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

Abstract

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.