Residual Strength and Crack Propagation of Reinforced Concrete Columns under High Temperatures

In the present study, reinforced concrete columns with dimensions of 200x200x1200 mm were tested under static loading and high temperatures. In the experimental work, square cross-section columns with compressive strength of 28 MPa were tested up to failure. Mechanical properties such as compressive strength, were examined under static load and then under temperatures such as 500 and 800 degrees C. Column specimens with the same geometry and with concrete covers of 10 and 17 mm were also put under test. Mode of failure, ductility, stiffness, and energy dissipation for all tested specimens are discussed. The test results showed that the strength capacity of reinforced concrete columns was affected by the column cover. The increment in temperature led to a reduction in the strength-carrying capacity of the columns and increased the axial and lateral displacements. The static compressive strength was reduced by 36.84 and 48.81% when the applied temperature was 500 and 800 degrees C, respectively. The stiffness of the specimen with 17 mm cover was 29.27 and 46.86% less than that of 10 mm cover for axial and lateral displacement, respectively. Also, the specimen with 10 mm cover exhibited decreased energy dissipation by 1.69 and 12.54% for axial and lateral displacement.