Abstract
Structural systems like timber trussed rafters and roof elements made of timber can be expected to have some degree of redundancy and nonlinear/plastic behaviour when the loading consists of for example snow or imposed load. In this paper this system effect is modelled and the statistic characteristics of the load-bearing capacity is estimated in the form of a characteristic value and a coefficient of variation. These two values are of primary importance for codes of practice based on the partial safety factor format since the partial safety factor is closely related to the coefficient of variation.
In the paper a stochastic model is described for the strength of a single piece of timber taking into account the stochastic variation of the strength and stiffness with length. Also stochastic models for different types of loads are formulated. First, simple representative systems with different types of redundancy and non-linearity are considered. The statistical characteristics of the load bearing capacity are determined by reliability analysis. Next, more complex systems are considered modelling the mechanical behaviour of timber roof elements I stressed skin panels made of timber. Using the above stochastic models, statistical characteristics (distribution function, 5% quantile and coefficient of variation) are determined. Generally, the results show that taking the system effects into account the characteristic load bearing capacity can be increased and the partial safety factor decreased compared to the values obtained if the system effects are not considered.
In the paper a stochastic model is described for the strength of a single piece of timber taking into account the stochastic variation of the strength and stiffness with length. Also stochastic models for different types of loads are formulated. First, simple representative systems with different types of redundancy and non-linearity are considered. The statistical characteristics of the load bearing capacity are determined by reliability analysis. Next, more complex systems are considered modelling the mechanical behaviour of timber roof elements I stressed skin panels made of timber. Using the above stochastic models, statistical characteristics (distribution function, 5% quantile and coefficient of variation) are determined. Generally, the results show that taking the system effects into account the characteristic load bearing capacity can be increased and the partial safety factor decreased compared to the values obtained if the system effects are not considered.
Original language | English |
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Title of host publication | Reliability and Optimization of Structural Systems : Proceedins of the 9th IFIP WG7.5 working conference on reliability and optimization of structural systems |
Editors | Andrzej S. Novak, Maria M. Szersen |
Number of pages | 8 |
Publisher | University of Michigan Press |
Publication date | 2000 |
Pages | 241-248 |
Publication status | Published - 2000 |
Event | Reliability and Optimization of Structural Systems: IFIP WG7.5 working conference on reliability and optimization of structural systems - Ann Arbor, Michigan, United States Duration: 25 Sept 2000 → 27 Sept 2000 Conference number: 9 |
Conference
Conference | Reliability and Optimization of Structural Systems |
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Number | 9 |
Country/Territory | United States |
City | Ann Arbor, Michigan |
Period | 25/09/2000 → 27/09/2000 |
Keywords
- Reliability Analysis
- Structural Timber