Wind characteristics at bridge site in a deep-cutting gorge by wind tunnel test

- A gigantic terrain model of bridge site in a deep-cutting gorge was made.
- A 3-D gradual curved transition section was specially developed in wind tunnel.
- The effects of different oncoming wind directions on the wind characteristics were investigated.
- The wind attack angles changing with the oncoming wind directions are related to the terrain features.
- Wind power spectrum, turbulence intensity profile and coherence are very special.

To study the wind characteristics at bridge site in a deep-cutting gorge, a gigantic bridge site terrain model was made in a wind tunnel. The effects of different oncoming wind directions on the wind characteristics over the bridge site were investigated in the simulated atmospheric boundary layer. Results show that the perpendicular wind speed profiles along the bridge main beam can be generally divided into two parts. The shapes of the wind speed profiles at the two bridge towers are much closer to the power law and log law than those of the bridge main beam. The wind attack angle required for the wind resistant design of the bridge should be determined in the range of −6° to 2°, which obviously exceeds the range of −3° to 3° that is usually considered in the homogeneous terrain. When the oncoming wind is from southwest, the wind power spectra at 1/4 span, mid-span and 3/4 span points match well with the spectra values by the Kaimal model. For two measurement points of the same distance, the decay factor of the coherence function varies along the bridge main beam as well as the bridge towers depending on their positions.