Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada
Over the years, structural engineering codes and specifications in Canada and elsewhere have moved from an allowable stress design (ASD) approach to a load and resistance factor design (LRFD) philosophy. LRFD methodology takes better account of the inherent variability in both loading and resistance...
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| Format: | Article |
| Language: | English |
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MDPI AG
2024-03-01
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| Series: | Buildings |
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| Online Access: | https://www.mdpi.com/2075-5309/14/3/855 |
| _version_ | 1797241727133679616 |
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| author | Sami W. Tabsh Moussa Leblouba |
| author_facet | Sami W. Tabsh Moussa Leblouba |
| author_sort | Sami W. Tabsh |
| collection | DOAJ |
| description | Over the years, structural engineering codes and specifications in Canada and elsewhere have moved from an allowable stress design (ASD) approach to a load and resistance factor design (LRFD) philosophy. LRFD methodology takes better account of the inherent variability in both loading and resistance by providing different factors of safety for loads of distinct natures with regard to their probability of overload, frequency of occurrences and changes in point of application. The method also results in safer structures because it considers the behavior at collapse. While resistance factors for traditional construction materials based on LRFD in the National Building Code (NBC) of Canada are available, they cannot be used for non-conventional ones. This is because the resistance of such materials due to various load effects has unique bias factors (λ<sub>R</sub>) and coefficients of variation (V<sub>R</sub>), which greatly impact their reliability index (β). In this study, relationships between the resistance factor ϕ and critical load effects from the NBC load combinations at ultimate limit states are developed for a wide range of resistance bias factors and coefficients of variation. The relationships are presented in the form of charts that are useful for researchers and code-writing professionals who have expertise in the various fields of structural engineering but lack proper background in reliability theory. The developed spectra showed that for the same ϕ, β increases with an increase in the live-to-dead load (L/D) ratio until it reaches 1; thereafter, the shape of the relationship will depend on the statistics of the resistance as well as on the magnitude of ϕ. For a small ϕ and V<sub>R</sub>, β will keep increasing with an increase in the L/D ratio from 1 until 3, albeit at a lesser rate. For L/D > 3, the relationship between the critical β and applied load is just about constant. This finding is also true for load combinations involving snow and wind. Application of the method is illustrated by a practical example involving the shear strength of a corrugated web steel beam. |
| first_indexed | 2024-04-24T18:27:55Z |
| format | Article |
| id | doaj.art-680adff91a3d448e854a5bfe7bdd5513 |
| institution | Directory Open Access Journal |
| issn | 2075-5309 |
| language | English |
| last_indexed | 2024-04-24T18:27:55Z |
| publishDate | 2024-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Buildings |
| spelling | doaj.art-680adff91a3d448e854a5bfe7bdd55132024-03-27T13:29:44ZengMDPI AGBuildings2075-53092024-03-0114385510.3390/buildings14030855Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of CanadaSami W. Tabsh0Moussa Leblouba1Department of Civil Engineering, College of Engineering, American University of Sharjah, Sharjah 26666, United Arab EmiratesDepartment of Civil & Environmental Engineering, College of Engineering, University of Sharjah, Sharjah 27272, United Arab EmiratesOver the years, structural engineering codes and specifications in Canada and elsewhere have moved from an allowable stress design (ASD) approach to a load and resistance factor design (LRFD) philosophy. LRFD methodology takes better account of the inherent variability in both loading and resistance by providing different factors of safety for loads of distinct natures with regard to their probability of overload, frequency of occurrences and changes in point of application. The method also results in safer structures because it considers the behavior at collapse. While resistance factors for traditional construction materials based on LRFD in the National Building Code (NBC) of Canada are available, they cannot be used for non-conventional ones. This is because the resistance of such materials due to various load effects has unique bias factors (λ<sub>R</sub>) and coefficients of variation (V<sub>R</sub>), which greatly impact their reliability index (β). In this study, relationships between the resistance factor ϕ and critical load effects from the NBC load combinations at ultimate limit states are developed for a wide range of resistance bias factors and coefficients of variation. The relationships are presented in the form of charts that are useful for researchers and code-writing professionals who have expertise in the various fields of structural engineering but lack proper background in reliability theory. The developed spectra showed that for the same ϕ, β increases with an increase in the live-to-dead load (L/D) ratio until it reaches 1; thereafter, the shape of the relationship will depend on the statistics of the resistance as well as on the magnitude of ϕ. For a small ϕ and V<sub>R</sub>, β will keep increasing with an increase in the L/D ratio from 1 until 3, albeit at a lesser rate. For L/D > 3, the relationship between the critical β and applied load is just about constant. This finding is also true for load combinations involving snow and wind. Application of the method is illustrated by a practical example involving the shear strength of a corrugated web steel beam.https://www.mdpi.com/2075-5309/14/3/855code calibrationload combinationload factorreliabilityresistance factorstructural safety |
| spellingShingle | Sami W. Tabsh Moussa Leblouba Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada Buildings code calibration load combination load factor reliability resistance factor structural safety |
| title | Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada |
| title_full | Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada |
| title_fullStr | Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada |
| title_full_unstemmed | Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada |
| title_short | Resistance Factor Spectra for the Ultimate Limit State of the National Building Code of Canada |
| title_sort | resistance factor spectra for the ultimate limit state of the national building code of canada |
| topic | code calibration load combination load factor reliability resistance factor structural safety |
| url | https://www.mdpi.com/2075-5309/14/3/855 |
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