# Refined 3D Solar Temperature Field and Effect Simulation of Ultra-High Steel Bridge Pylon
## 6 Influence of Shadow Occlusion on the Temperature Effect  
### Influence of Shadow Occlusion on Displacement of Bridge Shape  
In order to analyze the influence of shadow shading on the solar temperature effect of super-high steel bridge pylons, the displacement for the top of the pylon is calculated separately under the two conditions of considering and not considering the shadow. The asynchronous displacement diagram of the bridge pylon in winter is not listed because there is no shielding relationship between the pylons, and the two pylons deform simultaneously. The displacement difference between the two pylons is defined as the difference between the displacements of the west and east pylon columns. _TC_ and _LC_ represent the unsynchronized displacement in the transverse and longitudinal directions between the east and west pylon columns after considering shadow, and _DW_ represent the displacement difference between the pylon columns neglecting shadow effects.  
Figure 20a shows the unsynchronized displacement of the bridge pylon in spring and autumn. When the shadow is not considered, the deformation of the pylon columns on both sides is basically consistent with that of the east pylon column in the morning and the west pylon column in the afternoon. When considering the shadow, the transverse bridge displacement of the west pylon column is smaller than the east pylon column under the influence of the shading for the east pylon column to the west pylon column from 6:00 to 7:30. At 7:30, the maximum unsynchronized displacement difference of the east and west pylon columns can reach 16 mm in the transverse direction and can reach \(-\)10 mm in the longitudinal direction. From 15:00 to 18:00, the pylon wall on the west of the east pylon column is also partially sheltered by the west pylon column; at 17:30, the asynchronous deformation of the east and west pylon columns in the transverse bridge can reach 10 mm, and the asynchronous deformation of the longitudinal direction can reach 7 mm.  
Figure 20b shows the unsynchronized displacement of the bridge pylon in summer. When the shadow is not considered, the longitudinal and transverse bridge displacement difference of the east and west pylon columns can be neglected, and the two pylon columns will be synchronously deformed. When the shadow is considered, there is obvious shadow shielding between the east and west pylon columns, and the unsynchronized deformation between the east and west pylon columns of transverse bridge is obviously, while the unsynchronized deformation of longitudinal bridge is relatively small. From 7:00 to 9:00, the west pylon column is sheltered by the east pylon column, and from 13:30 to 15:00, the east pylon column is sheltered by the west pylon column; the unsynchronized maximum deformation between east and west pylon columns in transverse direction reached 40 mm at 9:00 and 42 mm at 16:00, respectively. The unsynchronized deformations in longitudinal direction can reach 18 mm at 8:30 and \(-\)15 mm at 16:30.  
According to the above analysis, after considering the influence of shadow on the deformation of steel bridge pylon, the unsynchronized deformation can be accurately reflected.  
Figure 20: Asynchronous displacement of bridge pylon deformation: (**a**) Asynchronous displacement in spring (autumn). (**b**) Asynchronous displacement in summer.