Experimental and numerical study on seismic performance of precast segmental CFST bridge columns with non-uniform prestressed steel tendons

Abstract

A precast segmental concrete-filled steel tube (PSCFST) bridge column set with non-uniform (external and internal) prestressed post-tensioned (PT) steel strands was proposed, then the seismic performance of this type of bridge column was researched in this paper. The external prestressed steel strands are arranged on the outside of the bridge column to provide re-centering force, which can facilitate to observe the damage state of the PT tendons and be rapidly replaced. Pseudo static test was carried out on three scaled specimens, including a reference monolithic reinforced concrete (MRC) column and two PSCFST columns. The test results showed that both PSCFST columns have good seismic and resilience performance, with no visible damage and little residual displacement. The PSCFST column with external and internal PT strands shows better self-centering performance. The external prestressed steel strand will yield earlier than the internal, so it can be used as an early damage warning device for the PSCFST column. Then, a detailed finite-element (FE) model was established and validated using the test specimen. The finite element calculation results are in good agreement with the experimental results, indicating that good applicability of the established FE model. Furthermore, based on the validated FE model, the non-uniform arrangement position and initial prestress level of the prestressed PT steel strand were analyzed. That is, analysis was conducted to investigate the seismic and resilience behaviors of the PSCFST specimen with different arrangements of PT strands and different ratios of initial prestress of the internal and external PT strands. Analytical results indicated that increasing the initial prestress value of the external steel strand can increase the bearing capacity of the PSCFST specimens, while the initial prestress of the external prestressed steel strand has little effect on the initial stiffness, drift ratio, or accumulative energy dissipation. Furthermore, allocating more external PT strands can increase the bearing capacity and initial stiffness of the PSCFST specimen, while decreasing the drift ratio.