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 (NBR8681:2003), and for steel (NBR8800:2008) and concrete (NBR6118:2014) 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.

This paper presents an investigation on the safety of structural elements submitted to pure bending, produced in reinforced concrete, in steel and steel-concrete composites, and designed according to Brazilian codes NBR8681:2003, NBR6118:2007 and NBR8800:2008. The study allows a comparison of the relative safety of beams produced with these materials and designed using these codes. Comparative studies between the performances of different materials are difficult to find in the published literature. The present study shows that reliability indexes for reinforced concrete beams are satisfactory; however, results for steel beams are below limit values established in international design standards. Reliability indexes found herein for steel-concrete composite beams are intermediate to concrete and steel beams.

This work presents a comparative analysis between two model hierarchies commonly applied in tunnel structural design: continuum ground models and bedded-beam models. Firstly, the main characteristics of each model and the interfaces between them are discussed. Based on those evaluations a simple procedure is proposed for determining the bedded-beam model imposed loads which lead to results compatible to those of a given continuum model. Said procedure is then explored to estimate simplified compatibilization loads for basic and illustrative cases, where a reasonable compatibilization was achieved for a relatively simple applied load.

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The construction methods currently adopted for multi-story concrete buildings resorts the strategy to cast columns and slabs with high and normal compressive concrete strength, respectively. The intersection region affects the load transfer performance of the columns, causing expressive confinement stress in interior columns. However, when the confinement is only provided by two sides, as corner columns, it is not enough to increase the lateral stress. The structural behavior of corner columns, represented by isolated columns, also called sandwich column, is investigated in this paper through numerical nonlinear models. The lateral stresses induced by the uniaxial load applied to the sandwich columns are computed when the influence of concrete strength column-slab ratio, slab thickness and the column width ratio and the biggest dimension of the column's cross section were tested. A set of expressions were proposed to calculate the effective compressive strength of the column based on numerical results. The predicted effective strength has shown a good agreement with experimental results collected from the literature.