Possibilities of using numerical modelling to determine the residual load capacity of concrete elements with composite reinforcement after fire

Abstract

Abstract During the service life of a structure, a number of phenomena occur that can affect the ability of the concrete structure to continue to perform its function. In the case of concrete load-bearing elements, fire and its effects represent significant influencing factor. Exposure to fire can, among other things, cause a great reduction of material properties of both concrete and reinforcement itself, but also affect their interaction. After a fire incident, it is necessary to assess the residual load capacity of the reinforced concrete elements. As part of the diagnostic work, material samples are usually taken from the structure after a fire. The purpose of the present paper was to investigate whether the experimentally obtained material characteristics can be used to verify the basic behaviour of concrete structures after fire. The structural material properties were used as input values for simplified numerical models of the structures. ATENA Cervenka Consulting software was chosen to construct a numerical model simulating the behaviour of the structural elements after exposure to fire loads. Finally, the effect of high temperatures on the residual load capacity of the beams determined by the numerical approach was compared with the experimental values of the load capacity of the beams after fire. The behaviour of concrete beams of dimensions 100 × 150 × 1800 mm reinforced with composite reinforcement was investigated. The specimens exposed to temperatures of 1000°C were subjected to mechanical bending tests after cooling to determine their residual load capacity.