Reinforced concrete bridge pier ductility analysis for different levels of detailing

Abstract

ResumoThe structural design under seismic loading has been for many years based on force methods to consider the effects of energy dissipation and elastoplastic behavior. Currently, displacement-based methods are being developed to take into account elastoplastic behavior. These methods use moment-curvature relationships to determine the ductility capacity of a structural element, which is the deformation capacity of the element before its collapse. The greater the plastic displacement or rotation a structural member can achieve before it collapses, the more energy it is capable of dissipating. This plastic displacement or rotation capacity of a member is known as the member ductility, which for reinforced concrete members is directly related to efficient concrete confinement. This study investigates at which extents transverse reinforcement detailing influences reinforced concrete column ductility. For this, a bridge located in Ecuador is modeled and analyzed, and its ductility evaluated considering several cases of axial loading and concrete confinement levels. After the performed displacement-based analyses, it is verified whether the response modification factor defined by AASHTO is adequate in the analyzed case.Keywords: seismic resistant structures, reinforced concrete seismic detailing, ductility capacity, plastic dissipation, seismic design of bridges, ductility, displacement-based design.O projeto estrutural para cargas sísmicas tem sido por muitos anos baseado em métodos de avaliação de forças para considerar os efeitos de dissipação de energia e comportamento elastoplástico. Presentemente métodos baseados em deslocamentos estão em desenvolvimento para a consideração do comportamento elastoplástico. Estes métodos usam relações momento-curvatura para determinar a ductilidade disponível de um elemento estrutural, que é a capacidade de deformação do elemento antes de seu colapso. Neste artigo é apresentada a análise e a avaliação do comportamento de pontes usando métodos baseados em deslocamentos. Para isso, uma ponte localizada no Equador é modelada e analisada e sua ductilidade disponível é verificada considerando-se diversos casos de carga axial e de situações de confinamento do concreto. Uma análise "push-over" é também realizada e os resultados obtidos são comparados.Palavras-chave: análise sísmica, análise dinâmica, análise sísmica de pontes, dutilidade, projeto baseado em deslocamentos.

A new methodology to assess the structural capacity of bridge portfolios: application in Northeastern Brazilian bridges

“…The results of the parametric analyses enable the generation of linear relations between the yield curvature and the reinforcement ratios. Such relations are useful to estimate capacity models for probabilistic or deterministic vulnerability assessments ( [11]- [17] and [53]) or displacement-based design procedures [54]. The former is particularly useful in Brazil, given the lack of studies that developed such relations, and the variety of old and new bridges designed according to different codes (consequently, different reinforcement ratios).…”