Shear-strength degradation model for RC columns subjected to cyclic loading

An analytical model was developed to estimate the shear-strength degradation and the deformation capacity of slender reinforced concrete columns subjected to cyclic transverse loading. The shear capacity of the concrete compression zone was defined as a function of the inelastic flexural deformation of the column, based on the material failure criteria of concrete. The shear capacity is degraded as the inelastic flexural deformation increases. The deformation capacity of a column is determined when the degraded shear capacity reaches the shear force demanded by flexural yielding of the column. Other failure mechanisms including rebar-buckling and -fracture and flexural failure were also considered to estimate the deformation capacity. The proposed model was applied to test specimens possessing various design parameters. The result showed that the proposed model estimated the shear-strength degradation and deformation capacity of the test specimens with reasonable precision.