Structural performance assessment of post-tensioned concrete beams by embedded continuous fibre optics

Prestressed concrete structures have numerous advantages over conventionally reinforced concrete, though the usage of post-tensioned structures has declined over the last two decades. By distributed optical fibre sensors, key performance indicators of the post-tensioned concrete specimens were monitored and evaluated. Initial losses and long-term effects affecting prestressing force, deflections and cracks were tracked and compared to theoretical calculation methods. It was found that the theoretical calculation methods mostly agreed well with results from the distributed optic fibre sensors. The loss of prestressing force due to mechanical creep and relaxation was overestimated in theoretical calculation methods by approximately 6 %, while the loss due to friction was overestimated by 0.6 %. Regarding deflections, the relative error ranged from 0 % to

3.3 % and 0 % to 2.9 % for the reference specimen and post-tensioned beam respectively.