Retrofitting of damaged structure using vibration monitoring technique

Abstract

Health monitoring of structures has become a popular research subject in recent years. The technique is mostly utilized for system identification through dynamic testing. System identification is required for a number of reasons like continuous monitoring of the state of the existing structures, evaluation of damages in the structure and assessment of residual strength. In this study, the evaluation procedure of the damages in the existing structure through dynamic testing is described and a suitable retrofitting strategy is proposed based on the experimental results. For this purpose, the results of the dynamic test of a five story building model representing properties on scaled prototype structure are collected to obtain its fundamental mode and fundamental frequencies of vibration. With the help of the above experimental data, a retrofitting strategy is developed to rehabilitate the structure to a desired lateral strength. The methodology consists of following steps: (i) recreating the same building model in computer to define a target strength and (ii) a static procedure for increasing the lateral stiffness of the damaged building is described from the measured mode shape and frequency of the damaged structure and those of the recreated structure. For verification of the accuracy of the retrofitting strategy, free vibration test of the retrofitted building is also carried out. The results of the study show that it is possible to design additional lateral resisting elements to increase the lateral strength of a damaged structure to target strength from the free vibration test results of the damaged structure.