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318 records – page 1 of 32.

Ultimate failure load analysis of cross-laminated timber panels subjected to in-plane compression

https://research.thinkwood.com/en/permalink/catalogue3310
Year of Publication
2023
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Heinisuo, Markku
Pajunen, Sami
Aspila, Aku
Organization
Tampere University
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Theory of Layered Beams
Axially Loaded Panel
Ultimate Failure Load Analysis
Research Status
Complete
Series
Structures
Summary
Cross-laminated timber (CLT) panels have proved their efficiency as vertical and horizontal load-carrying structures, and their design methods for serviceability and ultimate limit states are well defined. However, there is a lack of more general and versatile analytical methods for the ultimate load carrying capacity determination of CLT structures. In this paper, the classical layered beam theory is adopted for the ultimate failure load estimation of axially compressed CLT panels. The proposed method retains its accuracy both with an asymmetric layer setup and when the number of CLT layers exceeds five. The presented method is validated by adopting experimental test data from two test series produced by other researchers.
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Modeling of Cross-Laminated Timber (CLT) panels loaded with combined out-of-plane bending and compression

https://research.thinkwood.com/en/permalink/catalogue2842
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Author
Huang, Zirui
Huang, Dongsheng
Chui, Ying Hei
Shen, Yurong
Daneshvar, Hossein
Sheng, Baolu
Chen, Zhongfan
Organization
Southeast University
University of Alberta
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Topic
Mechanical Properties
Keywords
Rolling Shear
Beam-and-Column
Analytical Model
Load-Carrying Capacity
Research Status
Complete
Series
Engineering Structures
Summary
Rolling shear is one of the major concerns that significantly impact the performance of CLT walls if they are subjected to combined out-of-plane bending and compression loads. Because the effects of rolling shear and out-of-plane bending are coupled to each other, prediction of the load-carrying capacity of CLT wall is always a challenge for the design of CLT structures. Current design codes employ an Ayrton-Perry type interaction equation as the failure criterion to check the safety of a CLT panel loaded with combined bending and compression. Nevertheless, there is no model available to predict their load-carrying capacity. The presented work aims at developing an analytical model to predict the load-carrying capacity of CLT wall loaded with combined out-of-plane bending and compression. In total 12 five-layer CLT panels loaded with different initial load eccentricities were tested to investigate the failure modes. Observed during the test were two ultimate failure modes, i.e., compression crush on the concave side and tension rupture in convex side. Based on these failure modes and deeming the test member as a beam-column, an analytical model which takes rolling shear effects into account to predict the load-carry capacity of CLT compression-bending members was developed. An explicit formula based on compression failure mode was proposed. The model is capable of determining the distribution of rolling shear stress along longitudinal direction, rolling shear-induced axial force and moments in CLT beam-columns. By calculating the load-carrying capacities of the specimens tested in this study as well as the additional three- and seven-layer specimens tested by another studies, it was found that the compression failure mode-based formula can provide good agreements with the test results.
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Timber Semirigid Frame Connection with Improved Deformation Capacity and Ductility

https://research.thinkwood.com/en/permalink/catalogue3017
Year of Publication
2022
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Author
Johanides, Marek
Lokaj, Antonin
Mikolasek, David
Mynarcik, Petr
Dobes, Pavel
Sucharda, Oldrich
Organization
VSB-Technical University of Ostrava
Editor
Branco, Jorge Manuel
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Topic
Connections
Mechanical Properties
Keywords
Ductility
Load-capacity
Frame Connection
Screws
Bolts and Dowels
Research Status
Complete
Series
Buildings
Summary
The present study deals with the innovation and the possibilities of improving the design solution of a frame connection for two selected types of fasteners. All specimens were made of glued laminated timber. Dowel-type mechanical fasteners, a combination of bolts and dowels, and full-threaded screws were used for the connection. The main goal of this research was to replace the typical solution (common dowel-type fasteners) with a more modern, faster, and easier solution in order to improve the load-carrying capacity, ductility, and deformation capacity of this type of frame connection. This article also aimed to provide a detailed evaluation of the mechanical properties of the used glued laminated timber and fasteners in order to comprehensively evaluate the research task. For the design solution, a frame connection created from a system of two struts and a partition was chosen as the basis of the experimental program. Dowel-type mechanical fasteners, as well as combinations of bolts and dowels, were used for the connection; however, in addition to these standardly used mechanical fasteners, full-threaded screws were used. The article describes the use of static destructive testing to determine the ductility of the connection, considering different variations in the strengthening of the individual segments of the mentioned connection means. In the first variation, the individual components of the frame were not reinforced in any way. In the second, the crossbar was reinforced with two full-threaded bolts. In the third, the webs and the crossbar were reinforced with two full-threaded bolts. In the article, these ductility values were compared with each other and the procedure was set by the currently valid standard.
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The Effect of Periodic Loading of Glued Laminated Beams on Their Static Bending Strength

https://research.thinkwood.com/en/permalink/catalogue3102
Year of Publication
2022
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Dziurka, Dorota
Derkowski, Adam
Dukarska, Dorota
Kawalerczyk, Jakub
Mirski, Radoslaw
Organization
Poznan University of Life Sciences
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Periodic Loading
Static Bending Strength
Research Status
Complete
Series
Materials
Summary
Engineered wood products (EWP) such as glulam beams are gaining more and more popularity due to several advantages resulting from the wood itself, as well as the constant search for structural materials of natural origin. However, building materials face some requirements regarding their strength. Thus, the study aimed to assess the static bending strength of structural beams produced with the use of pine wood, after the periodic loading of approximately 80 kN for a year. The manufactured beams differed in the type of facing layers, i.e., pine timber with a high modulus of elasticity and plywood. The produced beams, regardless of their structure, are characterized by a similar static bending strength. Moreover, it has been shown that the loading of beams in the range of about 45% of their immediate capacity does not significantly affect their static bending strength and linear modulus of elasticity.
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Structural Performance of Mass Timber Panel-Concrete Composite Floors with Notched Connections

https://research.thinkwood.com/en/permalink/catalogue3122
Year of Publication
2022
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Zhang, Lei
Organization
University of Alberta
Year of Publication
2022
Format
Thesis
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Notched Connection
Discrete Bond Composite Beam Model
Mass Timber Panel
Connection Stiffness
Effective Bending Stiffness
Load-Carrying Capacity
Research Status
Complete
Summary
This thesis focuses on the structural performance of mass timber panel-concrete composite floors with notches. Mass timber panels (MTPs) such as cross-laminated timber, glue-laminated timber, and nail-laminated timber, are emerging construction materials in the building industry due to their high strength, great dimensional stability, and prefabrication. The combination of MTPs and concrete in the floor system offers many structural, economic, and ecological benefits. The structural performance of MTP-concrete composite floors is governed by the shear connection system between timber and concrete. The notched connections made by cutting grooves on timber and filling them with concrete are considered as a structurally efficient and cost-saving connecting solution for resisting shear forces and restricting relative slips between timber and concrete. However, the notched connection design in the composite floors is not standardized and the existing design guidelines are inadequate for MTP-concrete composite floors. To study the structural performance of notched connections and notch-connected composite floors, this thesis presented experimental, numerical, and analytical investigations. Push-out tests were conducted on the notched connections first, and then bending tests and vibration tests were conducted on full-scale composite floors. Finite element models were built for the notched connections to derive the connection shear stiffness. Finally, analytical solutions were developed to predict the internal actions of the composite floors under external loads. This study shows that the structural performance of notched connections is affected by the geometry of the connections and material properties of timber and concrete. The notch-connected MTP-concrete composite floors showed high bending stiffness but were not fully composite. The floors with shallow notches tended to fail in a ductile manner but had lower bending stiffness than floors with deep notches. The composite floors with deep notches, however, often fail abruptly in the concrete notches. By reinforcing the notched connections with steel fasteners, the composite floor can achieve high bending stiffness, high load-carrying capacity, and controlled failure pattern. The proper number and locations of notched connections in the composite floors can be determined from the proposed composite beam model. This thesis presented promising results in terms of the static and dynamic structural performance of notch-connected MTP-concrete composite floors. The test investigations added additional data to the current research body and prompted further evolvement of timber-concrete composite floors. The proposed empirical equations for estimating the connection stiffness and strength and composite beam model for predicting the serviceability and ultimate structural performance of composite floors provide useful tools to analyze the notch-connected MTP-concrete composite floors. The design recommendations for MTP-concrete composite floors with notches are provided in the thesis.
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Experimental and numerical investigations of two-way LVL–concrete composite plates with various support conditions

https://research.thinkwood.com/en/permalink/catalogue3138
Year of Publication
2022
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Author
Jaaranen, Joonas
Fink, Gerhard
Organization
Aalto University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Two-way Plate
Experimental Modal Analysis
Static Load Test
Finite Element Modelling
Research Status
Complete
Series
Engineering Structures
Summary
Design of modern timber floors is often governed by the vibration serviceability requirements. One way to improve vibration serviceability is through the design of two-way floor systems. In this paper, the behaviour of two-way LVL–concrete composite plates and a plate strip is investigated experimentally, with an emphasis on the performance of proposed dovetail joint for connecting the adjacent LVL panels. The investigations consist of the experimental modal analysis and static load deformation tests, performed under multiple support conditions. The results show a significant two-way action, indicated by about 45% higher fundamental natural frequency when four edges are supported instead of two. The point load deflection in the centre of the plate was reduced of about 9%. Furthermore, a numerical model for two-way TCC plates was developed and results show a wide agreement with the experimental behaviour, except for discrepancies related to deflections on the plate edge. The results from the experimental and numerical investigations indicate that the dovetail joint can produce a stiff connection, such that the LVL layer could be regarded as continuous in the connected direction.
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Performance and failure modes of mass timber buckling-restrained braces under cyclic loading

https://research.thinkwood.com/en/permalink/catalogue3159
Year of Publication
2022
Topic
Mechanical Properties
Author
Takeuchi, Toru
Terazawa, Yuki
Komuro, Shogo
Kurata, Takashi
Sitler, Ben
Organization
Tokyo Institute of Technology
Nippon Steel Engineering
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Topic
Mechanical Properties
Keywords
Buckling-restrained Brace
Mass Timber
Cyclic Loading Test
Bulging
Design Criteria
Research Status
Complete
Series
Engineering Structures
Summary
Buckling-restrained braces with mass timber restrainers (MT-BRBs) have recently been investigated by several researchers. However, timber restrainers exhibit brittle failure modes and have lower stiffness and strength than their composite and steel counterparts. Previous experiments have demonstrated that timber restrainers are particularly susceptible to local bulging and that this is a brittle failure resulting in a near total loss of strength. Nevertheless, local bulging and global stability design methods have not yet been established for BRBs with timber restrainers. This paper presents cyclic loading tests of MT-BRBs featuring different bolted restrainer compositions, core plate clearances, reinforcing plate arrangements, connections and boundary conditions. These tests produced a variety of weak- and strong-axis bulging and global buckling failure modes. Design methods were developed to prevent each failure mode and then used to design full-scale MT-BRBs that were successfully tested and exhibited excellent performance.
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Strengthening of Full-Scale Laminated Veneer Lumber Beams with CFRP Sheets

https://research.thinkwood.com/en/permalink/catalogue3212
Year of Publication
2022
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Bakalarz, Michal Marcin
Kossakowski, Pawel Grzegorz
Organization
Kielce University of Technology
Editor
Marcello, Angelo
Benzarti, Karim
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Mechanical Properties
Keywords
Composites
Carbon Fiber
Load-Bearing Capacity
Reinforcement
Stiffness
Research Status
Complete
Series
Materials
Summary
This paper presents the results of experimental research on full-size laminated veneer lumber (LVL) beams unreinforced and reinforced with CFRP sheets. The nominal dimensions of the tested beams were 45 mm × 200 mm × 3400 mm. The beams were reinforced using the so-called U-type reinforcement in three configurations, differing from each other in the thickness of the reinforcement and the side surface coverage. An epoxy resin adhesive was used to bond all the components together. A four-point static bending test was performed according to the guidelines in the relevant European standards. The effectiveness of the reinforcement increased with the level of coverage of the side surface and the level of reinforcement. The average increases of bending resistance were 42%, 51% and 58% for configurations B, C and D, respectively. The average value of bending stiffness increased for the beams of series B, C and D by 15%, 31% and 43%, respectively. Their failure mode changed from brittle fracture initiated in the tensile zone for unreinforced beams to more ductile fracture, initiated in the compression zone. The influence of the coverage of the side surface by the CFRP sheet and reinforcement ratio on the mechanism of failure and effectiveness of strengthening was studied in the article.
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Behavior and Damage Characterization of Impulsively Loaded Cross-Laminated Timber Panels

https://research.thinkwood.com/en/permalink/catalogue3282
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Flores, Noel R.
Gentry, Russell
Stewart, Lauren, K.
Organization
Georgia Institute of Technology
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Impulsive Loading
Damage
Shock
Blast
Impact
High-rate
Hydraulic Actuator
Research Status
Complete
Series
Applied Sciences
Summary
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.
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Strengthening of Structural Flexural Glued Laminated Beams of Ashlar with Cords and Carbon Laminates

https://research.thinkwood.com/en/permalink/catalogue3293
Year of Publication
2022
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Wdowiak-Postulak, Agnieszka
Organization
Kielce University of Technology
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Fibre-reinforced Timber
Load-Bearing Capacity
Stiffness
Ductility
Modulus of Elasticity
Bending Test
Carbon Cords
Carbon Laminates
Research Status
Complete
Series
Materials
Summary
Changes in the condition of existing timber structures can be caused by fatigue or biological attack, among other things. Replacing damaged timber is still very expensive, so it seems more advisable to repair or reinforce damaged elements. Therefore, in order to improve the static performance analysis of timber structures, reinforcement applications in timber elements are necessary. In this experimental study, technical-scale glulam beams measuring 82 × 162 × 3650 mm, which were reinforced with carbon strands and carbon laminates, were tested in flexure. A four-point bending test was used to determine the effectiveness of the reinforcement used in the timber beams. Internal strengthening (namely, glued carbon cords placed into cut grooves in the last and penultimate lamella) and an external surface of near-surface mounted (NSM) carbon laminates glued to the bottom surface of the beam were used to reinforce the laminated ashlar beams. As a result of this study, it was found that the bending-based mechanical properties of ash wood beams reinforced with carbon fibre-reinforced polymer composites were better than those of the reference beams. In this work, the beams were analysed in terms of the reinforcement variables used and the results were compared with those for the beams tested without reinforcement. This work proves the good behaviour of carbon fibre reinforced plastic (CFRP—Carbon fibre reinforced polymer) cords when applied to timber beams and carbon laminates. This study illustrated the different reinforcement mechanisms and showed their structural properties. Compared to the reference samples, it was found that reinforcement with carbon strings or carbon laminates increased the load-bearing capacity, flexural strength and modulus of elasticity, and reduced the amount of displacement of the timber materials, which is an excellent alternative to the use of ashlar and, above all, inferior grade materials due to the current shortage of choice grade. Experimental results showed that, with the use of carbon fibre (carbon cords SikaWrap® FX-50 C—Sika Poland Sp. z o.o., Warsaw), the load bearing capacity increased by 35.58%, or with carbon cords SikaWrap® FX-50 C and carbon laminates S&P C-Laminate type HM 50/1.4 - S&P Poland Sp. z o.o., Malbork, by 45.42%, compared to the unreinforced beams.
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318 records – page 1 of 32.