ASSESSMENT OF AERODYNAMIC RESPONSE OF THE NISSIBI CABLE-STAYED BRIDGE USING THREE-DIMENSIONAL COMPUTATIONAL FLUID DYNAMICS

Aerodynamic behavior has the greatest impact on long-span bridges and is the most important factor in the design of cable stayed bridges, which should not be overlooked. CFD (Computational Fluid Dynamics) is the most widely used technique, among bridge engineers, to predict wind speed, direction and vortex-shedding form before conducting wind tunnel tests. In this study, a bi-directional CFD analysis with the wind flow parallel and perpendicular to Nissibi Bridge's, which has a main span of 400 m and claimed the spot of Turkey's 3rd largest bridge, deck cross-section has been performed by approximate modelling of the bridge and the surrounding structures. The study is done by using CFD++ software/computer program. The results showed that the effect of wind acting on x direction of impact with 30 m/s has caused turbulence and vortex on conjugation area of the tower and it is observed that the upside down Y shape of the tower breaks down the balance of wind flow. However, bridge deck is not exposed to serious amount of vortex influence due to the wind on y direction. In addition, the analysis revealed that maximum pressure distribution occurred on vertical surface of the tower and it increases in direct proportion to the height of the tower.