## 3 Results and Discussion
### Ductility and Deformability
Moments and deflections for the ultimate limit state are obtained as the maximum values measured during the test. As can be seen in Table 7, the deformability factors (_J_) were higher than the minimum values in 4, as recommended by ISIS-07 [35]. This means that the tested continuous beams showed a certain kind of ductile behavior, although they contained GFRP reinforcement, which exhibits brittle behavior. The higher deflection factors (\(\Delta_{ult}/\Delta_{\text{ser}}\)) compared to strength factors (\(M_{ultl}/M_{s\sigma}\)) indicate that this ductile behavior of the beams is mainly a consequence of the high deformation capacity, which provides sufficient warning before failure. The deformability factor, as an important criterion for describing the quality response of structures, is the ratio between the ultimate limit state and the serviceability limit state with respect to load capacity and deformation. Thus, the serviceability criteria defined in Section 3.6 served as baselines for calculating deformability factors (also known as robustness indices) based on Equation (27), where (\(M_{ultl}/M_{ser}\)) is the strength factor and (\(\Delta_{ultl}/\Delta_{\text{ser}}\)) is the deflection factor. In Figures 12-14, the strength, deflection, and deformability factors are given, respectively, where moment and midspan deflection values under the serviceability limit state are defined for the serviceability criteria limitations given in Section 3.6. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline
**Beam** & \(M_{ult}\) **(kNm)** & \
\begin{tabular}{c} \(\Delta_{ult}\) \\ **(mm)** \\ \end{tabular} & \(M_{ser}\) **(kNm)** &
\begin{tabular}{c} \(\Delta_{ser}\) \\ **(mm)** \\ \end{tabular} & **Strength Factor** & **Deflection Factor** & \(J\) **Factor** \\ \hline G1-0 & 32.63 & 24.06 & 16.39 & 7.19 & 1.99 & 3.35 & 6.7 \\ G1-15 & 40.12 & 27.14 & 15.83 & 5.75 & 2.53 & 4.72 & 12.0 \\ G1-25 & 46.21 & 31.2 & 23.90 & 10.07 & 1.93 & 3.10 & 6.0 \\ G2-0 & 33.31 & 25.76 & 13.61 & 5.52 & 2.45 & 4.67 & 11.4 \\ G2-15 & 38.67 & 26.81 & 21.26 & 7.48 & 1.82 & 3.58 & 6.5 \\ G2-25 & 38.41 & 24.41 & 19.81 & 7.07 & 1.94 & 3.45 & 6.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Deformability factors for sections in the midspan for the tested beams. Figure 12: Strength factors for serviceability criteria limitations for the tested beams. As constituents of the deformability factors, it is noticeable that the deflection factors are significantly greater than the strength factors for all criteria for all tested beams, which is desirable for achieving better beam behavior. Due to the low levels of service loads, as a consequence of limiting the crack width to 0.7 mm, high values of deformability factors for beams series 2 are obtained. For the beams series 1, the deformability factors are the highest for the GFRP reinforcement stress limitation. Additionally, an increase of the deformability factors (along with the strength and deflection factors) with an increase of the designed moment redistribution is evident for the beams series 1 for all criteria, showing good bond strength between the ribbed GFRP bars and concrete. Generally, for service loads, the low modulus of elasticity of the GFRP reinforcement causes considerable deflections and wide cracks in continuous beams, which can be characterized as negative phenomena. However, with further loading, such a low modulus of elasticity with a high GFRP reinforcement tensile strength and with large deflections and wide cracks enables high safety coefficients and deformability factors to be reached. This provides sufficient warning of continuous beam failure, which is significant for prevention purposes. Thus, after overcoming the service loads, the low modulus of elasticity can be represented as a positive characteristic of the GFRP reinforcement. This especially refers to the continuous beams that achieved the designed moment redistribution. Figure 14: Deformability factors for serviceability criteria limitations for the tested beams.