A Review of Basic Mechanical Behavior of Laminated Bamboo Lumber

Over the past decade, the physical and mechanical performances of laminated bamboo lumber (LBL)–a bamboobased structural material, have been extensively studied using experimental, analytical, and numerical approaches. This paper presents a review of existing knowledge in the literature about the mechanical properties of LBL. The paper involved the review of the response of LBL to different types of loading such as tension, bending, compression, and shear. Based on results of the literature reviewed, the strength of LBL parallel to grain was 90–124 MPa with MOE of 10700 MPa in tension, 29.55–72.60 MPa, and MOE of 8396–11022 MPa in compression, 63.87– 128.4 MPa, and MOE of 8320–10912 MPa in bending, and 7.15–17.5 MPa in shear. The average strength of LBL was similar and in some cases exceeded the average values of bamboo- or wood-based materials, while the variability of its mechanical parameters was lower. The variability in strength values of LBL was affected by bamboo species, density and thickness of bamboo strips, growth portion, type of treatment, strips arrangements, and type of adhesive which in turn calls for classification of LBL by strength grades, degree of hardness, the capability of impregnation and penetration, as well as by areas of application in construction. The study provided and discussed concluding observations, the current research gap, and future research directions on the mechanical properties of LBL

Effects of Freeze-Thaw Cycles on Physical and Mechanical Properties of Glulam Exposed to Outdoor Environment

This paper presents an experimental investigation to identify suitable indices to assess durability of glulam when subjected to freeze-thaw cycles in an exposed enviroenment. In this study, two types of glulam specimens were tested for their performance when subjected to different levels of aging due to freezing and thawing. Effect of aging treatment on various parameters including thickness swelling rate, static bending strength, elastic modulus, shear strength, and peeling rate of adhesive layer were studied. Obtained results showed that freeze-thaw aging treatment did not affect the water-resistance of the specimens as measured by thickness swelling rate and had little effect on the dimensional stability of the material. However, the applied aging treatment weakened the bending resistance of the glulam specimens with more pronounced effects on on low-density wood. On the other hand, bond strength of high-density wood was relatively more affected due to the appliedfreeze-thaw cycles. For highdensity wood, it is suggested that the shear strength of the adhesive layer be taken as an important index to determine the durability of freeze-thaw cycles aging. For low-density wood, on the other hand, the static bending strength can be used as an index to determine the durability of glulam under freeze-thaw cycles aging

Slenderness Ratio Effect on the Eccentric Compression Performance of Chamfered Laminated Bamboo Lumber Columns

Eccentric compression tests on 15 chamfered laminated bamboo lumber (LBL) columns with a height ranging from 600 to 3000 mm were conducted in order to study the eccentric mechanical performance. The failure of all specimens was caused by the crack of bamboo fiber in the tensile region. When the ultimate strength was reached, except specimens with a height of 600 mm, all other specimens could bear large deformation, showing good ductility. The lateral displacements of the specimens under eccentric compression were approximately parabolic in the direction of column height. The ultimate bending moment of LBL columns with different slenderness ratios under compression with the same initial eccentricity was a fixed value. The relationship between ultimate capacity, axial displacement, lateral displacement, and slenderness ratio was analyzed based on test results. It was found that the plane section assumption could be used to express the stress and strain distribution of chamfered LBL columns under eccentric compression. A method for calculating the ultimate bearing capacity was proposed using a constitutive model based on the Ramberg-Osgood relation and the empirical formula for calculating the ultimate capacity was given on the basis of the former research as well as the test results in this paper

Properties and Applications of Bamboo Fiber-A Current-State-of-the Art

Fibers are used in many forms in engineering applications–one of the most common being used as reinforcement. Due to its renewable short natural growth cycle and abundance of bamboo resources, bamboo fiber has attracted attention over other natural fibers. Bamboo fiber has a complex natural structure but offers excellent mechanical properties, which are utilized in the textile, papermaking, construction, and composites industry. However, bamboo fibers can easily absorb moisture and are prone to corrosion limiting their use in engineering applications. Therefore, a better understanding of bamboo fiber is particularly important. This paper reviews all existing research on the mechanical characterization of bamboo fiber with an emphasis on the extraction and treatment techniques, and their effect on relevant properties. The chemical composition of bamboo fibers has also been thoroughly investigated and presented herein. Current applications and future opportunities for bamboo fibers in various fields have been presented with a focus on research needs. This work can serve as a reference for future research on bamboo fiber

A review on mechanical behavior of laminated bamboo lumber connections

Due to the transition of Architecture, Engineering and Construction (AEC) sector to a sustainable development, bamboo turned out to be a suitable option to conventional building materials due to its environmental friendliness and distinctive mechanical properties. Initially, it was impossible to use the original bamboo in flat applications due to its round cross-sectional shape, but engineered bamboo, in particular laminated bamboo lumber (LBL), solved this problem. Connections are one of the most important parts of building structures that are responsible for the distribution of loads and energy, ensuring the stability and safety of the structure by avoiding concentration of localized stress that can cause failures at the joints. Over the past decade, a series of experimental studies of connection performance of LBL have been conducted. In order to stimulate the use of laminated bamboo in construction industry, this article reviewed the existing published literature and described the behavior of LBL connections in terms of failure mechanisms and factors affecting the bearing capacity considering three connections categories, namely, LBL sheathing-to-framing connections, LBL dowel-type connections, and glued-in rods (GIROD) in LBL connections. According to the reviewed studies, LBL has great potential and can serve as a worthy alternative for conventional building materials. This work can provide a reference for engineering applications and future research

Research status of glued-in rods connections in wood structures

Glued-in rods connections are widely used as a post-anchoring reinforcement technique in timber structures. The rods are inserted into boreholes with adhesive and then cured to form a whole with high strength, stiffness, and aesthetic properties. Although the glued-in-bar connections have been applied successfully, there are still some problems in the research of these connections in wood structures. There is still no unified standard for glued-in connections in wood structures. In this paper, the state of the art in glued-in-rod connections in wood structures is presented, the main influencing factors, failure modes glued-in rod, and the design methods of glued-in rod connections are summarized. The study provides a reference to bonded bar connections and the development of recommended design methods glued-in rod

A Review of Basic Mechanical Behavior of Laminated Bamboo Lumber

Over the past decade, the physical and mechanical performances of laminated bamboo lumber (LBL)–a bamboobased structural material, have been extensively studied using experimental, analytical, and numerical approaches. This paper presents a review of existing knowledge in the literature about the mechanical properties of LBL. The paper involved the review of the response of LBL to different types of loading such as tension, bending, compression, and shear. Based on results of the literature reviewed, the strength of LBL parallel to grain was 90–124 MPa with MOE of 10700 MPa in tension, 29.55–72.60 MPa, and MOE of 8396–11022 MPa in compression, 63.87– 128.4 MPa, and MOE of 8320–10912 MPa in bending, and 7.15–17.5 MPa in shear. The average strength of LBL was similar and in some cases exceeded the average values of bamboo- or wood-based materials, while the variability of its mechanical parameters was lower. The variability in strength values of LBL was affected by bamboo species, density and thickness of bamboo strips, growth portion, type of treatment, strips arrangements, and type of adhesive which in turn calls for classification of LBL by strength grades, degree of hardness, the capability of impregnation and penetration, as well as by areas of application in construction. The study provided and discussed concluding observations, the current research gap, and future research directions on the mechanical properties of LBL

Effects of freeze-thaw cycles on physical and mechanical properties of glulam exposed to outdoor environment

This paper presents an experimental investigation to identify suitable indices to assess durability of glulam when subjected to freeze-thaw cycles in an exposed enviroenment. In this study, two types of glulam specimens were tested for their performance when subjected to different levels of aging due to freezing and thawing. Effect of aging treatment on various parameters including thickness swelling rate, static bending strength, elastic modulus, shear strength, and peeling rate of adhesive layer were studied. Obtained results showed that freeze-thaw aging treatment did not affect the water-resistance of the specimens as measured by thickness swelling rate and had little effect on the dimensional stability of the material. However, the applied aging treatment weakened the bending resistance of the glulam specimens with more pronounced effects on on low-density wood. On the other hand, bond strength of high-density wood was relatively more affected due to the appliedfreeze-thaw cycles. For highdensity wood, it is suggested that the shear strength of the adhesive layer be taken as an important index to determine the durability of freeze-thaw cycles aging. For low-density wood, on the other hand, the static bending strength can be used as an index to determine the durability of glulam under freeze-thaw cycles aging