Intumescent coatings on steel structures exposed to natural fires

Abstract

The main objective of this thesis is to evaluate the thermal and mechanical behaviour of intumescent coatings (also known as reactive fire protection materials) that are used to protect steel structures from a fire exposure due to natural fires. As the intumescence process of currently available coatings deemed to be highly dependent on the heating regime, comprehensive experimental investigations are performed to understand the correlation between the heating as well as the cooling regime and the thermomechanical performance of intumescent coatings. Due to differences in sensitivity, a solvent-borne and a waterborne intumescent coating are investigated by, among others, evaluating their insulation efficiency. Based on the experimental data, a thermomechanical material model is developed. This material model enables two- and three-dimensional finite element simulations of the intumescent coatings applied on steel structures. As natural fires can show arbitrary regimes characterised by various heating and cooling rates, the material model is formulated universally by taking the heating and cooling rate-dependent behaviour of the intumescent coatings into account. Additionally to the finite element modelling, a MATLAB-based calculation approach is developed, aiming to reduce the computational effort and, thus, providing a design procedure for the dry film thickness of intumescent coatings for any desired fire exposure that is covered by the examined parameter range. As no other approach exists yet, this is the first scientifically-based method for the determination of the required dry film thickness of intumescent coatings to protect steel structures when being exposed to natural fires.