Numerical Sensing of Plastic Hinge Regions in Concrete Beams with Hybrid (FRP and Steel) Bars

Abstract

Fibre-reinforced polymer (FRP)-reinforced concrete members exhibit low ductility due to the linear-elastic behaviour of FRP materials. Concrete members reinforced by hybrid FRP–steel bars can improve strength and ductility simultaneously. In this study, the plastic hinge problem of hybrid FRP–steel reinforced concrete beams was numerically assessed through finite element analysis (FEA). Firstly, a finite element model was proposed to validate the numerical method by comparing the simulation results with the test results. Then, three plastic hinge regions—the rebar yielding zone, concrete crushing zone, and curvature localisation zone—of the hybrid reinforced concrete beams were analysed in detail. Finally, the effects of the main parameters, including the beam aspect ratio, concrete grade, steel yield strength, steel reinforcement ratio, steel hardening modulus, and FRP elastic modulus on the lengths of the three plastic zones, were systematically evaluated through parametric studies. It is determined that the hybrid reinforcement ratio exerts a significant effect on the plastic hinge lengths. The larger the hybrid reinforcement ratio, the larger is the extent of the rebar yielding zone and curvature localisation zone. It is also determined that the beam aspect ratio, concrete compressive strength, and steel hardening ratio exert significant positive effects on the length of the rebar yielding zone.

Flexural behaviour of ECC and ECC–concrete composite beams reinforced with hybrid FRP and steel bars

“…FRP-reinforced concrete members have the advantages of high flexural strength and good durability, but the two inherent limitations of FRP bars, namely, low elastic modulus and poor ductility, limit their application in engineering structures (Abdalla, 2002;El-Nemr et al, 2018;GangaRao et al, 2006;Yuan and Wu, 2019;Zhang et al, 2021). The combined use of FRP and steel bars, in which FRP bars are placed at the corners of concrete members that are susceptible to corrosion, achieves a good corrosion resistance, high post-yield stiffness and small residual deformation (Aiello and Ombres, 2002;Bakis et al, 2001;Ge et al, 2015;Jo et al, 2004;Lau and Pam, 2010;Nanni et al, 1994;Qin et al, 2017;Qu et al, 2009;Yuan and Chen, 2018). However, owing to the tension brittle inherent in concrete, cracks with noticeable crack widths frequently appear in the RC member.…”

Experimental Investigation on Interfacial Defect Criticality of FRP-Confined Concrete Columns

“…Defects in FRP strengthened concrete structures could be induced from manufacture process, environmental deterioration, or impact from external load [7,8,9,10,11]. To detect the defects in FRP-concrete system, several non-destructive techniques and sensors have been developed to quantify the defect within the systems—such as acoustic-laser technique, optic-electronic sensors, laser-reflection technique, etc.—which can evaluate the material heterogeneity or defects through the measurement of vibrational frequency response for the materials [12,13,14,15,16,17,18]. After inspection, it is critical to evaluate the effect of detected defect, i.e., whether it can be merely neglected or significantly reduce the structural performance, so as to provide guidance on the repair schemes for the FRP reinforced concrete structures [19,20].…”

Compressive Behavior of Sustainable Steel-FRP Composite Bars with Different Slenderness Ratios

“…Based on parametric analyses and experimental studies, compressive stress-strain models were proposed and verified along with their corresponding cyclic models [4,[8][9][10][11]. To avoid deterioration of the mechanical properties of the steel bars due to corrosion, fiber reinforced polymer (FRP) bars were developed as an ideal reinforcement in concrete structures [12,13]. The partial or complete adoption of FRP composites as structural members can significantly enhance structural safety and sustainability [14][15][16].…”