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The creep of bamboo scrimber is an important factor to be considered in engineering applications. Simply using the creep test method not only consumes a lot of time and money, but also cannot be extended to the full stress level. Therefore, in this paper, the short-term creep tests of bamboo scrimber under different stress levels (30% and 40%) and ambient temperatures (30°C–70°C) were carried out. The multicomponent Kelvin-Voigt model and generalized Maxwell shear relaxation model of bamboo scrimber were established. The Maxwell-3 shear relaxation model was used as the constitutive model of bamboo scrimber, and the creep finite-element model of bamboo scrimber under parallel-to-grain compression was established, which verified the creep constitutive model of bamboo scrimber. The results showed that the shear relaxation modulus exhibited a significant decrease during the unstable creep stage, reaching a maximum reduction of 62.0%. It showed nonlinear for the effect of ambient temperature on the compression creep of bamboo scrimber, and the creep rate near the glass transition temperature was significantly higher than that at other temperatures. The fitting coefficients, R -square of creep compliance models, were sorted as KV-4 and KV-5>KV-3>Burgers>KV-2. The fitting coefficients, R -square of the generalized Maxwell model of shear relaxation modulus, were sorted as Maxwell-4 and Maxwell-3>Maxwell-2>Maxwell-1. The simulated creep displacement error of the two specimens was 2.8% and 0.1%, respectively, which verified the accuracy of the numerical simulation method. The paper proposed creep behavior and a constitutive model for bamboo scrimber under parallel-to-grain compression, which holds significant theoretical implications for its widespread application. [ABSTRACT FROM AUTHOR]

Creep performance is a crucial factor that must be considered in structural design. This paper aims to investigate the creep failure mode, creep strain, creep compliance, and other creep properties of bamboo scrimber under long-term tension in parallel-to-grain. To establish a general creep life prediction method for the full stress level of the bamboo scrimber, a multi-branch Kelvin–Voigt model, a generalized Maxwell model, and a creep finite element simulation were employed. The results showed that the creep strain curve of bamboo scrimber included the unsteady creep stage and the stable creep stage, but not the accelerated creep stage. When the stress ratio was less than 0.3, the residual strength decreased gradually. Below 70% of the ultimate load capacity, the creep characteristics of the bamboo scrimber were linear viscoelastic, and the creep compliance was generally independent of the load level. The creep finite element model of bamboo scrimber could accurately calculate the creep deformation of specimens. Based on this creep finite element model and creep failure rules, a life prediction model for the full stress level of bamboo scrimber was established, which could accurately predict the creep life. This paper provides theoretical guidance for the creep design of bamboo scrimber in engineering structures. [ABSTRACT FROM AUTHOR]

In the past decade, bamboo scrimber has developed rapidly in the field of building materials due to its excellent mechanical properties, such as high toughness and high tensile strength. However, when the applied stress exceeds the ultimate strength limit of bamboo scrimber, cracks occur, which affects the performance of bamboo scrimber in structural applications. Due to the propensity of cracks to propagate, it reduces the load-bearing capacity of the bamboo scrimber material. Therefore, research on the fracture toughness of bamboo scrimber contributes to determining the material's load-bearing capacity and failure mechanisms, enabling its widespread application in engineering failure analysis. The fracture toughness of bamboo scrimber was studied via the single-edge notched beam (SENB) experiment and compact compression (CC) method. Nine groups of longitudinal and transverse samples were selected for experimental investigation. The fracture toughness of longitudinal bamboo scrimber under tensile and compressive loadings was 3.59 MPa·m1/2 and 2.39 MPa·m1/2, respectively. In addition, the fracture toughness of transverse bamboo scrimber under tensile and compressive conditions was 0.38 MPa·m1/2 and 1.79 MPa·m1/2, respectively. The results show that, for this material, there was a significant distinction between longitudinal and transverse. Subsequently, three-point bending tests and simulations were studied. The results show that the failure mode and the force–displacement curve of the numerical simulation were highly consistent compared with the experimental results. It could verify the correctness of the test parameters. Finally, the flexural strength of bamboo scrimber was calculated to be as high as 143.16 MPa. This paper provides data accumulation for the numerical simulation of bamboo scrimber, which can further promote the development of bamboo scrimber parameters in all aspects of the application. [ABSTRACT FROM AUTHOR]

Both bamboo scrimber and section steel are extensively employed in the construction industry however bamboo scrimber as a large composite member, easily experiences buckling and splitting under compression. To solve the problem of insufficient bearing capacity, a partially encased bamboo scrimber (PEBS) column was developed in this paper, and the PEBS column consisted of an H-shaped steel member with two rectangular bamboo scrimber members placed inside the web and flanges, forming a partial buckling restraint configuration. The aim of this arrangement was to enhance the axial compressive performance of the bamboo scrimber members through partial lateral confinement. To investigate the influences of the composite effect and specimen size, a total of 45 specimens were tested under axial compression to analyse the failure modes, load–displacement relationships, and mechanical properties. The results revealed that the composite specimens ultimately failed owing to buckling and wedged splitting in the bamboo scrimber members. The partial buckling restraint exhibited a substantial improvement in axial bearing capacity through delaying the buckling of the H-shaped steel and failure of the inner bamboo scrimber, leading to a further enhancement in the safety stock. Finally, a calculation method was proposed to predict the ultimate bearing capacity of the PEBS column. [ABSTRACT FROM AUTHOR]

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The mechanical properties of the structural components (i.e., columns and beams produced from engineered bamboo products), such as, bamboo scrimber (also known as parallel bamboo strand lumber, PBSL) and Laminated Bamboo Lumber (LBL), have attracted considerable attention from researchers in recent years. In previous studies, researchers reported on the stress-strain behaviour of bamboo scrimber, LBL and glue laminated bamboo under compression and proposed some empirical and semi-empirical models, based on their individual studies. However, a generic constitutive model for engineered bamboo products is still not available. The compressive stress-strain curves of bamboo scrimber and LBL are reported to show a similar behaviour with three distinct stages i.e., a linear elastic stage followed by a nonlinear plastic stage and a plateau. As part of the current study, the previously proposed models for bamboo scrimber were carefully studied and all available material test results on engineered bamboo were used to develop a generic constitutive model, based on the Ramberg-Osgood (RO) formulation considering its suitability to capture its material nonlinearity. Based on the test results, it was observed that 1% proof stress can be used in a compound RO model to predict an accurate material response for bamboo scrimber. The proposed modelling technique has also been applied to predict the compressive behaviour of LBL. This paper proposes the RO coefficients for both bamboo scrimber and LBL that can be used to develop accurate nonlinear models for engineered bamboo products. [ABSTRACT FROM AUTHOR]

This paper studies the rotational behavior of beam-to-column bolted connections in bamboo scrimber structures. Three types of beam-to-column connections, including bolted connections with outer-clamping steel plates, bolted connections encased with T-shaped steel plates, and bolted connections encased with double L-shaped steel plates, were designed and tested under monotonic or reversed cyclic loads. The influence of bolt arrangement on the mechanical properties was also studied. Failure of the connections was mainly caused by cracking of the adhesive interface near the bolt at the tensile side of the beam, which was a weak point that needs further attention. The elastic stiffness, capacities, ductility coefficient, and energy dissipation capacity of the T-steel connections improved compared with the I-steel connections. The load-carrying capacities of the connections were calculated according to common standards. Results showed that for the I-, T-, and double L-steel connections, the different standards had different safety margins. [ABSTRACT FROM AUTHOR]

Bamboo scrimber is a sustainable biomass composite with physical and mechanical properties that has potential applications in furniture. However, its performance across different furniture needs evaluation considering the specific requirements for furniture with different functions. In this study, we simulated a traditional armchair model with bamboo scrimber, ash, or beech as the substrate. Using the finite element method, we analyzed stresses and deformations under six working conditions. The results show that bamboo scrimber had a lower maximum deformation and higher maximum stress under the vertical loading of the seat, backrest, legs, and armrests. Under armrest lateral loading, ash exhibited a higher maximum stress and lower maximum deformation. For selecting furniture material, we propose a strategy that optimizes furniture design by combining the advantages of traditional and new materials according to the structural characteristics and stresses of different parts of the furniture. The results confirm that bamboo scrimber has a good deformation resistance and structural stability and can be used as a substitute for traditional wood in furniture manufacturing, especially for chairs subjected to complex loads. Our findings will help to improve sustainable development by promoting the application of bamboo scrimber in the furniture manufacturing industry. [ABSTRACT FROM AUTHOR]

Creep performance is a crucial factor that must be considered in structural design. This paper aims to investigate the creep failure mode, creep strain, creep compliance, and other creep properties of bamboo scrimber under long-term tension in parallel-to-grain. To establish a general creep life prediction method for the full stress level of the bamboo scrimber, a multi-branch Kelvin–Voigt model, a generalized Maxwell model, and a creep finite element simulation were employed. The results showed that the creep strain curve of bamboo scrimber included the unsteady creep stage and the stable creep stage, but not the accelerated creep stage. When the stress ratio was less than 0.3, the residual strength decreased gradually. Below 70% of the ultimate load capacity, the creep characteristics of the bamboo scrimber were linear viscoelastic, and the creep compliance was generally independent of the load level. The creep finite element model of bamboo scrimber could accurately calculate the creep deformation of specimens. Based on this creep finite element model and creep failure rules, a life prediction model for the full stress level of bamboo scrimber was established, which could accurately predict the creep life. This paper provides theoretical guidance for the creep design of bamboo scrimber in engineering structures.

Bamboo scrimber is a new natural fiber-reinforced composite material in modern industry. In this paper, the tensile creep characteristics of this material were chosen as the object of the study. First, axial tensile fracture experiments were conducted on different test specimens to determine the corresponding strength data. Then six sets of standard tensile creep experiments were conducted under different given stress levels. Finally, the Maxwell constitutive model was applied in fitting the relationship between strain and time. The results showed that the traditional Maxwell viscoelasticity constitutive model will result in some errors in the fitting results, while the combined fractional and Maxwell model can provide much higher accuracy in this study, thus it is more suitable for engineering applications. This paper provides a solid foundation for a better understanding of the mechanism of the bamboo scrimber creep behavior.

This review summarizes the existing knowledge about the mechanical properties of bamboo scrimber (BS) in literature. According to literature reviews, the strength of BS under different load modes is affected by a series of factors, such as the type of original bamboo, growth position, resin content, treatment method and density. Therefore, different production processes can be adopted according to different requirements, and bamboo scrimbers can also be classified accordingly. In addition, this review summarizes the changes in different factors considered by scholars in the research on the mechanical properties of BS, so that readers can have an overall understanding of the existing research and make more innovative and valuable research on this basis. This review provides and discusses the conclusive observations, the current research gaps and future research directions on the mechanical properties of BS. [ABSTRACT FROM AUTHOR]

Bolted steel-bamboo scrimber-steel (SBSS) connections are commonly employed in composite bamboo structures, but their equivalent stiffness in the elastic phase is difficult to determine. This study develops a novel theoretical formula for estimating the equivalent stiffness in the elastic phase of single-bolted SBSS shear connections considering various failure modes. Specifically, the method focuses on calculating the contact stiffness between the bolt and the pre-drilled hole wall, as well as the shear load applied to the bolt end by the steel plate. The method uses the double-shear yield mode, which is included by European Yield Modes (EYM), and the beam on elastic foundation theory (BEFT), and considers the bamboo scrimber embedment stiffness, bolt diameter and steel plate strength class. The method is tested by conducting experiments on single-bolted SBSS connections with varying load and fiber direction (LFD) angles, bolt diameters, steel plate thicknesses and strength grades. The results show that the connection stiffness increases with bolt diameter and steel plate strength grade, decreases with LFD angle, and is not affected by steel plate thickness. The parameter μ , which is important in the theoretical equations, is also calibrated based on the experimental data. The proposed method is validated by comparing it with existing test results of single-bolted SBSS connections. This paper provides a simple and reliable model for predicting the equivalent stiffness in the elastic phase of bolted SBSS connections in bamboo scrimber structures and offers useful insights for their design. • We proposed a method to calculate the elastic stiffness of bolted steel-bamboo scrimber-steel (SBSS) connections. • The elastic stiffness of connections with Q235 steel plate is considerably lower than that of connections with higher-strength steel plates. • The elastic stiffness of bolted SBSS connections that fail in any possible mode can be estimated by using the elastic stiffness for yield mode III. [ABSTRACT FROM AUTHOR]

Bamboo scrimber beams are prone to brittle failure, and I-shaped steel beams are prone to buckling and out-of-plane instability. To address these issues, the failure process, failure mechanism, deformation and bearing capacity of composite beams made by combining I-shaped steel and bamboo scrimber plates with structural adhesive are studied, taking the shear span ratio (λ) as a variable. The failure modes of the composite beam are mainly bottom-up layer-by-layer tearing of the bamboo scrimber and slight out-of-plane deformation of the I-shaped steel in the late loading period. Meanwhile, the ultimate bearing capacity, load‒displacement curve, load–strain relationship and strain distribution of the mid-span section of the composite beams are obtained, indicating that the overall working performance of these beams is excellent and that the comprehensive effect of the components is remarkable. The shear capacity of the composite beam increases with decreasing shear span ratio. By referring to the existing calculation formula of the shear capacity and fitting the test results, we obtain a calculation model of the shear capacity of a composite beam. The average error between the theoretical values and the test values is 11%, indicating that the method can predict the shear capacity well. [ABSTRACT FROM AUTHOR]

A theoretical analysis of upward deflection and midspan deflection of prestressed bamboo-steel composite beams is presented in this study. The deflection analysis considers the influences of interface slippage and shear deformation. Furthermore, the calculation model for flexural capacity is proposed considering the two stages of loading. The theoretical results are verified with 8 specimens considering different prestressed load levels, load schemes, and prestress schemes. The results indicate that the proposed theoretical analysis provides a feasible prediction of the deflection and bearing capacity of bamboo-steel composite beams. For deflection analysis, the method considering the slippage and shear deformation provides better accuracy. The theoretical method for bearing capacity matches well with the test results, and the relative errors in the serviceability limit state and ultimate limit state are 4.95% and 5.85%, respectively, which meet the accuracy requirements of the engineered application. [ABSTRACT FROM AUTHOR]

Bamboo is a fast-growing plant with properties such as low cost, abundant resources, and good carbon sequestration effect. However, the swift growth of bamboo resources generates an immense quantity of processing waste, which is necessary to effectively utilize bamboo processing waste. The leftovers from bamboo processing can be reutilized by fast pyrolysis to prepare renewable bio-oil. In this study, bamboo bio-oil was partially substituted for phenol to synthesize phenolic resin with different substitution rates under the action of an alkaline catalyst, and then to serve as the adhesive to produce bamboo scrimber. Bamboo bundles were impregnated with synthetic bio-oil phenolic resin to create bamboo scrimber, which was subsequently hot-pressed. The research shows that modified phenolic resins with a bio-oil substitution rate of under 30% have good physical and chemical properties, while the free aldehyde content of phenolic resin with 40% bio-oil substitution exceeds the limit value (0.3%) specified in the Chinese National Standard. The thermal stability of phenolic resins was also increased after bio-oil modification, indicated by the movement of the TG curve to higher temperature ranges. It was found that the bamboo scrimber prepared with 20% BPF resin adhesive had the best comprehensive properties of a good mechanical strength, hydrophobicity, and mildew resistance, particularly with an elastic modulus of 9269 MPa and a static bending strength of 143 MPa. The microscopic morphology showed that the BPF resin was well impregnated into the interior of the bamboo bundle and had a compact bonding structure within the bamboo scrimber. The anti-mold performance experiment found that the bio-oil-modified resin increased the anti-mold level of the bamboo scrimber from slightly corrosion-resistant to strong corrosion-resistant. The conclusions obtained from this study have a good reference value for achieving the comprehensive utilization of bamboo, helping to promote the use of all components, reduce the production cost of bamboo scrimber, and improve its mildew resistance performance. This provides new ideas for the development of low-cost mildew resistant bamboo scrimber novel materials. [ABSTRACT FROM AUTHOR]

Engineered bamboo has been getting recognition as a forerunner in terms of desirable mechanical properties and a sustainable construction material. One of the most widespread variants is bamboo scrimber, also known as Parallel Bamboo Strand Lumber (PBSL). This paper presents a holistic investigation into the uniaxial compressive capacity of short bamboo scrimber columns in terms of failure mode, size effect, aspect ratio and failure strain. The studies in focus have been collated from published articles in literature. Furthermore, intermediately slender to long columns have been investigated with respect to the most common international timber standards and, elastic and inelastic theories. It is shown that the dominant failure mode affects the ultimate strength, especially a failure mode called kinking/local buckling. A size effect was observed and discussed with respect to the failure modes. In addition, a tangent modulus theory was proposed from a constitutive model called the Full-range Ramberg Osgood model that could better predict the critical buckling stress of intermediate-long columns over the conventional theory. Moreover, a modified AS1720 design approach was proposed to accommodate the inherent column behaviour of bamboo scrimber. Finally, a modified Newlin-Gahagan approach was proposed which produced consistent predictions for the experimental buckling stress for columns with varying slenderness across four different studies.

• The study examines the flexural behavior of bamboo scrimber-aluminum plate composite beams. • Aluminum plate thickness significantly improves flexural stiffness and capacity in the service limit state. • Increasing the depth-width ratio and shear span ratio improve flexural stiffness and capacity. • The shear strength of adhesive has a significant impact on flexural capacity. • Modified calculation formulae are proposed to predict the flexural capacity of composite beams. This paper presents a study on the flexural behavior of twelve bamboo scrimber-aluminum plate composite beam specimens. The research investigates the effects of aluminum plate thickness and shape on specimen failure mode, flexural moment–curvature relations, and flexural capacity. Finite element (FE) analysis is used to benchmark test results. The study also includes parametric studies that explore the impact of various factors such as aluminum yield strength, plate thickness, adhesive shear strength, shear span ratio, and depth to width ratio on the flexural capacity of the specimens. The results indicate that while increasing the yield strength of aluminum plate has little effect on flexural stiffness and capacity, increasing plate thickness significantly improves these characteristics in the service limit state. Additionally, increasing the depth-width ratio and shear span ratio correspondingly improves flexural stiffness and capacity. The shear strength of adhesive has a significant impact on flexural capacity, but only a minor effect on flexural stiffness during the elastic stage. Based on the parametric study, modified calculation formulae are proposed to predict the flexural capacity of composite beams with and without inter-layer slip. [ABSTRACT FROM AUTHOR]

The bamboo scrimber is an anisotropic material. The elastic constant values of the bamboo scrimber specimens measured by the dynamic and static methods are consistent, and the dynamic test method has the advantages of rapidity, simplicity, good repeatability, and high precision. Bamboo scrimber has strong potential as a building material, and its elastic constant is an important index to measure its mechanical properties. To quickly, simply, non-destructively, and accurately detect the elastic constant of the bamboo scrimber, they were dynamically tested by the free plate transient excitation method and cantilever plate torsional vibration method. The static four-point bending method was used to verify the accuracy and reliability of the dynamic elastic modulus, shear modulus, and Poisson's ratio of the bamboo scrimber. The mechanism analysis and evaluation of the quality grade, homogeneity, and size effect of the bamboo scrimber whole board were carried out. The main results show that the dynamic elastic modulus, shear modulus, and Poisson's ratio of the bamboo scrimber are 12 GPa, 1500 MPa, and 0.31, respectively, which meet the requirements of GB/T 40247-2021 for structural bamboo scrimber. [ABSTRACT FROM AUTHOR]

This paper presents a pilot experimental study aimed at evaluating the performance of engineered bamboo beams exposed to and following exposure to three-sided standard fire conditions. Nine tests were carried out including two constant applied load fire tests and seven flexural tests of engineered bamboo beams following exposure to fire. Test parameters include load ratio in fire tests, fire exposure duration, beam geometry and engineered bamboo type. Two engineered bamboo products: laminated bamboo and bamboo scrimber, commonly used in construction were considered. In all cases, regardless of fire exposure, the failure mode was flexural failure associated with tensile fracture of the extreme tension fibre. The stiffness and ultimate loads of engineered bamboo beams were observed to decrease with increased fire time and the strain distribution at the mid-span cross-section remained linear after exposure to the standard fire. The fire resistance of laminated bamboo beams decreased with increased applied load. Charring depth was measured for all beams after tests and equivalent charring rate was calculated. Result shows that laminated bamboo beams had a higher charring rate than the denser bamboo scrimber beams. Both sectional analysis and simplified methods based on the reduced cross-section method are used to determine the fire resistance and ultimate load capacity of the engineered bamboo beams following exposure to fire. • Performance of engineered bamboo beams exposed to fire were experimentally studied. • Performance of engineered bamboo beams after fire were experimentally studied. • Charring depth was measured after tests and equivalent charring rate was calculated. • Simplified methods based on the reduced cross-section method were developed. [ABSTRACT FROM AUTHOR]

Summary: To better understand the charring properties of bamboo scrimber, a standard fire test was conducted to examine the effect of moisture content, exposure time, and grain direction on the charring rate of bamboo scrimber. The bamboo scrimber specimens were exposed to fire on one side with furnace temperatures following the requirements of ISO 834. The experimental results indicated the charring depth decreased as moisture content increased from 6% to 18%. Due to the thermal insulation of the char layer of bamboo scrimber, the charring rate decreased non‐linearly as the fire exposure time increased from 10 to 40 minutes. The charring rate of bamboo scrimber parallel to grain was approximately 1.23 times that perpendicular to grain. The non‐linear equation to express the charring rate of bamboo scrimber with moisture content, exposure time, and grain direction was established by regression analysis of the test data. The temperature of the char front was approximately 280°C, determined by heat transfer analysis of the 3‐dimensional finite element method model. Compared with different timber species in the literature and in standards, bamboo scrimber has better fire performance and a lower charring rate. [ABSTRACT FROM AUTHOR]

• Eight bamboo scrimber I-beam-to-box-column connections with two types of detailing were tested under static loads. • Shear and moment resistances of beam-column connections were obtained from experimental tests. • Design methods were evaluated for shear and moment resistances of I-beam-to-box-column connections. As an eco-friendly construction material, bamboo scrimber has been increasingly investigated recently in terms of mechanical properties and member behaviour. However, limited test data about connection behaviour are available in published literature. This paper addresses the behaviour of bamboo scrimber I-beam-box-column connections under static loads. Two types of bamboo scrimber beam-column connections were tested, and the number of bolts connecting the beam flange and steel angles or T-stubs was also varied in the experimental programme. The moment resistance, failure mode and deformation capacity were obtained for connections. The shear strength and distortion of panel zones were quantified from experimental data. Comparisons were also made between the calculated shear strengths of panel zones and bamboo scrimbers. Finally, design methods were used to calculate the shear and moment resistances of bamboo scrimber I-beam-box-column connections subjected to static loads. Comparisons between experimental and calculated results suggest that the design methods could evaluate the shear and moment resistance of beams with good accuracy. [ABSTRACT FROM AUTHOR]

With bamboo’s rapid renewability, short rotation period, versatility, and good mechanical properties, engineered bamboo composites have undergone significant evolution. This paper examines the recent changes in bamboo product manufacturing, starting with a wholistic classification of culm breakdown to the plethora of different constituent elements: full culm, flattened bamboo, bamboo bundles, splits/strips, mats/curtains, and strands. Highly cracked flattened strips used in bamboo scrimber are 4–5 times greater in specific surface area than crack-free strips, requiring an estimated 6–10 times higher resin consumption than laminated bamboo. Based on their structure, bamboo composites can be classified into three categories: 1) lamination of minimally modified culms, 2) laminated mat structures with controlled or semi-random placement of constituent elements and 3) random mat structures composed of thin bamboo strands. Composite formation is transitioning from random placement of large, thick strips to more controlled layup with secondary elements of stitched strip curtains, helping minimize edge-to-edge strip overlaps and improve bonding efficiency with less mat compaction. Density-structure-strength property relationships are also compared between various engineered bamboo and common engineered wood products. Other technical advancements include crack-free flattened bamboo and hybrid bamboo-wood products.

This paper describes experimental and theoretical investigations on behaviour of short bamboo scrimber box columns under compression. In the experimental programme, six groups of short columns with different width-to-thickness ratios of plates were tested and the load capacity and failure modes of the columns were determined. Test results indicated that when the width-to-thickness ratio of plates was less than or equal to 10, box columns exhibited compression failure and the ultimate compressive strength of bamboo scrimber was reached at failure. However, local buckling of bamboo scrimber plates was observed instead of compression failure once the width-to-thickness ratio of plates exceeded 11, and the ultimate compressive stress decreased with increasing width-to-thickness ratio. Based on the experimental data, theoretical analyses were also performed by considering the nonlinear stress-strain relationship to quantify the buckling stress of bamboo scrimber plates with four simply-supported edges. Comparisons between experimental and theoretical results suggest that when the theoretical equation yields reasonably good estimations of the local buckling stress of columns with the width-to-thickness ratio of plates greater than 10.

Bamboo fiber composite (BFC) is a unidirectional and continuous bamboo fiber composite manufactured by consolidation and gluing of flattened, partially separated bamboo culm strips into thick and dense panels. The composite mechanical properties are primarily influenced by panel density, its variation and uniformity. This paper characterized the horizontal density distribution (HDD) within BFC panels and its controlling factors. It revealed that HDD follows a normal distribution, with its standard deviation (SD) strongly affected by sampling specimen size, panel thickness and panel locations. SD was lowest in the thickest (40 mm) panel and largest-size (150 × 150-mm2) specimens. There was also a systematic variation along the length of the BFC due to the tapering effect of bamboo culm thickness. Density was higher along panel edges due to restraint from the mold edges during hot pressing. The manual BFC mat forming process is presented and found to effectively minimize the density variation compared to machine-formed wood composites. This study provides a basic understanding of and a quality control guide to the formation uniformity of BFC products. [ABSTRACT FROM AUTHOR]

Bamboo scrimber refers to a lignocellulosic structural material, which is usually attacked by water, ultraviolet radiation and fungus. Surface coating is an effective way to protect it, and its coating properties depend on surface wettability. In this study, the surface wettability of bamboo scrimbers with varying resin content was investigated via the comprehensive analysis of surface roughness, surface contact angle, surface free energy, surface chemical composition and coating properties. The resultant scrimbers had a similar profile with low roughness. Their surface was hydrophilic, but the hydrophilicity decreased with the increase in resin content. High resin content gave rise to low total free energy, in which the Lifshitz–van der Waals component was dominant and it decreased with the increasing resin content. Meanwhile, the ratio of the electron-accepting component to the electron-donating component becomes higher. This was due to the decreasing hydrophilic groups (e.g., -OH and -COOH groups) and the increasing oxygen-free groups (e.g., C-H and -CH2 groups) on the scrimber surface. The resin content affected the adhesion by decreasing the surface wettability, but the coating adhesion still reached the level of 2 for all bamboo scrimbers. The results will provide a theoretical reference for the surface coating of bamboo scrimbers in the structural application for good coating durability. [ABSTRACT FROM AUTHOR]

As a modern bamboo composite with good mechanical properties, bamboo scrimber (BS) has achieved prominence in the sustainable architecture field. When used as a structural material, it is inevitably under continual tension perpendicular to the grain, therefore its mechanical response under long-term loading is significant for structural design. In this study, tensile tests were conducted on BS under short-term and long-term loads perpendicular to the grain. The duration of load (DOL) effect on BS perpendicular to grain and its creep effect were analyzed. Compared with BS parallel to the grain, the DOL effect on BS perpendicular to the grain was less severe, and the capacity for creep resistance was weaker. The threshold stress ratio and relative creep strain of BS perpendicular to the grain were 0.40 and 0.87, respectively. It was found that the DOL models and the viscoelastic model accurately predicted the DOL factor and creep strain. This study provides a scientific reference for the safe lifetime service of BS in practical engineering. [ABSTRACT FROM AUTHOR]

Bamboo scrimber is a sustainable engineered material that overcomes natural round bamboo's various weaknesses. This study compared the bamboo scrimber's mechanical (strength, stiffness, and ductility) to timber. The results showed that scrimber's physical and mechanical properties are comparable, even superior, to wood, especially in compression. Scrimber has a higher density than timber. Its drier equilibrium moisture content indicates that scrimber is more hydrophobic than timbers. The maximum crushing strength (σc//), compressive stress perpendicular-to-fiber at the proportional limit (σcp⊥) and that at the 0.04" deformation (σc0.04⊥), shear strength (τ//), longitudinal compressive modulus of elasticity (Ec//), lateral compressive modulus of elasticity (Ec⊥), and modulus of rigidity (G) of scrimber are higher than those of timbers. Both scrimber's and timber's flexural properties (modulus of rupture (σb) and flexural modulus of elasticity (Eb)) are comparable. On the contrary, the tensile strength parallel-to-fiber (σt//) of scrimber is weaker than that of timber. Scrimber is high ductility (μ > 6) when subjected to compression perpendicular-to-fiber, medium ductility (4 < μ ≤ 6) when subjected to compression parallel-to-fiber, and low ductility (brittle) when subjected to bending, shear, or tensile parallel-to-fiber. The higher ductility of scrimber may give an alarm and more time before failure than timbers. Timbers have brittle to lower ductility when receiving each kind of loading scheme. The ratio of shear modulus to strength (G/τ) and compression modulus to strength parallel-to-fiber (EC∥/σC∥) strongly correlates with the ductility ratio. However, the ratio of the flexural modulus of elasticity to the modulus of rupture (Eb/σb) and the ratio of the modulus Young to compression stress perpendicular-to-fiber (Ec⊥/σcp⊥) do not strongly correlate to the ductility value. [ABSTRACT FROM AUTHOR]

In the past decade, bamboo scrimber has developed rapidly in the field of building materials due to its excellent mechanical properties, such as high toughness and high tensile strength. However, when the applied stress exceeds the ultimate strength limit of bamboo scrimber, cracks occur, which affects the performance of bamboo scrimber in structural applications. Due to the propensity of cracks to propagate, it reduces the load-bearing capacity of the bamboo scrimber material. Therefore, research on the fracture toughness of bamboo scrimber contributes to determining the material’s load-bearing capacity and failure mechanisms, enabling its widespread application in engineering failure analysis. The fracture toughness of bamboo scrimber was studied via the single-edge notched beam (SENB) experiment and compact compression (CC) method. Nine groups of longitudinal and transverse samples were selected for experimental investigation. The fracture toughness of longitudinal bamboo scrimber under tensile and compressive loadings was 3.59 MPa·m1/2 and 2.39 MPa·m1/2, respectively. In addition, the fracture toughness of transverse bamboo scrimber under tensile and compressive conditions was 0.38 MPa·m1/2 and 1.79 MPa·m1/2, respectively. The results show that, for this material, there was a significant distinction between longitudinal and transverse. Subsequently, three-point bending tests and simulations were studied. The results show that the failure mode and the force–displacement curve of the numerical simulation were highly consistent compared with the experimental results. It could verify the correctness of the test parameters. Finally, the flexural strength of bamboo scrimber was calculated to be as high as 143.16 MPa. This paper provides data accumulation for the numerical simulation of bamboo scrimber, which can further promote the development of bamboo scrimber parameters in all aspects of the application.

For this paper, two kinds of waterborne coatings, polyurethane acrylate (PUA) and epoxy resin, were synthesized and then coated onto neat bamboo and bamboo scrimber (BS), respectively. The coating performance of the samples was investigated. The results showed that, for the two kinds of coatings, there was a chemical reaction occurring between both coatings and the substrates. The permeability with respect to bamboo was higher than that of BS, while that of the epoxy resin coating was better than PUA. However, the PUA film was smoother than epoxy resin. The epoxy resin coating on bamboo had the best adhesion, which was at a 1 level. The abrasion values of the four samples varied in the same substrate. A higher hardness of the coating film was obtained when coated with PUA. In general, the coating performance of bamboo scrimber was poorer than that of bamboo, either coated with PUA or epoxy resin. The epoxy resin had a better coating performance than PUA. [ABSTRACT FROM AUTHOR]

• The bamboo scrimber had higher rolling shear properties than those of SPF. • The most of CLTB specimens had higher bending properties than those of SPF CLT. • The main failure modes of CLTB specimens were different from those of SPF CLT. • There were good agreement of apparent bending stiffness of CLTB in various methods. Using bamboo and timber to manufacture cross-laminated timber-bamboo (CLTB) composites could utilize the advantages of two material to improve the mechanical properties and expand the raw material source of cross-laminated timber (CLT). To explore the feasibility of using engineered bamboo as CLT lamination, the rolling shear properties of two bamboo scrimbers and one bamboo plywood were evaluated. Two types of CLTB specimens, using bamboo scrimber as transverse layer or as both transverse layer and the outermost longitudinal layer, were developed in this study. The bending properties of CLTB and generic Spruce-pine-fir (SPF) CLT specimens were evaluated by dynamic tests and third-point bending tests, respectively. The shear analogy method was employed to calculate the apparent bending stiffness of CLT/CLTB specimen. The results indicated that the rolling shear modulus and strength of bamboo scrimber (group RB(F)-4.5) were 92.81% and 98.64% higher than those of bamboo plywood, respectively, and were 330.19% and 121.13% higher than those of SPF dimension lumber, respectively. The CLTB specimens, group BWBWB, had 23.69% and 60.50% higher apparent bending modulus and peak load than those of generic SPF CLT specimens. Most of the CLTB bending specimens had main failure mode of tensile failure in the bottom layer which replaced rolling shear failure in transverse bamboo scrimber layer. The apparent bending stiffness values of CLT/CLTB specimens obtained from dynamic test and shear analogy method were in good agreement with the static experimental values. The results presented in this paper can provide fundamental basis for supporting the potential engineering application of CLT panel products fabricated with bamboo scrimber. [ABSTRACT FROM AUTHOR]

The mechanical properties of the structural components (i.e., columns and beams produced from engineered bamboo products), such as, bamboo scrimber (also known as parallel bamboo strand lumber, PBSL) and Laminated Bamboo Lumber (LBL), have attracted considerable attention from researchers in recent years. In previous studies, researchers reported on the stress-strain behaviour of bamboo scrimber, LBL and glue laminated bamboo under compression and proposed some empirical and semi-empirical models, based on their individual studies. However, a generic constitutive model for engineered bamboo products is still not available. The compressive stress-strain curves of bamboo scrimber and LBL are reported to show a similar behaviour with three distinct stages i.e., a linear elastic stage followed by a nonlinear plastic stage and a plateau. As part of the current study, the previously proposed models for bamboo scrimber were carefully studied and all available material test results on engineered bamboo were used to develop a generic constitutive model, based on the Ramberg-Osgood (RO) formulation considering its suitability to capture its material nonlinearity. Based on the test results, it was observed that 1% proof stress can be used in a compound RO model to predict an accurate material response for bamboo scrimber. The proposed modelling technique has also been applied to predict the compressive behaviour of LBL. This paper proposes the RO coefficients for both bamboo scrimber and LBL that can be used to develop accurate nonlinear models for engineered bamboo products.

Bamboo scrimber is a new type of bamboo-based panel that is prone to be affected by biological and service environments under outdoor conditions. In this paper, the physical and mechanical performance and the microchemical and surface properties of untreated and hot-oil-treated bamboo scrimber were analyzed to illustrate the processing mechanism of scrimber. Methyl silicone oil treatment was carried out at 120, 140, and 160 °C for 2, 4, and 6 h. The density, mechanical properties, air-dried moisture content, surface morphology, chemical structure, swelling properties, color, and contact angle of the bamboo scrimber were analyzed to evaluate the treatment effectiveness. Observation of the environmental-scanning electron microscope indicated that the glue layer of the bamboo scrimber was not significantly damaged after hot oil treatment. At low temperatures, the mechanical properties did not change significantly. Infrared-spectrum analysis showed a significant decrease in mechanical properties at higher temperatures and longer treatment time for the degradation of hemicellulose. The contact angle test and swelling properties test showed that the hot oil treatment improved the dimensional stability and reduced the wettability on the surface of the bamboo scrimber. The above analysis results show that the treatment at 140 °C for 2 h is most effective. [ABSTRACT FROM AUTHOR]

• A-state-of-art review was conducted on novel engineered wood and bamboo composites. • Attentions were paid to their manufacturing technologies, modeling approaches, and mechanical properties. • Mechanical properties of the engineered wood and those of the engineered bamboo were compared. • Several structural application cases of these engineered wood/bamboo composites were illustrated. Both wood and bamboo are renewable anisotropic materials with a long application history in human society. Engineered wood or bamboo aiming to mitigate the variability of the natural material can provide better material properties and structural performance, compared to original sawn lumber or raw bamboo. In this paper, a state-of-the-art review was conducted on three types of novel engineered wood composites, namely fiber reinforced polymer (FRP) reinforced glulam, cross-laminated timber (CLT), and wood scrimber, as well as three types of novel engineered bamboo composites, namely laminated bamboo lumber (LBL), glued-laminated bamboo (glubam), and bamboo scrimber, with particular attentions to their manufacturing technologies, modeling approaches, and mechanical properties. Then, for these novel engineered wood/bamboo composites, a comprehensive comparison was conducted on their mechanical properties and on their densities. Finally, several cases of structural applications were respectively illustrated, in which these aforementioned engineered wood/bamboo composites were adopted as main building materials. Potentials of applying these engineered wood/bamboo composites for structures were confirmed, and their possible existing drawbacks were also discussed. [ABSTRACT FROM AUTHOR]

Bamboo scrimber is one of the most emerging structural materials for future building applications and it possesses properties comparable to other natural wood-based engineered materials such as glulam, laminated veneer lumber and cross-laminated timber. The goal of this work was to study the decay resistance of bamboo scrimber against white-rot (Trametes versicolor) and brown-rot fungi (Serpula lacrymans). Bamboo scrimber samples were incubated in petri dishes with the wood-decaying fungi and the weight loss after 12 weeks was measured. The surface morphology of fungal-degraded bamboo scrimber was evaluated using optical microscopy. Based on the percentage weight loss, bamboo scrimber could be classified as highly resistant against bio-deterioration by white and brown-rot fungi. [ABSTRACT FROM AUTHOR]

Bamboo fiber composite (BFC) is a unidirectional and continuous bamboo fiber composite manufactured by consolidation and gluing of flattened, partially separated bamboo culm strips into thick and dense panels. The composite mechanical properties are primarily influenced by panel density, its variation and uniformity. This paper characterized the horizontal density distribution (HDD) within BFC panels and its controlling factors. It revealed that HDD follows a normal distribution, with its standard deviation (SD) strongly affected by sampling specimen size, panel thickness and panel locations. SD was lowest in the thickest (40 mm) panel and largest-size (150 × 150-mm2) specimens. There was also a systematic variation along the length of the BFC due to the tapering effect of bamboo culm thickness. Density was higher along panel edges due to restraint from the mold edges during hot pressing. The manual BFC mat forming process is presented and found to effectively minimize the density variation compared to machine-formed wood composites. This study provides a basic understanding of and a quality control guide to the formation uniformity of BFC products.

Compact tension specimens were used to determine the mode I (opening crack) fracture toughness of bamboo scrimber, a bio-based product for engineering applications. The influence of thickness and grain mode were investigated, and the extended finite element method (XFEM) was used to simulate the fracture behavior of bamboo scrimber. The results showed that all of the specimens failed in a brittle way. There were no significant differences in fracture toughness among specimens with different thicknesses; however, the grain mode did have a significant effect. The average fracture toughness KIC for T-L and R-L grain modes of bamboo scrimber were 54.32 MPa·mm1/2 and 47.91 MPa·mm1/2, respectively, where the letter "L" represents the longitudinal direction, "R" represents the stack direction, and "T" represents the flattened tangential direction. Based on the results, compact tension specimens with a thickness of 10 mm are recommended to measure the mode I fracture toughness of bamboo scrimber. Furthermore, XFEM was confirmed as a useful tool to investigate the fracture behavior of bamboo scrimber. [ABSTRACT FROM AUTHOR]

Bamboo scrimber is a new type of bamboo-based panel that is prone to be affected by biological and service environments under outdoor conditions. In this paper, the physical and mechanical performance and the microchemical and surface properties of untreated and hot-oil-treated bamboo scrimber were analyzed to illustrate the processing mechanism of scrimber. Methyl silicone oil treatment was carried out at 120, 140, and 160 °C for 2, 4, and 6 h. The density, mechanical properties, air-dried moisture content, surface morphology, chemical structure, swelling properties, color, and contact angle of the bamboo scrimber were analyzed to evaluate the treatment effectiveness. Observation of the environmental-scanning electron microscope indicated that the glue layer of the bamboo scrimber was not significantly damaged after hot oil treatment. At low temperatures, the mechanical properties did not change significantly. Infrared-spectrum analysis showed a significant decrease in mechanical properties at higher temperatures and longer treatment time for the degradation of hemicellulose. The contact angle test and swelling properties test showed that the hot oil treatment improved the dimensional stability and reduced the wettability on the surface of the bamboo scrimber. The above analysis results show that the treatment at 140 °C for 2 h is most effective.

Bamboo is a category of fast-growing and widely distributed perennials having unique physical and mechanical properties. The mechanical properties of bamboo are often higher (typically by two to three times) than those of conventional timbers, and it has become a very important raw material for the household/building industries. Bamboo has been commercially used for the production of indoor and outdoor floors, furniture, and structural timber for building. Some performance defects/drawbacks of bamboo have been effectively remedied, due to the new technologies, such as bamboo scrimber, which facilitates the market penetration/acceptance of bamboo-based household and building products. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the compressive strength parallel to the grain of bamboo scrimber during and after exposure to various temperatures, in a range from 20 to 225 °C. These data were used to provide a basis for the evaluation of the fire performance of bamboo structures. A total of 152 specimens, assembled as group "during-fire" and "post-fire", were tested during and after exposure to high temperatures. The experimental results indicated that there were significant differences in compressive properties between the "during-fire" and "post-fire" groups. At one temperature level, the compressive strength and modulus of elasticity of the "post-fire" group were significantly higher than those properties of the "during fire" group, but the ductility coefficient was reversed. FTIR analysis results showed that 175 °C was a key turning point, at which thermal decomposition occurred in the cellulose of the bamboo and phenolic resin. [ABSTRACT FROM AUTHOR]

The effects of milling process parameters on cutting forces and surface roughness were studied during peripheral up milling of bamboo scrimber. The study results indicated that the effect of feed rate on cutting force components Fx, +Fy, -Fy, and surface roughness Ra were the most significant compared to spindle speed and cut depth during longitudinal milling. Fx, +Fy, -Fy, and Ra decreased slightly with increasing spindle speed, but increased greatly with increasing feed rate. In addition, cutting direction had a great effect on the cutting force components Fx and +Fy, as well as the machined surface roughness Ra. Fx, +Fy, and Ra during longitudinal cutting were always larger than those during end-grain cutting. Decreasing the feed rate appropriately could greatly improve the quality of the machined surface. [ABSTRACT FROM AUTHOR]