Reliability-based calibration of main Brazilian structural design codes

Wagner Carvalho Santiago Henrique Machado Kroetz Sérgio Hampshire de C. Santos Fernando Rebouças Stucchi André Teófilo Beck About the authors

Abstract

Structural reliability theory has long been recognized as the proper tool to guide selection of partial safety factors in limit state structural design codes. Brazilian design codes, however, have never been through this calibration process. This paper addresses the reliability-based calibration of partial safety factors of Brazilian design codes for loads (NBR8681:2003ABNT NBR 8681 (2003) Actions and safety of structures - procedure, Associação Brasileira de Normas Técnicas, Rio de Janeiro, RJ.), and for steel (NBR8800:2008ABNT NBR8800 (2008) Design of Steel and Steel-Concrete Composite Structures: Procedures, Associação Brasileira de Normas Técnicas, Rio de Janeiro, RJ.) and concrete (NBR6118:2014ABNT NBR6118 (2014) Design of concrete structures - procedure. Associação Brasileira de Normas Técnicas, Rio de Janeiro, RJ.) structures. The study is based on an extensive dataset of load and strength variables, addressing the Brazilian reality, as much as possible. Calibration minimizes the variations of reliability indexes of the most diverse structures designed according to the codes of interest, with regard to a target reliability index chosen by the analyst. The main result of calibration is to make reliability indexes more uniform, for different design configurations. In case of Brazilian codes, this could be achieved by increasing main variable loads, and reducing the combination values of secondary loads. This paper presents results that are not (yet) recommended for adoption in Brazilian codes, but which should be discussed with the community in order to reach minimal consensus.

Keywords:
code calibration; steel structures; concrete structures; reliability analysis; partial factor design; structural safety

Graphical Abstract

Keywords:
code calibration; steel structures; concrete structures; reliability analysis; partial factor design; structural safety

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