## 5 Numerical and Experimental Results
### Wind Attack Angles at Main Deck Level  
The numerical and experimental results of the wind attack angle at main deck level of the bridge for different cases are given in Figure 15. From Figure 15a, it can be seen that for case 1 (wind blows from the west), the wind attack angle at the main deck level of the bridge varied greatly along the bridge axis, which can be roughly divided into three parts; namely, mountain areas (I, III) and the central canyon area (II). For experimental results, the wind attack angles at the main deck level of the terrain model with BTS is about \(-15^{\circ}\)\(\sim\)\(-10^{\circ}\) in part II, while the wind attack angles at the main deck level of the terrain model without BTS is \(-20^{\circ}\)\(\sim\)\(-5^{\circ}\) in part II. For numerical results, the wind attack angles at the main deck level of the terrain model with BTS was about \(-10^{\circ}\)\(\sim\)\(0^{\circ}\), while the wind attack angles at the main deck level of the terrain model without BTS was \(-7.5^{\circ}\)\(\sim\)\(5^{\circ}\). Figure 14: Numerical results vs. experimental results of non-dimensional cross-bridge wind speed at main deck level under different cases. (**a**) Case 1 and 2; (**b**) Case 3 and 4. From Figure 15b, it can be seen that for case 2 (wind blows from the south), the wind attack angle at the main deck level of the bridge changes along the bridge axis. For experimental results, the wind attack angles at the main deck level of the terrain model with BTS was about \(-\)5\({}^{\circ}\)\(\sim\)0\({}^{\circ}\) in part II, while the wind attack angles at the main deck level of the terrain model without BTS was \(-\)5\({}^{\circ}\)\(\sim\)10\({}^{\circ}\) in part II. For numerical results, the wind attack angles at the main deck level of the terrain model with BTS was about \(-\)12\({}^{\circ}\)\(\sim\)2\({}^{\circ}\), while the wind attack angles at the main deck level of the terrain model without BTS was about 0\({}^{\circ}\)\(\sim\)10\({}^{\circ}\). From Figure 15c, it can be seen that for case 3 (wind blows from the east), for experimental results, the wind attack angles at the main deck level of the terrain model with BTS were about 5\({}^{\circ}\)\(\sim\)12\({}^{\circ}\)in part II, while the wind attack angles at the main deck level of the terrain model without BTS were 1\({}^{\circ}\)\(\sim\)12\({}^{\circ}\) in part II. For numerical results, the wind attack angles at the main deck level of the terrain model with BTS are about 0\({}^{\circ}\)\(\sim\)3\({}^{\circ}\), while the wind attack angles at the main deck level of the terrain model without BTS were about \(-\)7\({}^{\circ}\)\(\sim\)2\({}^{\circ}\). From Figure 15d, it can be seen that for case 4 (wind blows from the north), the experimental results of the wind attack angles at the main deck level of the terrain model with BTS were about \(-\)10\({}^{\circ}\)\(\sim\)7\({}^{\circ}\), while the wind attack angles at the main deck level of the terrain model without BTS were about 3\({}^{\circ}\)\(\sim\)5\({}^{\circ}\). For numerical simulation results, the wind attack angles at the main deck level of the terrain model with BTS were about \(-\)0.5\({}^{\circ}\)\(\sim\)7.5\({}^{\circ}\), while the wind attack angles at the main deck level of the terrain model without BTS were about \(-\)0.5\({}^{\circ}\)\(\sim\)10\({}^{\circ}\). In general, both numerical simulation and experimental results under different cases show that the range of the wind attack angles at the main deck level in part II with BTS is smaller than that of the terrain model without BTS. The reason is that the existence of the BTS effectively reduces the influence of artificial cliffs. Thus, the turbulence development of wind field with BTS is more sufficient than that without BTS; the wind attack angles with BTS are smaller than that without BTS.