Non-parametric and parametric damage indices through a case-study of a reinforced concrete bridge pier

Parametric indices are empirically related to two or more response parameters with a combination coefficient and do not conform to a physical definition of damage. The combination parameter is expected to be contingent on the loading and the state of calibration other than failure. Damage is also defined as the ‘deterioration of a physical quantity’ and the resulting non-parametric index does not involve any empirical constant. However, the non-parametric indices saturate much before unity. This paper first aims to assess the performance of some of the existing non-parametric indices. Experimental response until failure of a circular RC bridge pier under cyclic loading is numerically simulated for this purpose. A new physical-definition based non-parametric damage index is proposed. Setting this alternate definition as the benchmark, performance of parametric Park-Ang index, some of its variants and other non-parametric indices are studied at levels other than failure through a damage progression analysis using cyclic and seismic excitations. A parametric index and its simplified form consistent with that physical-definition are next proposed with weighted-hysteretic-energy and normalized-deformation as parameters. The same calibrated model is used in subsequent assessment. Associated combination-coefficient exhibits a stable relationship with peak drift and a loading-independent functional form is proposed.