EFFECT OF FIRE EXPOSURE ON AXIALLY AND BIAXIALLY LOADED REINFORCED CONCRETE COLUMNS

This paper presents the analytical investigation on the residual load capacity of reinforced concrete columns subjected to elevated temperature under axial and biaxial loads. The aims of the analytical program are verifying of the proposed numerical model and presenting a parametric study by using FEA program ANSYS V.13 for studying the effects of the concrete characteristic strength, rectangularity ratio, eccentricity ratio, and fire duration. Twenty-seven full-size columns models, which using ANSYS elements (Solid65, Solid70, Link8, and Link33), were constructed and subjected to axial and biaxial loads after fire exposure according to the ISO 834 standard fire curve. The firing time exposure are at room temperature, 1.5 hours and 3 hours. A comparison between the numerical predictions and the test results shows good agreements. The numerical results indicated that, the residual load capacity is directly proportional to the concrete characteristic strength. The column residual load capacity increased by increasing the concrete characteristic strength. The column residual load capacity decreased by increasing the rectangularity ratio and increasing firing duration.