| Title: | Toward a general and reliable application of overstrength in timber engineering |
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| Authors: | ID Brandner, Reinhard (Corresponding author)
ID Azinović, Boris (Corresponding author) |
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| Files: |  URL - Source URL, visit https://doi.org/10.1016/j.engstruct.2026.123156
 PDF - Presentation file, download (1,89 MB)
MD5: 806BE73037F06FD7EFE1F43A9D4BB067
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| Language: | English |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: |  ZAG - Slovenian National Building and Civil Engineering Institute
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| Abstract: | Capacity design is fundamental to achieve ductile structural behaviour, yet its implementation in timber engineering remains challenging due to the material’s inherent variability and brittleness. Existing definitions of the overstrength factor – whether based on the load-and-resistance factor design (LRFD) framework or derived from component-level structural reliability analysis – often fail to ensure the intended failure hierarchy or result in uneconomic designs. This paper revisits the concept of overstrength, focusing on the unique characteristics of timber structures, where ductility is typically provided by steel connectors with negligibly varying properties while properties of timber components exhibit significantly greater stochastic variability. A new system-based reliability concept is introduced that simultaneously accounts for interactions between actions, ductile capacities, and brittle capacities. By linking target failure probabilities for ductile and non-ductile components, the proposed definition ensures that brittle failure remains consistently less likely than ductile yielding, even in cases where the variability of the brittle, non-ductile components is much higher than of the ductile component, as common in timber engineering. A comprehensive parametric study involving 60 cases evaluates the influence of load ratios, model uncertainty, and variability in actions and capacities within structural reliability analyses. The outcome from the structural reliability-based overstrength formulation was converted into overstrength factors applicable within the LRFD framework. Results show that current overstrength provisions may be insufficient or conservative, whereas the proposed approach provides a more reliable, transparent, and adaptable basis for future code development. |
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| Keywords: | overstrength, timber engineering, connections, joints, ductile failure, brittle failure |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Publication date: | 20.06.2026 |
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| Publisher: | Elsevier |
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| Year of publishing: | 2026 |
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| Number of pages: | str. 1-16 |
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| Numbering: | Vol. 365, [article no.] 123156 |
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| PID: | 20.500.12556/DiRROS-31173  |
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| UDC: | 624.07 |
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| ISSN on article: | 1873-7323 |
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| DOI: | 10.1016/j.engstruct.2026.123156 |
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| COBISS.SI-ID: | 283548675 |
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| Copyright: | © 2026 The Author(s) |
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| Note: |
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| Publication date in DiRROS: | 17.07.2026 |
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| Views: | 26 |
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| Downloads: | 11 |
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