An innovative precast segmental bridge column (PSBC) was proposed to achieve a better durability performance in an aggressive coastal environment, which was reinforced with both longitudinal stainless steel (SS) bars and glass fiber reinforced polymer (GFRP) bars. Four 3/20-scale PSBCs with various ratios of GFRP to SS bars were tested quasi-statically. Test results showed that compared to SS-reinforced PSBCs (SR-PSBCs), the SS-GFRP-reinforced PSBCs (SFR-PSBCs) exhibited higher displacement ductility, less stiffness degradation, lower postyield stiffness ratios, and smaller residual drift ratios, although they presented lower lateral loading capacity and energy dissipation. Increasing the ratio of longitudinal GFRP bar to SS bar in SFR-PSBCs resulted in higher displacement ductility performance and more gentle stiffness degradation behavior. Furthermore, the increase of axial load affects the seismic behavior of SFR-PSBCs in an unfavorable way, which could result in severer damage, significant reduction in the displacement ductility, faster stiffness degradation beyond the peak lateral strength point, and increase in the residual displacement.

Prestressed structures are widely employed in bridges and large-span spatial structures, and the accurate evaluation of prestress state is of great importance for structural maintenance. This paper reviews the nondestructive testing (NDT) and health monitoring techniques for structural effective prestress. Specifically, the fiber Bragg grating (FBG) sensor-based, magnetic-elastic (ME) sensor-based, dynamic response-based, ultrasonic guided wave (UGW)-based, electromechanical impedance (EMI)-based, and electrical resistance-based methods are reviewed in this paper. Firstly, the principle, application range, and measuring accuracy of each technique are introduced and analyzed, and the benefits and limitations of each technique are summarized: The FBG sensor and ME sensor take on high measuring accuracy and have been applied in practical engineering, but they are required to be preinstalled during structural construction; the dynamic response-based method is greatly effective in cable force assessment but not suitable for prestress evaluation of prestressed concrete (PSC) structures; the UGW-based, EMI-based, and electrical resistance-based methods have shown favorable potential for prestress assessment in laboratory experiments, but their feasibility and accuracy in practical engineering need to be verified. Secondly, the challenges and discussion of each method are discussed in the following four aspects: measuring range, reliability of measuring results, stability and durability considering long-term monitoring, and cost-efficiency. Finally, a decision tree is proposed to choose the most appropriate prestress evaluation method in a specific application scenario.

Polyethylene terephthalate (PET) fiber has attracted significant attention for reinforced concrete (RC) structure rehabilitation due to its large rupture strain (LRS; more than 7%) characteristic and recyclability from waste plastic bottles. This study presents a dynamic tensile test of PET fiber bundles performed using a drop-weight impact system. Results showed that the tensile strength and the elastic modulus of the PET fiber bundles increased, whereas the failure strain and the toughness decreased with the increasing strain rate from 1/600 to 160 s⁻¹. In addition, the performance of concrete confined with the PET fiber-reinforced polymer (FRP) under impact loading was investigated based on a 75 mm-diameter split Hopkinson pressure bar (SHPB) device and a drop-weight apparatus. For the SHPB test, owing to the large rupture strain property of PET FRP, the PET FRP-confined concrete exhibited significantly better performance under impact loading compared to its counterpart confined with carbon FRPs (CFRPs). During the drop-weight test, the confinement of the PET FRP composites to the concrete columns as external jackets not only improved the peak impact force, but also prolonged the impact process.