Experimental Evaluation of PSC Structures from FRP with a Prestressing Strengthening Method

Abstract

A prestressed concrete (PSC) structure is subject to prestress losses in the long and short terms, and the structure ages over time. The structure is susceptible to corrosion from exposure to environmental factors such as moisture, chloride, and carbonation, thus causing prestress loss. Therefore, strengthening the structure is needed to address this problem. Here, the near surface mounted (NSM) method and the external prestressing (EP) method were selected because they are capable of applying additional prestressing. Further, we used fiber-reinforced plastics or polymers, or carbon fiber-reinforced plastics or polymers because of their high tensile strength and noncorrosive properties. For EP tests, prestressed strands were used. Accordingly, this study performs four-point flexural tests and evaluations for 12 types of specimens fabricated with different PSC methods. All specimens fabricated with the NSM (prestressing, no prestressing) and EP methods achieved stiffness that was 50–60% higher than that of the control PSC specimen. It was observed that the EP method in conjunction with prestressing yielded the best strengthening effect. It is expected that the results of this study will be applied to real structures for strengthening them and improving their performances.

Experimental Study on Effects of Additional Prestressing Using Fiber Reinforced Polymers and Strands on Deterioration of PSC Bridge Structure

“…The NSM method strengthens a structure by creating grooves with a constant depth and embedding FRP plates or FRP rods instead of attaching reinforcement on the concrete surface, as in the existing EB method. Kim et al [ 18 ] reported that the NSM method affords a relatively higher performance improvement than the EB method owing to its superior resistance to bond failure. Moreover, they reported that damage due to fire or vehicular collision could be avoided, unlike in the case where the reinforcement is bonded on the surface, because the reinforcement is embedded in the concrete.…”

“…In both these methods, additional prestressing is applied upon completing construction. With regard to FRPs, glass fiber-reinforced polymers, such as aramid FRPs (AFRPs) and carbon FRPs (CFRPs) have been used as major strengthening materials [ 18 ]. FRPs exhibit brittle failure but have superior strength, weight, durability, creep, and fatigue resistance, compared to existing construction materials [ 19 , 20 , 21 , 22 ].…”

A State-of-the-Art Review on Structural Strengthening Techniques with FRPs: Effectiveness, Shortcomings, and Future Research Directions

“…Figure 17 displays the step-by-step procedure for applying externally prestressed CFRP for structural strengthening [ 212 ]. Kim et al [ 213 ] carried out research to address prestress losses and aging in prestressed concrete structures (PSCs); strengthening methods such as NSM and EP were used, utilizing FRPs, particularly CFRPs, for their non-corrosive and high tensile strength properties. The NSM and EP methods remarkably improved the stiffness by 50–60% compared to the control PSC specimen.…”

Evaluation of the Performance and Ductility Index of Concrete Structures Using Advanced Composite Material Strengthening Methods

“…Table 1 shows the load-displacement test results of PSC structures reinforced with FRPs by Kim et al [ 31 , 32 , 33 ]. Four-node tests were also conducted.…”

“…With the application of the EP method, cracks occurred at the anchorage. Therefore, it is thought that EP and NSM methods will show improved strengthening effects when these practical problems are resolved [ 31 ].…”