Experimental and numerical investigations of self-centering post-tensioned precast beam-to-column connections with steel top and seat angles

Abstract

There is growing interest in the development of earthquake resilient structures. This paper proposes a new kind of self-centering post-tensioned precast beam-to-column connection, assembled using unbonded posttensioning strands, and steel top and seat angles (PTSA). A series of cyclic loading tests along with numerical simulations were performed to investigate the seismic behavior of the PTSA connection. In the experimental tests, eight subassembly specimens were prepared with varying specimen parameters including the initial posttensioned force, beam depth, and type of steel angles. Test results show that the properly designed specimens had large initial stiffness, good recentering capacity, and high ductility. Permanent deformation was concentrated in the steel angles, which were relatively easy to replace. Precast beams, columns, and PT strands in each subassembly behaved almost elastically up to 3.5% drift. Additional tests on a previously tested PTSA specimen with newly replaced steel angles demonstrated that the cyclic responses were almost identical to the original counterpart. Numerical analyses were carried out using the platform OpenSees to examine the effects of the concrete initial compressive stress, the initial prestress, the concrete compressive strength, and the beam cross-sectional width on the mechanical response of PTSA. Results indicate that appropriate areas and initial prestress of the PT strands, and concrete compressive strength were beneficial to the load-carrying and deformation capacities of PTSA. Increasing the beam cross-sectional width may improve the ductility of PTSA.