborhood of the pyrolytic decomposition of materials. These tests monitor the transient behavior of the composite material and characterize the parameters involved in the thermo-mechanical analysis of elements constructed using this type of engineered wood product. The tests are used for the calibration of the material models involved in the numerical analysis and for the analysis of potential prototypes, considering the transient thermal load and heat propagation through the materials. By taking such tests, benchmark models and laboratory procedures are defined that can be used in the future to evaluate different materials, existing or new, and material combinations used to construct such a composite.

Mechanical properties and probabilistic models of wood and engineered wood products: A review of green construction materials

Mechanical properties and probabilistic models of wood and engineered wood products: A review of green construction materials

Fragility functions for low‐damage post‐tensioned timber frames

AbstractThe growing concern over environmental impact and the significant improvement in the quality of engineered wood products have led to the rapid growth of the timber building industry in the last decades. Although traditional, yet recent, mass timber structural systems, such as cross‐laminated timber walls, can provide satisfactory seismic performance during earthquakes in terms of life‐safety, the crucial need for more resilient timber buildings has prompted the development of low‐damage high‐performance self‐centring and dissipative solutions based on unbonded post‐tensioned hybrid connections, referred to as Pres‐Lam technology. The flexibility of design and construction speed, combined with the enhanced seismic performance, create a unique potential towards an earthquake‐proof sustainable building system. Despite the growing popularity of the technology, a comprehensive framework for the fragility analysis, to be used in risk and loss modelling applications, has not yet been developed for both component and building levels.This article aims to develop a framework for assessing the fragility curves of moment‐resisting Pres‐Lam frame systems, at both structural system and connection levels, by using and comparing different approaches that involve nonlinear static (pushover) and time history dynamic analyses. A Python‐based parametric workflow was developed to evaluate fragility curves for a wide range of case‐study buildings. Particularly, three distinct structures were selected, and their fragility curves were evaluated utilizing alternative methodologies at a building structural‐system level. Finally, fragility models were fitted for individual structural connections using the results of time‐history analyses. These models are intended for use in a component‐based loss assessment.

Numerical investigation on flexural performance of dowel laminated timber with laminas made of laminated veneer lumber

Numerical investigation on flexural performance of dowel laminated timber with laminas made of laminated veneer lumber