Flexural Response of RC beams cast with normal and steel fibre concrete internally reinforced with various types of FRP bars

Šipke od vlaknima armiranih polimera (FRP) mogu se koristiti kao zamjena za čelične šipke da bi se izbjegla korozija čelika. U ovom radu su pripremljeni i ispitani uzorci armiranobetonskih greda od običnog betona i betona s čeličnim vlaknima (SFC) armirani šipkama od staklenih vlakana, armiranih polimera (GFRP) ili čeličnim šipkama. Rezultati ispitivanja pokazali su da se tlačna čvrstoća betona povećala s povećanjem omjera čeličnih vlakana (SF) koji su korišteni u ovom istraživanju (od 0 % do 1,5 %). Jednako tako, grede armirane GFRP šipkama imale su nižu početnu krutost i veću duktilnost nego one armirane čeličnim šipkama.Fibre Reinforced Polymer (FRP) bars can be used as an alternate for reinforcing bars to avoid corrosion of steel. Samples of reinforced concrete beams cast with normal or steel fibre concrete (SFC), internally reinforced with Glass Fibre Reinforced Polymer (GFRP) or steel bars, are prepared and tested in this paper. Experimental results show that compressive strength of concrete increases with an increase in steel fibre (SF) ratio used in this study (from 0% to 1.5%). Also, the beams reinforced with GFRP bars have a lower initial stiffness and higher ductility than those reinforced with steel bars

Flexural response of GFRP RC beams strengthened with side and bottom NSM GFRP bars

This study exhibits the bending performance of reinforced concrete (RC) beams with glass fiber-reinforced polymer (GFRP) rods. The beams were strengthened with the bottom or side near surface mounted (BNSM or SNSM) methods. Applying BNSM strengthening to the RC beam is difficult in some cases, so the SNSM became essential. Due to the limited research dealing with this type of beam, this study focuses on the effect of internal and NSM reinforcement areas and the NSM position on the response of the beams. Two un-strengthened and six strengthened RC beams were tested in bending. The GFRP RC beams upgraded with SNSM GFRP bars showed higher deflection, energy dissipation, ductility, and ductile failure than those upgraded with BNSM ones. On the contrary, the load-carrying capability and flexural stiffness of GFRP RC beams strengthened with BNSM GFRP rods were slightly higher than those strengthened with SNSM GFRP. Consequently, a parametric investigation relying on the verified finite element (FE) model was executed. This parametric work aimed to add additional data to the literature related to the influences of the internal and NSM reinforcement type and area on the performance of beams with ‎SNSM. According to the FE results, increasing the NSM reinforcement area improved the capacity and stiffness of the upgraded beams regardless of the combination of the internal and NSM reinforcement. The relative axial stiffness between internal and NSM materials significantly impacted the beam performance. Moreover, using GFRP with CFRP or steel with CFRP indicated higher performance than using steel with GFRP, regardless of which one was located as NSM