Abstract:Current design and construction codes and standards for bamboo do not contain strength grading procedures beyond cursory visual inspections. This deficiency arguably limits the safe and economic use of the material. This paper presents findings from an international research project which seeks to develop a strength grading system for bamboo culms. Over 200 four-point bending tests were carried out on Guadua angustifolia Kunth (Guadua a.k.) culms for which numerous mechanical and physical properties were measured.Correlations between flexural strength (fm,0), static modulus of elasticity (Em,s), dynamic modulus of elasticity from stress-waves (Ed) and density (ρ), provided mediocre results with R 2 ranging from 0.27 to 0.47. However, properties such as flexural stiffness (EIm,s), flexural capacity (Mmax) and mass per unit length (q), which are less dependent on geometric properties, provided much stronger correlations with R 2 ranging from 0.86 to 0.92.
The use of small diameter whole-culm (bars) and/or split bamboo (a.k.a. splints or round strips) has often been proposed as an alternative to relatively expensive reinforcing steel in reinforced concrete. The motivation for such replacement is typically cost-bamboo is readily available in many tropical and sub-tropical locations, whereas steel reinforcement is relatively more expensive-and more recently, the drive to find more sustainable alternatives in the construction industry. This review addresses such 'bamboo-reinforced concrete' and assesses its structural and environmental performance as an alternative to steel reinforced concrete. A prototype three bay portal frame, that would not be uncommon in regions of the world where bambooreinforced concrete may be considered, is used to illustrate bamboo reinforced concrete design and as a basis for a life cycle assessment of the same. The authors conclude that, although bamboo is a material with extraordinary mechanical properties, its use in bamboo-reinforced concrete is an ill-considered concept, having significant durability, strength and stiffness issues, and does not meet the environmentally friendly credentials often attributed to it.
The past five decades have witnessed an unprecedented growth in population. This has led to an ever-growing housing demand. It has been proposed that the use of bio-based materials, and specifically bamboo, can help alleviate the housing demand in a sustainable manner. The present paper aims to assess the environmental impact caused by using four different construction materials (bamboo, brick, concrete hollow block, and engineered bamboo) in buildings. A comparative life cycle assessment (LCA) was carried out to measure the environmental impact of the different construction materials in the construction of single and multi-storey buildings. The LCA considered the extraction, production, transport, and use of the construction materials. The IPCC2013 evaluation method from the Intergovernmental Panel on Climate Change IPCC2013 was used for the calculations of CO2 emissions. The assessment was geographically located in Colombia, South America, and estimates the transport distances of the construction materials. The results show that transportation and reinforcing materials significantly contribute to the environmental impact, whereas the engineered bamboo construction system has the lowest environmental impact. The adoption of bamboo-based construction systems has a significant potential to support the regenerative development of regions where they could be used and might lead to long-lasting improvements to economies, environments, and livelihoods.
Bamboo is a functionally graded material that has evolved to resist its primary loading in nature. This study focuses on the effects of geometric and material property variation along the culm length on the capacity of an axially-loaded member. Conservatively, compression capacity may be calculated using the smallest section of the member; however, this results in an inefficient use of the culm and may limit the use of long compression members. A more realistic estimate of capacity is obtained by considering the effects of culm taper on buckling capacity. Culm taper is experimentally investigated for three representative bamboo species. The effects of culm section gradient on geometric properties is examined followed by an assessment of geometric variation along the culm height. Following this, a series of buckling analyses of tapered culms is conducted to illustrate the significant effects of taper on culm compression capacity. This analysis is supplemented with comparisons to experimental culm buckling data. Beyond compressive capacity, the implications of culm taper are discussed in terms of flexural behaviour, design of gridshells (involving pre-bent axial load-carrying members), visual grading of bamboo and ultimately classification of the many species of bamboo presently used in construction worldwide.
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