Seismic vulnerability evaluation of regular reinforced concrete buildings in Brazil through the development of fragility curves

Author(s)

Isabela Durci Rodrigues

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Civil, Arquitetura e Urbanismo
• Defense date: 2021-01-22

Examining board members

Gustavo Henrique Siqueira; Isaias Vizotto; André Teófilo Beck

• Advisor: Gustavo Henrique Siqueira; Luiz Carlos Marcos Vieira Junior

Abstract

This work aims to evaluate the damage that a seismic event can cause to regular Brazilian reinforced concrete structures, through the development of analytical fragility curves. For many years Brazil, due its geographical location inside a tectonic plate, built up structures with no design recommendations regarding seismicity events. Brazilian seismic standard, ABNT NBR 15421 (2006), is recent and has some differences when compared with international standards in the subject. Furthermore, recent studies show that Brazilian territory has registered seismic events with representative magnitude. If such events happens in urban areas with high demographic density, the structural damage might be catastrophic, since most buildings don¿t have specific standard design prescriptions for this kind of actions. In order to assess the vulnerability of regular reinforced concrete structures subject to seismic event, this work aims to quantify the probability of reaching a Damage Limit State given an intensity measure of the earthquake (IM) in Brazilian standard buildings with statistical tools. Ordinary buildings are considered and seismic events that represent Brazilian scenario are chosen, and, after a nonlinear analysis of these structures, fragility curves are developed for different levels of damage of its components. With these results, it is possible to assess how structures designed and built in a specific Brazilian region would behave if they were exposed to a seismic event. The city chosen for this study is the city of Natal, on the state of Rio Grande do Norte, because of the seismic activity on the state. A structural design representative of the buildings in the area is chosen, and it is modelled with the Finite Element Method using OpenSees (MCKENNA et al., 2006). Deterministic non-linear static (Pushover) and dynamic (Incremental Dynamic) analysis are developed to know the demand and capacity of the structural model, based on earthquake¿s records that represent the area of study. Then, the uncertainties of the model and from the earthquake are considered, and a probabilistic analysis is done to calculate the fragility curve for each one of the established Damage Limit States. This methodology is part of the Performance-Based Earthquake Engineering (PBEE) for the design based on different loss scenarios. The results indicate that seismic event that may happen in Natal can cause sligth and moderate damage on structures with a probability of 100%, considering the spectral acceleration values proposed by Petersen et al. (2018) for different return periods. Buildings with 8 and 10 storeys have higher probability of having Extensive and Complete damage than 6 storey buildings (AU)

• FAPESP's process: 18/23304-9 - Seismic vulnerability evaluation of regular reinforced concrete buildings in Brazil through the development of fragility curves
• Grantee: Isabela Durci Rodrigues
• Support Opportunities: Scholarships in Brazil - Master