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Performance of reinforced concrete columns under realistic load pattern and history

Load pattern, including independent variation of the biaxial lateral force or deflection and axial load and their history has a significant effect on the flexural and shear strength, ductility, stiffness, and energy dissipation of Reinforced Concrete (RC) members This is more pronounced in earthquake excitations, specifically in near-fault regions with high independent accelerations of vertical and bi-axial horizontal ground motions, large velocity pulses, directional effects, repetitive pulse effects, and aftershocks.
While the performance of RC columns under uniaxial monotonic or cyclic lateral force or deflection and constant axial load has been studied by many researchers; the number of studies with a non-sequential variation of axial load is limited. However, there is virtually no study in which the independent variation of bi-axial lateral force and deflection is combined with independent axial load change.
Performance of concrete columns under various scenarios of independently fluctuating axial force and bi-axial lateral force/displacement was assessed through an extensive analytical program, benchmarked against experimental data. It was shown in this study that parameters such as relative frequency and intensity of bi-axial independent force and displacement as well as axial load variation, can significantly affect the strength, ductility and energy absorption of an RC column.

Author(s):

Fatemeh Shirmohammadi    
Kansas State University
United States

Asad Esmaeily    
Kansas State University
United States