An Experimental Study on the Repair Evaluation of Deteriorated RC Beams Using Natural Frequency and Mechanical Behavior Related to Damage Condition

This study aims to quantitatively evaluate the repair of deteriorated RC beams for reuse through natural frequency and proposes a method that describes the mechanical behavior of structures. A static loading test was conducted to determine the load-carrying capacity and deformation performance of structures. To investigate the soundness of the RC beam based on the change of the natural frequency at each load stage, an impact vibration test (IVT) was conducted. Then, a higher vibration mode of natural frequencies, which can better reflect the degree of damage of a frame, was used as an evaluation index to represent the mechanical behavior of structures. The result confirmed that, although in case where IVT is challenging to perform due to location limitations, the damage condition can be estimated from the axial stiffness (EA) of RC beams by axial impact to measure the natural frequencies. Regarding the defined model of mechanical behavior, the results in each deteriorated pattern or load stage to be organized by level of damage. Accordingly, the reliability of the quantitative evaluation of repair effectiveness using the proposed method was verified.