Unidad de Posgrado Civil y Mecánica

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Subject: search.filters.subject.MODAL ESPECTRAL

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    Evaluación de vulnerabilidad sísmica de edificaciones de estructuras metálicas en la parroquia Huachi Loreto, 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, 2024-05) Balseca Pinos, Edgar Rafael; Chérrez Gavilanes, Diego Sebastián
    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 seismic events. The seismic vulnerability of buildings allows us to quantify structural damage based on their own characteristics, being 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. For this reason, it was essential to evaluate the existing metal structure buildings in the parish of Huachi Loreto, to provide an overview of the degree of vulnerability and seismic risk index that they present, and thus, apply a detailed vulnerability analysis for one of the most representative buildings and design a proposal for structural strengthening. To evaluate the seismic vulnerability, approved methodologies of rapid visual inspection were used through the forms established in the NEC 15, FEMA P-154 and FUNVISIS, these formats were adequate to evaluate a wide set of buildings in metal structure and collect general data of the parish Huachi Loreto, which showed that the vulnerability of the buildings is mostly high. Based on this study, the structure called EM09 corresponding to Plaza Pachano was selected to perform a more detailed vulnerability analysis using computational resources to apply the linear static and spectral modal method, with which the limits of floor drifts, basal shear and deflections were checked. The most relevant pathologies were the presence of corrosion, non-prequalified connections, inadequate assembly conditions, local and lateral buckling of the main and secondary elements. The strengthening strategy included increasing the cross-sections of the main elements until they were compact and also changing the secondary elements for more efficient sections. Finally, suggestions were made to maintain the structural system in favorable conditions for serviceability and seismic conditions.
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    Diseño por capacidad partiendo de un análisis comparativo entre el método modal espectral y el método tiempo historia con el uso de acelerogramas sintéticos y la Norma Ecuatoriana de la Construcción 2015; de un edificio de 9 pisos en estructura metálica
    (Universidad Técnica de Ambato. Facultad de Ingeniería Civil y Mecánica. Maestría en Ingeniería Civil con Mención en Estructuras Metálicas, 2022-09) Cevallos Cabrera, Jorge Washington; Medina Robalino, Wilson Santiago
    National and international regulations are being updated based on the lessons learned from seismic events; having buildings designed in some cases with regulations that were not very demanding in the dynamic part and in other cases built without any technical procedure; it is necessary to improve the analysis of the behavior of the structure subjected to lateral forces produced by earthquakes in a controlled manner, leading to a theoretical collapse of the structure. This variation is achieved by progressively increasing the amplitudes of the accelerograms used as dynamic excitation. In this work, this numerical procedure for the evaluation of the seismic behavior of structures is applied in order to evaluate the values of the behavior factor postulated in the Ecuadorian Standard for the seismic-resistant design of special steel moment-resisting frames. However, due to the non-linear behavior of the soil, the solution is limited to a set of activities inherent to the correct structural modeling and use of properly filtered seismic records. Regarding the generation of synthetic accelerograms, they must be adjusted to an objective spectrum involving the non-linear behavior of the soil; although it is true that spectral adjustments in the time domain, due to the existence of public domain software, are relatively simple procedures to execute, it is necessary to have a wide knowledge in this type of procedure. In the process of verifying the compatibility of the responses of the vibration period of the structure by placing it as a percentage of the distance and moving the center of masses according to the Ecuadorian standard, it was evidenced that the period of the structures does not affect, due to the fact that the static eccentricity between the center of masses and the center of stiffness can increase more or less; being noticeable the more irregular the structure. By scaling the accelerograms with the response spectrum provided by the NEC; to make synthetic accelerograms, the pseudo-spectral acceleration tends to be similar to the acceleration of the target spectrum, so it could be more productive to work with accelerograms of low magnitude earthquakes, being indispensable to take into consideration the parameters of focal depth, type of fault, soil conditions, etc. For capacity analysis, it is possible to choose only the structural elements that could have some suspicion of failure, concentrating all our effort in solving these elements; it should be clear that the design by capacity does not provide design data, the results obtained serve to analyze the possible complications that could occur in the structure during a seismic movement; it is important to emphasize that they are not totally real data, taking into account that an earthquake has many variables that are not taken into account during the nonlinear analysis.