Effects of vertical central stabilizers on nonlinear wind-induced stabilization of a closed-box girder suspension bridge with various aspect ratios

Abstract

Aerodynamic shape of a closed-box girder plays an important role in the wind-induced stabilization of long-span suspension bridges. The purpose of this study is to investigate the effects of the combination of five aspect ratios and a downward vertical central stabilizer (DVCS) on nonlinear flutter and aerostatic behaviors of a super long-span suspension bridge with closed-box girders. Through conducting a series of wind-tunnel tests and nonlinear finite element analysis, the results show that the nonlinear self-excited forces and the critical wind speed (Ucr) gradually increases as the increase of the aspect ratio (i.e. the width to height ratios). Particularly, the application of 20% deck height DVCS could significantly increase the Ucr for these aspect ratios, and the enhancement in the flutter performance of the bridge is more obvious for a relatively small aspect ratio.Furthermore, the installation of the DVCS could change the flutter divergence patterns of the bridge from soft flutter to hard flutter, especially for a small aspect ratio. In addition, the aerostatic force coefficients and torsional divergence critical wind speeds of the larger aspect ratio with DVCS are significantly larger than that without DVCS. A relatively small aspect ratio of the bridge has better aerostatic performance than that of a larger aspect ratio.