Energy-based damage assessment of RC frames with non-seismic beam-column joint detailing using crack image processing techniques

Abstract

Quantitative post-earthquake failure safety assessment of RC framed buildings with non-ductile joints, as one of the most vulnerable structures, is presented in this study utilizing crack image analysis. For this purpose, energy-based damage indices, as the representatives of the cyclic behavior of earthquakes, are considered to quantify seismic damage. The complexity and irregularity of the crack images are quantified through the generalized fractal dimensions of the crack maps for the damaged RC beam-column joints with non-seismic details. The presented method takes advantage of a collected databank by the authors, including 255 images of surface crack maps of 56 beam-column joint specimens under cyclic loading covering a wide range of energy-based damage indices. In this study, a basic damage index based on energy dissipation along with a combined damage index based on deformation and energy dissipation are used to estimate the extent of the damage. Five symbolic regression-based predictive equations for each of the damage indices are presented based on the after-event access of the structural details. Finally, the efficiency of the proposed method is evaluated for a sample seismically damaged RC beam-column joint specimen. The post-earthquake estimation of the presented damage indices can be used for quantitative failure safety assessment of seismically damaged buildings against aftershocks, secondary numerical seismic analysis, and providing strengthening solutions for damaged RC buildings with non-seismic detailing.