## 1 Introduction
The results revealed that the Reynolds number effect was not significant at negative angles of attack, but as the Reynolds number increased at 0\({}^{\circ}\) and positive angles of attack, the drag coefficient decreased, and the lift coefficient increased. Other scholars [23, 24, 25, 26, 27] have also used pressure or force measurements to confirm that changes in the Reynolds number do indeed havean effect on the three force coefficients. However, existing studies have only analyzed the effects of the Reynolds number on the static wind pressure coefficients, while the effects of the Reynolds number on the wind pressure coefficients under a free vibration state need to be improved, and there is a lack of comparative studies on the effects of the Reynolds number on the wind pressure coefficients in both static and free vibration states. Therefore, this study is based on static and dynamic tests to compare and analyze the effects of the Reynolds number on the wind pressure coefficients. The influences of the motion state of the main beam on the Reynolds number effects of the wind pressure coefficients are revealed. In the field of VIV, some scholars have studied the effects of the Reynolds number on the VIV characteristics of cylinders. They reported that as the Reynolds number changed, the amplitude [28; 29], frequency [30], wind speed corresponding to the maximum amplitude [31], and phase difference between the aerodynamic forces and displacement [32] all changed. Other researchers have investigated the effects of the Reynolds number on the aerodynamic characteristics of airfoils and the VIV characteristics of streamlined box girders. [PERSON] et al. [33] showed that the aerodynamic characteristics of supercritical airfoils are highly sensitive to the Reynolds number and that the design and optimization of large aircraft using supercritical airfoils should consider Reynolds number effects. Several scholars have used vibration and pressure measurement tests to study the effects of the Reynolds number on the VIV amplitude, vortex shedding frequency, and other characteristics of streamlined box girders [34; 35; 36]. [PERSON] et al. [12] further studied the surface wind pressure distribution and aerodynamic characteristics of the main beam at different Reynolds numbers and reported that the VIV of streamlined main beams is significantly influenced by the Reynolds number. Other scholars [12; 37; 38; 39] investigated the pressure amplitude at the dominant frequency, the correlation and phase difference between the aerodynamic forces and the VIF, and the contribution coefficients of the aerodynamic forces to the VIF. They reported that at different Reynolds numbers, the surface wind pressure and the phase difference between the local aerodynamic forces and VIF vary significantly, indicating a clear Reynolds number effect. [PERSON] et al. [40] analyzed the effects of the Reynolds number on the VIV amplitude, vibration amplitude spectrum, wind pressure distribution, fluctuating pressure dominant frequency, and pitching moment coefficient time history and the correlation between the local and total pitching moment coefficients, revealing that the effects of the Reynolds number on the correlation between the local and total aerodynamic forces, as well as on \(\mathrm{C_{p,rms}}\), are the underlying causes of the effects of the Reynolds number on VIV. Although a lot of work has been done by scholars, the interval span of the Reynolds number is large, and the number of comparison groups is small, resulting in weak regularity. In addition, the existing studies only analyze the effects of the Reynolds number on VIV characteristics, but there is a lack of research on the formation mechanism. Therefore, in this study, the number of Reynolds number comparison groups is increased, the effects of the Reynolds number on VIV characteristics are improved, and the time-frequency characteristics of VIV are studied, which reveals the formation mechanism of the effects of the Reynolds number on VIV.