# Design Proposal for Masonry Infill Walls Subject to Seismic Actions
## 3. Shake Table Tests
### Shake Table Input and Acquisition Setup  
Eight artificial accelerograms were generated using a LNEC-SPA [30] to obtain the four stages of the shake table tests, with increasing amplitude, see Table 4. The accelerograms of the first three stages were adapted to the response spectra (damping ratio equal to 5%) of each damage limit state that was defined in part 3 of EC8, see Figure 8 Damage Limitation (DL 225 YRP); Significant Damage (SD 475 YRP); Near Collapse (NC 2475 YRP): here, YRP equals Years of the Return Period. A last stage was defined as the maximum capacity of the table in terms of velocity, given the size and mass of the model, and it corresponds to 4574 YRP. One signal was introduced for each horizontal direction for the shake table, namely North-South (N-S), or longitudinal, and East-West (E-W), or transversal. Before the first stage and after each stage, the model was subjected to two white-noise small amplitude inputs, again orthogonal, horizontal, and uncorrelated, specifically generated to obtain the dynamic properties of the model (natural frequencies, mode shapes and damping ratios) and their evolution during the experiment. The out-of-plane behaviours of the infill walls were captured by a set of accelerometers (ACC) distributed on the surface of the walls, see Figure 9. In the solid walls of the South facade, three ACC were placed at mid-height, one in the centre and the other two at half the distance to the RC columns. The West facade had one ACC in each infill of the lower storey, under the midpoint of the opening. The same occurred in the lower storey of the East facade. The North facade had three ACC in each infill, below the openings at the centre. In model 1, due to the existence of two leaves, the ACC had to be placed in the inner and outer leaves at the same position. This scheme can be seen in the outer leaf and was repeated in the inner leaf at the same position, totalling thirty-eight ACC. Models 2 and 3 followed a similar scheme, which did not repeat itself on the inside, as these models had single leaf infill walls. Except for the infill wall on the upper storey of the North facade, all the positions for the ACC in the outer leaf of model 1 were repeated in models 2 and 3. The ACC that were not used inside the model were applied outside, increasing the number of measurement points considerably. Each solid wall on the South facade received two extra rows of ACC, directly above and below the ones in model 1, at the upper and lower third of the height. The West facade had the same setup in all three models and the East facade received four extra ACC. The lower infill of the North facade received two extra ACC, totalling thirty-four ACC on the infill walls. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Model** & **Design** & **Concrete** & **Rebar Class** & **Infill Solution** \\
**Number** & **Standards** & **Class** & **Class** & **Infill Solution** \\ \hline
1 & RSA/REBAP & C20/25 & S400 & Double leaf clay brick \\  & & & & unreinforced wall \\ \hline
2 & EC2/EC8 & C30/37 & S500 & Single leaf clay brick wall \\  & & & & with bed joint reinforcement \\  & & & & every two joints \\ \hline
3 & EC2/EC8 & C30/37 & S500 & Single leaf clay brick wall \\  & & & & with reinforced plaster on \\  & & & & both sides \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Description of the tested models. Figure 8: Comparison between the pseudo-acceleration response spectra of the accelerograms generated and the response spectra obtained from EC8 (scaled).