Correlation of High Cycle Fatigue Behavior of Circular and Square Reinforced Concrete Columns Subjected to Shear Controlled Cyclic Loading

In current design practice, mostly architectural needs govern the shape of reinforced concrete columns. There is a need to study and compare the load-deflection behavior and failure pattern of high strength reinforced concrete columns of different shapes. This paper presents a correlation between the performance of equivalent area circular and square columns subjected to shear controlled cyclic loading. Square and circular columns with equal cross-sectional area were experimentally tested in this research. Experimental results show that the maximum load, number of loading cycles and maximum deflection in case of square and circular columns were found to be close however, the final failure pattern was different. In case of columns without shear stirrups, the square column resisted 6.7% more loading cycles as compared to the circular column. However, the square column showed 19% lesser deflection at ultimate stage. In case of columns with shear stirrups, square column resisted only 9% more loading cycles as compared to circular column and exhibited similar ultimate deflection. The fatigue performance of equivalent area circular and square columns was found to be comparable in shear controlled conditions. However, the final failure pattern of circular columns shifted from shear to flexure near final failure.