Ingeniería Civil y Mecánica

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Author: search.filters.author.Mayorga Ases, Leticia Abigail

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    Evaluación de vulnerabilidad sísmica de edificaciones de estructuras metálicas en la parroquia La Matriz, Ambato, Ecuador: Propuesta de reforzamiento estructural de una edificación representativa
    (Universidad Técnica de Ambato. Facultad de Ingeniería Civil y Mecánica. Maestría en Ingeniería Civil con Mención en Estructuras Metálicas, 2023-03) Mayorga Ases, Leticia Abigail; Caiza Sánchez, Pablo Enrique
    The city of Ambato is one of the areas with high seismic hazard in Ecuador, this parameter combined with the vulnerability of the buildings and the level of exposure represent the level of seismic risk that could occur in the event of seismic events. The vulnerability of buildings is the only variable that can be influenced to reduce the level of risk, since it depends on aspects such as the type of structural system, presence of irregularities in plan and elevation, level of maintenance of the building, application of regulations and building codes, and other parameters that are controllable. For this reason, it was essential to evaluate the seismic vulnerability of existing metal structure buildings to provide an overview of the degree of vulnerability of buildings in La Matriz district and, related to this, the seismic risk index. To evaluate the seismic vulnerability, methodologies approved by national and international entities were used, such as the NEC 15, FEMA P-154 and FUNVISIS rapid visual inspection forms, which showed good results to evaluate a wide range of buildings and collect general data for the La Matriz district. Based on this analysis, the Plaza Cívica Mercado Urbina was selected for a more detailed vulnerability analysis using computational resources to apply linear static, spectral modal, and nonlinear static analysis. With the detailed methodology it was possible to know in detail the conditions in which the building was found and the seismic performance, it was determined that the structural system is robust and that it behaves rigidly in the presence of seismic loads, however, there are construction details that could generate collapses by rupture failure mechanisms in the areas of stress accumulation, this was the case of the connections between beams and columns. To mitigate future problems in the building, a system of reinforcement and stress dissipation was proposed by means of a finite element analysis. Finally, suggestions were made to maintain the structural system in favorable conditions for service conditions.
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    Evaluación del desgaste de las herramientas de corte y acabado superficial en el torneado del acero inoxidable AISI 304 mediante lubricación hibrida CO2 + NANO TiO2
    (Universidad Técnica de Ambato. Facultad de Ingeniería Civil y Mecánica, Carrera de Ingeniería Mecánica, 2020-08) Mayorga Ases, Leticia Abigail; Carranza Calero, Diego Mauricio; Núñez Núñez, Diego Fernando
    The present research focused on studying the influence of a hybrid lubrication method, which involves the use of cryogenic CO2 and a minimum lubricant quantity (MQL) system combined with titanium dioxide nanoparticles on the surface finish of elements automatically processes of turning, and flank wear of cutting tools, the evaluation was carried out in a finishing process on a conventional lathe, however, the proposed lubrication and cooling method can also be handled on CNC lathes. To analyze the analyzes, tungsten carbide inserts with a single tip radius established at 0.8 mm were used, the machining parameters to be varied were the cutting speed and feed, the recommended values and the maximum values of these will be used. two parameters to establish the experimental combinations, as well as the lubrication method, for half of the combinations it was carried out dry, while for the rest it was made use of the proposed hybrid refrigeration and lubrication system. The hybrid lubrication system comprises the use of liquid and gaseous CO2 combined with a minimum lubricant quantity system that uses a nano fluid composed of a biodegradable vegetable oil mixed with nanoparticles of titanium dioxide at a concentration of 0.5 per cent by weight , the mixture of cryogenic fluid and nano fluid was directed towards the part-tool contact area to counteract friction and lower cutting temperatures. Standard instruments such as a roughness tester capable of recording surface quality values Ra and Rz and a scanning electron microscope that detect and measure the evolution of flank wear of the flanges are used to evaluate the roughness and flank wear in the different parameter combinations. inserts in a precise manner in accordance with ISO 3685.