Continuous Dynamic Monitoring and Model-Based Damage Assessment of a RC Frame Building

The study focuses on Structural Health Monitoring (SHM) for early damage detection and localization in civil structures, which is crucial for safety and prompt intervention after extreme events. A model-based methodology originally developed for masonry towers is adapted to a reinforced concrete frame building. By tracking natural frequencies using a few strategically placed sensors, structural damage can be identified and localized, as damage induces frequency changes tied to its location. The SHM strategy includes three key steps: (1) simulating damage scenarios with a calibrated structural model to create a Damage Location Reference Matrix (DLRM) based on frequency shifts; (2) detecting damage through statistical analysis of continuously monitored frequencies; and (3) localizing damage by comparing detected frequency changes to those in the DLRM. This approach is applied to a 54-m-tall RC frame building from the 1980s, permanently instrumented with 5 accelerometers. The FE model of the building is calibrated using the modal data from the initial ambient vibration testing. Modal parameters from continuous monitoring are identified using an automated SSI-based technique, with environmental effects mitigated via Principal Component Analysis (PCA). Subsequently, three damage scenarios are inflicted on the identified natural frequencies, showing the DLRM method's effectiveness in identifying damage. The findings highlight the feasibility of using limited sensors and model-based techniques for precise damage localization in RC structures.