The typical U-shaped deep-cut canyon is widely distributed in the western mountainous areas of China, especially in Sichuan province and Yunnan province. The deep-cut canyon has the characteristics of the high drop in elevation, high-temperature difference, and complex wind environment. A 50 m high meteorological mast with a total of eight anemometers was erected in such topography, and a long-span suspension bridge will be constructed in the area where the meteorological mast is located. Based on the long-term monitor data, the wind characteristic parameters including average and fluctuating wind characteristics and coherence between different heights are investigated. The results are as follows. The dominant wind direction which depends on the topography is north–south. The attack angle of wind is mainly less than zero, and its probability distribution obeys the hypothetical Gaussian distribution. Both the increases in height of anemometer and in wind speed reduce the dispersion of the attack angle of wind. The gust factor has a similar change law of attack angle of wind. Turbulence intensities are affected by the height of the anemometer and the wind speed, and they are different from the recommended value of China Codes. In terms of turbulence integral length scale, the value increases with an increase in the height of the anemometer in the same component. The largest value occurs in the longitudinal direction and the smallest occurs in the vertical direction at the same level. The coherence between any two locations is relatively strong, and the longitudinal component is stronger than others. The measured wind power spectrum for longitudinal, lateral, and vertical wind in deep-cut canyon fits the von Kármán model better.

The sea-crossing railway bridge is exposed to a high risk of wind and wave, which threatens the safety of the bridge and railway. A wind–wave–vehicle–bridge dynamic analysis model for sea-crossing railway bridge under wind and wave loadings is developed by extending the previous wind–vehicle–bridge model. The developed wind–wave–vehicle–bridge model involves multipoint fluctuating wind field, irregular wave field, finite element model of the bridge, and mass–spring–damper model of the vehicle. The correlation between wind and wave is considered by an empirical curve derived based on field measurement. Static, buffeting, and self-excited wind forces on the bridge and vehicle are considered with coefficients obtained from wind tunnel tests. The wave forces on the bridge are calculated by Morison equation including stretching modification. The governing equations of the wind–wave–vehicle–bridge model are solved in time domain by Newmark-β method to compute the dynamic response of bridge and vehicle. The dynamic response of bridge and vehicle is compared and discussed in both wind–wave–vehicle–bridge and wind–vehicle–bridge model. The performance of bridge and vehicle are finally evaluated. Studies of dynamic response under correlated wind and wave are found to be imperative for assessment of structural and vehicle safety and driving comfort of sea-crossing railway bridge.

To investigate the shielding effects of mountains in front of a bridge on the wind field at the bridge site in an area with complex topography, a numerical simulation model of the bridge site, which is located in a deep cut V-shaped gorge, was conducted by a computational fluid dynamics method. In this study, taking the shielding effects of mountains in front of the bridge into consideration, the mean velocity, wind attack angle, wind profile, and wind direction angle under different flow cases were calculated and compared. The spatial distribution characteristics of the wind field in an area with complex topography considering shielding effects are presented. The calculation results indicate that the characteristics of the wind field near the mountain at the bridge site are affected by the mountain and the direction of the incoming flow. The shielding effects of the mountain on the eastern side of the bridge are very different under different flow directions. The wind load distribution along the girder is severely uneven in some cases due to a local cyclone existing around the girder. The conclusions of this study provide a basis for improved wind resistance designs of bridges.

To improve the flutter stability of a long-span suspension bridge with double-decks, aerodynamic optimization on the upper and lower bridge decks is studied, and a series of countermeasures are considered, including slotted deck, wind fairings, porosity of guardrail, and horizontal and vertical stabilizers. Wind tunnel tests were performed to measure the critical flutter wind speed of the bridge and find effective aerodynamic countermeasures for improvement of the flutter stability. The results show that double-vertical stabilizers symmetrically installed at the two sides of the bottom of the lower deck with the distance of 9.32 or 11.55 m to the center efficiently improve the flutter performance of the original section at −3°, 0°, and 3° angles of attack simultaneously, while other common aerodynamic measures can hardly achieve this effect alone. The composite measure which consists of two central stabilizers installed on the top of the upper and lower decks, respectively, is promise and superior to the single measure. The combination of wind fairing and central stabilizer on the top of the lower deck is also an effective countermeasure. The results can provide the reference information for flutter optimization of the long-span steel truss girder suspension bridge with double-deck in the future.