Numerical analysis of reinforced concrete beams strengthened in shear using carbon fiber reinforced polymer materials

Abstract

Purpose This paper aims to analyze the performance of reinforced concrete (RC) beams strengthened in shear with carbon fiber-reinforced polymer (CFRP) sheets subjected to four-point bending. Design/methodology/approach ANSYS software is used to build six models. In addition, SOILD65, LINK180, SHELL181 and SOLID185 elements are used, respectively, to model concrete, steel reinforcement, polymer and steel plate support. A comparative study between the nonlinear finite element and analytical models, including the ACI 440.2 R-08 and FIB14 models as well as experimental data, is also carried out. Findings The comparative study of the nonlinear finite element results with analytical models shows that the difference between the predicted load capacity ranges from 4.44%–24.49% in the case of the ACI 440.2 R-08 model, while the difference for FIB14 code ranges from 2.69%–26.03%. It is clear that there is a good agreement between the nonlinear finite element analysis (NLFEA) results and the different expected CFRP codes. Practical implications This model can be used to explore the behavior and predict the RC beams strengthened in shear with different CFRP properties. They could be used as a numerical platform in contrast to expensive and time-consuming experimental tests. Originality/value On the basis of the results, a good match is found between the model results and the experimental data at all stages of loading the tested samples. Load capacities as well as load deflection curves are also presented. It is concluded that the differences between the loads at failure ranged from 0.09%–6.16% and 0.56%–4.98%, comparing with experimental study. In addition, the increase in compressive strength produces an increase in the ultimate load capacity of the beam. The difference in the ultimate load capacity was less than 30% when compared with the American Concrete Institute and FIB14 codes.

Finite-element modeling of partially prestressed concrete beams with unbonded tendon under monotonic loadings

“…The cracking of concrete is model by assigning four basic parameters based on the William and Warnke model that are open and close shear retention coefficients, tensile strength (modulus of rupture stress) of concrete which is calculated based on the equation recommended in ACI 318–19 code (ACI 318–19) as given in equation (2), the value of compressive strength of concrete was not entered in the material data, instead the value was kept as −1 (due to convergence issue), whereas the other parameters are kept as ANSYS default (Pandimani et al , 2021). The tension stiffening phenomenon of concrete is included using the bilinear tensile stress–strain relationship as a default model available in ANSYS with a stress relaxation of 40% and then linearly decreases to zero stress to smoothly converge the nonlinear solution, as shown in Figure 2(b) (Barour and Zergua, 2020; Wolanski, 2004; ANSYS, 2007): …”

“…The untensioned steel reinforcements (tensile, compressive and shear) are modeled through a discrete reinforcement approach, which is one of the most widely used methods to model the reinforcements embedded inside the concrete volume (Pandimani et al , 2021; Wolanski, 2004). The 3-D two-node link180 truss element is used to represent these reinforcements, having three translational DOF (x-, y- and z-directions) at each node, as shown in Figure 4(b) (Pandimani et al , 2021; Barour and Zergua, 2020; Mehmet and Hakan, 2019). This link180 element is assigned with real constants that represent the area of steel bars.…”

“…The modulus of elasticity of steel bars E s = 200 GPa and Poisson’s ratio = 0.3 is assigned for linear property, whereas the nonlinear behavior is modeled by assigning the yield stress and tangent modulus values to the link element. It is also assuming that the steel reinforcements are behaving like elastic-perfectly plastic materials that are identical in compression and tension (Pandimani et al , 2021; Barour and Zergua, 2020). The stress-strain relationship of conventional steel bars can be estimated using the expressions given in equations (7) and (8).…”

Nonlinear modelling and finite element analysis on the load-bearing capacity of RC beams with considering the bond–slip effect

“…In ANSYS, William and Warnke’s model governs the failure criteria of concrete, which require a minimum of four parameters to define the failure that is ultimate tensile stress of concrete (f t ), the maximum compressive stress of concrete (fc’) and the open and closed shear transfer coefficients βo and βc , respectively, at cracking face (Dahmani et al , 2010; Jawdhari and Harik, 2018; Kachlakev et al , 2001; Wolanski, 2004). The βo and βc values range from 0–1 (Godínez-Domínguez et al , 2015; Barour and Zergua, 2020; Barour et al , 2019). At the cracking face, 0 denotes a complete loss of shear transfer and 1 denotes no loss of shear transfer (ANSYS, 2007; Barour et al , 2019).…”

“…An eight-node SOLID185 brick element with three translational DOF at each node is used to model the steel plates at the support and loading locations (Kadhim et al , 2019; Barour and Zergua, 2020). The SOLID185 element acts as cushion plates, which reduce the stress concentrations at these locations (Vasudevan et al , 2013; Wolanski, 2004).…”