Research on Seismic Performance of Square-Steel-Tube-Constrained, Prefabricated Segmental Concrete Piers with Hybrid Joints

The impact of hybrid joints (combination of grouting sleeves and steel-tube shear connectors) and constraining square steel tubes on the seismic performance of prefabricated segmental concrete piers of square cross-section is studied. Three concrete specimens, one with hybrid joints and constraining steel tubes, one with grouting sleeves and constraining square steel tubes, and one with grouting sleeves and without constraint, were prepared for quasi-static test. Finite element models were also built up to analyze the parameters concerning the seismic performance of the structure, including failure modes, structural ductility, energy dissipation capacity, strength degradation, stiffness degradation and residual displacement. The results show that the failure modes of these three types of specimens are basically similar, all belonging to bending failure. Compared with the specimen without constraint, the peak horizontal loads and displacement ductility coefficient of the specimen with constraining square steel tubes are higher. Compared with the specimen with grouting sleeves, the hysteresis curves of the specimen with hybrid joints are full and show no significant pinching，which indicates good seismic performance For the specimen with hybrid joints and square steel tubes, either increasing the axial compression ratio or reducing the slenderness ratio can result in the improvement of the load bearing capacity of the pier, but weakens the ductility. Increasing the constraint coefficient can improve both the load bearing capacity and ductility of the specimen. For the prefabricated segmental concrete pier with hybrid joints and constraining square steel tubes, the suggested axial compression coefficient is 0. 3 or less, the slenderness ratio is 12 or less, and the constraining coefficient is within the range of 0.58 to 0.90. © 2023 Wuhan Bridge Research Institute. All rights reserved.