Shear strength degradation due to flexural ductility demand in circular RC columns

An analytical model was developed to estimate the shear-strength degradation and the residual capacity of circular reinforced concrete (RC) columns subjected to seismic action. The proposed model is an upgrade of a previously proposed model for axial force N, bending moment M and shear force V (N–M–V) interaction domain evaluation for rectangular and circular cross-section RC elements subjected to static loading. The model was extended to the case of circular cross-sections subjected to seismic actions with limitation of the range of variability of the deviation angle between the directions of the stress fields and the crack inclinations, as a function of the amplitude of the flexural ductility demand. Numerical evaluation of resistance domains for circular RC columns having the current structural configuration, like bridge piers, highlights the increment in the risk level induced by shear strength degradation due to flexural ductility demand.