## 2 Materials and Methods
**(b)** Cross-section RC T-beam specimen. **(c)** Four-point loading arrangement used in all tests together with the concept of forming the “unit T-beam” specimens (see also Figure 7a,b). A Novel Laboratory Set-Up to Test the Force Transfer Mechanism for Open Hoop CFRP Strips with or without Specific Mechanical Anchoring Devices  
Before testing the simple-supported prototype RC T-beam depicted in Figure 5a-c without or with CFRP external transverse shear reinforcement, a simple experimental procedure was conceived in order to study the force transfer mechanisms that develop in this external CFRP strip transverse shear reinforcement and the concrete volume. For this purpose, T-beam specimens were constructed of relatively small length having the same cross-section as the prototype T-beam of full length (Figure 5b). The length of these specimens, denoted as \"unit T-beams\", was equal to 250 mm, which was sufficient to provide the necessary bond surface to house a CFRP external transverse shear reinforcing strip having a width of approximately 100 mm, as shown in Figure 7a,b (see also Figure 10a-c). Figure 8a-d depicts the corresponding cross-sections of such \"unit T-beam\" specimens hosting a typical CFRP shear strip (100 mm wide) bonded to such a \"unit T-beam\" specimen with resin provided by the manufacturers, following the typical for the CFRP construction technique. A simple experimental loading procedure is used, aiming to quantify the axial tensile capacity of FRP shear strips without or with an anchoring device, which is its main forcing transfer mechanism, as indicated in Figure 9a-c, and the interaction with the concrete volume. As can be seen in Figure 8a-d, these specimens have the same cross-section as the prototype full-length RC T-beam (Figure 5a-c). However, as explained before, the length of these specimens, named \"unit T-beams\", is equal to 250 mm which is a portion of the full-length prototype RC T-beam, as indicated in Figures 5a-c, 7a,b and 10a-c, which is sufficient to host the width of one CFRP shear strip. In order to study the force transfer behavior of the CFRP stirrups, each \"unit T-beam\" is subjected to a tensile stress field by applying an external vertical load, as shown in Figures 7b and 9a-c with an arrow. In this way, the force transfer mechanism under investigation was replicated, as will be explained in detail in what will follow. The experimental set-up for testing these \"unit T-beam\" specimens is shown in Figure 9a-c. Each of these specimens, after the CFRP strip was set approximately seven days after being bonded at both sides of the \"unit T-beam\" in all \begin{table}
\begin{tabular}{c c c} \hline
**Specimen No** & **Maximum Compressive Axial Load (kN)** & **Compressive Strength (MPa)** \\ \hline Specim 1 & 420 & 23.77 \\ Specim 2 & 330 & 18.67 \\ Specim 3 & 329 & 18.62 \\ Specim 4 & 331 & 18.73 \\ Specim 5 & 352 & 19.92 \\ Average concrete cylinder compressive strength \(\ell_{\text{ck}}\) = 19.94 MPa (STDEV = 2.21 MPa) \\ \hline \end{tabular}
\end{table} 
Table 1: Results of concrete cylinders tested in uni-axial compression. The specimens’ diameter = 150 mm, height = 300 mm. Figure 6: (a) Typical tensile test results of longitudinal reinforcement. (b) Typical tensile test results of CFRP strip. cases, were loaded axially as indicated in these figures. In this way, each side of the tested CFRP strip is subjected to tension with an axial tensile force resultant assumed to be \(\frac{1}{2}\) of the externally applied load that needs to be transferred in a way similar to the force transfer mechanism shown in Figure 7a,b. As described before, the same force transfer mechanism develops in the corresponding full-length prototype RC T-beam (Figures 5a-c and 7a) in order to resist the shear, after the development of the diagonal shear cracks. The CFRP strips are bonded in both cases, with or without the presence of an anchoring device.