Effect of Fire Damage on Seismic Behavior of Cast-in-Place Reinforced Concrete Columns

This paper presents the results of an experimental study that was conducted to investigate the postfire seismic behavior of reinforced concrete columns. Five full-scale, flexure-critical code-complying (e.g., ACI 318-14) cast-in-place reinforced concrete columns were tested to failure under a constant axial load and reversed cyclic lateral displacements after being exposed to an ISO-834 standard fire for 30, 60, and 90 min. Other than the effects of the duration of the fire exposure, the effects of the thickness of the concrete cover (25 and 40 mm) on the structural performance was also investigated for the short fire exposure duration (30 min). The responses of the columns were analyzed in terms of lateral load-displacement relationships, ductility, stiffness, energy dissipation capacities, and residual displacements. The test results indicated that the fire exposure reduced the lateral load capacity of the columns, whereas the deformability capabilities were found to be satisfactory in terms of a structural response. It was also observed that the thickness of the concrete cover had only a slight influence on the postfire seismic behavior of the columns. Furthermore, a numerical study was conducted to predict the load-displacement response of the fire exposed columns. The comparison of the experimentally and numerically obtained load-displacement relationships indicated that the principles of structural mechanics usually applied to conventional columns are also valid for the columns exposed to fire.