Issue 48

M. Estrada et alii, Frattura ed Integrità Strutturale, 48 (2019) 348-356; DOI: 10.3221/IGF-ESIS.48.33 355 C ONCLUSIONS he numerical constitutive model proposed in this work represents correctly the crack pattern of LGB specimen subjected to a static load, which produce tensile and shear stress. The numerical model is robust enough to detect the different failure modes according to different fiber orientations in shear tests. Tensile tests show that two different crack patterns are possible: longitudinal crack at transition zone of the cross-section and transverse crack in reduced cross-section. The model showed that both types of failure are always present, but they occur at different times. In the zone of reduction of the specimen, a concentration of stresses in the early stages of the test is presented, which implies a possible failure by shear in this region. Subsequently, if the material has enough shear strength to avoid this type of fracture, the appearance of a failure by traction in the reduced area will be seen. In essence, traction failure can only be obtained if it is guaranteed that the specimen has sufficient shear strength to avoid failure in the area of cross-sectional area reduction. R EFERENCES [1] Londoño, X. (2003).Recurso sostenible de incunable valor. Guadua: arquitectura y diseño, Bogotá, Colombia, Villegas editores, pp. 22–39. [2] López, L.F., Silva, M.F. (2000).Comportamiento sismorresistente de estructuras en bahareque. Universidad Nacional de Colombia, Manizales, 2000. [3] Ghavami, K., Rodríguez, C.S., Paciornik, S. (2003). Bamboo: Functionally Graded Composite Material, Asian J. Civ. Eng. (Building Housing), 4(1), pp. 1–10. [4] López, L.F., Correal, J.F. (2009). Estudio exploratorio de los laminados de bambú Guadua angustifolia como material estructural, Maderas Cienc. y Tecnol., 11(3), pp. 171–82. [5] Takeuchi, C.P., Rivera, J.F., Rusinque, M. (2009).Structural Behaviour of Braced Guadua Frames. Non-Conventional Materials and Technologies (NOCMAT), Bath, UK, pp. 6–9. [6] Takeuchi, C.P. (2013).Caracterización mecánca del bambú guadua laminado para uso estructural. Universidad Nacional de Colombia, 2013. [7] Liese, W. (1998). The Anatomy of Bamboo Culms, International Network for Bamboo and Rattan (INBAR). [8] Liese, W. (1992).The Structure of Bamboo in Relation to its Properties and Utilization. Bamboo and its Use: International Symposium on Industrial Use of Bamboo, Beijing, China, International Tropical Timber Organization and Chinese Academy of Forestry, pp. 95–100. [9] Liese, W. (1985). Bamboos - Biology, Silvics, Properties, Utilization, Germany, Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ). [10] Gritsch, C.S., Abranson, K., Vélez, G.C.C., Rashid, M., Murphy, R.J., Camargo, J.C. (2004). Anatomical culm analysis of Guadua angustifolia in relation to age, site, and physico-mechanical properties. Simposio internacional Guadua, Pereira, Colombia. [11] Silva, E.C.N., Walters, M.C., Paulino, G.H. (2006). Modeling bamboo as a functionally graded material: lessons for the analysis of affordable materials, J. Mater. Sci., 41(21), pp. 6991–7004, DOI: 10.1007/s10853-006-0232-3. [12] Moreno, L.E., Trujillo, E.E., Osorio, L.R. (2007). Estudio de las características físicas de haces de fibra de Guadua angustifolia, Sci. Tech. Año XIII, 34, pp. 613–7. [13] Osorio, J.A., Vélez, J.M., Ciro, H.J. (2007). Estructura interna de la Guadua y su incidencia en las propiedades mecánicas, Dyna, 74(153), pp. 81–94. [14] Estrada, M. (2017).Modelo numérico micromecánico del proceso de fractura de estructuras fabricadas con bambú Guadua angustifolia. Universidad Nacional de Colombia. [15] Dvorak, G.J., Bahei-El-Din, Y.A. (1982). Plasticity Analysis of Fibrous Composites, J. Appl. Mech., 49(2), pp. 327. [16] Simó, J., Ju, J. (1987). Strain and stress based continuum damage models. I. Formulation, Int. J. Solid Struct., 23, pp. 821–840. [17] Simo, J.C., Hughes, T.J.R. (1998). Computational Inelasticity, Springer. [18] Estrada, M., Linero, D.L., Ramírez, F. (2013). Constitutive relationship of the fiber cluster of bamboo Guadua angustifolia, determined by means of a Weibull probability function and a model of progressive failure, Mech. Mater., 63, pp. 12–20, DOI: 10.1016/j.mechmat.2013.04.007. [19] Oliver, J., Huespe, A.E., Linero, D.L. (2005).Strong Discontinuity Approach to Fracture of Composite Materials. 11th