Resistance factor calibration for cold-formed steel compression members

Freitas, Marcílio Sousa da Rocha; Brandão, André Luiz; Freitas, Arlene Maria Sarmanho

doi:10.1590/s0370-44672013000200015

Cited by 3 publications

(2 citation statements)

References 12 publications

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“…When calibration is performed from LSD data (Figure 2), with a target index 𝛽 of 3.0, most of the results obtained are not satisfactory, with 𝛽 predominantly lower than the target. This behavior was observed in works developed by Ganesan (2010), Freitas, Brandão andFreitas (2013) and Capanema (2018). The 𝛽 values calculated by the FOSM method were those that came closest to the target.…”

Section: Resultssupporting

confidence: 63%

Resistance Factor Calibration for Perforated Cold-Formed Steel Compression Members

Jardim

Freitas

Brandão

2021

ric

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Cold-formed Steel profiles are structural profiles widely used in civil construction. They are often manufactured with perforations. The designing can be performed using the direct resistance method. Formulations were adapted by Moen and Schafer (2008) to consider the presence of perforations in these profiles. The objective of this study is to investigate the structural safety of columns with web perforations. The calculation of the resistance capacity was performed using the formulations proposed by the authors. The reliability indexes were determined using the First Order Reliability Method (FORM), First Order Second Moment (FOSM) and Monte Carlo Method (MCM), which are reliability methods for the Load and Resistance Factor Design (LRFD) and Limit States Design (LSD) philosophies. Following the same criteria performed by AISI S100, the resistance factors were obtained from the FOSM method. Based on the results, it was found that the desired security level for the LSD philosophy was not achieved. The calculated resistance factors are predominantly lower than the target. However, for the LRFD philosophy, the safety level was achieved, and the resistance factors were higher than the target.

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Section: Resultssupporting

confidence: 63%

Resistance Factor Calibration for Perforated Cold-Formed Steel Compression Members

Jardim

Freitas

Brandão

2021

ric

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“…From the values of the professional factor, the average of the random variable, P m , which indicates the biased character of the theoretical model, was generated. Thus, P m , which should be unitary if the model represents exactly the studied physical phenomenon, reveals how conservative or not the model in question is, so that possible corrections are made (Brandão, 2012;Freitas et al, 2013;Freitas et al, 2018). The coefficient of variation (V P ) is the ratio of the standard deviation to the mean.…”

Section: Professional Factormentioning

confidence: 99%

Reliability assessment of cold-formed steel beams by the FORM method

2021

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This article presents a procedure for the reliability assessment of cold-formed steel beams based on the Direct Strength Method (DSM) and the Effective Section Method (ESM). Using a comprehensive database, a statistical analysis of the test results was performed to determine the statistical properties of the professional factor random variable. The statistical parameters related to material strength, geometric properties and load effects were obtained from established references for reliability analysis. Safety levels compatible with the North American and the Brazilian codes relating to structural design of cold-formed steel members have been established. The first-order reliability method (FORM) was used to calculate resistance factors φ for usual nominal live-dead ratios. The results of the reliability analysis showed that the DSM and ESM design methods have similar levels of reliability. The same resistance factor as the DSM can be used for the ESM, without compromising the minimum level of reliability established. The results obtained with the LRFD calibration data, presented a good approximation with the load factor φ = 0.90, except for the distortional mode. With the LSD calibration data, values well below the specified were required in order to achieve the required level of reliability. It was also found that the load factor γ = 1.25, in the format of the Brazilian standard, could reach the safety requirements established for all buckling modes.

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