Post-earthquake damage evaluation of non-ductile RC moment frames using surface crack patterns

In this paper, a methodology is developed for seismic damage identification of non-ductile reinforced concrete moment frames using surface crack images. A comprehensive database comprising 264 surface crack patterns from quasi-static test results of 61 non-ductile beam-column joint specimens at various damage levels is collected. The database covers a broad range of structural and geometric properties. Multifractal dimensions of the column and joint regions of damaged beam-column subassembly images are obtained and used as the complexity and irregularity index of the surface crack patterns. Predictive equations are developed that estimate the peak drift ratio during an earthquake using the multifractal dimensions of surface crack patterns. Six scenarios are considered for obtaining the predictive equations. The developed empirical equations rely on the multifractal dimensions along with the structural properties of the non-ductile beam-column joint. The peak drift ratio estimated by the proposed methodology can finally be used as the input engineering demand parameter to the existing fragility curves in the literature to identify the probability of exceedance from damage states of non-ductile reinforced concrete moment frames.