Seismic behavior of self-centering prestressed precast concrete frame subassembly using steel top and seat angles

In order to improve the seismic resilience of the precast concrete structures, a novel prestressed self-centering concrete frame structure is proposed in this study. The beam-column and the column-foundation connections are all assembled using the post-tensioning (PT) tendons and steel angles. Both the experimental and numerical studies were conducted on a 1/2-scaled frame subassembly to investigate the seismic behavior of the specimen. The test results showed that the precast beam/column members and the PT tendons behaved almost elastically during the course of tests. The steel angles provided energy dissipation capacity for the subassembly through significant plastic deformation. The use of PT tendons ensured a good self-centering capacity of the specimen. The seismic performance of the repaired specimen was also evaluated through experiments and showed comparable load-carrying and energy dissipation capacities that were comparable to the original specimen. The good repairability of the specimen was due to the low damage and residual deformation that was induced to the precast concrete members. Based upon the finite element platform OpenSees, numerical modeling was performed to investigate the effects of various design parameters, including initial PT force, area of the PT tendons, geometry of the steel angles, on the cyclic response of the subassembly. The numerical results indicated that an increase in the initial PT force and the area of PT tendons improved the stiffness and the load-carrying capacity of the specimen. A decrease in the thickness, or an increase in the column gage length of the steel angle may result in a reduction in the energy dissipation capacity of the subassembly.