## 3 Cyclic Behaviour of a RC One-Bay, One-Story Frame Retrofitted with an RC Infill Panel
### Unit T-Beams with Open Hoop CFRP Strips Employing Specific Mechanical Anchoring Devices
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{\begin{tabular}{c} **Code** \\ **Name** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Initial Hor.** \\ **Stiffness** \\ **(kN/mm)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **H\({}_{\text{max}}\)** \\ **Maximum * \\ **Hor. Load** \\ **(kN)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Normalized ** \\ **Inter-Story** \\ **Drift at H\({}_{\text{max}}\)** \\ **(kN/mm)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Cumulative** \\ **Plastic** \\ **Stiffness** \\ **Ratio *** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Initial** \\ **Hor. Load** \\ **Ratio *** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Maximum** \\ **Energy Ratio** \\ **Ratio *** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Cumulative** \\ **Energy Ratio** \\ **Ratio *** \\ \end{tabular} } \\ \hline \hline
**(1)** & **(2)** & **(3)** & **(4)** & **(5)** & **(6)** & **(7)** & **(8)** \\ \hline Bare 1 & 2 & 11.12 & 1.48\% & 1241.8 & \multirow{2}{*}{6.0} & \multirow{2}{*}{11.18} & \multirow{2}{*}{11.3} \\ \hline UC-IP 1 & 12 & 124.30 & 0.7\% & 14,048.6 & \multirow{2}{*}{5.26} & \multirow{2}{*}{6.06} & \multirow{2}{*}{1.98} \\ \hline Bare jacket1 & 13.3 & 55.81 & 1.48\% & 7574.3 & \multirow{2}{*}{18.75} & \multirow{2}{*}{7.7} & \multirow{2}{*}{10.75} \\ \hline UC-IP 2 & 70 & 338.4 & 1.48\% & 15,028.3 & \multirow{2}{*}{18.75} & \multirow{2}{*}{7.7} & \multirow{2}{*}{10.75} \\ \hline Bare jacket2 & 3.2 & 52.99 & 2.4\% & 5913.4 & \multirow{2}{*}{18.75} & \multirow{2}{*}{7.7} & \multirow{2}{*}{10.75} \\ \hline RC-IP 3 & 60 & 408.25 & 2.86\% & 63,597.9 & \multirow{2}{*}{18.75} & \multirow{2}{*}{7.7} & \multirow{2}{*}{10.75} \\ \hline \end{tabular}   
* *is substantially increased by the inclusion of the steel reinforcing net. Secondly, the development of cracking within the panel is controlled by the net reinforcement in such a way that it does not lead to a sudden decrease to its bearing capacity, even for much larger normalized interstory drift values reaching 2.5% (column 4 Table 3). This contributing mechanism mobilizes even further the steel ties connecting the panel with the frame, which represents an additional plastic energy accumulation medium. This combined effect for specimen RC-IP 3 explains the eleven times increase in cumulative plastic energy when compared to the jacketed frame (column 8 of Table 3), whereas the corresponding increase for the UR-IP 2 specimen is only twofold. * The fact that the RC infill panel sustains large horizontal forces and interacts successfully with the surrounding frame can also be seen by the level of shear strains which develop within the infill panel when the maximum horizontal load capacity is reached (Figure 14c). * All the above is expected to be valid for prototype structures. Constructing such an RC infill in a prototype frame bay needs proper design. The numerical simulation in Section 4 presents such a methodology. Figure 13: Damage of UC-IP 1, UC-IP 2, and RC-IP 3. (**a**) Crushing of the UC infill panel and the RC frame at the corner. Specim UC-IP 1. (**b**) Large cracking of the UC infill panel. Specim UC-IP 2. (**c**) Control of cracking of the reinforced infilled panel. Specim RC-IP 3. In order to monitor the behaviour of the UC or RC infill panel itself, a number of displacement transducers were attached at both facades of this panel during testing measuring the variation of the length of its two main diagonals throughout the loading sequence. By  
Figure 14: (**a**) Shear strain response of UC-IP 1. (**b**) Shear strain response of UC-IP 2. (**c**) Shear strain response of UC-IP 3.  
combining these measurements, the average shear strain response of the concrete infill panel was obtained, and it is plotted in Figure 14a-c against the applied load (diag).