An experimental and analytical investigation of reinforced concrete beam-column joints strengthened with a range of CFRP schemes applied only to the beam

Abstract

This paper investigates the experimental and analytical behaviour of beam-column joints that are subjected to a combination of torque, flexural and direct shear forces, where different Carbon Fibre Polymer (CFRP) strengthening wraps have been applied only to the beam. These wrapping schemes have previously been determined by the research community as an effective method of enhancing the torsional capacities of simply supported reinforced concrete beams. In this investigation, four 3/4-scale exterior beam-column joints were subjected to combined monotonic loading; three different beam wrapping schemes were employed to strengthen the beam region of the joint. The paper suggests a series of rational formulae, based on the space truss mechanism, which can be used to evaluate the joint shear demand of the beams wrapped in these various ways. Further, an iterative model, based on the average stress-strain method, has been introduced to predict joint strength. The proposed analytical approaches show good agreement with the experimental results. The experimental outcomes along with the adopted analytical methods reflect the consistent influence of the wrapping ratio, the interaction between the combined forces, the concrete strut capacity and the fibre orientation on the joint forces, the failure mode and the distortion levels. A large rise in the strut force resulting from shear stresses generated from this combination of forces is demonstrated and leads to a sudden-brittle failure. Likewise, increases in the beams’ main steel rebar strains are identified at the column face, again influenced by the load interactions and the wrapping systems used.

Shear strengthening of RC beams with NSM FRP. I: Review of strength models

“…The application of fiber-reinforced polymer (FRP) in the strengthening of reinforced concrete (RC) members in various ways and under different load applications (e.g. Akid et al, 2021; Ali and Forth 2021; Chen et al, 2007; Dhindsa et al, 2021; Dias and Barros 2013; Hollaway et al, 2008; Kian et al, 2021; Li et al, 2021a; Majed et al 2021; Mostakhdemin et al, 2021; Muhammad et al, 2016; Nie et al, 2022; Ozbakkaloglu and Vincent 2014; Rahimi and Hutchinson 2001; Silva et al, 2021; Teng and Lam 2004; Tobbi et al, 2014; Yuan and Hu 2021) has become prevalent in the last few decades, on account of many advantages of FRP such as high strength, good corrosion resistance and lightweight (e.g. Bakis et al, 2002).…”

Shear strengthening of RC beams with NSM FRP. II: Assessment of strength models

“…Fiber-reinforced polymer (FRP) was used in civil engineering over the few decades, mainly as a strengthening material for reinforced concrete (RC) structures (e.g. Rahimi and Hutchinson 2001; Teng and Lam 2004; Hollaway and Teng 2008; Dias and Barros 2013; Ozbakkaloglu and Vincent 2014; Tobbi et al, 2014; Muhammad et al, 2016; Oehlers et al, 2016; Akid et al, 2021; Ali and Forth 2021; Dhindsa et al, 2021; Kian et al, 2021; Li et al, 2021; Majed et al 2021; Mostakhdemin Hosseini et al 2021; Silva et al, 2021; Yuan and Hu 2021). The use of near-surface mounted (NSM) FRP for strengthening RC beams owns many advantages such as higher bond efficiency with concrete and better durability, compared to the traditional externally bonded (EB) FRP technique (De Lorenzis and Teng 2007; Seracino et al, 2007b; Bilotta et al 2011, 2015).…”

Artificial neural networks approach for prediction of axial loading capacity of circular normal strength concrete columns confined by both transverse steel reinforcement and carbon fiber reinforced polymer wraps

“…This improvement is ascribed to the high strength-to-weight ratio, high corrosion resistance, easier application in narrowed spaces, lessening labor costs, and easiness in site handling for FRP composites (Ali et al, 2020; Aslam et al, 2021; El Ouni and Raza, 2021; Ilki et al, 2008; Pour et al, 2019; Raza et al 2019, 2021a, 2021b, 2021c; Raza and Rafique, 2020; Rafique et al, 2021). The FRP composites are advanced materials for the strengthening and stiffening of the structural elements (Ali and Forth, 2021; El-Kashif et al, 2020; Huang et al, 2020; İşleyen et al, 2021; Tu et al, 2019; Wang et al, 2015; Wu et al, 2006; Zhang et al, 2020; Li and Jiao, 2021; Zhu et al, 2005; Zeng et al, 2021). In this context, several studies were performed to investigate the axial compression performance of CFRP-wrapped concrete in a circular section (Al-Nimry and Neqresh, 2019; Cui and Sheikh, 2010; Ferrotto et al, 2018; Jiang and Teng, 2007; Khan et al, 2020; Lam and Teng, 2003, 2004; Lam et al, 2006; Lin and Teng, 2019; Mirmiran et al, 1998; Spoelstra and Monti, 1999; Shahawy et al, 2000; Smith et al, 2010; Teng et al, 2009; Rousakis et al, 2012; Xiao and Wu, 2003; Youssf et al, 2017).…”