BASIC PARAMETERS TEST AND 3D MODELLING OF BOND IN HSC AFTER ELEVATED TEMPERATURES

The chemical adhesive and friction coefficient of the bond between concrete and reinforcing steel in high-strength concrete after exposure to high temperatures was measured by a self-designed setup, and their variation with elevated temperatures has been obtained. Using the measured parameters, the elastic plastic Coulomb-type friction criterion is defined, and is used in 3D FEM modelling. Surface-to-surface contact elements are employed for the mechanical properties of the concrete-to-bar interface. The mechanical interlock between steel bar ribs and concrete has been modelled by means of an explicit discretization of the bar ribs. The comparison between numerical results and experimental data shows that the model proposed in this paper can be used to simulate the bond slip between the steel bars and concrete after elevated temperatures. Finally, the stress distribution and crack propagation during the pull-out process in concrete which has experienced 400°C temperatures have been studied in detail.