Numerical simulation on the galloping performance of portal type bridge tower considering the aerodynamic interference effect

To solve the galloping problem of portal type bridge tower with variable section during the construction of long-span suspension bridge, a practical numerical method for analyzing the galloping performance of high-rise structure with variable section was advanced by combining finite element with CFD. Taking the north bridge tower of certain long-span suspension bridge of East China Sea for example, this method was adopted to analyze the galloping performance under typical working condition during the construction of portal type bridge tower considering the aerodynamic interference effect between twin columns. Results show that no galloping instability will happen in longitudinal direction since the galloping coefficients of both the twin columns and single column for portal type bridge tower are greater than zero. In the lateral direction, because the portal type bridge tower is influenced by the aerodynamic interference effect between twin columns, its galloping performance is different from that without considering the aerodynamic interference, and the chamfer section is disadvantageous for the galloping performance of portal type bridge tower. The galloping coefficients of anterior column with rectangular and chamfer sections are greater than zero, but those of posterior columns are less than zero, and the absolute values of the galloping coefficients for posterior column are larger than those for the total of the portal type bridge tower. Accordingly, the galloping performance of the posterior column in the lateral direction without crossbeams should be mainly researched in galloping analysis during the construction of portal type bridge tower.