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La Molina is one of the districts with the bigger green areas and ecological awareness in the city of Lima. The Universidad Nacional Agraria La Molina (UNALM) represents about half of the green areas in the district; being the Schinus molle L. «molle serrano» the second most abundant tree species in the campus and one of the most planted in Lima. This native tree with recognized cultural importance is widely used in the arboriculture crops for its ornamental and rustic character, resistant to the drought and plagues; whose top formed by hanging branches offers shade and when having a fast replacement of foliage, it is able to filter the air capturing particles in suspension and CO2. However, it has been observed the presence of burls along the shaft and branches in trees of this species altering its ornamental character and representing a probable risk. Therefore, the internal structure of the tree was studied using the Arbosonic 3D forest tomograph and/or the resistance of healthy wood, wood with burl and wood with rot by means of the physical and mechanical properties of the wood: basic density (DB), resistance to bending or modulus of rupture (MOR) and rigidity or modulus of elasticity (MOE). The results determined the absence of Schinus molle L. tree risk due to the presence of burls, evidencing the importance of the use of the forest tomograph in the management of arboriculture crops in Lima. [ABSTRACT FROM AUTHOR]

This design of high value-added products and the calculus of structures in wood requires reliable elastic characteristics related to a theoretical model that explains in a rational way the elastic behavior of wood. This research presents the methodology and the results of the experimental determination of the elastic characteristics of two Canadian woods: Acer rubrum and Abies balsamea. The characteristics examined were modulus of elasticity, modulus of rigidity and Poisson's ratio. Compression tests within the elastic regime were performed in the orthotropic directions of wood: radial tangential and longitudinal. The moisture content of A. rubrum was 9% and 10% for A. balsamea. The densities were 651 kg/m³ and 393 kg/m³ respectively. With the empirically obtained characteristics, the properties and orthotropic relations of the elastic constants matrix of the general elastic model were analyzed. The experimental values of the elastic characteristics of A. rubrum and of A. balsamea woods are comparable with values corresponding to these woods determined in other studies. Likewise, it was proved that the orthotropic postulates of the general elastic model are -within some confidence level- valid. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to analyze the applicability of two unified model of shear modulus degradation curves in the sand of Guayuriba River (Department of Meta, Colombia). To achieve the objective, it was performed acyclic triaxial tests with controlled strain, by varying the confining pressure, the particle size and the compaction degree of the material. The outcome were the modulus degradation curves, which were compared against the model proposed by Ishibashi and Zhang, and the model proposed by Santos and Gomes Correia, showing that the behavior of these materials fit better to the second one. [ABSTRACT FROM AUTHOR]