Evaluating longitudinal vibration characteristics of bonded strands embedded in prestressed concrete beams by a system identification approach

This study is to investigate the wire rope governing equation in order to establish the longitudinal vibration characteristics of bonded PSC strands. For this purpose, the longitudinal vibration tests have been conducted for six bonded PSC specimens with the different stress levels. Subsequently, the wave velocities of the strands have been estimated from the test results. Then, a sensitivity-based system identification algorithm has been applied to evaluate the constitutive constants of the strands using the measured wave velocities. The present study demonstrates that the longitudinal dynamic behaviour of the strands is governed by coupled extensional-torsional oscillations. The study also reveals that longitudinal elastic wave velocity of not only the bonded strands but also unbounded strands is nonlinearly increased as the applied tensile stress level increases.