## 3 Results and Discussion
### Ductility and Deformability  
Ductility is a non-linear structural behavior that causes significant deformations before failure and creates the conditions for the redistribution of internal forces in the critical sections of the continuous beams. For structures with steel reinforcement, the ductility is defined by the ductility coefficient, which represents the ratio of total elastoplastic deformation and deformation at yielding. As FRP reinforcement shows linear elastic behavior until failure, this method of estimating ductility is not applicable to elements reinforced with FRP bars. For sections with FRP reinforcement, the concept of deformability is used to determine the development of deformation before failure of the structure. [PERSON] et al. (2017) and [PERSON] et al. (2018) proposed the deformability factor (\(J\)), as the product of the strength factor and deflection or curvature factor, for ultimate and service states:  
\[J=\frac{M_{ult}\cdot\varphi_{ult}}{M_{ser}\cdot\varphi_{ser}}\quad\text{or} \quad J=\frac{M_{ult}\cdot\Delta_{ult}}{M_{ser}\cdot\Delta_{ser}} \tag{27}\]  
where \(M_{ult}\), \(\varphi_{ult}\), and \(\Delta_{ult}\) are the moment, curvature, and deflection under the ultimate limit state, respectively; and \(M_{ser}\), \(\varphi_{ser}\), and \(\Delta_{ser}\) are the moment, curvature, and deflection under the serviceability limit state, respectively. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Beam**} & \multicolumn{2}{c}{**Experimental Service Load \(P_{ser}\) (kN)**} & \multicolumn{2}{c}{**Experimental Ultimate Load**} & \multicolumn{2}{c}{\(P_{ser}\)/\(P_{ult}\) (\%)} \\ \cline{2-6}  & **Midspan** & **Middle Support** & \(P_{ult}\) (kN)** & **Midspan** & **Middle Support** & **Min** \\ \hline G1-0 & 41.7 & 48.5 & 125.2 & 33.3 & 38.7 & 33.3 \\ G1-15 & 42.4 & 35.0 & 124.9 & 33.9 & 28.0 & 28.0 \\ G1-25 & 42.4 & 30.4 & 137.8 & 30.8 & 22.1 & 22.1 \\ G2-0 & 41.1 & 56.1 & 115.6 & 35.6 & 48.5 & 35.6 \\ G2-15 & 51.6 & 33.3 & 115.2 & 44.8 & 28.9 & 28.9 \\ G2-25 & 55.6 & 37.3 & 119.6 & 46.5 & 31.2 & 31.2 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Experimental service load for tested beams at which stress in the GFRP reinforcement reaches 20% of tensile strength. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Beam**} & \multicolumn{2}{c}{**Experimental Service Load**} & \multicolumn{2}{c}{**Experimental Ultimate**} & \multirow{2}{*}{\(P_{ser}\)/\(P_{ult}\) (\%)} \\ \cline{2-3}  & \(P_{ser}\) (kN) & & **Load \(P_{ult}\) (kN)** & \\ \hline G1-0 & 63.2 & 125.2 & 50.5 \\ G1-15 & 60.5 & 124.9 & 48.4 \\ G1-25 & 64.6 & 137.8 & 46.9 \\ G2-0 & 61.3 & 115.6 & 53.0 \\ G2-15 & 65.7 & 115.2 & 57.0 \\ G2-25 & 65.3 & 119.6 & 54.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Experimental service load for tested beams at which midspan deflection reaches L/240. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Beam**} & \multicolumn{2}{c}{**Experimental Service Load**} & \multicolumn{2}{c}{**Experimental Ultimate**} & \multirow{2}{*}{\(P_{ser}\)/\(P_{ult}\) (\%)} \\ \cline{2-3}  & **Midspan** & **Middle Support** & & **\(P_{ult}\) (kN)** & \\ \hline G1-0 & 78.0 & 106.0 & 125.2 & 62.3 & 84.7 & 62.3 \\ G1-15 & 90.0 & 66.0 & 124.9 & 72.1 & 52.8 & 52.8 \\ G1-25 & 110.0 & 43.0 & 137.8 & 79.8 & 31.2 & 31.2 \\ G2-0 & 28.0 & 35.0 & 115.6 & 24.2 & 30.3 & 24.2 \\ G2 For the service state, the values for the moment and deflection or curvature correspond to a maximum concrete compressive strain of 1%o. The strain of 1%o is considered as the beginning of inelastic deformation of the concrete. Applying this approach, ISIS-07 [35] suggests that the deformability factor for sections with FRP reinforcement should be greater than 4 for rectangular sections and greater than 6 for T-sections. As a criterion for determining the deformability factor in this research, the criterion of deflection is selected rather than the criterion of curvature.