Aerodynamic Countermeasure Schemes of Super Long-Span Suspension Bridges with Various Aspect Ratios

Abstract

The purpose of this study is to investigate the flutter control scheme of super long-span bridges with various aspect ratios (e.g. width to height (B/H)) using passive aerodynamic countermeasures. Through a series of wind tunnel testing and theoretical analysis, three types of passive aerodynamic countermeasures, i.e. vertical central stabilizer (VCS), wind barrier and inspection rail, were investigated for five typical aspect ratios of a closed-box girder bridge. The results show that both the aspect ratio and flutter critical wind speed generally increase with the decrease of the ratio of torsional and vertical frequencies of the bridge. In the case of an aspect ratio of 8.9, a downward VCS (DVCS) has a much better flutter performance than that of an upward VCS (UVCS) because aerodynamic damping of Part A and Part D could produce a higher heaving degree of freedom (DOF) participation level. Furthermore, the position variation of wind barriers is superior to their shape variation for the bridge with an aspect ratio of 8.3, and the flutter performance of the girder with a combination of the wind barrier (WB3P3) and UDVCS with 0.3[Formula: see text]h/H DVCS appears to be better than that without countermeasures. In addition, the installation of an inspection rail near the bottom point of an inclined-web (IR3) has the best flutter control effect among four positions of inspection rails.