ABSTRACT The fire response of structural elements depends on the thermal, mechanical and deformation properties of concrete. The properties vary significantly with temperature and depend on the composition and characteristics of the concrete. Thus, the objective of this work was to perform an analysis of the behavior of concrete subjected to high temperatures. For this, the experimental programs adopted were to investigate the behavior of the modulus of elasticity of the concrete, the resistance to the residual compression according to the type of cooling, exposure time, the concrete fck and the addition content of polypropylene fiber, besides of the analysis of mass loss and ultrasonic pulse velocity. The temperatures at which the concrete was subjected were 200 °C, 400 °C, 600 °C and 800 °C. It can be concluded that concrete exposed to high temperatures undergoes significant deterioration such as reduction of modulus of elasticity and compressive strength, spalling of concrete and consequently loss of durability. The addition of polypropylene fibers helped prevent spalling at temperatures up to 600 ºC. Furthermore, based on statistical tests, the results showed that the A type of cooling does not influence the residual resistance, since the exposure time, the type of fck and the addition content of polypropylene fibers influence significantly.

ABSTRACT The fire response of structural elements depends on the thermal, mechanical and deformation properties of concrete. The properties vary significantly with temperature and depend on the composition and characteristics of the concrete. Thus, the objective of this work was to perform an analysis of the behavior of concrete subjected to high temperatures. For this, the experimental programs adopted were to investigate the behavior of the modulus of elasticity of the concrete, the resistance to the residual compression according to the type of cooling, exposure time, the concrete fck and the addition content of polypropylene fiber, besides of the analysis of mass loss and ultrasonic pulse velocity. The temperatures at which the concrete was subjected were 200 °C, 400 °C, 600 °C and 800 °C. It can be concluded that concrete exposed to high temperatures undergoes significant deterioration such as reduction of modulus of elasticity and compressive strength, spalling of concrete and consequently loss of durability. The addition of polypropylene fibers helped prevent spalling at temperatures up to 600 ºC. Furthermore, based on statistical tests, the results showed that the A type of cooling does not influence the residual resistance, since the exposure time, the type of fck and the addition content of polypropylene fibers influence significantly.