Sensibilidad de la respuesta estructural de marcos arriostrados concéntricos a métodos de selección de registros sísmicos.
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Date
2025
Authors
Aedo Sanhueza, Rebeca Ester
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Publisher
Universidad de Concepción
Abstract
Esta investigación evalúa el impacto de la selección de registros sísmicos en el diseño de estructuras industriales, comparando los espectros de peligro uniforme (UHS) donde se utiliza el espectro de referencia de la norma NCh2369 considerado como una buena representación de esta amenaza y el Espectro Medio Condicionado (CMS). La selección adecuada de registros sísmicos y una acertada modificación espectral determina la representatividad de los análisis dinámicos y la fiabilidad de los diseños estructurales. En este estudio, se emplean dos métodos de modificación espectral: el Escalamiento Espectral y el Ajuste Espectral, con el fin de analizar su influencia en la respuesta estructural bajo distintos escenarios de demanda sísmica.
La metodología de análisis se basa en generar registros sísmicos artificiales de la base de datos sísmica de Chile, los cuales se aplican a modelos de SAP2000 representativos de estructuras industriales. Se consideran tres configuraciones estructurales con distintos periodos fundamentales de vibración, con el objetivo de evaluar su respuesta ante conjuntos de 3, siete y 11 registros sísmicos. De esta forma, se evalúa la influencia del número de registros seleccionados en la dispersión de los resultados, identificando la cantidad mínima recomendada para obtener respuestas estructurales confiables.
Los resultados muestran que la selección del espectro objetivo y el método de ajuste espectral afectan significativamente la demanda estructural en términos de desplazamientos, esfuerzos internos y variabilidad en la respuesta estructural. Se observa que el uso de espectros CMS reduce la dispersión en la respuesta estructural en comparación con los espectros UHS, los cuales tienden a sobreestimar la demanda sísmica. Asimismo, el método de Ajuste Espectral proporciona un ajuste más preciso a la demanda objetivo, pero puede introducir modificaciones en la frecuencia del contenido espectral de los registros, lo que puede no representar de manera óptima la demanda sísmica en ciertos casos.
Otro aspecto relevante analizado es el impacto del número de registros empleados en la variabilidad de los resultados. Se identificó que, si bien el uso de tres registros puede ser suficiente para ciertos análisis preliminares, en otros casos resulta conservador, por lo que el empleo de siete u once registros reduce significativamente la dispersión en las respuestas estructurales, proporcionando mayor confiabilidad en el diseño sísmico.
Finalmente, se presentan recomendaciones clave para la selección de registros en diseño estructural, considerando tanto la normativa vigente como los objetivos de diseño sísmico. Se enfatiza la importancia de definir criterios adecuados para la selección del espectro objetivo y del método de ajuste espectral, así como la cantidad mínima de registros requeridos para obtener resultados confiables. Adicionalmente, se destaca la necesidad de extender el estudio a estructuras tridimensionales para incorporar parámetros como la torsión y la interacción entre diferentes direcciones de respuesta, lo que permitiría obtener una visión más integral del comportamiento estructural bajo demandas sísmicas.
This research evaluates the impact of seismic record selection on the design of industrial structures, comparing Uniform Hazard Spectra (UHS), where the reference spectrum of the NCh2369 standard is used as a good representation of seismic threat, and the Conditional Mean Spectrum (CMS). The proper selection of seismic records and accurate spectral modification determine the representativeness of dynamic analyses and the reliability of structural designs. This study employs two spectral modification methods: Spectral Scaling and Spectral Matching, in order to analyze their influence on structural response under different seismic demand scenarios. The analysis methodology is based on artificial seismic records from the Chilean seismic database, which are applied to SAP2000 models representing industrial structures. Three structural configurations with different fundamental vibration periods are considered, with the aim of evaluating their response to sets of 3, 7, and 11 seismic records. This way, the influence of the number of selected records on the dispersion of results is evaluated, identifying the minimum recommended number of records to obtain reliable structural responses. The results show that the selection of the target spectrum and the spectral adjustment method significantly affect structural demand in terms of displacements, internal forces, and variability in structural response. It is observed that the use of CMS spectra reduces the dispersion in structural response compared to UHS spectra, which tend to overestimate seismic demand. Additionally, the Spectral Matching method provides a more accurate fit to the target demand but can introduce modifications in the spectral content frequency of the records, which may not optimally represent seismic demand in certain cases. Another relevant aspect analyzed is the impact of the number of records used on the variability of results. It was identified that while using three records may be sufficient for certain preliminary analyses, in other cases it proves conservative, so the use of seven or eleven records significantly reduces dispersion in structural responses, providing greater reliability in seismic design. Finally, key recommendations for seismic record selection in structural design are presented, considering both the current regulations and seismic design objectives. The importance of defining appropriate criteria for selecting the target spectrum and spectral adjustment method, as well as the minimum number of records required to obtain reliable results, is emphasized. Additionally, the need to extend the study to three-dimensional structures is highlighted, to incorporate parameters such as torsion and the interaction between different response directions, which would provide a more comprehensive view of structural behavior under seismic demands."
This research evaluates the impact of seismic record selection on the design of industrial structures, comparing Uniform Hazard Spectra (UHS), where the reference spectrum of the NCh2369 standard is used as a good representation of seismic threat, and the Conditional Mean Spectrum (CMS). The proper selection of seismic records and accurate spectral modification determine the representativeness of dynamic analyses and the reliability of structural designs. This study employs two spectral modification methods: Spectral Scaling and Spectral Matching, in order to analyze their influence on structural response under different seismic demand scenarios. The analysis methodology is based on artificial seismic records from the Chilean seismic database, which are applied to SAP2000 models representing industrial structures. Three structural configurations with different fundamental vibration periods are considered, with the aim of evaluating their response to sets of 3, 7, and 11 seismic records. This way, the influence of the number of selected records on the dispersion of results is evaluated, identifying the minimum recommended number of records to obtain reliable structural responses. The results show that the selection of the target spectrum and the spectral adjustment method significantly affect structural demand in terms of displacements, internal forces, and variability in structural response. It is observed that the use of CMS spectra reduces the dispersion in structural response compared to UHS spectra, which tend to overestimate seismic demand. Additionally, the Spectral Matching method provides a more accurate fit to the target demand but can introduce modifications in the spectral content frequency of the records, which may not optimally represent seismic demand in certain cases. Another relevant aspect analyzed is the impact of the number of records used on the variability of results. It was identified that while using three records may be sufficient for certain preliminary analyses, in other cases it proves conservative, so the use of seven or eleven records significantly reduces dispersion in structural responses, providing greater reliability in seismic design. Finally, key recommendations for seismic record selection in structural design are presented, considering both the current regulations and seismic design objectives. The importance of defining appropriate criteria for selecting the target spectrum and spectral adjustment method, as well as the minimum number of records required to obtain reliable results, is emphasized. Additionally, the need to extend the study to three-dimensional structures is highlighted, to incorporate parameters such as torsion and the interaction between different response directions, which would provide a more comprehensive view of structural behavior under seismic demands."
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Keywords
Dinámica estructural, Diseño antisísmico