Abstract
A finite element model updating technique based on measured strain responses is used to monitor the health of prestressed concrete structures. In this work health corresponds to the existing prestressing force present and the associated stiffness properties of the structure. Measurements are taken on post-tensioned beams, both bonded and un-bonded. The measured response is the total strain of the beams at predefined locations and the natural frequencies of the structures. In this work uncertainties in the measured data and those in the stiffness parameters are considered. The uncertainties are modeled using both Bayesian technique and interval analysis. The uncertain parameters in the finite element model are then estimated using Markov chain Monte Carlo technique in Bayesian framework and set inversion via interval analysis in interval analysis framework. The existing prestressing force estimated by both the mentioned techniques are then compared with the measured actual prestressing force present in the structure. To check the robustness of the proposed algorithm tests are conducted at different time spans corresponding to different prestress loss and different material stiffness.