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This study aimed to conduct a finite element analysis-based seismic evaluation of an existing reinforced concrete (RC) building for a high seismic zone in northeast India. The building model was evaluated for demands using response spectrum analysis (RSA) per the latest Indian standards. Data on the condition of existing material strength, geometry, and initial design are collected on site. Here, a procedure has been introduced to evaluate the seismic demand and capacity of structural members, for prioritizing strengthening work. The focus of the study was on assessing the potential failure of columns, with an aim to evaluate a building's susceptibility to failure and collapse. This evaluation procedure was applied to an existing low-rise RC building in northeastern India that was originally designed for gravity loads. The building had significant plan irregularities and stiffness irregularities. As anticipated, it was observed that the building did not withstand seismic design action, and all the columns failed, while the beams failed partially. For various load combinations, the demand–capacity ratio, particularly in terms of axial load and biaxial bending moments of the columns, emerged as a critical force-based factor in evaluating the building's safety under combined forces. The obtained results were validated on site by visual inspection of structural longitudinal cracks under high combined (axial with biaxial moment) demand in columns. The case study identified the six most critical columns that might lead to building collapse and need immediate strengthening. This approach demonstrated its feasibility as a tool for assessing the seismic performance of existing low-rise RC buildings for prioritizing structural strengthening work. [ABSTRACT FROM AUTHOR]