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In this study, the finite element method (FEM) was used to determine the effect of the optimal angle of the thread and double thread application among self-tapping screw (STS) design information on the improvement of the withdrawal capacity of the connection. It was modeled by reflecting the design information of an Italian STS distributed in the domestic wooden building market, and the stress distribution of the connections was compared according to the change in the thread angle. A cross laminated timber (CLT) composed of five layers was modeled as a member. The STS modeling was centered on the threaded area, and two threaded angles were applied: 90° and 95°. Additionally, the stress changes were compared when double threads located in the middle of the thread pitch in the screw pitch were applied to improve the withdrawal capacity of the connection. The domestic STSs were manufactured using four materials and two shapes. The finite element analysis and strength performance tests of the STS types indicated that the material properties, angle of the screw thread, and shape of the screw thread affect the Korean CLT withdrawal capacity.

The end-grain bonding of timber components using the Timber Structures 3.0 technology (TS3) is an advancing construction method in timber engineering. This technology allows the realisation of any plate size by bonding plates on-site where low temperatures influence the performance. Therefore, investigations are underway to evaluate the influence of the low temperatures on the curing process. Additionally, research is in progress to discover techniques to reduce any adverse effects of low curing temperatures on the mechanical properties of the bond. The implementation of particular measures, such as the inclusion of milled heating wires into the joint and the pre-heating of the joint with a hot air blower, has been identified as advancing the potential for grouting even in the face of low external temperatures, as recent research has indicated. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) has been one of the principal materials in mass timber construction, and now it is possible to find mid-rise and high-rise projects around the globe. This study makes a scientometric review comparison between CLT and the impact of the fourth industrial revolution (formally known as Industry 4.0) in the construction industry, focusing on worldwide academic publications between 2006 and 2022. The analysis considers keywords, co-author, co-citation, and clustering analysis. This study used 1320 documents, including journals and conference proceedings from the Scopus database, where 753 were for cross-laminated timber and 567 for Industry 4.0. Key researchers, research institutions, journals, publications, citation patterns, and trends are some of the results obtained from the scientometric analysis. Once the knowledge mapping was conducted for both fields, scrutiny of the interconnection of both areas was performed to find possible research gaps from a manufacturing perspective. Among the conclusions, it is logical to say that Industry 4.0 implementation in cross-laminated timber is still in its infancy. One of the most popular technologies impacting construction is the digital twin concept; however, no work is reported for CLT on this topic. Additionally, digital automation is a necessity in any research practice, and the use of industrial robots is shown to be an essential asset for CLT as these robots can handle complex shapes.

This research bridges the gap between the quasi-static and high-strain-rate loading regimes in cross-laminated timber (CLT) by investigating two areas that have remained unstudied or elusive, i.e., rolling shear failure of CLT under impulsive, blast-like loading and intermediate strain rates in CLT. To study the conditions that would promote shear modes of failure, a novel, highly adaptable center-point testing system and methodology were developed that permitted the application of impulsive loading to undamaged CLT panels in a highly controlled and repeatable manner. The loading condition and low span-to-depth ratio (6.40 ≤ L:h ≤ 6.55) CLT were selected to encourage the development of shear modes of failure. Changes to the rotational rigidity at the boundary conditions allowed for the empirical simulation of realistic boundary conditions. Digital Image Correlation (DIC) and load cell data were used to identify failure modes following loss in resistance in the specimens. Overall, the experiment was successful in consistently eliciting shear modes of failure and providing damage characterization in impulsively loaded CLT. Shear modes of failure resulted in the dramatic loss of resistance in all specimens tested. Strain-rate enhancement in the dynamic apparent flexural stiffness of CLT of 1.3 to 7.2 times was observed. Lower levels of damage were observed in specimens with higher levels of boundary-condition rotational rigidity. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) has been one of the principal materials in mass timber construction, and now it is possible to find mid-rise and high-rise projects around the globe. This study makes a scientometric review comparison between CLT and the impact of the fourth industrial revolution (formally known as Industry 4.0) in the construction industry, focusing on worldwide academic publications between 2006 and 2022. The analysis considers keywords, co-author, co-citation, and clustering analysis. This study used 1320 documents, including journals and conference proceedings from the Scopus database, where 753 were for cross-laminated timber and 567 for Industry 4.0. Key researchers, research institutions, journals, publications, citation patterns, and trends are some of the results obtained from the scientometric analysis. Once the knowledge mapping was conducted for both fields, scrutiny of the interconnection of both areas was performed to find possible research gaps from a manufacturing perspective. Among the conclusions, it is logical to say that Industry 4.0 implementation in cross-laminated timber is still in its infancy. One of the most popular technologies impacting construction is the digital twin concept; however, no work is reported for CLT on this topic. Additionally, digital automation is a necessity in any research practice, and the use of industrial robots is shown to be an essential asset for CLT as these robots can handle complex shapes. [ABSTRACT FROM AUTHOR]

Abstract To learn the characteristics of a cross-laminated timber (CLT) panel, it is crucial to perform experimental tests. This study presents two experimental test methods to measure the in-plane shear modulus of CLT panels. This characteristic can be measured by multiple methods such as the picture frame test, the diagonal compression test, and the diaphragm shear test. In this study, the same CLT panels are tested and evaluated in the diaphragm shear test and the diagonal compression test to see if more reliable results can be achieved from the diaphragm shear test. This evaluation is done by experimental tests and finite element simulations. The theoretical pure shear simulation is used as a reference case. Finite element simulations are made for both edge glued and non-edge glued CLT panels. Nine CLT panels are tested in the diaphragm shear test and the diagonal compression test. During ideal conditions (uniform material properties and contact conditions), all three simulated methods result in an almost equal shear modulus. During the experimental testing, the diagonal compression test gives more coherent results with the expected shear modulus based on finite element simulations. Based on the diaphragm shear test results, the CLT panels behave like edge glued, but this situation is dismissed. However, during ideal conditions, the diaphragm shear test is seen as a more reliable method due to the higher proportion of shear in the measured area. Article Highlights Comparing the two experimental methods: the diaphragm shear test and the diagonal compression test. Using the theoretical pure shear simulations to verify the experimental methods. Experimental testing and finite element analysis of the same cross-laminated timber panel.

Recent design guides include charring models for cross-laminated plane timber (CLT) members. When the bond line integrity is not maintained, charring is illustrated as a combination of sequenced phases. Significant research has been conducted on the charring behaviour of CLT panels, and the criterion of 300 °C has been an accepted definition for the char front line. The charring rate of a solid wood-based panel is determined by the char depth divided by the time to reach the char depth. In the CLT structure, this method can be applied to the first lamella layer. However, due to the char fall-off, it cannot be directly applied to the lamella layers behind the first layer. In this research, eight fire tests were conducted to investigate how charring rates of different lamella layers can be determined from measured temperatures. An assessment method based on the mean char depth development determined from experimental temperature distributions of CLT panels is introduced. Also, the effects of thermocouple positioning and specimen orientation on the assessment results were analysed. The charring rates determined for both horizontal and vertical specimens align well with the results calculated using the European Charring Model and a post-protection factor k 3 of 2. [ABSTRACT FROM AUTHOR]

This research bridges the gap between the quasi-static and high-strain-rate loading regimes in cross-laminated timber (CLT) by investigating two areas that have remained unstudied or elusive, i.e., rolling shear failure of CLT under impulsive, blast-like loading and intermediate strain rates in CLT. To study the conditions that would promote shear modes of failure, a novel, highly adaptable center-point testing system and methodology were developed that permitted the application of impulsive loading to undamaged CLT panels in a highly controlled and repeatable manner. The loading condition and low span-to-depth ratio (6.40 ≤ L:h ≤ 6.55) CLT were selected to encourage the development of shear modes of failure. Changes to the rotational rigidity at the boundary conditions allowed for the empirical simulation of realistic boundary conditions. Digital Image Correlation (DIC) and load cell data were used to identify failure modes following loss in resistance in the specimens. Overall, the experiment was successful in consistently eliciting shear modes of failure and providing damage characterization in impulsively loaded CLT. Shear modes of failure resulted in the dramatic loss of resistance in all specimens tested. Strain-rate enhancement in the dynamic apparent flexural stiffness of CLT of 1.3 to 7.2 times was observed. Lower levels of damage were observed in specimens with higher levels of boundary-condition rotational rigidity.

The use of cross-laminated lumber (CLT) for building construction has gained interest in the United States (US) and Canada. Although anecdotal market size claims exist, few quantitative studies have estimated the potential market size or discussed the impact of CLT on lumber supply. This paper presents a method to quantify CLT markets and lumber supplies based on data for the Northwest US. The western US was chosen for its early adoption of CLT combined with a long history of commercial timber construction. Structural designs of archetype buildings were combined with projected multifamily residential and commercial building construction to estimate the demand for CLT. These figures were reduced to account for assumptions that address market penetration and population density. In the case study for the Northwest, the total potential market is less than the existing CLT production in western North America. Thus, the demand region was expanded to include the US and Canada west of the Rocky Mountains, resulting in an estimated demand of 800,000 m³/yr by 2030. A regional lumber supply study suggests that the lumber supply will support the existing CLT industry, which utilizes approximately 2% of the selected lumber classifications, with an unknown impact on lumber cost and production. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) is a bio-based building material that enables rapid construction and buildings with low embodied energy. Despite its comparative maturity in European markets, relatively little information regarding process design and economics for the manufacture of cross-laminated timber is available in the literature. Two techno-economic analyses were conducted to quantify the mill-gate cost of cross-laminated timber. The cross-laminated timber manufacturing process was described, and costs were analyzed for two facility scales. Cross-laminated timber produced at the large-scale facility using lumber priced at an average value for the northwest United States has a minimum selling price of $536/m³. Sensitivity analyses were used to define the impact of plant size, asset utilization, lumber price, plant capital cost, material waste, and other variables on minimum selling price. The cost of cross laminated timber rises quickly when a facility is not fully utilized. The second-ranking cost controlling variable is lumber price, while energy prices have minimal influence. The price of cross laminated timber can be optimized by locating a facility near low-cost lumber. The lowest-price region analyzed was the southeast United States using Southern Pine, which reduced the cost of cross laminated timber to $518/m³. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) construction has received significant attention for potential North American markets; however, few claims have been substantiated with structural design details that assess the amount of CLT to be used in various classifications of buildings. This article presents a design process used for the development of archetype buildings to estimate the potential CLT demand. Three types of structural systems were identified: platform construction, rocking walls with a separate gravity system, and hybrid construction consisting of reinforced concrete elevator cores and rocking walls. Platform construction was used for buildings 1 to 6 stories in height, the rocking wall system was used for buildings 6 to 12 stories in height, and the hybrid structural system was used for buildings 12 to 18 stories in height. The assumptions and design process for each of these archetypes are presented in this paper. Based on the structural analyses, CLT use factors were developed for predicting market demand as well as cost estimation of CLT building projects. [ABSTRACT FROM AUTHOR]

Fire concerns are one reason for building code restrictions against tall wood buildings in US. Despite growing body of empirical data on fire performance of cross-laminated timber (CLT) generated in Europe and Canada, lack of full-scale tests performed on structural CLT "made in the USA" is often quoted as a barrier for approval of massive timber in tall buildings in the US. The goal of this project was to contribute towards removing this barrier by testing the fire resistance of three full-scale unprotected CLT floor assemblies fabricated by two US-based manufacturers. The assemblies represented two species groups (SPF and DF-L), and two adhesive systems (PUR and MF). All assemblies met ASTM E119 standard qualifying criteria for 2-h fire rating in loaded condition. While char fall-off was observed in assemblies bonded with PUR, the differences in mean char rates in the first two layers between assemblies bonded with PUR and MF were smaller than the variability of char rates within individual assemblies. Statistical significant difference was observed only for cumulative char rate for the entire time of exposure. The effect of softening of the PUR bonds was most apparent as an accelerated rate of assembly deflection in the late stage of the tests. The unprotected half-lap joints provided adequate barrier against transmission of hot gases and flames through the assemblies. • Three unprotected CLT floors assemblies made in USA qualified for 2-h fire rating per ASTM E119. • Assemblies made with spruce-pine-fir and Douglas fir-larch lumber, and polyurethane or melamine formaldehyde adhesives. • Mean char rates in layers 1 and 2 of the assemblies differed less than within the same layer of individual assembly. • In test assemblies bonded with PUR, softening in the bonds accelerated rate of the deflection in the final 40 min. • Unprotected half-lap joints provided adequate barrier against transmission of hot gases through the assemblies. [ABSTRACT FROM AUTHOR]

Highlights • Created first-ever public ballistic data set for Cross-laminated Timber. • Related the ballistic performance to the species of wood found in the CLT (Spruce Pine Fir – South and Southern Yellow Pine). • Developed and calibrated models for predicting the embedment depth as well as residual velocity. Abstract Cross-laminated Timber (CLT) is a relatively new building material that has gained recent attention in the United States construction industry. CLT is a prefabricated, engineered wood product, composed of three or more plies of lumber with alternating ply directions. CLT is relatively strong and stiff, with the potential to meet the requirements for structures that are subjected to a variety of loading conditions. While CLT's response to static, dynamic (i.e., seismic), and fire loads has been characterized in the past, its response to the loads seen in force protection scenarios (i.e., blast or ballistic) is much less understood. In order to begin to fill this gap in knowledge, one of the first known sets of ballistic experiments were conducted on CLT and the results were used to develop and validate predictive models. This article describes the results of 122 ballistic experiments conducted at the United States Army Engineer Research and Development Center (ERDC). The experiments were conducted on two species of CLT of varying thicknesses: Spruce Pine Fir-South and Southern Yellow Pine. The experiments measured either penetration depth or residual velocity over a range of intermediate striking velocities. The effects of weathering (i.e., moisture content) were also explored on a data set. The results of the experiments were compared to existing United States Unified Facilities Criteria models for predicting the ballistic response of wood. The findings show the deficiencies in utilizing this wood model for CLT and explore alternate models for prediction. In general, it was found that models that incorporate both projectile and CLT target parameters most accurately predict the response. Most importantly, the results reinforce the necessity for re-calibration of models as new parameters are added to the CLT ballistic characterization database. [ABSTRACT FROM AUTHOR]

Cross-laminated timber, or CLT, is receiving attention for its potential application in tall building structures. As a combustible material, one of the main challenges for the construction of these buildings is the fire risk that results from its use in the structure. Unprotected CLT can burn along with the fuel load present in a compartment. Irrespective of the structure's fire resistance rating, it is uncertain whether the structure will be totally consumed in the event of a complete burnout. If the structure would continue to burn, this could result in collapse of the building. Alternatively, the fire could decay by self-extinguishment. Self-extinguishment of CLT was investigated with a theoretical model that describes the conditions under which it could be achieved. Two series of experiments were conducted to quantify these conditions. It was concluded that there is a potential for self-extinguishment of CLT if fall-off of charred layers is prevented by applying sufficiently thick lamellae, if the heat flux on the CLT during smouldering is below 5–6 kW/m2, and if the airflow over the surface during smouldering is limited to a speed of 0.5 m/s. An exploration towards design implementation is presented. Image 100 • There is a potential for CLT to self-extinguish. • Prevent char fall-off with sufficiently thick lamellae. • Limit heat flux during smouldering to ≤5–6 kW/m2 • Ensure sufficiently low airflow with speed ≤0.5 m/s at these levels of heat flux. [ABSTRACT FROM AUTHOR]

The objective of this paper is to report on and analyse strategies for cost reduction, design processes and procurement models of a wooden nearly zero energy building (nZEB) in Norway. This publication is part of the dissemination activities of the EU Horizon 2020 project NERO, whose scope is to demonstrate the feasibility of cost reduction of nZEBs built in wood in the Nordic countries. Case buildings from Estonia, Finland, Norway and Sweden are studied with respect to their technological solutions, energy use and construction cost. The Norwegian building investigated in this paper is the Moholt Allmenning, a newly built student accommodation located in Moholt, Trondheim. Interviews with the building's owner and the contractor were carried out to obtain information on the decision-making process during the procurement phase, the planning phase and the execution phase. The results show that the environmental goal and the requirement for the use of wood set out in the tender announcement were decisive driving forces for the selection of cross-laminated timber (CLT) in the final design. The results also show that the cost of using CLT in student residences is competitive when compared to using concrete and steel. Given the requirement for minimal greenhouse gas (GHG) emissions from materials production in nZEBs, the use of CLT is, however, a better choice. [ABSTRACT FROM AUTHOR]

Observations on the linearity of damage accumulation in timber construction Based on fatigue tests on cross‐laminated timber under in‐plane shear loading the damage accumulation behaviour is observed. For this purpose, the accumulated deformation is taken as an indication of the accumulated damage. It is shown that the popular assumption of a linear damage accumulation is on the safe side for most of the fatigue life under invariable loading conditions (such as amplitude and maximum load). For small load cycle numbers, though, a critical spectrum is identified, where the safe application of a linear damage accumulation theory is questionable and needs further investigation. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT or X-Lam) is a modern building material used for load-bearing construction purposes in residential and non-residential buildings. CLT production has been increasing rapidly in recent years. CLT is suitable for wall, floor, ceiling and roof elements in the construction of houses, multi-family apartment buildings, industrial and storage halls and other buildings and bridges. Manufacturers demonstrate compliance with the essential requirements of the European Construction Products Regulation (CPR) on the basis of an initial type testing and the findings of a factory production control examination. In 2015, a harmonized European standard for CLT was adopted, which defines the requirements for built-in materials, the production and demonstration of constancy of performance, and the CE marking. The article presents the production technology and basic characteristics of CLT and the content of standard EN 16351.

The effects of irregularity in elevation of cross-laminated timber buildings have not been fully analysed in literature to provide useful information for the design. In this work, a number of building configurations, regular or irregular in elevation, characterized by a different arrangement per storey of the floor-wall joints have been analysed by means of non-linear dynamic analyses. Comparative results in terms of ratio between the behaviour q-factor of the investigated irregular configurations and that of reference regular ones, show that less dissipative capacity can be expected if the building is irregular due to a disequilibrium among storeys between the actual and the required strength provided by the floor-wall joints. A correlation method to estimate the behaviour q-factor for perfectly regular cross-laminated timber buildings is here presented and extended to in-elevation irregular ones. A new empirical formulation to assess the reliable corrective factor accounting for the irregularity in elevation of cross-laminated timber buildings, according to Eurocode 8 provisions, is also proposed. A final discussion about the implications of in-elevation irregularity on the building design is reported. [ABSTRACT FROM AUTHOR]

Dissipative steel plate connections for CLT diaphragms Due to their high shear strength and stiffness, cross laminated timber (CLT) members are especially suited for in-plane loads. The ductility and energy dissipation capacity of a CLT structure is mainly determined by the number and properties of the mechanical connections. Presently, the required energy dissipation capacity for earthquake loading is often achieved by metallic dowel-type fasteners loaded beyond their yield load. The load-slip curves for connections with laterally loaded dowel-type fasteners show pinched hysteresis loops under cyclic loads. Additionally, the achieved load at a certain displacement decreases under repeated loading - impairment of strength. For seismic loads, however, connections with stable load-slip behaviour and high energy dissipation under repeated loading are needed. In this contribution experimental, numerical and analytical investigations of newly developed dissipative steel plate-to-timber connections are presented. For the dissipative shear wall joints the typical pinching and impairment of strength of hysteresis loops could nearly completely be avoided by arranging a gap between the CLT members around the steel plate fastener. Dissipative joints for shear walls using steel plate fasteners have a simple geometry and are easy to manufacture and hence constitute an economic and robust solution. [ABSTRACT FROM AUTHOR]

There are currently no standards regulating water management for mass timber elements during construction, little knowledge of impacts of moisture exposure (wetting and drying performance, dimensional stability, checking), and few precedents serving as guidelines for monitoring moisture response of mass timber. To address these gaps, a hygrothermal monitoring study was devised to track moisture performance of U.S. made cross laminated timber (CLT) and glulam at a three-story mass timber building. This paper discusses moisture measurements that were collected during the first six months of construction at a CLT rocking shear wall and a timber floor connection. Despite the limited number of structural systems monitored during construction, the distribution and number of sensors in these elements allow to draw some important conclusions. The data confirmed that moisture distribution and wetting/drying rates varied based on local conditions and details (aspect, coatings, connections, etc.), with measurements at an uncoated, north-facing area showing the highest moisture levels (reaching fiber saturation at multiple ply depths and locations). Most locations rarely exceeded 16% moisture content for more than a few months. Certain moisture-trapping details consistently showed higher moisture levels (i.e., above 16%) and poorer drying. Some interior plies continued to show slow increases in MC even after months of drying conditions. These observations suggest preventative approaches implementable in the design (e.g., avoiding moisture trapping details), during fabrication (e.g., localized coating), and construction (e.g., sequencing installation to minimize exposure and allow drying).

The main objective of this work was to study the structural viability of using small-diameter logs of Uruguayan Loblolly/Slash pine, mainly from thinning operations, to design cross-laminated timber (CLT) panels. A visual grade named “CTH” (coniferous thinning) was proposed, and 45 specimens of sawn timber boards were tested, resulting in 51% lower bending strength than that of the minimum strength class C14. Subsequently, 20 CLT panels were manufactured and experimentally tested, the results showed that the bending strength of the CLT panels was 43% above that of the individual layers. Additionally, the structural performance of the CLT panels for use in floors was calculated, and the thickness-span relationship depending on strength class and imposed load are presented. Results showed than the use of CTH timber to design CLT floors implies a volume (m3/m2) 17% higher than that using C24 timber.

An innovative steel-timber hybrid floor diaphragm with modular prefabricated composite elements is presented. Building elements have been designed to be quickly joined on site using only bolts and screws. The paper mainly deals with an experimental study on the response of the hybrid floor under horizontal loads. Monotonic and cyclic shear tests of a full-scale floor were executed in order to investigate the in-plane stiffness, bearing capacity, effective stress state and strain state, as well as damage to floor components. The forces transmitted through the timber and steel components were also assessed. The test results showed that the main deformations of the floor were localised at the beam-to-beam steel joints while the steel-timber hybrid elements behaved elastically without breakages. The use of CLT panel-to-panel connections was very effective in increasing the stiffness and the ability to recover the initial non-deformed shape after the removal of the acting loads. The findings revealed how the diaphragm behaviour of the floor was influenced by the mutual interaction between the modular staggered composite elements and in particular by the response of the connections. Several design recommendations for steel and timber connections are therefore provided here. [ABSTRACT FROM AUTHOR]

The seismic response of cross-laminated timber buildings is analysed with the aim of assessing the correlation between the dissipative capacity (i.e., q-factor) and the assembling methodologies and geometrical properties. A parametric study was performed by means of incremental dynamic analyses on various building configurations with varying constructive features such as density of panel-to-panel joints and building slenderness. The results are firstly used to define parameters representative of the building geometry and assembling methodology and then to develop an analytical relationship to compute their most suitable q-factor starting from such parameters. The proposed method is finally validated referring to significant case studies available in literature. [ABSTRACT FROM AUTHOR]

Timber panel construction using Cross-Laminated Timber (CLT) or Laminated Veneer Lumber (LVL) panels have been developed for cost and construction efficiencies in the building industry. The increased use of timber as a sustainable construction material in buildings is expected to expand the forest industry and increase carbon stock. Heavy timber structural elements with sufficient load bearing capacity could be used in tall buildings. However, sufficient data are not yet available to understand the structural and thermal behaviors of domestic timber panel elements with cross laminations/layers when they are exposed to fire. In this study, fire testing data for timber panels are obtained and the charring characteristics and failure modes of structural elements under standard fire exposure are investigated to develop a simple method for estimating the fire resistance of timber panels. Toward this end, a series of experiments consisting of heating tests and load bearing tests for walls in furnaces with various experimental parameters was conducted. The experimental parameters considered include the adhesive type, thicknesses of laminations and panels, wood species, fire protection, and applied loads of the panels. Experiments without loading showed that CLT and LVL panels and joints of panels with 135 mm thickness showed sufficient thermal insulation and integrity over 90 min in standard fire tests. Smoke leakage from the joints of the timber panels was observed in the early stage of the fire tests because of a lack of air-tightness. Delamination of almost all charred layers glued with an API adhesive was observed in fire tests of CLT panels; however, delamination of LVL and CLT panels with a RPF adhesive was limited. The estimated charring rates of a Japanese cedar CLT panel with API and RPF adhesives were 0.78 mm/min and 0.66 mm/min at 260°C, respectively. The charring rate of LVL panels was ∼0.6 mm/min at 260°C, less than that of CLT panels. The load bearing capacity of timber walls subjected to one-sided fire exposure depended on the buckling strength under the eccentric load caused by asymmetric charring. A prediction method based on the Secant formula was presented to estimate the buckling strength in fire tests. An equation that considered the effect of the degradation of elasticity at high temperatures and eccentricity of loading provided the approximate buckling strength of the timber panel specimens in the fire tests. [ABSTRACT FROM AUTHOR]

Keeping wood dry both under construction and service is important to prevent possible moisture damages in wooden buildings. However, practice has shown that without weather protection, wooden structures may get soaked during construction. Therefore, our aim was to evaluate the impact of vapour permeable and low permeable highly insulated external wall assemblies, façade orientation, and initial moisture content on the hygrothermal performance of cross-laminated timber (CLT) external walls. We carried out field measurements in the cold and humid Estonian climate, for which five types of test walls were designed and manufactured. Simulation models for future research were also created and validated. Field measurements showed that the CLT external walls were hygrothermally safe in the observed cold and humid climate and the CLT panel provided sufficient control of the water vapour diffusion. The use of low vapour permeable external insulation can be beneficial against vapour permeable insulation if low moisture content of the CLT panel (factory dry) during construction is maintained and insulation is installed airtightly. Cellulose insulation can be a safe choice when selecting water vapour permeable insulation for the external wall in case the construction is planned without weather protection. Mould growth risk calculations based on measured hygrothermal conditions showed that the high moisture content in the thin surface layer of the CLT panel may not be critical when dry-out time is short. The probability of failure must be determined by stochastic analysis using a variety of influencing parameters. • Cellulose insulation had advantage in CLT external wall in higher moisture load. • In the moisture safely built CLT external wall, vapour tight layers were beneficial. • High insulation with vapour open wind barrier posed no moisture damage risk. • The orientation of the external walls had no significant effect. [ABSTRACT FROM AUTHOR]

As the mitigation of climate change becomes critical, the public perception of wood as a sustainable building material that can facilitate the shift towards a bio-based economy is crucial to consider. This study aimed to explore the attitudes towards timber construction among young millennials in Austria, a cohort that in the coming years will increasingly occupy decision-making positions and gain purchasing power. A representative online survey (quota sample, n = 757) was conducted to explore the attitudes of 20 to 29-year-olds towards timber construction and the forest-based sector. In general, timber construction was described positively in comparison to other construction methods, in particular, it was considered aesthetically appealing and ecologically advantageous. Indecisiveness prevailed regarding the role of wood in climate change mitigation. The industry's current approach to advertising does not attract much attention. Doubts were expressed about the sustainability of sourcing wood as a building material and certain physical characteristics for building were perceived as a disadvantage. Four distinct market segments were then identified by means of exploratory factor analysis and a cluster analysis using Timber Construction Affinity and Opinion Leadership Wood as categorization factors. Two segments are essential for future marketing measures: Passive Preservers showed the most negative view of the industry, its practices and its offerings, while Active Supporters were in favor of increased wood use and actively promoted timber constructions among peers. Subsequently, marketing implications were given to develop "preserving" into "supporting" clusters and to further involve Active Supporters in the communication of wood and timber construction related topics. [Display omitted] • The attitude of 20- to 29-year-olds towards timber construction and the forest-based sector in Austria was examined (n = 757). • In general timber construction was viewed positively, especially as aesthetical and ecologically advantageous. • Respondents were concerned about building physics and the sustainability of wood sourcing. • Four distinct market segments were identified using Timber Construction Affinity and Opinion Leadership Wood. • Recommendations for communication measures were given to address this future customer group. [ABSTRACT FROM AUTHOR]

Cross-laminated timber (CLT) is recently attracting significant attention due to the high demand for environmentally friendly materials. As a result, the number of buildings and structures comprising CLT is increasing. However, CLT exhibits brittle behavior which can be detrimental to its performance under blast loads. The structure of CLT shows a striking resemblance to that of conch shells, which is also highly composed of brittle materials but exhibits excellent damage tolerance. This paper mimics numerous features from the cross-lamellar structure of conch to enhance the performance of CLT under blast loading. Numerous finite element models were developed to simulate the behaviors of bioinspired conch-like panels under blast loading, and their performance was benchmarked against a traditional CLT panel. The energy dissipation, peak reaction force, and peak displacement and velocity were used as the key performance criteria. The results showed that the conch-like panel can improve the performance of CLT under blast loading through several damage mitigating mechanisms, which increased energy dissipation by up to 82% in the low damage regime, reduced the reaction force by up to 11% in the moderate damage regime and reduced the back face fragment velocity by up to 28% in the high damage regime. [ABSTRACT FROM AUTHOR]

• The dynamic response of cross laminated timber (CLT) panels was investigated. • Simulated blast tests were conducted on the CLT panels using a shock tube. • Analytical/numerical models were used to predict the dynamic increase factor on stiffness (DIF E). • DIFs were predicted using the Young's modulus. • The analytical and numerical models agreed well with the experiments. The construction industry, which accounts for almost 20% of Australia's carbon emissions, is responding to climate change by increasing the demand for sustainable and environmentally friendly materials. Cross-laminated timber (CLT) is an innovative eco-friendly engineering material that can satisfy this demand due to its excellent properties, including fire and seismic resilience, natural insulation and lightweight, to name a few. This study presents the results of 8 blast tests, which were conducted on two types of Radiata pine CLT panels sourced in Australia. The CLT panels were subjected to simulated blast loads from a shock tube apparatus. The dynamic increase factor (DIF E) of the panels was quantified by comparing their stiffness in the dynamic and static loading regimes. Single degree of freedom (SDOF) and numerical models were developed to predict the elastic response of the CLT panels. Interestingly, the SDOF model predicted DIF E from 1.12 to 1.57 whilst the numerical model predicted DIF E from 1.05 to 1.43. The experimental and analytical results can supplement the development of design guidelines for predicting the behavior of Australian Radiata pine CLT panels under blast loading. [ABSTRACT FROM AUTHOR]