Concentrically Loaded Circular RC Columns Partially Confined with FRP

Abstract

Wrapping reinforced concrete (RC) columns with fiber reinforced polymer (FRP) composites is effective in increasing their capacity. The current state of the art concentrates primarily on fully wrapped columns and few studies dealt with partially wrapped ones. The objective herein is to evaluate the effectiveness of partial wraps (or strips) and to develop a confined concrete compressive stress-strain (f c − ε c) model that accounts for partial wrapping. Three-dimensional finite element (FE) models are generated to evaluate the influence of different parameters on the behavior of concentrically loaded RC circular columns that are partially and fully wrapped with FRP. The results indicated an increase in ductility as the number of FRP strips is increased, and revealed that longitudinal steel had little influence on the confined f c − ε c relationship. The proposed f c − ε c model, derived from the parametric study, accounts for the effect of partial and full confinement, the unconfined concrete strength f ′ c , and yielding of transverse steel. Comparison of the results generated using the proposed model with FE and experimental results are in good agreement.

Design-oriented axial stress–strain model for partially fiber-reinforced-polymer-confined normal-strength concrete

“…To verify the accuracy and reliability of the proposed model in predicting the mechanical performance of partially FRP-confined normal-strength concrete, another different database of 100 circular concrete specimens wrapped with FRP strips was collected by using the same criteria as stated before to make the verifications more credible. These specimens were from the studies conducted by Chen (2017), Ghanem and Harik (2018), and Ni (2018). It should be noted that most of the specimens in this database are FRP partially wrapped plain concrete columns except the strengthened RC columns reported by Ghanem and Harik (2018).…”

“…These specimens were from the studies conducted by Chen (2017), Ghanem and Harik (2018), and Ni (2018). It should be noted that most of the specimens in this database are FRP partially wrapped plain concrete columns except the strengthened RC columns reported by Ghanem and Harik (2018). However, given that the longitudinal reinforcement ratio is relatively small and hence the effect of reinforced bars in confined concrete is degraded significantly, the specimens are still used in for verification.…”

A robust 3D finite element model for concrete columns confined by FRCM system

“…Concrete columns confined by FRP jackets/sheets have been modelled successfully with the Drucker-Prager (DP) plasticity model [16,17]. Conventional DP model assumes an elastic-perfectly plastic response under both tensile and compressive stresses, and utilizes a modified version of the Von Mises yield criterion to account for the effects of hydrostatic pressure [16]. However, this model is unable to simulate the large difference in tensile and compressive responses of concrete and doesn't include softening after cracking or crushing [13].…”

Predicting the behavior of reinforced concrete columns confined by fiber reinforced polymers using data mining techniques

“…Most studies about RC columns wrapped with FRP in literature ignored the internal steel reinforcement [4] or estimated the total confinement pressure as the sum of the confinement pressure due to the external FRP and the confinement pressure due to the internal steel [5], with few models to account for both [6,7].…”