The hybrid “M and P” technique for seismic damage identification in planar dual reinforced concrete frames

This paper presents the effectiveness of the newly proposed hybrid "M and P″ technique for identifying seismic damage in existing, planar, multistory Reinforced Concrete (RC) frames featuring a dual structural frame-wall system. The methodology integrates instrumental Monitoring (M) of the structure with Pushover analysis (P) to provide a comprehensive evaluation framework. Αfter a major seismic event followed by various subsequent aftershocks have taken place, the examined structure must be inspected immediately to identify potential damage. We consider the case where the examined structure has significant damage, but after the seismic vibrations have reached a quiet state. In order to identify the damage of the structure, we can use the "M and P″ technique, since the performing of a nonlinear time history analysis is impractical due to a lack of sufficient information regarding the seismic ground excitations and the current state of the structure. A key component of the approach lies in plotting the dual frame's eigenfrequencies for each analysis step (where linear behavior is assumed) within the inelastic domain, against seismic roof displacement. The fundamental eigenfrequency of the examined dual RC frame, derived during the monitoring phase due to ambient causes, is utilized in this representation to determine the corresponding inelastic roof displacement, which indicates the damage state of the frame. This displacement serves as the target for pushover analysis, facilitating the accurate evaluation of the location and severity of seismic damage. The methodology is applied to a six-story RC frame with a dual structural system, showcasing its practical implementation with valided results.