Evaluación desempeño sismico de edificio de remolienda diseñado según norma NCH2369 2023
Loading...
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Chile ha experimentado terremotos de diversa magnitud a lo largo de su historia, convirtiéndose en una parte inherente de la realidad nacional y quedando totalmente arraigados en la memoria colectiva del pueblo chileno. Dada la necesidad de tener estructuras lo suficientemente resistentes que cumplan con las necesidades de la industria nacional nace la normativa NCh2369 “Diseño sísmico de estructuras e instalaciones industriales” oficializada en el año 2003 cuya filosofía es entregar sobrerresistencia y ductilidad moderada a las estructuras para cumplir con los objetivos continuidad de operación y protección de vida en la industria. Esta normativa fue puesta a prueba con el terremoto del Maule 2010 en donde se evidenciaron daños en las estructuras. Estos eventos combinados con los cambios en las necesidades del país y los avances en el conocimiento y herramientas de análisis impulsaron la actualización de la normativa NCh2369 a la versión 2023. En esta actualización se reemplaza el espectro de Blume por espectros que vienen de una estimación formal de amenaza sísmica. Además, se definen límites de esbeltez local más estrictos y se otorga mayor sobrerresistencia a elementos estructurales que no estén pensados como fusibles sísmicos, con el objetivo de proteger el sistema gravitacional. Cabe destacar que la filosofía tradicional de diseño no cambia, sino que, esta actualización busca garantizar que se cumplan con objetivos de la norma.
El presente texto tiene como objetivo evaluar el desempeño sísmico de un Edificio de Remolienda, estructurado en base a marcos de momento en la dirección transversal y arriostrado longitudinalmente. Primero se diseñó esta estructura en base a la normativa 2023, luego se realiza el análisis no lineal tiempo historia para nivel de diseño SDI y máximo sismo posible SMP, considerando no linealidad de columnas, vigas y arriostramientos. De esta forma se validan las nuevas disposiciones de la normativa.
Para análisis lineal se optimizaron las columnas para tener factores de utilización cercanos a 1, en cuanto arriostramientos se consideraron perfiles tubulares en toda la altura, estos quedan controlados por límites de esbeltez local y global. El diseño de pernos de anclaje quedó controlado por cargas de viento debido al alto valor del factor de reducción R = 5. Con respecto al análisis no lineal la incursión no lineal se enfocó principalmente en los arriostramientos, por lo que en general, la estructura operó dentro del rango de la sobrerresistencia con leve incursión no lineal de columnas y vigas. Además, se cumple con los criterios de aceptación de NCh2369 2023 para columnas, vigas y arriostramientos.
Throughout history, Chile has been recognized for being a highly seismic country, becoming part of the collective identity of Chileans. From the perspective of civil engineering, these events make it possible to evaluate the behavior of structures and, therefore, adjust and/or modify seismic-resistant standards, such as NCh 2369 "Seismic design of structures and industrial facilities," whose first edition was officially ratified in 2003. Within this context, the 2010 Maule earthquake identified shortcomings in the normative, which, combined with new knowledge and analysis tools, prompted its update, always considering the Chilean industrial design philosophy based on overstrength and moderate ductility, where bracing and anchor bolts play a fundamental role in energy dissipation. This update incorporates new spectral shapes, changes in compactness limits, and the application of seismic loads amplified by 0.7R1≥1.0, as a unified criterion for designing members that do not aim to dissipate energy. The main objective of this work is to evaluate the seismic performance of a Column Cell Building, constituted based on concentrically braced frames (CBF). To achieve this, it was first designed according to the provisions of the NCh2369 update, and then a nonlinear time-history analysis was carried out considering the nonlinearity of anchor bolts and bracing for two seismic demand scenarios: design level (SDI) and maximum probable seismic level (SMP). In order to follow the guidelines of the original design, the design was carried out with a factor R=3 and I=1.0, resulting in a structure with overstrength. The bracings were made up of hollow square profiles HSS, as they better comply with the new compactness limits and were sized to be as tight as possible, however, these compactness limits in many cases controlled the design. On the other hand, the configuration of the anchor bolts is controlled by a single anchor for each type of column, leaving the rest of the anchors oversized. In the nonlinear analysis, the structure worked in its overstrength range, with moderate use of ductility. Bracing dissipates considerably more energy than anchor bolts in all cases, with an average energy dissipation participation of 30% and 47% for SDI and SMP levels, respectively.
Throughout history, Chile has been recognized for being a highly seismic country, becoming part of the collective identity of Chileans. From the perspective of civil engineering, these events make it possible to evaluate the behavior of structures and, therefore, adjust and/or modify seismic-resistant standards, such as NCh 2369 "Seismic design of structures and industrial facilities," whose first edition was officially ratified in 2003. Within this context, the 2010 Maule earthquake identified shortcomings in the normative, which, combined with new knowledge and analysis tools, prompted its update, always considering the Chilean industrial design philosophy based on overstrength and moderate ductility, where bracing and anchor bolts play a fundamental role in energy dissipation. This update incorporates new spectral shapes, changes in compactness limits, and the application of seismic loads amplified by 0.7R1≥1.0, as a unified criterion for designing members that do not aim to dissipate energy. The main objective of this work is to evaluate the seismic performance of a Column Cell Building, constituted based on concentrically braced frames (CBF). To achieve this, it was first designed according to the provisions of the NCh2369 update, and then a nonlinear time-history analysis was carried out considering the nonlinearity of anchor bolts and bracing for two seismic demand scenarios: design level (SDI) and maximum probable seismic level (SMP). In order to follow the guidelines of the original design, the design was carried out with a factor R=3 and I=1.0, resulting in a structure with overstrength. The bracings were made up of hollow square profiles HSS, as they better comply with the new compactness limits and were sized to be as tight as possible, however, these compactness limits in many cases controlled the design. On the other hand, the configuration of the anchor bolts is controlled by a single anchor for each type of column, leaving the rest of the anchors oversized. In the nonlinear analysis, the structure worked in its overstrength range, with moderate use of ductility. Bracing dissipates considerably more energy than anchor bolts in all cases, with an average energy dissipation participation of 30% and 47% for SDI and SMP levels, respectively.
Description
Tesis para optar al título profesional de Ingeniero/a Civil
Keywords
Sismos, Diseño de estructuras