Linear and nonlinear analysis methods are defined in the 2018 Turkish Building Earthquake Code (TBDY-2018) to determine the existing earthquake safety of reinforced concrete (RC) buildings. After applying the relevant calculation methods in many buildings, the experience gained was numerically sampled on an existing three-story RC building, and an answer was sought as to whether the linear analysis method is too conservative. When the seismic performance of the RC building was applied using the linear analysis method suggested in TBDY-2018, it was concluded that the building could not provide the 'Controlled Damage (KH)' performance level. On the other hand, as a result of non-linear time history analysesusing 11 earthquake records with the assumption of lumped plastic hinges and pushover analyses based on the spread plasticity, it was concluded that the building provides the 'Controlled Damage (KH)' performance level. It has been concluded that the difference in the evaluation is due to the fact that rotation is taken as "zero (0)" at the lower ends of the lowest story columns in the equation (15A.1) in the sub-title of displaced axis rotation in TBDY-2018 Section Annex 15.A.2.