Experimental observations on reinforced concrete bearing walls subjected to all-sided fire exposure

Experimental observations were made on eight reinforced concrete wall specimens, with all sides being exposed to an International Organization for Standardization standard heating curve. The main variables were wall thickness, level of axial load, reinforcement ratio, concrete compressive strength and curing period. During the test, temperature increases in the wall, and the heating time plotted against axial deformations, were measured. The effects of the main variables on the fire resistance and axial deformation of the wall in fire were investigated. The walls with shorter curing periods and the wall of high-strength concrete with a thin wall thickness under concentric load were more susceptible to the loss of fire resistance. Initial axial extension followed by contraction to failure was observed for relatively thin walls that were subjected to an axial load during the fire test. Based on comparisons between the experimental observations and code provisions, it was suggested that the incorporation of load levels and the exposure condition of the wall in fire could improve the accuracy of estimation of the fire resistance.