Moment redistribution in continuous FRP reinforced concrete beams

Abstract

The main purpose of this paper is to assess moment redistribution in continuous concrete beams reinforced with fibre reinforced polymer (FRP) bars. A numerical technique based on equilibrium of forces and full compatibility of strains has been developed to evaluate the moment-curvature relationships and moment capacities of FRP and steel reinforced concrete sections. Moment redistribution has then been assessed by comparing elastic and experimental moments at failure, and moment capacity at critical sections of continuous FRP reinforced concrete beams reported on the literature.The curvature of under reinforced FRP sections was large at FRP rupture but failure was sudden, that would not allow any moment redistribution. On the other hand, FRP over reinforced sections experienced higher curvature at failure than steel over reinforced sections owing to the lower FRP modulus of elasticity. Although the experimental and elastic bending moment distributions at failure are significantly different for many beams tested elsewhere, in particular CFRP reinforced concrete beams, the experimental bending moment over the middle support at failure was far lower than the corresponding moment capacity owing to the de-bonding of FRP bars from concrete in the middle support region. Furthermore, the hogging moment redistribution over the middle support is always larger than that at mid-span by around 66%. It was also shown that the load 2 capacity prediction of continuous FRP reinforced concrete beams using the de-bonding moment at the middle support section was the closest to the experimental failure load.

Neutral axis depth and moment redistribution in FRP and steel reinforced concrete continuous beams

“…Santos et al [15] conducted an experimental and numerical study of ductility and moment redistribution in continuous GFRP reinforced concrete T-shaped beams. Kara and Ashour [16] assessed redistribution of moments in FRP reinforced concrete beams by comparing the actual moments at ultimate with the corresponding elastic values. More recently, Mahroug et al [17,18] reported test results of a series of BFRP and CFRP reinforced concrete continuous slabs.…”

Prediction of load–deflection behavior of multi-span FRP and steel reinforced concrete beams

“…Recently, there has been extensive research to investigate the flexural behavior of FRP reinforced concrete members [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Many design approaches to calculate the deflection of FRP reinforced concrete members have been proposed in these studies.…”

Behavior of Glass Fiber–Reinforced Polymer Reinforced Concrete Continuous T-Beams

“…This property raised concerns about the ability of FRP-RC members to redistribute moments between the critical sections. However, moment redistribution in such elements was reported in many studies (Mostofinejad 1997;Habeeb and Ashour 2008;ElMogy et al 2010ElMogy et al , 2011Matos et al 2011;Kara and Ashour 2013;Santos et al 2013;El-Salakawy 2014, 2016). In these studies, parameters such as material type, reinforcement ratio and configuration, concrete strength, stirrup spacing in the context of beams with rectangular and T-section were investigated; however, the beams were tested under symmetrical loading conditions.…”