Seismic fragility assessment, retrofit and functional recovery of reinforced concrete wall buildings
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Date
2023
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Abstract
Reinforced concrete (RC) wall buildings have generally exhibited adequate behavior during recent earthquakes to prevent collapse and protect lives. Nevertheless, significant damage and associated economic losses have been observed. For instance, following the 2010 Chile earthquake, medium-rise RC wall buildings with thin unconfined walls sustained extensive localized brittle damage due to high axial loads. Although only about 2% of this building class displayed significant damage, many similar buildings experienced minor or no damage. This study aimed to assess the seismic performance of RC wall buildings and evaluate the effectiveness of different retrofit strategies in achieving functional recovery goals. The first part of the research focused on the seismic fragility assessment of mediumrise RC wall buildings with high wall densities, thin unconfined walls under high axial loads, and significant vertical irregularities. Finite element models of archetype buildings were developed, and nonlinear time-history analyses were conducted to estimate engineering demand parameters. The results indicated that existing component damage fragility models did not accurately capture the damage in these buildings. Consequently, new damage limit states, better aligned with expected and previously observed damage, were proposed. In the second part of this research, a qualitative analysis with experienced seismic retrofit participants identified barriers and opportunities for functional recovery in seismic retrofit decisions, revealing issues related to costs, tools, guidelines, and communication. Potential opportunities to address these barriers included improving funding mechanisms, enhancing benefit communication, and developing tools and guidelines. Additionally, a study was carried out to quantitatively assess the seismic performance of RC wall buildings before and after retrofitting, focusing on achieving functional recovery goals. Results showed that retrofit strategies, such as adding new RC walls or increasing wall thickness, improved collapse capacity and reduced drift demands, significantly decreasing recovery times despite increased acceleration demands. Modifications are needed to U.S. based seismic assessment frameworks for applicability in Chile and other context.
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Tesis (Doctor in Engineering Sciences)--Pontificia Universidad Católica de Chile, 2023
Tesis (Doctor of Philosophy)--University of Colorado Boulder, 2023
Tesis (Doctor of Philosophy)--University of Colorado Boulder, 2023
Keywords
Reinforced concrete wall buildings, Seismic performance, Fragility assessment, Seismic retrofit, Functional recovery assessment