## 3 Simulation Analysis
### Simulation Results
#### 3.3.2 Six-Layer Model  
The six-layer model mainly examines the effect of the propagation of the vibration on the overall structure of the house. The vibration's propagation law through the whole building will be different from that indoors. Taking the transformer that is at position #3 as an example, the vibration displacement nephogram is shown in Figure 27 under the condition that the same excitation is applied to the transformer. As can be seen from the Figure 27, the areas that have higher amplitude are near the transformer. The vibration in the basement structure can propagate to the distant areas, and maintain a certain amplitude. It has a large attenuation during the upward transmission, and only affects the boundary region, while having less influence on the central region which is more stable. In the six-layer model, the monitoring points are set as in Figure 10. ABC represent the three different directions that vibration propagates. A1-A6 represent the six monitoring points of vertical direction, reflecting the propagation law of the vibration along the vertical direction. B1-B8 are eight monitoring points of horizontal direction, reflecting the propagation law of the vibration along the horizontal direction of the building. The C1-C3 three monitoring points are used to reflect the propagation characteristics of the vibration along the longitudinal direction of the building. The simulation results of the six monitoring points along the vertical direction are shown below in Figure 28, which are basically in accordance with the actual situation. As the story rises, the vibration from the bottom will be gradually weakened. Numerically, when vibration propagates up by a layer, the maximum of the vibration will be reduced by 20% to 50% relative to the lower layer. The vibration in the sixth layer is less than 20% of that in the first layer, so the attenuation in this direction is relatively rapid. Figure 27: Displacement nephogram of the whole building when transformer is at position #3. The simulation results of the monitoring points B1-B8 of the horizontal direction are shown in Figure 29. It can be seen that in the horizontal direction, the closer to the transformer, the stronger the vibration. The values of the monitoring points 1, and 2 on the left side are greater than those of the monitoring points 7, and 8 on the right side. This is because in the model, position #3 is closer to the left position. There are four unit structures in the horizontal direction and eight monitoring points can be divided into four groups (1, 2), (3, 4), (5, 6), (7, 8). There is a wall between each unit structure, which will cause greater attenuation to the vibration. Furthermore, from (3, 4) to (1, 2), the attenuation of vibration is about 50%, the same as from (5, 6) to (7, 8). The simulation results of the monitoring points C1-C3 of the longitudinal direction are shown in Figure 30. In the longitudinal direction, the vibration of the central position is lower than that of both sides. However, the maximum amplitude in this direction is only 30% of that in the vertical direction, and 75% of the horizontal direction, relatively the smallest of the three. Figure 28: Results of monitoring points A1–A6 when transformer is at position #3. Figure 29: Results of horizontal monitoring points B1–B8 when the transformer is at position #3. When the transformer's position changes, the corresponding vibration intensity will be different. In the six-layer model, situations when the transformer is at positions #1, #3, and #6, are mainly considered. The displacement nephograms are respectively shown in Figures 31 and 32. Some basic conclusions can be obtained by combining the three displacement nephogram results. When the transformer's position changes, the impact of the vibration on the overall structure of the building will change.