Browsing by Author "López-García, Diego"

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    Behavior of reinforced concrete shear wall buildings subjected to large earthquakes
    (2017) Ugalde Bedoya, David Guillermo; López-García, Diego
    Frame systems are the preferred structural systems in most seismic regions, where they are sometimes also combined with braces or walls. On the other hand Chile, one of the most seismically active countries in the world, is an exception to this practice. Any Chilean residential building higher than 5 stories is almost completely made up of reinforced concrete shear walls. Surprisingly, only 2% of the residential building inventory subjected to the 2010 Chile earthquake (M-w 8.8) suffered severe damage, even though many structures were affected by ground accelerations larger than those prescribed in the Chilean seismic design code. This observation suggests that there is a large (and unintended) overstrength in this type of buildings. In a previous study, the authors showed that some of the traditional sources of overstrength mentioned in the literature could explain the lack of damage in low rise buildings but not in taller structures. Motivated by this observation, representative tall buildings were reanalyzed using more realistic models (e.g., flexural capacity of the walls assessed by fiber models) in order to get more insight into their actual seismic capacity. Two actual buildings of 17 and 26 stories that survived with no damage the 2010 Chile earthquake were analyzed by response history analysis. Results show that consideration of wall flanges (usually omitted in practice) cannot explain the lack of damage. On the other hand, it is observed that good performance might be a consequence of possible foundation uplift. Finally, the analyses also suggest that, even when there is no damage, elastic analysis has limitations to reproduce the actual observed behavior. (C) 2017 The Authors. Published by Elsevier Ltd.
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    Criterio unificado para distribución en planta de disipadores de energía en estructuras asimétricas lineales sometidas a sismo
    (2008) Almazán Campillay, José Luis; López-García, Diego; Llera Martin, Juan Carlos de la
    La asimetría en planta es considerada por las normas de diseño sísmico y por la profesión en general como una propiedad no deseada de una estructura. De hecho, algunas normas limitan y castigan severamente la construcción de edificios fuertemente asimétricos. Sin embargo, y debido principalmente a razones arquitectónicas, estas estructuras se construyen muy frecuentemente en la práctica, haciendo indispensable el desarrollo de procedimientos para controlar su respuesta torsional. El uso de disipadores pasivos de energía es, en muchos casos, la solución práctica más aconsejable en la actualidad. Para atenuar los efectos torsionales y hacer un uso eficiente de estos disipadores, se requiere estudiar cuidadosamente tanto su distribución en altura como en planta. En los últimos 15 años se han propuesto numerosos métodos para optimizar la distribución en altura. Algunos de ellos proponen minimizar un cierto funcional definido en forma más o menos heurística, mientras que otros son aplicaciones de la teoría de control. En base a estudios sobre modelos planos de múltiples pisos, los resultados indican claramente que la reducción de la respuesta es muy sensible a la distribución en altura. Un poco más recientemente, se han propuesto también criterios para la distribución en planta de los disipadores, aunque la mayoría de ellos sólo son aplicables a modelos de un piso. Por lo tanto, no existe claridad respecto a cómo este conocimiento puede aplicarse a estructuras reales. Para ayudar a resolver este problema, se presenta en este trabajo un método que permite encontrar la distribución en planta y en altura en forma simultánea. El método consiste en minimizar un funcional calculado a partir de las deformaciones de entrepiso en los bordes del edificio, y en cada una de las dos direcciones principales. Los resultados encontrados indican que este procedimiento logra uniformar las deformaciones de entrepiso tanto en planta como en altura. Aunque en este caso se han usado modelos lineales sometidos a excitación sísmica probabilística, es posible aplicar el concepto a modelos no-lineales sometidos a cualquier tipo excitación.
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    Loss and Downtime Assessment of RC Dual Wall–Frame Office Buildings Toward Resilient Seismic Performance
    (2025) Gallegos Calderón, Marco Fernando; Araya Letelier, Gerardo Andrés; López-García, Diego; Molina Hutt, Carlos
    This study quantitatively assesses the impact of seismic design strategies on the performance of reinforced concrete (RC) dual wall–frame office buildings by comparing direct and indirect economic losses and downtime in life-cycle terms. A high-rise archetype building located in Santiago, Chile, on stiff soil was evaluated as a benchmark case study. Three design strategies to potentially enhance the seismic performance of a building designed conventionally were explored: (i) incorporating fluid viscous dampers (FVDs) in the lateral load-resisting structure; (ii) replacing conventional non-structural components with enhanced ones (ENCs); and (iii) a combination of the previous two strategies. First, probabilistic structural responses were estimated through incremental dynamic analyses using three-dimensional nonlinear models of the archetypes subjected to a set of hazard-consistent Chilean ground motions. Second, FEMA P-58 time-based assessment was conducted to estimate expected annual losses (EALs) for economic loss estimation. Finally, for downtime assessment, a novel probabilistic framework, built on the FEMA P-58 methodology and the REDi guidelines, was employed to estimate the expected annual downtimes (EADs) to achieve specific target recovery states, such as reoccupancy (RO) and functional recovery (FR). Results revealed that seismically enhancing RC dual wall–frame buildings with FVDs significantly improves resilience by reducing loss and downtime. For example, the enhanced building with FVDs achieved an EAL of 0.093% and EAL of 8.6 days for FR, compared to the archetype base building without design improvements, which exhibited an EAL of 0.125% and an EAD of 9.5 days for FR. In contrast, the impact of ENCs alone was minor, compared to the effect of FVDs, with an EAL of 0.106% and an EAD of 9.1 days for FR. With this detailed recovery modeling, probabilistic methods, and a focus on intermediate recovery states, this framework represents a significant advancement in resilience-based seismic design and recovery planning.