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

Tae-Kyun Kim,Jong-Sup Park

doi:10.3390/polym13234239

Abstract

The performance of concrete structures deteriorates over time. Thus, improving their performance using fiber-reinforced polymers (FRPs), PS strands, and various strengthening methods is important. Reinforced concrete (RC) and prestressed concrete (PSC) structures develop initial cracks in concrete during bending tests, and destruction occurs over a certain period of time after a certain load is generated, and then after the reinforcements and strands yield. However, in the case of FRP structures, after an initial concrete crack occurs, FRPs exhibit a rapid shape deformation of the structure after yielding. Thus, in this study we used FRP and PS strand materials and evaluated the ductility index using the load-displacement results obtained from structural tests conducted using various strengthening methods. The ductility index evaluation method compares and analyzes the change rates in the ductility index of PSC and RC structures based on a method that uses structural deflection and the derivation of the energy area ratio. The ductility evaluation results based on the energy area ratio at the crack, yield, and ultimate points showed that all the RC structures, except for the specimens strengthened with reinforcing materials from company H, were in the ductility and semi-ductility sections. Thus, all the PSC structures, except for the control specimens and PH4NP, were found to be brittle.

Highlights

IntroductionPerformance degradation occurs over time owing to the actions of the environment and external forces, and structural reinforcement is required [3,4]
The ductility index evaluation method compares and analyzes the change rates in the ductility index of prestressed concrete (PSC) and Reinforced concrete (RC) structures based on a method that uses structural deflection and the derivation of the energy area ratio [22,23]
The ductility evaluation results based on the energy area ratio at the crack, yield, and ultimate points showed that all of the RC structures, except for the specimens strengthened with reinforcing materials from company H, were in the ductility and semi-ductility sections

Summary

Introduction

Performance degradation occurs over time owing to the actions of the environment and external forces, and structural reinforcement is required [3,4]. For fiber reinforcement, enabling integrated behavior between the sheet attached and the structure is the most important requirement; the bonding performance of the adhesive must be excellent [6,7]. External prestressing (EP) is a construction method primarily applied to restore the load-carrying capacity of old bridges or to improve the load-carrying capacity of existing bridges owing to various changes in the use environment. For the EP method, prestressing is introduced by installing anchorage devices for tendon installation and PS tendons on the outside of an existing concrete structure.

Methods

Results

Conclusion