Experimental studies and theoretical models for concrete columns confined with FRP composites: a review

Abstract

Purpose Advanced fibre-reinforced polymer (FRP) composites have been increasingly used over the past two decades for strengthening, upgrading and restoring degraded civil engineering infrastructure. Substantial experimental investigations have been conducted in recent years to understand the compressive behaviour of FRP-confined concrete columns. A considerable number of confinement models to predict the compressive behaviour of FRP-strengthened concrete columns have been developed from the results of these experimental investigations. The purpose of this paper is to present a comprehensive review of experimental investigations and theoretical models of circular and non-circular concrete columns confined with FRP reinforcement. Design/methodology/approach The paper reviews previous experimental test results on circular and non-circular concrete columns confined with FRP reinforcement under concentric and eccentric loading conditions and highlights the behaviour and mechanics of FRP confinement in these columns. The paper also reviews existing confinement models for concrete columns confined with FRP composites in both circular and non-circular sections. Findings This paper demonstrates that the performance and effectiveness of FRP confinement in concrete columns have been extensively investigated and proven effective in enhancing the structural performance and ductility of strengthened columns. The strength and ductility enhancement depend on the number of FRP layers, concrete compressive strength, corner radius for non-circular columns and intensity of load eccentricity for eccentrically loaded columns. The impact of existing theoretical models and directions for future research are also presented. Originality/value Potential researchers will gain insight into existing experimental and theoretical studies and future research directions.

Confinement of FRP concrete columns: Review of design guidelines and comparison with experimental results

“…Regarding the influence of concrete strength on the strengthening ratio (Figure 6), all the guidelines show a decreasing strengthening ratio as unconfined concrete strength increases, meaning that the strength enhancement capacity of FRP confinement is higher in concretes with a lower strength class. This statement is in accordance with the literature (22)(23)(24)(25). The sharp changes in the guideline curves are due to the design guidelines' limits.…”

“…The final confined strength depends on lateral FRP pressure and unconfined concrete strength, as shown in Equation [1]. The improvement observed in the maximum confined concrete strength of FRP-wrapped columns decreases as unconfined concrete strength increases (22)(23)(24)(25).…”

Experimental behavior and reliability of predamaged concrete columns externally repaired with FRP spiral strips under axial compression

“…The application of FRP composites have experienced a great expansion especially in the field of building and public works, because of the evolution of manufacturing techniques of these materials (Moghtadernejad et al , 2021; Li et al , 2022), and therefore the reduction of their cost combined to the ease of their implementation (Bentayeb et al , 2009; Si Salem et al , 2015). In the last decade, extensive studies have been performed on glass and carbon FRP (G/CFRPs)-confined concrete columns (Sirach et al , 2022; Rodsin, 2021; Li et al , 2021; Zeng et al , 2020; Gora et al , 2019). Moreover, the bonding fabric or stratified strips based on carbon fiber has now become a common practice which is recognized worldwide (Faleschini et al , 2020; Ismail et al , 2019; Huang et al , 2022; Xu et al , 2022; Gao et al , 2021).…”