# Retrofitting Masonry Walls against Out-Of-Plane Loading with Timber Based Panels
## 3 Experimental Study
### Small-Scale Tests  
#### 3.2.1 Flexural Bond Strength of Masonry Prisms  
Flexural strength of masonry prisms (MP) was obtained from a four-point bending test conducted on MPs according to the provisions of [16; 17]. The small-scale test helped to understand the behaviour of masonry and the connection between the masonry prism and timber panel proposed for retrofitting masonry wall. The test provided an insight on the effectiveness of the proposed timber panel retrofit on flexural behaviour of masonry prisms, and it also enabled the design and implementation of the large-scale test to be straightforward. The MP test specimens were constructed as nine courses stacked bonded prisms, 215 \(\times\) 102.5 \(\times\) 665 mm with mortar joints of 10 \(\pm\) 1.5 mm thickness. The test specimens were constructed using English bond consisting of alternate rows of headers and stretchers. Nine single leaf masonry prisms (MPs) were tested in the laboratory under the four-point bending test using a quasi-static monotonic loading scheme. The \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Property**} & \multicolumn{2}{c}{**Values**} & \multirow{2}{*}{**Requirement**} \\ \cline{2-2} \cline{4-4}  & **Experiment** & & **Manufacturer** \\ \hline \(\gamma_{du}\) (kg/m\({}^{3}\)) & 2200 & 2310 & \begin{tabular}{c} shall not be less than 2079 kg/m\({}^{3}\), \\ i.e., 90\% of specified density [20] \\ \end{tabular} \\ \hline \(W_{u}\) (\%) & 3.9 & \(\leq\)7 & \begin{tabular}{c} shall not be more than \\ manufacturer limit [21] \\ \end{tabular} \\ \hline \(f_{b}\) (N/mm\({}^{2}\)) & 87.9 & 75 & \
\begin{tabular}{c} shall be not less than the declared \\ compressive strength [22] \\ \end{tabular} \\ \hline \(E_{b}\) (N/mm\({}^{2}\)) & 32,500 & \(\leq\)34,000 &
\begin{tabular}{c} between 3500 and 34,000 for \\ different types of clay unit [28] \\ \end{tabular} \\ \hline \(\mu_{b}\) [\(\backslash\)] & 0.26 & 0.15–0.40 & range for clay unit [28] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Experimental results on properties of brick units vs. manufacturer’s specification. Figure 4: Masonry cubic: (**a**) geometry and (**b**) failure. small-scale experimental campaign involved testing (a) three samples of plain MP to serve as references to measure the effectiveness of the proposed retrofit techniques; (b) three samples of retrofitted MP, each retrofitted with an 18 mm-thick OSB type-3 timber panel using adhesive anchor connections (C1); and (c) three samples of MP retrofitted with 18 mm-thick OSB type-3 using mechanical connections (C2). The MP specimens constructed on the 10 mm-thick steel plate were tested adopting the test set up shown in Figure 5. No vertical precompression loads were applied to any of the nine specimens. The specimen on the steel plate was rested on a 25 mm-diameter cylindrical roller with the axis of the roller parallel to the face of the specimen to allow it to freely rotate around its base while deflecting out-of-plane and prevent a restrained end condition. At the back of the specimen, a 25 \(\times\) 5 mm-thick metal plate was fixed across the middle of the top and bottom brick unit each. This 5 mm-thick plate provided a smooth contact for the \(\O 25\) mm supporting rollers fixed on an existing steel reaction frame in the laboratory. On the front side of the specimen, two additional 25 \(\times\) 5 mm-thick metal plates were fixed at the third and seventh course of the specimen each to provide a contact for the loading rollers. The loading of the specimens is such of a four-point testing arrangement, where the loads were applied on the specimen using a high-force hydraulic jack and distributed through a spreader beam. The spreader beam spanned between two \(\O 25\) mm cylindrical rollers placed across the third and seventh course of the specimen. The direction of the load application is perpendicular to the specimen surface. The applied load on the masonry prism was monitored using a 200 kN-capacity ring load cell.