| Precast and precast-prestressed concrete structures have been shown to be cost-efficient structural systems. However, their full implementation in seismic regions in the United States has been limited. One of the major reasons for this situation is the lack of development of seismic resistant beam-column connections appropriate for these structures. This investigation focuses on the behavior of cast-in-place (CIP) fiber reinforced concrete (FRC) connections for precast concrete frames subjected to inelastic cyclic loading. In the frame studied, beams and columns remain in their elastic range of behavior while damage is confined to the CIP connection.; The research program included designing and constructing an experimental fixture, designing and constructing half-scale models of CIP connections, and testing the specimens under reversed cyclic loading, and the evaluation of each specimen's performance in meeting the demands for strength, ductility, and energy dissipation.; Thirteen connection specimens were tested to devise a reinforcement scheme for locating beam plastic hinges inside FRC cast-in-place connections, to investigate the effect of different design parameters on the stability of the hysteretic response of the connections, and to ascertain what reduction of the connection transverse reinforcement could be achieved by using steel fibers in the connection matrix. The main parameters studied were the beam shear span-to-effective depth ratio, the amount of shear/confining steel reinforcement, the fiber volume fraction, the fiber material, and the joint composite. The connection performance was evaluated in terms of the mode of failure, connection strength, displacement and rotation ductilities, connection flexural and shear deformations, energy dissipation, and loss of stiffness due to cyclic loading.; Several conclusions were drawn on the basis of the results of this research. The reinforcement arrangement designed can successfully locate the plastic hinge inside the CIP connections. The use of steel fibers in the connection matrix significantly improved the CIP joint performance. Steel fiber reinforced concrete connections with reduced confinement reinforcement resulted in improved behavior compared to normal reinforced concrete connections with full confinement. |
