Restoring Force Characteristics of Precast Concrete Beams Post-Tensioned by Unbonded Tendons at Widened Beam Ends

This paper proposes a modeling approach for the restoring force characteristics of unbonded precast prestressed concrete (PCaPC) beams with widened beam ends. Two models are introduced: one uses rotational springs at the outer ends of the general and widened beam zones, while the other uses a single rotational spring with an equivalent rigid zone. To validate the models, ten unbonded PCaPC beams with varying parameters, such as the amount of longitudinal rebar, the size of the widened beam ends, and the level of prestressing force, were constructed and tested. The proposed models demonstrated good accuracy in capturing the restoring force characteristics observed in the experimental results.