scholarly journals Evaluating Timoshenko Method for Analyzing CLT under Out-of-Plane Loading

Buildings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 184
Author(s):  
MD Tanvir Rahman ◽  
Mahmud Ashraf ◽  
Kazem Ghabraie ◽  
Mahbube Subhani
Keyword(s):  
Shear Modulus ◽  
Shear Deformation ◽  
Numerical Study ◽  
Wood Products ◽  
Tangential Plane ◽  
Rolling Shear ◽  
Laminated Veneer Lumber ◽  
Engineered Wood ◽  
Out Of Plane ◽  
Cross Layers

Cross-laminated timber (CLT) is an engineered wood product made up of layers of structurally graded timber, where subsequent layers are oriented orthogonally to each other. In CLT, the layers oriented in transverse direction, generally termed as cross-layer, are subjected to shear in radial–tangential plane, which is commonly known as rolling shear. As the shear modulus of cross-layers is significantly lower than that in other planes, CLT exhibits higher shear deformation under out-of-plane loading in contrast to other engineered wood products such as laminated veneer lumber (LVL) and glue laminated timber (GLT). Several analytical methods such as Timoshenko, modified gamma and shear analogy methods were proposed to account for this excessive shear deformation in CLT. This paper focuses on the effectiveness of Timoshenko method in hybrid CLT, in which hardwood cross-layers are used due to their higher rolling shear modulus. A comprehensive numerical study was conducted and obtained results were carefully analyzed for a range of hybrid combinations. It was observed that Timoshenko method could not accurately predict the shear response of CLTs with hardwood cross layers. Comprehensive parametric analysis was conducted to generate reliable numerical results, which were subsequently used to propose modified design equations for hybrid CLTs.

ASSESSMENT OF SHEAR ANALOGY AND TIMOSHENKO METHOD FOR ANALYZING HYBRID CLT UNDER OUT-OF-PLANE LOADING

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
MD Tanvir Rahman ◽  
Mahud Ashraf ◽  
Kazem Ghabraie ◽  
Mahbube Subhani
Keyword(s):  
Shear Modulus ◽  
Numerical Models ◽  
Natural Material ◽  
Fiber Direction ◽  
Viable Option ◽  
Rolling Shear ◽  
Significant Interest ◽  
Out Of Plane ◽  
Superior Mechanical Properties ◽  
Cross Layers

Timber is a natural material which offers superior mechanical properties in parallel to fiber direction when compared against those in perpendicular to the fibers. Cross-laminated timber (CLT) is made up of layers of structurally graded timber, orthogonally oriented in layers whereby it can sustain loading in both directions. CLT is often used as floor panels, and hence, its performance under out-of-plane loading is of significant interest. Low rolling shear modulus resulting in higher shear flexibility of the cross-layers tend to decrease the effective bending stiffness of CLT sections. Developing hybrid CLT using timbers with higher rolling shear modulus as cross-layers in CLT is considered a viable option to improve its performance under out-of-plane loading. The present study investigates the performance of shear analogy and Timoshenko methods in predicting the deflection of hybrid CLT panels while considering different span-to-depth ratios and various combinations of rolling shear modulus. Numerical models were developed to conduct a parametric study and obtained deflection results were compared against those calculated from the shear analogy method and Timoshenko method. It was observed that for CLT with a small span-to-depth ratio and cross-layers made from material with higher rolling shear modulus, the deflection calculated from the analytical methods deviates from the values obtained from the numerical model.

Experimental Study on High-Performance Buckling-Restrained Braces with Perforated Core Plates

2018 ◽  
Vol 19 (01) ◽  
pp. 1940004 ◽  
Author(s):  
Liang-Jiu Jia ◽  
Yang Dong ◽  
Hanbin Ge ◽  
Kana Kondo ◽  
Ping Xiang
Keyword(s):  
Experimental Study ◽  
Shear Deformation ◽  
High Performance ◽  
Numerical Study ◽  
Slenderness Ratio ◽  
Compressive Deformation ◽  
Plane Shear ◽  
Buckling Restrained Braces ◽  
Out Of Plane ◽  
Global Buckling

The compressive deformation is mainly contributed by axial compressive deformation and high-order in-plane and out-of-plane global buckling deformation for conventional buckling-restrained braces (BRBs). A novel type of all-steel BRBs with perforated core plates, termed as perforated BRBs (PBRBs), are proposed in this study, where shear deformation can occur in addition to the aforementioned deformations in a conventional BRB under compression. Experimental study was carried out using five specimens with different configurations of holes under cyclic loading. Stable hysteretic properties, high ductility, and energy dissipation capacity were obtained for the PBRBs. The effects of two parameters, i.e. the slenderness ratio of the chord and hole spacing factor defined as the ratio of the hole length to the hole spacing, on seismic performance of the specimens were investigated. The compressive deformation mechanisms of the PBRBs were further investigated through a numerical study. The compressive deformation was found to be composed of axial compressive deformation, flexural deformation owing to in-plane and out-of-plane global buckling, and in-plane shear deformation of the latticed core plate.

scholarly journals Engineered Wood Products as a Sustainable Construction Material: A Review

2021 ◽  
Author(s):  
Ranjana Yadav ◽  
Jitendra Kumar
Keyword(s):  
Building Materials ◽  
Construction Material ◽  
High Strength ◽  
Wood Products ◽  
Sustainable Construction ◽  
Environmental Aspects ◽  
Laminated Veneer Lumber ◽  
Glued Laminated Timber ◽  
Engineered Wood Products ◽  
Engineered Wood

Engineered wood products are considered as best building materials due to environmentally friendly. Huge change to the way in which wood has been utilized in primary application of construction in the course of the most recent 25 years are in light of decreased admittance to high strength timber from growth forests, and the turn of events and creation of various new design of manufactured wood products. Engineered wood products are available in different variety of sizes and measurements like laminated veneer lumber, glued laminated timber, finger jointed lumber, oriental strand board etc. It is utilized for rooftop and floor sheathing, solid structure, beams and the hull of boats. This review objectively explores not only the environmental aspects of the use of different engineered wood composites as a building material, but also their economic aspects, to understand their effect on sustainability.

scholarly journals Experimental measurements and numerical modelling of the mechanical behaviour of a glass plain weave composite reinforcement

2019 ◽  
Vol 39 (1-2) ◽  
pp. 45-59 ◽  
Author(s):  
Mehdi Ghazimoradi ◽  
Valter Carvelli ◽  
Naim Naouar ◽  
Philippe Boisse
Keyword(s):  
Shear Deformation ◽  
Mechanical Behaviour ◽  
Numerical Study ◽  
Plane Shear ◽  
Plain Weave ◽  
Out Of Plane ◽  
Bias Extension Test ◽  
Bias Extension ◽  
Meso Scale ◽  
Composite Reinforcement

The study deals with the mechanical behaviour of a glass plain weave composite reinforcement. The experimental activities were focused mainly on uniaxial and biaxial extension tests. Besides, in-plane shear deformation was measured by bias extension test, and for the sake of completeness out-of-plane bending behaviour. In the numerical study, a hyperelastic constitutive model for the yarn material was adopted and validated for the meso scale prediction of the mechanical behaviour of the glass plain weave reinforcement. The model was validated for biaxial tensile and in-plane shear deformation.

Einsatzmöglichkeiten von Holzwerkstoffen im Bauwesen | Possibilities of the use of wood-based materials in construction

2003 ◽  
Vol 154 (12) ◽  
pp. 472-479
Author(s):  
Peter Niemz
Keyword(s):  
Solid Wood ◽  
Wood Products ◽  
New Developments ◽  
Laminated Veneer Lumber ◽  
General Overview ◽  
Thermally Processed ◽  
Engineered Wood Products ◽  
Engineered Wood ◽  
Fibre Products ◽  
Parallel Strand Lumber

Wood-based materials and wood products are becoming increasingly important in construction. Engineered wood products, especially, are being used as a substitute for solid wood. The use of thermally processed solid wood is also increasing. Following a general overview of materials (materials based on solid wood, or laminated, veneer and fibre products)we describe their composition and most important characteristics. Emphasis is given to new developments as, for example, laminated strand lumber (LSL), laminated veneer lumber (LVL) and parallel strand lumber (parallam). We conclude with an overview of the possibilities for the use of woodbased materials in construction.

Rolling shear modulus and strength of beech wood laminations

Holzforschung ◽  
2016 ◽  
Vol 70 (8) ◽  
pp. 773-781 ◽  
Author(s):  
Simon Aicher ◽  
Zachary Christian ◽  
Maren Hirsch
Keyword(s):  
Shear Strength ◽  
Shear Modulus ◽  
Beech Wood ◽  
European Beech ◽  
Rolling Shear ◽  
Shear Properties ◽  
Shear Moduli ◽  
Major Interest ◽  
Characteristic Values ◽  
Cross Layers

Abstract Previous research indicated that the rolling shear properties of European beech wood (Fagus sylvatica) are considerably higher than those of softwood. The aim of the presented investigation was to substantiate previous data on rolling shear modulus and strength of European beech wood and to further evaluate its substitution of softwoods in applications where shear properties are influential, namely as cross layers in cross-laminated timber (CLT). Further, the effect of the annual ring orientation within the boards on shear modulus and strength was of major interest. The beech specimens comprised four different sawing patterns, classified unambiguously with reference to the pith location. The shear properties were determined by 50, two-plate shear tests with specimen cross-section dimensions of 33 mm × 135 mm. A mean rolling shear modulus of 370 N mm-2 was obtained, whereby no significant detrimental effect for pith boards with cracks was observed. In agreement with continuum mechanics, the semi-quarter-sawn boards revealed the highest shear moduli whereas the quarter-sawn boards showed roughly 30% lower values. The mean rolling shear strength was 5.6 N mm-2 for all specimens, whereby pith specimens resulted in generally lower values. The 5% quantile, disregarding pith specimens, was 4.5 N mm-2. In conclusion, the rolling shear strength and modulus exceed the respective characteristic values for softwoods by roughly factors of 5 and 7, indicating great potential for beech wood cross-layers in CLT.

scholarly journals The Rolling Shear Influence on the Out-of-Plane Behavior of CLT Panels: A Comparative Analysis

Buildings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 42 ◽  
Author(s):  
Antonio Sandoli ◽  
Bruno Calderoni
Keyword(s):  
Shear Modulus ◽  
Flexural Behavior ◽  
Finite Element Models ◽  
Limit States ◽  
Shear Deformations ◽  
Rolling Shear ◽  
Tangential Stresses ◽  
Aspect Ratios ◽  
Out Of Plane ◽  
Fully Connected

This paper deals with the influence of the rolling shear deformation on the flexural behavior of CLT (Cross-Laminated Timber) panels. The morphological configuration of the panels, which consist of orthogonal overlapped layers of boards, led to a particular shear behavior when subjected to out-of-plane loadings: the low value of the shear modulus in orthogonal to grain direction (i.e., rolling shear modulus) gives rise to significant shear deformations in the transverse layers of boards, whose grains direction is perpendicular with respect to the tangential stresses direction. This produces increases of deflections and vibrations under service loads, creating discomfort for the users. Different analytical methods accounting for this phenomenon have been already developed and presented in literature. Comparative analyses among the results provided by some of these methods have been carried out in the present paper and the influence of the rolling shear deformations, with reference to different span-to-depth (L/H) ratios investigated. Moreover, the analytical results have also been compared with those obtained by more accurate 2D finite element models. The results show that, at the service limit states, the influence of the rolling shear can be significant when the aspect ratios became less than L/H = 30, and the phenomenon must be accurately considered in both deflection and stress analysis of CLT floors. Contrariwise, in the case of higher aspect ratios (slender panels), the deflections and stresses can be evaluated neglecting the rolling shear influence, assuming the layers of boards as fully-connected.

scholarly journals Effects of Grain Pattern on the Rolling Shear Properties of Wood in Cross-Laminated Timber

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 668
Author(s):  
Guofang Wu ◽  
Yong Zhong ◽  
Haiqing Ren
Keyword(s):  
Shear Modulus ◽  
Mechanical Performance ◽  
Wood Products ◽  
Rolling Shear ◽  
Shear Moduli ◽  
Factors Affecting ◽  
Cross Laminated Timber ◽  
Aspect Ratios ◽  
Shear Property ◽  
Pure Rolling

Rolling shear modulus and strength are the key factors affecting the mechanical performance of some wood products such as cross-laminated timber (CLT). As reported, rolling shear property strongly depends on the sawing pattern such as the aspect ratio and grain direction (grain mode). However, the mechanism behind this phenomenon has not yet been clarified. In this work, the rolling shear modulus and strength of spruce-pine-fir (SPF) with different grain modes and aspect ratios were experimentally investigated. In addition, a theoretical investigation was carried out to reveal the mechanism behind this phenomenon. The results exhibited that the rolling shear moduli of 0° and 90° grain-mode wood were the same. This value can be called the pure rolling shear modulus. Rolling shear modulus of wood with angles other than 0° and 90° can be calculated from the pure rolling shear modulus and grain angle. Therefore, this modulus can be called the apparent rolling shear modulus. Thus, using 0° and 90° grain-mode specimens to determine the pure rolling shear modulus and strength of wood is recommended.

Determination of the Shear Modulus of Orthotropic Thin Sheets With the Anticlastic-Plate-Bending Experiment

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Nengxiu Deng ◽  
Yannis P. Korkolis
Keyword(s):  
Shear Modulus ◽  
Numerical Study ◽  
Pure Shear ◽  
High Strength Steels ◽  
High Strength ◽  
Elastoplastic Material ◽  
Plate Bending ◽  
Thin Sheets ◽  
Principal Stresses ◽  
Advanced High Strength Steels

The shear modulus of orthotropic thin sheets from three advanced high-strength steels (AHSS) is measured using the anticlastic-plate-bending (APB) experiment. In APB, a thin square plate is loaded by point forces at its four corners, paired in opposite directions. It thus assumes the shape of a hyperbolic paraboloid, at least initially. The principal stress directions coincide with the plate diagonals, and the principal stresses are equal and opposite. Hence, at 45 deg to these, a state of pure shear exists. A finite element (FE) study of APB is reported first, using both elastic and elastoplastic material models. This study confirms the theoretical predictions of the stress field that develops in APB. The numerical model is then treated as a virtual experiment. The input shear modulus is recovered through this procedure, thus validating this approach. A major conclusion from this numerical study is that the shear modulus for these three AHSS should be determined before the shear strain exceeds 2 × 10−4 (or 200 με). Subsequently, APB experiments are performed on the three AHSS (DP 980, DP 1180 and MS 1700). The responses recorded in these experiments confirm that over 3 × 10−4 strain (or 300 με) the response differs from the theoretically expected one, due to excessive deflections, yielding, changing contact conditions with the loading rollers and, in general, the breaking of symmetry. But under that limit, the responses recorded are linear, and can be used to determine the shear modulus.

scholarly journals Environmental Product Declarations of Structural Wood: A Review of Impacts and Potential Pitfalls for Practice

Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 362
Author(s):  
Freja Nygaard Rasmussen ◽  
Camilla Ernst Andersen ◽  
Alexandra Wittchen ◽  
Rasmus Nøddegaard Hansen ◽  
Harpa Birgisdóttir
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Product Category ◽  
Wood Products ◽  
Third Party ◽  
Data Uncertainty ◽  
Product Categories ◽  
Laminated Veneer Lumber ◽  
Environmental Product Declarations ◽  
Timber Products

The use of wood and timber products in the construction of buildings is repeatedly pointed towards as a mean for lowering the environmental footprint. With several countries preparing regulation for life cycle assessment of buildings, practitioners from industry will presumably look to the pool of data on wood products found in environmental product declarations (EPDs). However, the EPDs may vary broadly in terms of reporting and results. This study provides a comprehensive review of 81 third-party verified EN 15804 EPDs of cross laminated timber (CLT), glulam, laminated veneer lumber (LVL) and timber. The 81 EPDs represent 86 different products and 152 different product scenarios. The EPDs mainly represent European production, but also North America and Australia/New Zealand productions are represented. Reported global warming potential (GWP) from the EPDs vary within each of the investigated product categories, due to density of the products and the end-of-life scenarios applied. Median results per kg of product, excluding the biogenic CO2, are found at 0.26, 0.24, and 0.17 kg CO2e for CLT, glulam, and timber, respectively. Results further showed that the correlation between GWP and other impact categories is limited. Analysis of the inherent data uncertainty showed to add up to ±41% to reported impacts when assessed with an uncertainty method from the literature. However, in some of the average EPDs, even larger uncertainties of up to 90% for GWP are reported. Life cycle assessment practitioners can use the median values from this study as generic data in their assessments of buildings. To make the EPDs easier to use for practitioners, a more detailed coordination between EPD programs and their product category rules is recommended, as well as digitalization of EPD data.

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