## 2 Finite Element Numerical Simulation
### Analysis of Calculation Results
#### 2.3.4 Longitudinal and Transverse Axial Bias Loads  
The effect of different longitudinal and transverse axial bias loads on the upper turntable and steel spherical hinge stresses was obtained by Ansys finite element analysis; the results were shown in Figure 21a. When the eccentricity value is 10 mm, the stress on each rotating device increases steeply, which was analyzed to be due to the longitudinal and transverse axial bias loads together, and the bottom of the bridge carries more pressure when it is skewed, so the eccentricity condition has a greater impact on the rotating device. By increasing the eccentricity on this basis, the rise in stress decreases, but the value of stress increases with increasing eccentricity. When the eccentricity value is 257.4 mm, the normal compressive stress of the lower steel spherical hinge has reached 224.98 MPa, which is close to the yield strength of the material, and the bridge is in danger of overturning. The local enlargement at an eccentricity of 257.4 mm is shown in Figure 21b. From the figure, it can be seen that when the ultimate eccentricity of 257.4 mm is reached, the stresses on the upper turntable have exceeded the permissible stress value of 37.5 MPa for the compressive strength of C50 concrete, and the bridge has overturned. When the eccentricity is 180 mm, the equivalent force on the upper turntable is at the limit working condition. From the above conclusion, it can be seen that the bridge can withstand the longitudinal and transverse axial bias loads that are less than the unidirectional eccentricity value. In order to ensure the safety and stability of the bridge construction, the longitudinal and transverse axial bias loads should be greatly reduced.  
Figure 19: Cloud diagram of upper steel spherical hinge (eccentricity is 257.4 mm): (**a**) equivalent stress cloud; (**b**) total deformation cloud.  
Figure 20: Cloud diagram of lower steel spherical hinge (eccentricity is 257.4 mm): (**a**) equivalent stress cloud; (**b**) total deformation cloud.  
The simulation results with an eccentricity of 257.4 mm are shown in the following figures; the cloud diagrams of the equivalent stresses and deformations of the upper turntable are shown in Figure 22. The cloud diagrams of the upper steel spherical hinge equivalent stress and deformation are shown in Figure 23; the cloud diagrams of the lower steel spherical hinge equivalent stress and deformation are shown in Figure 24. From the figure, it can be seen that when reaching the limit of eccentricity, the rotating device of each part of the stress concentration is more obvious than not eccentric; the pattern of stress change is the same as the above two eccentric working conditions; the stress value is slightly larger than the unidirectional eccentricity, and the maximum stress value point is located at the eccentricity position. In order to ensure the safety of the project, it is necessary to pay attention to the influence of longitudinal and transverse axial bias loads on the process of bridge turning.  
This is shown by analyzing the three different eccentricities: transformer bridges operate under eccentricity conditions; the phenomenon of stress concentration occurs in all components of the rotating system and increases with the increase in eccentricity; the strength of the upper turntable determines the permissible eccentricity value of the bridge.  
Figure 21: Effect of eccentricity on stress: (**a**) overall picture; (**b**) enlarged picture.  
Figure 22: Cloud diagram of upper turntable (eccentricity is 257.4 mm): (**a**) equivalent stress cloud; (**b**) total deformation cloud.