## 2 Experimental Program
### Test Setup and Monitoring System  
Since the supplier of the GFRP gratings did not provide their material properties, two representative samples of G_type1 and G_type2 were tested according to the setup shown in Figure 4a. The modulus of elasticity of the GFRP gratings was obtained from the force vs. centre deflection in these experimental tests, by simulating numerically these tests, a subject covered in Section 2.4.2. This test setup includes a supporting system for the specimens with a geometry according to the recommendations of BS EN 124:1994 [42], Figure 5. This supporting system was made by HFRC with a clear opening of 600 mm (Figure 5a), containing four additional openings near its base for providing access to its interior for the installation displacement transducers (LVDTs) to measure the deflection of the specimen (Figure 5b). The support is complemented with a 5 mm thick steel sheet that covers its top surface (Figure 5a,b) to avoid direct contact between the specimen and the supporting concrete block, preventing any possible deterioration in the referred surface due to abrasion/friction effect during the tests.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Specimen** & **Type of GFRP** & **Type of FRC** & **Geometry and GFRP Position** \\ \hline \hline \begin{tabular}{c} PFRM80\_c15\_g35 \\ \end{tabular} & G\_type1 & PFRM & 8035 \\ \hline \begin{tabular}{c} PFRM100\_c15\_g35 \\ \end{tabular} & G\_type1 & PFRM & 645 \\ \hline \begin{tabular}{c} HFRC80\_c25\_g35 \\ \end{tabular} & G\_type1 & HFRC & 8035 \\ \hline \begin{tabular}{c} HFRC100\_c30\_g35 \\ \end{tabular} & G\_type1 & HFRC & 645 \\ \hline \begin{tabular}{c} HFRC100\_c25\_g50 \\ \end{tabular} & G\_type2 & HFRC & 100 \\ \hline \
\begin{tabular}{c} HFRC100\_c00\_g50 \\ \end{tabular} & G\_type2 & HFRC & 600 \\ \hline
\begin{tabular}{c} HFRC110\_c40\_g50 \\ \end{tabular} & G\_type2 & HFRC & 110 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Details of the specimens included in the experimental program (dimensions in mm).  
Each test was carried out using a servocontrolled testing machine, with a load-carrying capacity of 500 kN. The internal LVDT of the actuator was used to control the vertical displacements during the test. The test procedure consisted of applying a monotonic load in a circular steel plate of 250 mm diameter and 100 mm thickness, disposed in the centre of the specimen (Figure 4). To also record the response of the specimens in their post-peak load-carrying phase, the loading was displacement controlled at a rate of 20 \(\upmu\)m/s up to their failure.  
Figures 4b and 6 show the test setup adopted for testing the manholes indicated in Table 2. It is practically the same adopted for testing the GFRP gratings, with the exception that the deflection of the manhole specimens was recorded by two external LVDTs disposed of according to the schematic representation of Figure 4a,b: LVDT1 in the centre of the specimen and LVDT2 at 170 mm distance from LVDT1.  
Figure 4: Test setup adopted for testing: (**a**) GFRP gratings and (**b**) manhole cover specimens.  
Figure 5: Support system for the GFRP grating and manhole cover specimens: (**a**) schematic representation (dimensions in mm) and (**b**) photo.