•Method for determining the in-plane shear stiffness of cross laminated timber.•The in-plane shear stiffness cannot be set to a fixed value.•The board width affected the in-plane shear stiffness.•The ...thickness ratio between layers affected the in-plane shear stiffness.•Increasing the in-plane shear stiffness can be at the cost of other properties.
Board width-to-thickness ratios in non-edge-glued cross laminated timber (CLT) panels influence the in-plane shear stiffness of the panel. The objective is to show the impact of board width-to-thickness ratios for 3- and 5-layer CLT panels. Shear stiffnesses were calculated using finite element analysis and are shown as reduction factors relative to the shear stiffnesses of edge-glued CLT panels. Board width-to-thickness ratios were independently varied for outer and inner layers. Results show that the reduction factor lies in the interval of 0.6 to 0.9 for most width-to-thickness ratios. Results show also that using boards with low width-to-thickness ratios give low reduction factors. The calculated result differed by 2.9% compared to existing experimental data.
•Created the first ballistic dataset for enhanced cross-laminated timber (ECLT).•Compared partial and full penetration results utilizing eight known ballistic resistant materials.•Developed ...benefit-cost assessment of panel configurations.
Cross-laminated timber (CLT), an engineered wood product, has grown in popularity in the United States over the last decade due to its ease of assembly, aesthetic appeal, and potential to serve as a sustainable and renewable alternative building material. The improved robustness of CLT over light-frame timber structures has increased its potential in force-protected infrastructure that must resist blast waves and ballistic projectile penetration, but softwood CLT is typically not sufficient to fulfill standard criteria for ballistic threats. To address these threats, enhanced CLT (ECLT) composite panels were manufactured with layers of various reinforcing materials (e.g., steel, FRP) placed between wood laminations. These panels were tested against various ballistic threats during two sets of laboratory tests in order to provide a basis for future research. The first set of testing subjected laboratory-produced Southern Yellow Pine (SYP) ECLT to 84 shots of 0.50-inch (1.27 cm) steel sphere projectiles to evaluate the performance of various reinforcing materials, layups, and fastening methods. A subsequent set of tests subjected commercially produced ECLT of steel-reinforced Spruce-Pine-Fir (South) (SPF-S) to 36 shots of NATO ammunition projectiles traveling at realistic, standard striking velocities. Except for a panel using four layers of a thin and finely woven steel hardware cloth, steel reinforcement was effective in stopping projectiles from all three types of NATO ammunition fired. Ultimately considering the results of these two sets of tests, an initial cost-benefit structure was developed and discussed to compare ECLT configurations holistically, a multi-material wood analytical model framework was established and compared to experimental results, and the first ballistic experimental database for ECLT was created.
In building interpersonal relationships through omotenashi no kokoro (Excellent Service), Keigo is a crucial aspect to consider when communicating in Japanese. Keigo, both in terms of grammar and its ...usage concept, is quite complicated. Therefore, the role of instructors in delivering Keigo learning materials is expected to motivate students to improve their communication skills while mastering the art of creating interpersonal connections. Communicative Language Teaching (CLT) is chosen as the teaching method. This research aims to provide an alternative teaching experience focusing on omotenashi no kokoro. The research method used is descriptive with a qualitative approach. The research subjects are students of the Japanese Language Program at Universitas Teknologi Yogyakarta (UTY) taking the hospitality course. The research is conducted through observation by analyzing CLT-based learning activities using three steps: mechanical practice, meaningful practice, and communicative practice. The study results indicate that with the CLT method, students can use Keigo through word or phrase repetition, understand the meaning of words and expressions in sentences, and freely actualize themselves through improvisation and exploration of conversational contexts. A new finding from this research is that the CLT teaching method is effective when applied to the hospitality course, emphasizing building interpersonal relationships through omotenashi no kokoro.
A new connection concept for joining cross-laminated timber (CLT) plates in their secondary direction is presented. The connection consists of two laminated veneer lumber (LVL) gusset plates with ...finger-joint-like profiles milled on one side which are glued onto the outermost layers of the CLT. It is demonstrated that the joint represents a stiff moment resistant connection, enabling the activation of the normally underutilized biaxiality of CLT plates and expanding the design freedom of architects and engineers. The concept was analyzed by means of analytical and finite element (FE) models for two geometry alternatives, differing in either a 2D or 3D tapered finger profile. The 3D tapered finger profile produced a stress reduction of around 5% in the region of stress concentration and a more even shear stress distribution on the bonded surface. Thereafter, four specimens were manufactured – two of each geometry alternative – and then tested in four- and three-point bending setups in order to assess the behavior at pure bending as well as at combined moment and shear loading, respectively. At pure bending, the studied connection delivered bending capacities of 100% of the characteristic value of the unjointed CLT material. For the case of moment and shear loading, the global capacity was determined by a bending failure in the CLT region subjected to maximum moment, while the joints remained unbroken. Measured deformations and strains during the tests validated the FE model, which can be used to further develop the connection concept, which allows for a full activation of the biaxial behavior of large-span CLT floors.
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•New LVL-based edge connection for CLT plates in the weak direction.•Simulations and experimental results proof a rigid joint behavior.•The connection enables full biaxial behavior of jointed CLT plates.•Experiments reveal a connection resistance similar to the characteristic CLT plate capacity.•The beech LVL gusset plates are profiled with a finger-joint-like pattern.•The connection relies on CNC/robotic milling.•A gap-filling adhesive was used.
This study aims to determine whether the CLT method improves students' English vocabulary mastery before and after learning using the CLT method. This is a quantitative study with a pre-experimental ...design. In this research design, the researcher only uses one class as an experimental class which was given treatment in the form of vocabulary learning using the CLT method. However, before the treatment was given, students would be given a test in the form of a pre-test and post-test that aimed to see the effect of the CLT method in improving students' vocabulary skills. The data from the test was collected and then the data was analyzed through descriptive statistics. The population used was all students of SMP Negeri 50 Halmahera Selatan and all were selected as samples in this study. The instrument used to collect quantitative data in this study was a vocabulary test. This test is in the form of multiple choice consisting of 30 question items. Tests distributed before and after the treatment were given as pre-test and post-test. In addition to comparing the significance value (Sig.) with a probability of 0.05, the authors also compared the t-count value with the t-table to test the hypothesis that had been made previously. The t count based on the result of paired sample test is 38,076 and the t table based on the value of df (34) is 2,042. This shows that the value of t arithmetic (37.769) > t table (2.042) it can be concluded that H0 is rejected and Ha is accepted. In other words, there is an average difference between the learning outcomes of the pre-test and post-test, which means the CLT method improves the students’ English vocabulary at SMP Negeri 50 Halmahera Selatan.
본 연구에서는 층재 수종과 길이방향의 합판 접합방식과 접합부의 접착제 도포 여부에 따른 휨 성능 및 파괴 양상 분석을 통하여 합판을 코어로 사용한 CLT에 적합한 합판의 접합 방식을 최적화 하고자 하였다. 더글라스 퍼 층재의 경우 길이방향 접합에 의해 휨탄성계수 약 11.5% 감소, 휨강도는 접착제 도포 및 접합방식에 따라 증가 또는 감소하였다. 접착제 ...미도포 butt joint, 접착제 도포 half lap joint, butt joint 조건이 최적조건으로 도출 되었다. 낙엽송 층재의 경우 길이방향 접합에 의해 휨강도는 약 15%, 휨탄성계수는 약 40% 감소하였으며 접합방식에 따른 차이를 나타내지 않았다. half lab joint와 tongue & groove joint 사용 시 합판 층의 접합부에서 휨에 파괴를 1차적으로 방지해줌으로써 중층의 층재로 전달되는 하중을 감소시켜 주는 것으로 판단된다. 본 연구 결과를 통해 Ply-lam CLT 제조과정에서 낙엽송 층재를 사용하는 경우 접합방법에 따른 차이를 나타내지 않았으며 더글라스퍼 층재를 사용할 경우 butt joint와 half lap 접합 방식이 적합할 것으로 판단된다.
The purpose of this study is to optimize the bonding method of the plywood suitable for cross-laminated timber (CLT) with plywood as a core by analyzing the flexural performance and failure mode according to the lamina species, the method of bonding plywood in the longitudinal direction, and whether or not adhesive is applied to the joint. In the case of the Douglas fir lamina layer, the modulus of elasticity decreased by about 11.5% due to longitudinal bonding, and the modulus of rupture increased or decreased according to the adhesive application and bonding method. The optimal conditions were derived as the butt joint without adhesive, half lap joint with adhesive, and butt joint. In the case of the larch lamina layer, the modulus of rupture and the modulus of elasticity decreased by about 15% and 40%, respectively. When using the half lab joint and tongue & groove joint, it is believed that it reduces the load transmitted to the middle layer by primarily preventing the failure on flexure at the joint of the plywood layer. From the results of this study, the larch lamina layer used in the manufacturing process of Ply-lam CLT did not show any difference based on the bonding method. Butt joint and half lap joint bonding method are determined to be suitable when using Douglas fir lamina layer.
•Radiata Pine manufactured cross laminated timber (CLT) using heterogeneous lamella were investigated.•There was a good agreement in bending results of CLT between the theoretical methods and ...experimental tests.•Developed FE modelling technique could capture the structural performance of CLT.•Improved bending performance was observed for panels with thinner thickness.
Cross laminated timber (CLT) is a sustainable and innovative engineered timber product validated as a viable alternative to more traditional construction materials like reinforced concrete and steel for use in mid-rise prefabricated construction. The structural response of CLT heavily relies on the species of timber used in manufacturing with feedstock varying significantly due to the original source and plantation stand. In Australia, Radiata Pine commonly used for general purpose structural timber mainly in residential house framing. Australia’s largest CLT manufacturer, XLam, use Radiata Pine to produce panels for prefabricated construction. The present paper investigates the out-of-plane bending behaviour of 24 XLam CLT panels utilising four-point loading configurations. Experimental results indicated brittle failure modes when the samples were loaded along both the major and minor axes. In addition, plane cross-sections remain plane assumption were confirmed from the strain data obtained from the experimental tests. Various analytical methods (Timoshenko, Gamma (γ), K, and Shear Analogy methods) assessed the bending properties of the test samples, with the shear analogy method yielding the most accurate prediction. Other theoretical methods produced reasonable outcomes in accessing the effective bending stiffness together with bending and shear strengths. Finally, the bending properties of CLT were investigated using finite element analysis, which capture the overall behaviour of Radiata Pine CLT panels adequately. The effect of panel thickness was then examined numerically to observe its effect on bending.
This paper presents an experimental study aimed at characterizing the lateral cyclic behaviour of Glulam (GL), Laminated Veneer Lumber (LVL), and Glued Laminated Veneer Lumber (GLVL) shear walls ...anchored to the foundation by means of conventional hold downs and angle brackets, which are fastened to the timber walls with annular ring nails. Monotonic and cyclic tests are conducted on these mechanical anchors, with hold down connections tested under tensile loads and angle bracket connections under shear loads. Withdrawal tests on annular ring nails embedded in GL, LVL, and GLVL elements are also conducted, to investigate the withdrawal response of the fasteners. The experimental tests reveal that the lateral behaviour of GL, LVL, and GLVL shear walls is similar to that of Cross-Laminated Timber (CLT) shear walls, primarily governed by the wall base connections and by the wall geometry. Hold down and angle bracket connections exhibited a mechanical behaviour governed by the steel-to-timber joints, to large extent comparable with that of typical hold downs and angle brackets fastened to CLT elements. Generally, higher ductility and lower load carrying capacity were reached by hold downs and angle brackets fastened to GL elements compared to those reached by hold downs and angle brackets fastened to LVL and GLVL elements. All quantities relevant for the seismic design, such as stiffness, load carrying capacity, ductility, and overstrength factors are calculated and discussed through the paper. These quantities are then compared with results from different experimental investigations on hold downs and angle brackets fastened to CLT elements available in the literature. Finally, an analytical model for the calculation of the lateral load carrying capacity of the shear walls is presented and used to verify that the same calculation models used for CLT shear walls can be adopted for GL, LVL, and GLVL shear walls.
•The lateral behaviour of Glulam, LVL and GLVL shear walls is investigated.•The cyclic behaviour of hold downs and angle brackets fastened to Glulam, LVL and GLVL elements is investigated.•Mechanical properties and overstrength factors of the wall base connections are presented.
•Combined out-of-plane bending and compression is an inevitable loading condition for CLT walls.•The experimental program consisted of 36 CLT panel specimens.•The damage was caused by the local ...buckling near the mid-height of the outer layer on the compression side.•Signs of shear failure of cross layers were evident almost simultaneously with the outer layer failure.•The interaction equations specified in the Canadian design standard are appropriate for the CLT panels under small load eccentricities.
Combined out-of-plane bending and compression is an inevitable loading condition for cross-laminated timber (CLT) walls due to the out of plumbness, initial panel curvature and load eccentricity. Because of the weaker cross layers, the mechanical performance and failure mode of the CLT panels under such loading significantly differ from those of the other wood members, such as sawn timber and glulam. This experimental study focuses on investigating the behavior of CLT panels under the stated loading scenario. The experimental program consisted of 36 specimens, including 12 five-layer CLT panels provided by two Canadian manufacturers, as well as 12 three-layer and 12 five-layer CLT panels provided by a Chinese manufacturer. All the specimens were tested in Canada and China, respectively, using the same test setup. It was found that in the majority of the specimens, the damage was caused by the local buckling near the mid-height of the outer layer on the concave compression side at about 45%–60% of the ultimate failure load and 25%–35% of the ultimate deflection. The dominant failure mode was characterized as the crushing yield of the outer layer on the concave side (fibers in compression) near the mid-height after the local buckling progressed. Signs of shear failure of cross layers were evident almost simultaneously with the outer layer failure. Hence, although the dominant failure mode was likely triggered by the fracture in the cross layers due to rolling shear, the load-carrying capacity of the CLT panels under the combined out-of-plane bending and compression is governed by the compression failure of the longitudinal outer layers. It was found that a cross-layered panel can maintain its integrity before failure. It was also noted that the interaction equations specified in the Canadian design standard are appropriate for the CLT panels under small load eccentricity, while for panels that have large load eccentricity, the appropriateness of the interaction equation is questionable. Based on the test results obtained, the validity of the interaction equation for the prediction of the load-carrying capacity of CLT columns, specified in the CSA O86-19, is confirmed for cases in which Pf/Pr>0.5 and Mf/Mr<0.3. For the cases of Pf/Pr<0.5 and Mf/Mr>0.3, modification of the equation is needed.
•Design challenges of CLT structures and CLT components.•Load distribution in CLT shear walls.•Assessment of strength of CLT shear walls.•Assessment of lateral stiffness of CLT shear walls.
In the ...last years, the timber construction practice has been revived. Cross-laminated timber (CLT) plays a key role in this timber renaissance. CLT constructions has seen a noticeable increase in the last decade, especially in Europe, as it enables tall wooden buildings using a sustainable material. Unfortunately, a consequence of the rapid advancements of timber technologies and construction techniques of the past years is that modern timber engineering codes are struggling to keep up to date. Furthermore, the results of scientific research in this field is often inhomogeneous and fragmented, and do not help in proving that these new methods and construction techniques are reliable and safe to use.
To overcome this gap, COST Action FP1402 was created which main purpose is to create new, and improve on existing, knowledge of timber design and construction. This paper provides a summary of multiple fundamental aspects of design of CLT shear walls through a review of relevant scientific papers. This paper thus aims to be a “state-of-the-art” of available methods used to assess the load-carrying capacity and the displacement of CLT shear walls.
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