# Refined 3D Solar Temperature Field and Effect Simulation of Ultra-High Steel Bridge Pylon
## 5 Temperature Effect of Bridge Pylon
### Pylon Displacement  
The displacement for the top of the pylon changes in four seasons as shown in Figure 19. The transverse direction of the pylon is east-west, and the longitudinal direction is north-south. East displacement means the displacement is greater than 0 mm in the transverse direction, and south displacement means the displacement is greater than 0 mm in the longitudinal direction and vice versa. \(TE\) and \(TW\) represent the transverse displacement of the east and west pylon columns, respectively. \(LE\) and \(LW\) represent the longitudinal bridge displacement of the east and west pylon columns, respectively.  
The displacements of different pylon columns are similar in spring, autumn, and winter for both transverse and longitudinal directions. The displacement of the longitudinal bridge (north-south) on the top of the pylon reaches the maximum at 14:00 to the south, and the maximum displacement in the whole year is 370 mm in winter. The displacements on the top of the bridge pylon in transverse directions (east-west) of the bridge can reach maximum at 10:00 to the west and at 16:00 to the east, respectively, and the daily fluctuation amplitude can reach 190 mm in spring and 120 mm in winter.  
Figure 18: Stress curve of pylon in winter: (**a**) Thermal Stress curve of cross-section A-A; (**b**) Vertical stress distribution of bridge pylon at 12:00.  
There is an obvious occlusion relationship between the east and west pylon columns in summer. The displacement at the top of the west pylon column reach its maximum to the south at 8:00 in the longitudinal direction (north-south), and the displacement of the east pylon realm reach its maximum to the south at 14:00, both of which are 80 mm. The asynchronous deformation between two pylons is obvious at 9:00 and 17:00 under the effect of shadow occlusion. At 9:00, the transverse displacement (east-west) of the east pylon column reaches a maximum of 110 mm to west in a year, while the west pylon column is only 70 mm at this time; at 17:00, the transverse displacement (east-west) of the west pylon column reaches a maximum of 109 mm to east, while the east pylon column is only 77 mm at this time. In summer, the maximum displacement between the two pylons can reach 220 mm in the transverse direction (east-west).  
Because the Chinese specification of JTG/T D65-05-2015 \"Specifications for Design of Highway Suspension Bridge\" [29] does not specify the requirements of the plane error of pylon, learning from the article 8.3.1 of JTG/T 3365-01-2020 \"Code for Design of Highway Cable-stayed Bridges\" [30] requirements, the plane error of the pylon axis should be controlled within H/3000 and not greater than 30 mm. The displacement diagram for the top of the pylon in four seasons shows that maximum transverse displacement at the top of pylon can reach 110 mm under the solar temperature in spring, summer, and autumn, and the longitudinal direction reaches 370 mm in winter. At the same time, the alignment shape of the steel bridge pylon fluctuates greatly in a day; the alignment shape for the pylon should be accurately considered under the influence of sunshine-induced temperature during the construction.  
Figure 19: Displacement of pylon: (**a**) Spring (Autumn) displacement. (**b**) Summer displacement. (**c**) Winter displacement.