Temperature analysis of steel structures protected by intumescent paint with steel claddings in fire

It is of great interest to understand the stabilization effect of steel structures by steel claddings in fire. Structural fire analysis using finite-element method, including temperature analysis and structural analysis, is important to investigate the stabilization effect. However, temperature-dependent thermal material data for the insulation layer of sandwich panels and the intumescent paint for fire protection of steel sections are still scarce. In this paper, the available thermal properties of these materials from the literature are summarized, and 2D and 3D temperature analyses were carried out for steel sections with steel claddings, such as sandwich panels with mineral wool and polyisocyanurate (PIR) cores and trapezoidal sheeting with mineral wool insulation. The analysis results were compared with the fire tests conducted in European research project STABFI (Stabilization of Steel Structures by Steel Claddings in Fire). The study shows reasonable accuracy of modeling using existing thermal material data for temperature-dependent insulation properties and thermal data for intumescent paint, for intumescent coatings (IC) protected steel beam with mineral wool sandwich panel and trapezoidal sheeting claddings. Larger discrepancy between finite element (FE) prediction and test measurement was observed for the case of sandwich cladding with PIR core. Gaps for further research were identified. The study also shows the heat sink effect of the steel section by sandwich panels with a mineral wool core. Therefore, it is recommended that the sandwich panels should be included in the thermal analysis model for steel sections with sandwich claddings.