## 3 Experimental Setup
### Results and Discussion  
The control sample CS1, which bore no FRP, was tested monotonically to failure. The tip load versus displacement of the CS1 and RS1 is shown in Figure 4. The capability of the flange-bonded retrofit in enhancing capacity can be deduced from these curves. It is obvious that the response is almost linear up to 9 KN, at which load the first crack develops and the joint enters non-linear responses with a gradually decreasing stiffness as the load increases. The joint cracking is not visible at that load; it is only assumed from the shape of the force-displacement curve. The first flexural cracks of the beam initiate with the tip load of 20 KN, corresponding to a displacement of about 9 mm. Moreover, beam flexural cracks were raised at different locations off the column face as loading progressed. The  
Figure 3: Schematic view of the LVDT sensor positions in experimental test.  
longitudinal reinforcing of the beam yielded an ordinary load equal to 39 KN with an average yield displacement of 32 mm. The test was stopped at the load reached the joint's peak capacity, which was almost 45 KN, corresponding to a 43.6 mm displacement. As the column was constantly subjected to a 150 kN load, the experimental test was halted when the beam's resistance significantly dropped, primarily due to the development of severe cracks and the crushing of the compression area of the beam concrete, posing a safety concern.  
Consequently, the force-displacement graph has been plotted up to the point where the beam's resistance reached its maximum, i.e., before experiencing a noticeable reduction in strength capacity. This peak resistance force is then used to determine the load-bearing capacity of the beam. Though loading was over, some flexural cracks were noticed to have been formed near the beam, close to the column face, and others had progressed into the beam (Figure 5a).  
The test for case RS1 (retrofitted and strengthened by five 300 mm CFRP layers stretching from the column) was stopped when the load reached the joint's peak capacity at 56.58 KN, which corresponded to a 38.4 mm displacement. As shown in Figure 5b, the beam failed, demonstrating ductile behavior right where FRP was cut off and sending the plastic hinge off the joint core.  
No considerable debonding was experimentally observed in this research, which presents moderate ductility. Furthermore, Table 1 shows that the flange-bonded retrofit had increased the original frame capacity by 26%, while decreasing the displacement capacity by 17%. It is seen that the maximum bar strains at the end point of FRP in the longitudinal reinforcements are greater than the rebar yield strain.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{\multirow{2}{*}{**Model**}} & \multicolumn{3}{c}{**Max Bar Strain**} & \multicolumn{2}{c}{**Max Concrete Strain**} & \multicolumn{1}{c}{**Pmax**} & \multirow{2}{*}{**\(\Delta\)max (mm)**} \\  & & **Column Face** & **End of CFRP** & **Column Face** & **End of CFRP** & **(kN)** & \\ \hline Original & Left & \(2.24\times 10^{-2}\) & - & \(-3.48\times 10^{-3}\) & & 43.65 & 45 \\ (CS1) & Right & \(2.15\times 10^{-2}\) & & \(-3.21\times 10^{-3}\) & & 30.12 & 43.4 \\ Retrofitted & Left & & \(1.8\times 10^{-2}\) & & \(-4.44\times 10^{-3}\) & 53.58 & 38.4 \\ (RS1) & Right & & \(1.6\times 10^{-2}\) & & \(-3.56\times 10^{-3}\) & 39.75 & 37.1 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Steel yield stress–plastic strain.  
Figure 4: Beam tip load versus tip displacement of the specimens (left side).