Artan biçimde hasarlanmış betonarme çerçevelerin modal parametre tahmini ve hasar tanımlaması

In the profession of civil engineering, experimental eigenfrequencies and mode shapes estimated by operational modal analysis techniques, are found the most suited parameters used in structural damage identification. The main focus of this study is to perform a damage identification study of an experimentally tested half-scale reinforced concrete (RC) frame by means of degradation of Young's modulus in structural elements; which is done by using the sensitivity-based finite element model updating method. Damage is created by imposing the frame with progressive drift ratios by a displacement-controlled hydraulic actuator using single-cycle quasi-static lateral loading along its in-plane direction. Dynamic tests are conducted using an electro-dynamic shaker and system identification at different damage levels is performed using output-only methods NExT-ERA, EFDD and SSI. The objective function used for damage identification is then constructed by the modal parameter differences constructed between the experimentally identified and finite element (FE) predicted. Results are obtained through the minimization of this function by applying the numerical optimization technique Gauss-Newton method with trust region implementation. Study is performed in three subsequent steps: (i) The system identification results of RC structure at undamaged and various damage levels are obtained (ii) The reference FE model using the experimental modal parameters corresponding to the undamaged test frame is obtained (iii) the reference model is updated for increasing damage levels using the modal parameters corresponding to these levels to identify existence of damage, its location, and extent. Results are presented in terms of stiffness reduction factors on the column(s) bottom and beam ends. In the final part of the thesis, the uncertainty in the damage identification results are investigated using the modal parameters polluted with two levels of noise.