WIND LOAD AND AERODYNAMIC DISTURBANCE CHARACTERISTICS OF SUPER-LONG SPAN BRIDGE TOWER COLUMNS WITH ADDITIONAL SIGHTSEEING ELEVATORS

Relying on long-span bridges to build tourist platforms and enhance tourist attractions is an important measure to develop tourism resources and jointly seek economic and social utilization. In order to build a sightseeing platform on the top of the pylon of a long-span suspension bridge, elevator wells should be laid on the existing pylons. The layout of elevator shaft will change the shape of tower column and significantly increase the cross section size under wind load, which may affect the safety and serviceability of bridge. In the paper, a two-dimensional RANS equation based on the SST k-ω turbulence model was used to model the flow around the tower shaft (Reynolds number Re=7.7×10⁶) with attached under multi-conditions, and the transverse drag coefficient of the new tower under multi-conditions was obtained. The results showed that the addition of elevators and stairwells led to a significant increase wind load on bridge towers; hollowing out of the connection between elevators and stairwells and original bridge towers and fillet treatment of plane edges and corners could significantly reduce the transverse drag coefficient of bridge towers; the increase of column cross section led to an increase in aerodynamic interference effect between upstream and downstream towers, but this interference effect varied with wind direction angle. In the Wind-Resistent Design Specification for Highway Bridges(JTG/T 3360-01-2018), the recommended values of transverse resistance coefficient based on single bridge tower might be unsafe and could not reflect the interference effect between towers and columns. The significant increase of wind load on bridge towers might lead to insufficient shear bearing capacity of bridge towers and beams. When constructing such sightseeing structures on bridges, attention should be paid to the shear design of cross beams.