Structural health monitoring (SHM) for detecting and quantifying multiple damages in complex structural systems remains a significant challenge in the field. This study represents an experimental approach that employs the electromechanical impedance (EMI) technique for the detection, localization, and severity assessment of damage in the concrete structures. Using piezoelectric transducers, the EMI method captures the coupled mechanical and electrical responses of specimens under different damage conditions. In this research focus, multiple damage scenarios were simulated in the concrete specimens, and corresponding conductance value were recorded. The shifts in the conductance values, representing the real part of admittance, were systematically analyzed to identify and the localize damage. Statistical metrics, such as the root mean square deviation (RMSD), were employed to quantify the changes in the conductance signature and provide an accurate assessment of the structural integrity degradation. Furthermore, a novel damage localization methodology and an impedance-based severity index were developed to precisely quantify the extent of damage. The experimental show that EMI technique is highly effective in detecting, locating, and evaluating multiple damages within complex structural systems. This non-invasive and real-time monitoring approach offers a robust solution to enhance safety, reliability, and the maintenance practices of modern civil infrastructures. The findings underscore the potential of EMI-based methods to revolutionize structural health management by providing accurate, efficient, and reliable damage assessment, thereby ensuring the long-term durability and performance of critical infrastructure systems. These promising results clearly pave the way for further advanced SHM innovations.