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 concrete structures present several geometric deviations, some of them considered indirectly in the safety factors of the design. However, the imperfections of the element axes, especially columns, should be explicitly considered in the structural analysis because they have great influence over the building stability. The NBR 6118:2014, Brazilian standard code for the design of concrete structures, defines a global geometric inclination to the columns, also called “out-of-plumb columns”, that causes additional forces not presented in the “perfect” structure, which must be considered as a permanent action. The code also sets the design equations, as well as the load combination criteria. Although the expressions for the out-of-plumb angle calculation are used in the designs, they are not well understood by the technical community or even really explained in Brazilian publications. This paper discusses the theoretical basis that supports such expressions and compares what is presented in NBR 6118:2014 to other international codes. Structural analysis results are discussed, considering buildings with different heights and loadings, to evaluate how the global out-of-plumb effect seems to be relevant. The main objective is to contribute to a better understanding of the concrete building design principles and, specifically, fill a gap in national technical literature about this global imperfection.