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

Nodes Effect on the Bending Performance of Laminated Bamboo Lumber Unit

This research studied the ultimate bearing capacity of laminated bamboo lumber (LBL) unit and thereby calculated the maximum bending moment. The load-displacement chart for all specimens was obtained. Then the flexural capacity of members with and without bamboo nodes in the middle section was coMPared. The bending experiment phenomenon of LBL unit was concluded. Different failure modes of bending components were analysed and concluded. Finally, the bending behaviour of LBL units is coMPared with other bamboo and timber products. It is shown that the average ultimate load of BS members is 866.1 N, the average flexural strength is 101 MPa, the average modulus of elasticity is 8.3 GPa, and the average maximum displacement is 17.02 mm. The average ultimate load of BNS members is 1008.1 N, the average flexural strength is 118.02 MPa, the average modulus of elasticity is 9.9 GPa, and the average maximum displacement is 18.26 mm. Laminated bamboo lumber (LBL) unit without bamboo nodes (BNS) has relatively higher flexural strength coMPared with LBL unit with bamboo nodes (BS). The presence of bamboo nodes reduces the strength of the entire structure. Three failure modes were concluded for BS members, and two failure modes were observed for BNS members during the experimental process. According to a coMParison between the LBL unit and other products, the flexural strength and bending modulus of elasticity of the LBL unit are similar as bamboo scrimber and raw bamboo components, which is much higher than timber components

Effects of chemical modification and nanotechnology on wood properties

As a green material, wood is widely used in building decoration, railway construction, and other fields. However, the wood itself has inherent defects of being easy to absorb water and deform, rot, and decrease in strength. The physical and mechanical strengths and stability of artificial fast-growing forest wood are even worse. As wood modification can improve the dimensional stability, durability, strength, and other properties of wood, it has been widely used. Chemical modification is the main method of wood modification. The development of nanotechnology has brought more possibilities for wood modification. Owing to the extensive literature available, this article summarizes the representative achievements of wood chemical modification and nanotechnology. The principle, production process, advantages, and disadvantages of various wood chemical modification methods were analyzed, compared, and evaluated. Finally, according to the application status of wood-modified materials, the problems existing in the current wood chemical modification methods and the application of nanotechnology, and the development trend in the future are analyzed

Review on Connections for Original Bamboo Structures

Bamboo is a green construction material in line with sustainable development strategies. The use of raw bamboo in architecture has existed since ancient times. In the long development years of original bamboo buildings, many areas in the world gradually formed unique bamboo buildings, which have become an important local cultural feature. For building structures, joints are the key to ensure structural load transfer. Because of hollow and thin-walled material property of bamboo, the connection in raw bamboo buildings has always been a major difficulty and problem in the application of bamboo, which seriously hinders the development of original bamboo structures. In order to promote the use of raw bamboo, two traditional connection methods in raw bamboo structures are described in this paper firstly, with the advantages and disadvantages of the two methods pointed out. Also, research progress on four categories of raw bamboo building joints is described namely, bolt joints, steel member joints, filler reinforced joints and other types of joints. This work can provide a reference for future research and engineering applications

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

Review of connections for engineered bamboo structures

Bamboo is a green building material that is environmentally friendly and has great development value. However, the limited mechanical properties and heterogeneous dimensions of natural bamboo poles curb the application of bamboo in building structures. A transverse section of engineered bamboo is regular and compact, and its mechanical properties are stable, which can meet the requirements for physical and mechanical properties of materials in modern building structures. Though application of engineered bamboo has just started, it is of great significance to study the connection performance and corresponding influence factors for popularization and application of modern bamboo structures. This paper is focused on a review of research progress for connections in engineered bamboo structures. Firstly, a study on embedding strength and the performance of bolted joints is presented, including calculation methods described with a proposal for future development of standards suitable for the characteristics of engineered bamboo materials. Secondly, research on carpentry joints is introduced, namely tenon-mortise joints, nail joints and truss plate joints. Finally, some engineering examples are briefly introduced. This work can provide a reference for further research on connections in engineered bamboo structures

The eEF1γ Subunit Contacts RNA Polymerase II and Binds Vimentin Promoter Region

Here, we show that the eukaryotic translation elongation factor 1 gamma (eEF1γ) physically interacts with the RNA polymerase II (pol II) core subunit 3 (RPB3), both in isolation and in the context of the holo-enzyme. Importantly, eEF1γ has been recently shown to bind Vimentin mRNA. By chromatin immunoprecipitation experiments, we demonstrate, for the first time, that eEF1γ is also physically present on the genomic locus corresponding to the promoter region of human Vimentin gene. The eEF1γ depletion causes the Vimentin protein to be incorrectly compartmentalised and to severely compromise cellular shape and mitochondria localisation. We demonstrate that eEF1γ partially colocalises with the mitochondrial marker Tom20 and that eEF1γ depletion increases mitochondrial superoxide generation as well as the total levels of carbonylated proteins. Finally, we hypothesise that eEF1γ, in addition to its role in translation elongation complex, is involved in regulating Vimentin gene by contacting both pol II and the Vimentin promoter region and then shuttling/nursing the Vimentin mRNA from its gene locus to its appropriate cellular compartment for translation