A Study on High-Temperature Tensile Strength Characteristics and Residual Strength of Natural Timber from a Fire Safety Perspective : Temperature and Heating-Time Based Residual Strength Models for Ipe, Malas, and Merbau
Abstract
Purpose: Despite the rapid adoption of natural timber driven by carbon-neutral policies, quantitative evidence on the mechanical degradation of structural wood exposed to fire-induced high temperatures remains scarce. This study clarifies how temperature and heating duration affect the tensile strength and residual strength ratio of three tropical hardwoods widely used as decking materials in Korea, and derives prediction models applicable to performance-based fire safety design. Method: Four temperature levels(20, 80, 140, 200℃) and two heating durations(30 and 60 minutes) were applied to Ipe, Malas, and Merbau specimens, yielding 63 test pieces in total: 9 ambient controls shared as the common baseline and 54 heated specimens. Specimens prepared under KS F 2150 were heated isothermally in an electric convection furnace and immediately tested on a universal testing machine. Two-way ANOVA was performed on the 54 heated observations, and both linear and interaction-term regression models were constructed. Results: All species exhibited monotonic strength reductions with markedly steeper degradation above 140℃. Ambient tensile strengths were 43.4, 35.8, and 30.1MPa for Ipe, Malas, and Merbau. After 60 minutes at 200℃, residual strength ratios were 55.2%, 39.9%, and 45.1% respectively. Conclusion: Species selection is a critical design variable governing both fire safety and life-cycle economy. The models may serve as a reference for preliminary estimation of the residual performance of fire-damaged timber members, although validation under real fire conditions is required before practical application, as the experiments were conducted under isothermal and non-combustion conditions. The 30-year life-cycle cost analysis confirmed that Ipe achieves optimal cost-effectiveness despite the highest initial price.
Reference
Korea Safety Culture Society; Doo Hwan Kim; Jong Yong Park; Yong Hoon An. (2026). A Study on High-Temperature Tensile Strength Characteristics and Residual Strength of Natural Timber from a Fire Safety Perspective : Temperature and Heating-Time Based Residual Strength Models for Ipe, Malas, and Merbau. Forum of Public Safety and Culture. https://doi.org/10.52902/kjsc.2026.58.859
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