Caori Takeuchi

Experimental Analysis of Frames Made with Glued Laminated Pressed Bamboo Guadua

This article presents the experimental tests results of frames made with glued laminated pressed bamboo guadua under lateral load. The tested frames had two floors with 1.40m of height each one and 2.80m of total height; the width of the frames was 2.10m. Beams and columns had square box cross-section of 0.10m side and 0.015m of wall. Three frames had bracing type K and other threes had panels. The adhesive used for the manufacture of beams, columns and braces was Urea Melamine Formaldehyde and for the elaboration of panels was Polyvinyl Acetate. The frames of glued laminated pressed bamboo guadua had elastoplastic behavior with great ductility.

Variation in the Fiber Percentage in Specimens of Laminated Bamboo Guadua angustifolia

Raw bamboo is a composite graded naturally material with variable distribution of fibers in the culm wall thickness and also in height. The strength and fiber volume fraction obtained in tests of round bamboo are very variable, while laminated bamboo has more uniform properties. The fiber volume fraction was determined in two groups of specimens of laminated bamboo Guadua angustifolia and also in two groups of bamboo clapboards. Although the average values of fiber volume fraction was around 45% for all cases, it was found that the coefficient of variation in the groups of specimens of laminated bamboo guadua was 6%, while in the groups of slats was 29%.

Determinación experimental de valores característicos de resistencia para Guadua angustifolia

For the design of structures built with bamboo Guadua angustifolia as structural material it is necessary to know the characteristics values of its mechanical properties and elastics modulus. This article shows the experimental methodology used in the determination of characteristics values for bending, compression, shear and tensile parallel to fiber, torsion, compression perpendicular to fiber and elastics modulus for Guadua angustifolia. Tests were performed in samples taken from the bottom, middle and upper parts of culms of bamboos from three different areas of Colombia. Characteristic values of compression, tension and shear parallel to the fiber, bending, torsion and perpendicular compression strengths were found. Also the elastic longitudinal modulus and the circumferential modulus were determined.

Approach to the Load Resistance in Two Kinds of Bamboo Reinforced Concrete Slab

Steel reinforced concrete is generally used in houses structure elements. However bamboo strength properties similarly to the wood, make it an alternative concrete composite material. Load test were performed in two kinds of bamboo guadua concrete reinforced composite slabs. During the tests the slabs functioned as domestic roofing-flooring in standing houses, the slab systems tested were bamboo stem covered slab and stem free slab. Two different tests were designed to measure the deflection in the middle of the composite slab and along a single bamboo stem. In three different slab sizes and after replications, no deflection under the applied load was recorded. Therefore, bamboo composite slabs without steel reinforcing seem likely to be used in long lasting houses for middle and high class dwellings in Colombia.

Determination of Shear Stress in Pull out Tests in Laminated Bamboo Guadua angustifolia

Specimens of laminated bamboo Guadua angustifolia do not usually fail due to fiber breakage when submitted to shear stresses. The common failure mechanism in that case is slippage in the fiber-matrix interface, accompanied by degradation of the lignin matrix (parenchyma). In this study the shear strength of laminated bamboo Guadua angustifolia specimens was determined by tension tests reducing the cross section area. The perimeter of the slipped area was determined using digital image processing. Shear stresses were calculated taking into account the load and slipped area in specimens of two different groups, depending on the orientation of the laminated boards. It was found that the average value of the shear strength on pull out tests were 2.9 MPa, which is a mechanical property of the material that is useful, for example, in the analysis of the behavior of the joints, and analysis of the fracture process.

The Elastic Modulus and Poisson's Ratio of Laminated Bamboo Guadua angustifolia

Laminated bamboo is a natural composite material with cellulose fibers, parenchyma cells, and vascular bundles. The mechanical characterization of this material includes not only the determination of its strength, but also of its elastic constants. Given the anisotropic nature of the laminated material, compression tests were performed on three groups of specimens. The elastic modulus in the load direction and the Poissons ratio were determined, and the results showed that the materials physical anisotropy causes an anisotropic mechanical behavior. The average values obtained for the elastic modulus ranged from 30044 MPa for group 1 to 265 MPa for group 2. The results of the test to determine the Poissons ratio in compression perpendicular to the fibers, ranged from 0.013 to 0.278 whereas those obtained in compression parallel to the fibers, ranged from 0.621 to 1.506.

Mechanical Behavior of Glued Laminated Pressed Bamboo Guadua Using Different Adhesives and Environmental Conditions

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.

Determination of the Delamination Percentage of Compacted Bamboo Guadua Using Extended Field Digital Images Processing

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.

Analysis of the Fiber Density in Bamboo Guadua angustifolia Kunth by Extended Field Microscopy and High Resolution Images Processing

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.