TIMBER CLADDINGS AS FIRE PROTECTION FOR STEEL COLUMNS: EXPERIMENTAL STUDY AND PRACTICAL DESIGN RULES

Timber claddings offer a sustainable alternative to conventional fire protection for steel columns in hybrid steel–timber structures, but design rules and the influence of detailing remain insufficiently quantified. This paper presents an experimental and numerical study on the fire behavior of timber‑cladded steel columns. Furnace tests on thermally loaded, mechanically unloaded columns with varying profile factors and different cladding systems (single‑layer box claddings, double‑layer claddings with staggered joints, and claddings on timber battens with cross‑screws) were conducted under ISO 834 fire exposure. Steel temperatures and characteristic cladding failure modes were evaluated. A 3D heat‑transfer model with a simplified cladding‑failure representation was calibrated and used for parametric studies. Results show that timber claddings can provide effective protection, but performance depends heavily on joint layout, supports, and fixings. Simple box claddings often exhibit early joint opening and internal hot‑gas flow, while claddings on battens with cross‑screws demonstrate robust behavior across a wide range of fire resistance levels. The model reproduces steel temperatures with sufficient accuracy for design purposes and enables simplified relations between cladding thickness, profile factor, and fire duration. The findings support preliminary design rules and identify priorities for further research.      «

Timber claddings offer a sustainable alternative to conventional fire protection for steel columns in hybrid steel–timber structures, but design rules and the influence of detailing remain insufficiently quantified. This paper presents an experimental and numerical study on the fire behavior of timber‑cladded steel columns. Furnace tests on thermally loaded, mechanically unloaded columns with varying profile factors and different cladding systems (single‑layer box claddings, double‑layer...     »