Precast columns connected with grouted corrugated steel sleeves and UHPC tenon under combined bending and compression

Abstract

The authors propose a hybrid joint connection using grouted corrugated steel sleeves and cast-in-place UHPC tenon (abbreviated as GS-UHPC) for precast bridge piers. The GS-UHPC joint is not disconnected between the adjacent precast segmental reinforced concrete (RC) bridge piers and improves the integrity as well as accelerates construction of the structures. The failure modes, carrying load capacity, joint opening performance, rotation capacity, and ductility of the jointed columns with GS-UHPC were investigated through the compression-bending static test. Furthermore, the hysteretic behavior, energy dissipation capacity, residual deformation and stiffness degradation of the jointed column were discussed through the cyclic loading test. The experimental results indicated that under the static loading, the GS-UHPC joint presented a ductile failure characterized by the concrete crushing at the compression zone, severe joint opening, and the yielding of the connecting rebars. The flexural stiffness of the jointed column was similar to the complete RC column at the same axial compression ratio before the yielding of the connecting rebars, but the crack resistance and displacement ductility were better than the complete RC column. As the axial compression ratio increased, the ductility, rotation capacity, severity of joint opening, and tensile stress development speed of the connecting rebars of the jointed columns were reduced. Under the cyclic loading, the GS-UHPC joint had a good deformation resilience before the yielding of the connecting rebars, while the hysteresis loops were wide with a good energy dissipation after the yielding of the connecting rebars. In addition, the profile of the skeleton curve of the jointed column was almost overlapped with the load-deflection curve under the monotonic loading. The degradation of equivalent stiffness (Ks) gradually slowed down as the joint opened (or RC cracked), and the yield and ultimate loads reached.