Abstract: Bamboo is a pipe produced by solar energy. It is a plant of the graminae family which grows up all over tropical and part of subtropical regions of the world in more than 1250 species. High biomass production, high mechanical resistance, low specific weight and easy workability has done of bamboo a promise to future generations in relationship to sustainable construction systems. Bamboos of the Phyllostachys pubescens species are one of the most resistant and straight axis bamboos, used in China as material construction and other applications, as paper and fabrics. They are the most commercial bamboos of China and its forests covers 5,6 millions of hectare in that country. This exotic species is met on small plantations in Rio de Janeiro and São Paulo states of Brazil. Many characteristics turns bamboo a smart structural element: high resistance/weight ratio; natural nodes spaced along the culm which avoids local buckling and graded distribution of the fibers from inner to outer side of the thickness wall. So, the application of bamboos as tensile structures supports is a coherent choice since these modern tents characterize a lightweight architecture. Some structural bamboos can attain even more than 15 meters long with 10 cm mean diameter. To increase the load capacity of this slender bar and make feasible bamboo use as masts for tensile structures, an hybrid mast using bamboo as axis and 4 steel cables along of was designed and tested in the Structural System Laboratory LASE, and Structures Experimental Analysis Laboratory LAEES, respectively. In this paper it will be presented the results of the mechanical tests for 2 different masts with 6 meters long. Both masts have the same design but important differences which will be discussed in the paper.
Abstract: The fiber density per cross section of the Bamboo Guadua Angustifolia Kunth (GAK) was calculated by digital images processing. Three processes were done in the development of this work: preparation of the samples, digital pre-processing of the images acquired, and digital processing of the images acquired. For the preparation of the samples, the polishing with different abrasive papers and wool were done, and afterwards, it was added revealing ink on surface to make better the contrast between the fiber zones. The digital pre-processing of the images was based on the acquisition of sequences of images, doing a sweeping of the samples using an automatic plate. The digital processing consisted in the generation of panoramas with sequences of images acquired from the sample. The cross section fiber density was obtained by the calculus of the reason between digital measurement of the total area of the fibers and the total area of the sample. Finally, the values obtained for the fiber density were: 0.34, 0.41 and 0.43 for bottom, middle and top part of the culm respectively.
Abstract: The percentages of delamination of Compacted Bamboo Guadua were calculated using digital images processing. Three processes were done in the development of this project: tests of delamination, digital image pre-processing and digital image processing of the images acquired. The test of delamination followed the ASTM 5824. The digital image pre-processing was supported on the acquisition of sequences of images, doing a sweeping of the samples, and finally the digital processing worked in the generation of panoramas with sequences of images acquired from the sample. Additionally, the total area from the sample was measured digitally, the segmentation and the measurement of delamination area were done, finding the ratio between the delamination area and the total area of the sample, and obtaining the value of percentage of delamination per section. Digitally, the obtained values for samples made with fibers obtained from Stick (Varillón), Top (Sobrebasa), Middle (Basa) parts and mixture of them were 16.97%, 9.96%, 5.96% and 8.64% respectively.
Abstract: The urgency for energy and material efficiency in the building sector increases every day. In the case of Switzerland, a buildings main energy demand occurs during its use/operation phase and is mainly related to heating demands during the winter season. As a means of reducing these demands, current building practice in Switzerland is to insulate with 30cm of foam and to mechanically control indoor environments. Recent research has shown, however, that alternatives to current practice are readily available. With these alternative techniques, natural materials with low embodied energy are used to produce high efficiency building envelopes. The bahareque construction method (bamboo plastered with mortar cement) studied in this paper has been identified as a promising technology both in terms of producing energy efficient building envelopes and also with regards to reducing the environmental impact associated with the construction of buildings in Switzerland. The main objective of the research presented here was to identify the Environmental Savings Potential (ESP) of bahareque in comparison with state of the art technologies in Switzerland. The calculations were geographically limited to Switzerland and the main data sets used for the life cycle assessment models corresponded to this region. Specific datasets were developed for bamboo and bahareque to account for transoceanic transportation. The results showed that bahareque achieves an ESP of 32% compared with clay brick construction and 40% when compared with concrete block construction. It was shown that it is feasible to develop highly efficient building envelopes with low embodied energy that can be used within the Swiss context.
Abstract: If we believe there is a crisis regarding global warming, pollution, and social injustice, and if we want to act on it, we need to open our minds, change our attitudes, and start preparing with our young students. Together we need to develop a way of thinking that implies the use of a new set of values that differs from today’s mind-set and values that caused this crisis in the first place.With this in mind we proposed a group of students and professors to consider building structures with an alternative material: bamboo, a material with which neither students nor professors had any experience in. During the course of this exercise the conceived structures developed from simple to complex designs, from required forms to free ones designed by the students, from small 1:100 scaled models to bigger 1:20 ones.Not theory but the practice itself generated a tremendous amount of enthusiasm within the group of students and within the group of professors. Knowledge of the stability of skeletal structures was gained in a playful way; theoretical thinking-errors were immediately tested by the practical execution of the newly developed model. The existence of alternative construction materials, in this case bamboo, the feel for the material and its numerous possibilities for construction purposes were being revealed! For the involved students and professors the practical aspects of this exercise created more awareness and knowledge on the topic than any theoretical lecture could.
Abstract: The bamboo species Guadua angustifolia is a natural functionally graded material with a high potential to help solving the housing deficit in Latin American countries. Bamboo plantations also play an important role to help reducing the devastation of tropical forests. Many studies have demonstrated the excellent mechanical properties of bamboo along the length of the culm. However, other properties like the strength under circumferential tension and shear are low and the associated types of failure are fragile. Therefore, longitudinal fissures are often initiated in the structural joints which avoid taking advantage of the high resistance along the longitudinal direction. To the best of our knowledge, no study has been devoted to study the mechanical behavior of bamboo along the thickness of the culm or radial direction. This characterization may be crucial to improve the performance of the joints in bamboo structures. The aim of this study was to determine the strength and the Young ́s modulus of Guadua angustifolia along the radial direction. Thus, 27 small hexahedral elements of approximately 11 mm × 6 mm × 7 mm were tested under compression along the thickness of the culm. The stress-strain curves depicted a typical ductile behavior with an average failure strain of 37.8 ± 5.4 %. The failure was characterized by fissures on planes parallel to the fibers and forming angles in the range 35° - 55° with respect to the axis of loading. The secant Young ́s modulus and the radial strength were equal to 44.50 ±9.60 MPa, and 18.50 ±4.20 MPa respectively and there was no significant difference with position along the culm. The initial Young ́s modulus was equal to 96.73 ±52.30 MPa, 37.00 ±24.35 MPa and 48.90 ±7.31 MPa for the bottom, middle and upper portions of the culm and there was a significant difference (p=0.025) between the bottom and middle locations. The high variations of the initial Young ́s modulus may be explained by the irregular form of the surfaces of contact with the testing machine, that were not cut perfectly flat in order to preserve the intact material. These experiments show that Guadua behaves as a ductile material under compression along the thickness of the culm. This property may be used to improve the efficiency of structural joints by applying radial compression.
Abstract: This paper presents the mechanical properties measured on glued laminated pressed guadua samples. Experimental tests like shear parallel to fiber, tensile and shear perpendicular to fiber and flexural tests were carried out using three different types of adhesives: European Melamine Urea Formaldehyde, Colombian Melamine Urea Formaldehyde, and Polivinil Acetate humidity resistant. In order to study the behavior of the material in aggressive environmental conditions, half of the samples used in the mechanical tests were introduced in a temperature and humidity chamber for 45 days set to 45°C of temperature and 95% of relative humidity, usual environmental conditions in Chocó Colombia.The results showed that the highest values of mechanical strength were obtained for samples made with European Melamine Urea Formaldehyde. In addition, it was found that this adhesive was the one with better behavior under the aggressive environmental conditions simulated.
Abstract: Increasing bond between bamboo and concrete is one of the important concerns in using bamboo as reinforcement. Concrete cover rupture and bond failure between bamboo and concrete could be considered as two important causes of element rupture.In this paper, bamboo corrugation as a new method has been proposed. Bamboo corrugation is suggested as a mechanism to interlock bamboo and concrete in order to assist the cohesion and skin friction and increase the total bond. Because of remarkable difference between steel shear strength and longitudinal shear strength of bamboo, the interlock mechanism is different. First, the relation between parameters like bamboo longitudinal shear strength, concrete shear strength and the kind of coating or treating of bamboo has been investigated. Then, the proper shape of bamboo corrugation (relation between size, depth and space between dents) will obtain. Using corrugated bamboo strip can improve bond between these two materials even if bamboo strips have not been treated.
Abstract: This article aims to disclose some aspects of the research and constructive methods on lightweight structures made of tied-up bamboos developed by the Laboratory for Investigation in Living Design, LILD, from PUC-Rio. In this paper, we demonstrate the way of obtaining a shape similar to the one of a soap bubble when blown and manipulated by the researcher, according to previously established parameters. The approximation of such a geometry is achieved through a variety of interactive experiments between the states of a model electronic, manufactured /miniature, and in use that follow the logics of geodesic lines, obtained by means of a grid when inflated. Finally, we present results of initial observations of the assemblage of the bamboo reticular structure in the in use state, that we call The Bubble Hall.