Browsing by Author "Siqueira, Gustavo Henrique"

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    Seismic fragility assessment of typical bridges in Northeastern Brazil
    (SciELO, 2022) Cavalcante, Gustavo Henrique Ferreira; Pereira, Eduardo Marques Vieira; Rodrigues, Isabela Durci; Vieira Júnior, Luiz Carlos Marcos; Padgett, Jamie Ellen; Siqueira, Gustavo Henrique
    This paper presents a seismic fragility assessment of bridges commonly found in Northeastern Brazil. A generic three-dimensional nonlinear finite-element model is generated in OpenSees to enable variation of geometric features and component modeling. A parametric analysis is performed to evaluate the impact of the geometric and physical variations of the bridge inventory on the seismic behavior of the structures. Nonlinear time-history analyses using four sets of natural earthquake records are performed to obtain the Probabilistic Seismic Demand Model for the bridges. Capacity models are adopted according to previous studies to be combined with demand models to generate fragility functions. This article helps the decision markers to predict the seismic behavior of typical bridges in Northeastern Brazil, which enables the evaluation of risk mitigation methods.
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    Seismic Performance Assessment of a Retrofitted Bridge with Natural Rubber Isolators in Cold Weather Environments Using Fragility Surfaces
    (ASCE, 2022) Bandini, Pedro Alexandre Conde; Siqueira, Gustavo Henrique; Padgett, Jamie Ellen; Paultre, Patrick
    Rubber-based seismic isolation has been demonstrated to be one of the most effective measures to protect structural elements from damage during earthquakes and a viable option to retrofit existing structures with poor seismic detailing. The main constituent of these isolation units is rubber, a material that is subject to stiffening when exposed to low air temperatures. In the case of isolated highway bridges, thermal stiffening might reduce the efficiency of isolators, transferring higher forces to the substructure. Assessment of the seismic response of retrofitted structures using rubber isolators in cold regions is thus necessary. Accordingly, in this study, the effect of low temperatures on the seismic performance of a highway bridge retrofitted with natural rubber (NR) isolators is quantified using a probabilistic framework based on fragility surfaces. From the component- and system-level surfaces, it is revealed that the effects of cold temperatures on highway bridges retrofitted with elastomeric isolators may be negligible, depending on the configuration of lateral restraining structures. However, when isolators are able to perform their function without impediment, their thermal stiffening might be significantly detrimental to the bridge’s substructure, mainly affecting bent columns.