Fire Behaviour of Timber-Encased Steel Composite Structures: A Meta-Analytic Review of Experimental Findings and Design Implications
Girmay Mengesha Azanaw
Girmay Mengesha Azanaw, Lecturer, Department of Civil Engineering, University of Gondar, Gondar, Ethiopia.
Manuscript received on 30 October 2025 | First Revised Manuscript received on 04 November 2025 | Second Revised Manuscript received on 18 November 2025 | Manuscript Accepted on 15 December 2025 | Manuscript published on 30 December 2025 | PP: 1-5 | Volume-14 Issue-1, December 2025 | Retrieval Number: 100.1/ijese.L263113121125 | DOI: 10.35940/ijese.L2631.14011225
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: Timber-encased steel composite (TESC) systems have emerged as a promising structural solution combining strength, sustainability, and enhanced fire performance. This meta analytic review synthesises experimental and numerical findings reported between 2020 and 2025 to assess the influence of timber encasement on the fire resistance of steel members. Data from full-scale and small-scale fire tests were statistically aggregated using random-effects models to determine pooled fire resistance and to quantify the effects of parameters such as timber thickness and moisture content. Results show that complete timber encasement markedly delays steel heating and improves fire endurance. On average, each additional millimetre of timber cover contributes approximately 1.9 minutes of fire resistance (p < 0.01), with 50 mm of encasement providing roughly 1 hour of protection under ISO 834 conditions. Moisture within the timber further reduces the rate of temperature rise by absorbing latent heat during evaporation. The study confirms that the insulating and charring behaviour of timber functions as an effective passive fire-protection layer, offering an alternative to conventional coatings or boards. The design implications are significant: empirical correlations between cover thickness and fire resistance can inform future fire design models and code calibrations. Remaining research needs include long-term performance of composite joints and validation under realistic fire scenarios. Overall, the review provides quantitative evidence supporting timber encasement as a viable, sustainable, and code integrable approach for improving the fire safety of composite steel structures.
Keywords: Timber-Encased Steel, Fire Performance, Composite Structures, Meta-Analysis, And Structural Design.
Scope of the Article: Structural Engineering