The fiber hinge model for unbonded post-tensioned beam-column connections

The precast concrete frame with unbonded post-tensioned beam-column connections (UPBC) has been emphasized in recent years for it is capable of sustaining a design-basis earthquake with minor damage. The fiber hinge model (FHM), which is a simple and effective approach, is proposed in this paper for the simulation of UPBC. In the FHM, the mild steels and prestressed tendons crossing the interface are integrated into one element. The mechanism and behavior of the FHM are presented in this paper. The proposed model, which is developed in OpenSees, has been validated by tests, and the FHM is able to accurately describe the shift of compressive center induced by the opening of the interface between the precast beam and column, as well as "beam elongation effects."