Load capacity predictions of continuous concrete deep beams reinforced with GFRP bars

Abstract

Nine continuous concrete deep beams reinforced with glass fibre reinforced polymer (GFRP) bars were experimentally tested to failure. Three main parameters were investigated, namely, shear span-to-overall depth ratio, web reinforcement and size effect. The experimental results confirmed the impacts of web reinforcement and size effect that were not considered by the strut-and-tie method (STM) of the only code provision, the Canadian S806-12, that addressed such elements. The experimental results were employed to evaluate the applicability of the methods suggested by the American, European and Canadian codes as well as the previous studies to predict the load capacities of continuous deep beams reinforced with GFRP bars. It was found that these methods were unable to reflect the influences of size effect and/or web reinforcement, the impact of which has been confirmed by the current experimental investigation. Therefore, a new effectiveness factor was recommended to be used with the STM. Additionally, an upper-bound analysis was developed to predict the load capacity of the tested specimens considering a reduced bond strength of GFRP bars. A good agreement between the predicted results and the experimental ones was obtained with the mean and coefficient of variation values of 1.02 and 5.9%, respectively, for the STM and 1.03 and 8.6%, respectively, for the upper-bound analysis.

Effects of the Concrete Strength and FRP Reinforcement Type on the Non-Linear Behavior of Concrete Deep Beams

“…As per the results, the load capacity of the beams was dramatically reduced as the a/h ratio increased due to a drop in the strut's angle of inclination. Zinkaah and Ashour [46] predicted the load capacity of continuous concrete deep beams strengthened with GFRP rebars. They showed that the expected loads of the specimens strengthened with GFRP rebars were overestimated by the upper bound analysis.…”

Proposed prediction models for shear strength of fiber reinforced polymer reinforced concrete deep members without stirrups

“…From the literature, 106 beams with a shear span to depth ratio (a/d) of less than 2.5 were compiled (Abed et al, 2012; Abu-Obaida et al, 2018; Alam and Hussein, 2017; Andermatt and Lubell, 2013b; El-Sayed et al, 2012; Farghaly and Benmokrane, 2013; Guadagnini et al, 2006; Kim and Jang, 2014; Kim et al, 2014; Mahmoud and El-Salakawy, 2016; Nehdi et al, 2008; Razaqpur et al, 2004; Tottori and Wakui, 1993; Zinkaah and Ashour, 2019). The beams were only reinforced in the longitudinal direction without transverse reinforcement.…”

“…The authors also highlighted the need for further studies to refine the strut effectiveness factor, taking into account the non-linear effects of stress distribution. Zinkaah and Ashour (Zinkaah and Ashour, 2019) proposed another modification to the CSA STM effectiveness factor (CSA, 2012). The modification was assessed using nine continuous DBs reinforced with GFRP.…”

Effect of Support Conditions on Performance of Continuous Reinforced Concrete Deep Beams

“…It was reported that failure was triggered by a major diagonal crack in the middle shear span between the load and interior support, and that the comparison between test results and code provisions, specifically the ACI Building Code (318-89) and CIRIA Guide 2, showed slight agreement. Zinkaah et al [7] and Zinkaah and Ashour [8] tested one steel-reinforced and nine (Glass Fiber Reinforced Polymer) GFRP-reinforced continuous shear-critical members. The experimental member load-carrying capacities were compared with capacities predicted by a strut-and-tie model (STM) following the American (ACI 318-2014) and Canadian (S806-2012) code guidelines.…”