Resumo Pesquisadores devem decidir sobre como modelar a resposta não linear do material em uma simulação com Elementos Finitos para avaliar a vulnerabilidade sísmica. Esse trabalho pretende auxiliar nessa tomada de decisão ao comparar os modelos de Fibra e de Plasticidade Concentrada em Elementos Finitos em análises não lineares estáticas e dinâmicas de um pórtico em concreto armado. A metodologia é baseada na engenharia de desempenho sísmico (PBEE) para determinar o dano nas estruturas. Os resultados indicam que os dois modelos apresentam uma boa correspondência em uma análise estática, e ao considerar os Estados Limite de Dano Extensivo e Completo na análise dinâmica. A escolha entre os dois depende dos objetivos principais do pesquisador e dos recursos disponíveis, já que eles apresentam uma significativa diferença no tempo de processamento. sísmica armado PBEE (PBEE estruturas estática dinâmica disponíveis processamento

Abstract Researchers must decide on how they will model the non-linear material response in a Finite Element simulation to assess seismic vulnerability. This paper aims at giving an insight into these modelling decisions by comparing Fiber and Lumped Plasticity Finite Element Models in static and dynamic non-linear analysis in a RC frame. The methodology is based on the performance-based earthquake engineering to determine the expected damage on structures. The results indicate that both models are in good agreement with the static analysis, and when considering Extensive and Complete Damage Limit States on the dynamic analysis. The choice between them depends on the main goals of the research and resources available, since they have a significant difference in processing time. nonlinear non linear vulnerability frame performancebased performance structures available time

RESUMO Este artigo apresenta uma proposta para determinação da capacidade estrutural de portfólios de pontes. Uma prática comum é o uso de modelos de capacidade baseados na ductilidade. Neste trabalho, a ductilidade é substituída por curvatura ou drift como parâmetros de demanda, uma vez que a variabilidade dos parâmetros que definem classes de pontes é considerada nos resultados e análises multidirecionais do tipo Pushover são realizadas para avaliar cenários de forças bidirecionais. Uma aplicação da metodologia é exemplificada para um inventário de pontes típicas situadas no Nordeste do Brasil. Análises paramétricas são realizadas por meio da variação das taxas de armaduras para determinação dos estados-limites dentro dos valores estudados. Os resultados dos estados limites de capacidade são informações valiosas para realização de estudos de vulnerabilidade de portfólios de pontes para diferentes fontes de ameaça, como sismos.

ABSTRACT This article presents a new proposal to estimate structural capacity models for bridge portfolios. A common approach is the use of ductility-based capacity models. Herein, a ductility replacement for curvature or drift as engineering demand parameters is conducted, as variability within the bridge’s classes is considered in the results and multidirectional pushover analyses are performed to assess a bi-directional load scenario. Application of the methodology is exemplified for an inventory of Northeastern Brazilian bridges. Parametric analyses are performed by varying the reinforcement ratios to estimate the capacity limit states within the range of values used. These results from probabilistic models define the capacity limit state that can be used to perform vulnerability assessment of bridges to different hazard sources, such as earthquakes.

resumo: Diante da escassez de estudos sobre a avaliação sísmica de edificações brasileiras, esse estudo tem como objetivo apresentar e discutir a avaliação da confiabilidade sísmica de um pórtico de concreto armado dimensionado de acordo com a ABNT NBR 6118:2014 sem a consideração do dimensionamento sísmico prescrito pela ABNT NBR 15421:2006. Neste trabalho, funções de fragilidade são geradas através de análises probabilísticas de demanda sísmica e integradas com curvas de ameaça sísmica da região Nordeste do Brasil para gerar mapas regionais de probabilidade de falha para três estados limites: Ocupação Imediata (IO), Segurança à Vida (LS) e Prevenção ao Colapso (CP). Os resultados indicam que o desempenho da edificação é adequado para IO, mas para LS e CP, um desempenho inaceitável é observado.

abstract: Due to the paucity of studies regarding the seismic assessment of buildings in Brazil, this study aims to present and discuss a seismic reliability assessment of a reinforced concrete framed structure designed according to the Brazilian standard ABNT NBR 6118:2014 without the consideration of the seismic design requirements of ABNT NBR 15421:2006. Herein, fragility functions are generated through probabilistic seismic demand analysis, and integrated with hazard curves for Northeastern Brazil to generate regional failure probability maps for three limit-states: Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP). The results indicated that the building performance is adequate for IO; however, for LS and CP, an unacceptable performance is observed.

Abstract 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.

RESUMO Diante da tendência mundial de mapas de dimensionamento sísmico com risco-alvo, é importante que o Brasil seja inserido nesse contexto. Este estudo objetiva aplicar a metodologia de risco-alvo para o Nordeste do Brasil, mais especificamente a região dentro da Zona 1 da norma ABNT NBR 15421:2006. Diferentes dados de entrada para a metodologia são explorados e combinados com estudos já existentes de ameaça sísmica para a região, e seus impactos no mapa final são avaliados. Os resultados demonstram que, dependendo do nível de segurança exigido, as acelerações de projeto podem ser menores que as comumente adotadas nas normas, mas podem também ser consideravelmente maiores. Os resultados também são comparados com a norma atual e suas diferenças discutidas, fornecendo informações sobre o nível de segurança fornecido pela norma.

ABSTRACT Given the tendency of risk-targeted seismic design maps worldwide, it is important that Brazil is inserted in this context as well. This study aims to apply the risk-targeting methodology for Northeastern Brazil, more specifically the region within Zone 1 of the Brazilian earthquake-resistant design code ABNT NBR 15421:2006. Different inputs for the methodology are explored and combined with existing hazard studies for the region, and their impact in the final map are evaluated. The results outline that, depending on the safety level required, the provisioned design accelerations could be lower than the commonly used in codes, but may as well be much higher. The results are also compared with the current code provisions and their differences are discussed, providing insights on the code provisioned level of safety.

Abstract The ultimate limit state of stability by equilibrium bifurcation, the limit states for stress and strain resulting from this condition were evaluated for an extremely slender real structure of reinforced concrete, with geometry varying along its length. The aspects related to nonlinearities of the material were considered through the recommendations on NBR 6118:2014, from the Brazilian Association of Technical Standards (ABNT). In the analytical solution, developed for stability analysis, all elements of the structural dynamics present in the system were taken into account, including the column self-weight. The critical buckling load was then dynamically defined to different instants of time. Reductions of 70% for the modulus of elasticity and 59% for the critical buckling force were found in analyses performed from zero and five thousand days. It was also possible to obtain the induced stresses on the homogenized cross-sections and those transferred to reinforcement steel bars.

Abstract The Brazilian design load standard still provides a wind speed map developed in 1977. Since then, new data have been collected and new charts have been proposed in literature. The literature not only alerts to changes in short-term wind gust patterns, but it also warns that the wind speed values are higher than observed in the past. Many researchers have suggested that these differences are correlated to climate change effects. Besides the geophysical and societal impacts of climate change, there is a general concern between designers on the impacts of higher wind speeds on structural design. This paper aims to analyze the wind speed as a stochastic variable and its influence on the design of steel structures when changes in wind speed occur. A stochastic approach is used to evaluate expected stress values for a steel beam-column example. A Monte Carlo analysis is performed on a forty-story steel frame to compare the impact of different wind speed scenarios and types of analysis. In the analyses, the wind speed is approached by a Gumbel distribution and future wind scenarios are generated for sensitiveness evaluation. The analytical and Monte Carlo analyses indicate that greater attention shall be given to the consequences of using an average wind speed value instead of a probability distribution function.