## 6 Computational Model of the Structure
### Dynamic Analysis  
The dynamic analysis of such a complex structure resulted in a wide range of free vibration frequencies and vibration modes. However, only certain free vibration frequencies are associated with vibration modes, during which the whole structure is excited and the displacements of all elements are in phase with each other (Figure 25).  
On the other hand, the vast majority of free vibration frequencies, especially those with higher values, are associated with vibration modes during which only part of the structure is excited. Figure 26 shows the vibration modes corresponding to the frequencies at which the multi-branch internal columns located between the naive and the aisle are excited. Such local behavior is associated with much higher frequency values.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Model**} & \multicolumn{2}{c}{**South-East Wind**} & \multicolumn{2}{c}{**North-West Wind**} \\ \cline{2-5}  & \(u_{x}\) & \(u_{y}\) & \(u_{x}\) & \(u_{y}\) \\  & **[mm]** & **[mm]** & **[mm]** & **[mm]** \\ \hline SE-S4 & 1.2 & 4.1 & 2.4 & 9.1 \\ SE-S4-RC & 1.1 & 4.0 & 2.3 & 8.8 \\ SE-S5 & 0.4 & 1.9 & 0.8 & 4.5 \\ SE-S5-RC & 0.4 & 1.9 & 0.7 & 4.5 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Values of extreme nodal displacements in the columns of the nave.  
Figure 25: Selected vibration mode in which the whole structure is excited, frequency f = 3050 Hz (SE-S5 model).  
of the building. The described method also provides a new perspective on the protection and possible reinforcement of complex wooden structures.  
Summarizing the results of the obtained geodetic measurements, there was no danger to the structure from static deformations, while in order to mitigate the observed dynamic behavior (excessive vibrations), it was decided to design the strengthening of the weakest parts of the structure, i.e., short sections of the walls at the junction of the nave and chancel (P1, P2--panels) with steel ties. They will be introduced in the next stages of restoration and renovation works of the analyzed building. Surveying will continue, which will be the basis for assessing the effectiveness of the strengthening work undertaken.  
Conceptualization, P.M., Z.M.P. and I.W.; Methodology, Z.M.P. and I.W.; Software, Z.M.P. and I.W.; Validation, P.M., Z.M.P. and I.W.; Formal Analysis, Z.M.P. and I.W.; Investigation, Z.M.P. and I.W.; Resources, I.W.; Data curation, I.W.; Writing--Original Draft Preparation, P.M. and Z.M.P.; Writing--Review and Editing, P.M., Z.M.P. and I.W; Visualization, Z.M.P.; Supervision, P.M.; Project Administration, P.M.; Funding Acquisition, P.M. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Rector of Poznan University of Technology, grant number: 0112/SIGR/0193.  
Not applicable.  
The detailed measurement results contain data from eighteen months of operation. All data are stored on the servers of the Poznan University of Technology. Due to the protection of information and internal procedures, they may be made available via e-mail contact: [EMAIL_ADDRESS].  
No potential conflicts of interest were reported by the authors.