# Numerical Analysis on Spanwise Correlation of Vortex-Induced Force of Split Double-Box Beam
## 6 Conclusions and Prospect  
Taking Xihoumen Bridge as the engineering background, the spanwise correlation of vortex-induced force on the split double-box beam was studied in this study through the method of numerical simulation. The two-dimensional and three-dimensional numerical models were established and the numerical simulation of the bypass of a split double-box beam in static state was carried out through the fluid calculation software FLUENT. The vortex-induced vibration of the numerical model was simulated by the Newmark-\(\beta\) algorithm as well. The spanwise correlation of the aerodynamic coefficient, the surface pressure coefficient, and the wake wind velocity of the model under static and vibrational state was analyzed. Furthermore, a comparison with the field measurement results of relevant documents was conducted to verify the reliability of the results. The conclusions can be summarized as follows. * The spanwise correlation of the aerodynamic coefficients of the split double-box beam decrease with the increase of the spanwise spacing overall. The attenuation speed of the lift is the slowest, the torque is the second, and the resistance is the fastest; moreover, the attenuation trend is independent of the wind velocity. The spanwise  
Figure 16: Spanwise correlation of pressure coefficient in wake region of downstream section of bridge of numerical simulation and Li, H’s measurement [26]. (**a**) Spanwise correlation of pressure coefficient of an upper surface; (**b**) Spanwise correlation of pressure coefficient of a lower surface. correlation of aerodynamic coefficients in the vibrational state is stronger compared to those in the static state and the speed of attenuation is slower as well. * The spanwise correlation of the surface pressure coefficient of the split double-box beam decreases with the increase of the spanwise spacing overall. The spanwise correlation of the pressure coefficient of the upstream panel is higher than that of the downstream panel under the same wind speed. The spanwise correlation coefficient of the pressure coefficient in the vibrational state is stronger compared to that in the static state. * The spanwise correlation of the wake wind velocity of the split double-box beam decreases with the increase of the spanwise spacing overall. The attenuation speed of vertical-wind fluctuating wind is the slowest, the along-wind is the second, and the across-wind is the fastest; moreover, the spanwise correlation of across-wind fluctuating wind velocity is worse than that of the other two wind directions under the same wind speed. The spanwise correlation of wake wind velocity under the vibrational state, especially the vertical wind fluctuating wind velocity, is lower than those in the static state. * Although the pressure distribution law of numerical simulation within the lock-in region of vortex-induced vibration of split double-box beam is slightly different from that of field measurement in the document [16], the correlation values are basically the same. Therefore, the numerical simulation results in this paper are reliable. The study and discussion of the spreading correlation during vortex vibration of split double-box beam sections in this paper can be used as a supplement to the study of the direction of gas bypassing for vortex vibration of split double-box beam, which is of great scientific and engineering significance in understanding the vortex vibration characteristics of such complex sections as well as optimizing the bridge design and enhancing its wind resistance performance. However, there is still much room for improvement and refinement in this study due to the various aspects involved in the numerical simulation process, such as the establishment of the bridge model, the setting of the wind area conditions, and the selection of the solver:  
* The numerical simulation of the bridge was carried out under the condition of a constant wind field, which is different from the more random wind field in the actual engineering.