A study on the aerodynamic characteristics of an asymmetric П shaped girder and an asymmetric streamlined box girder via a wind tunnel test

To study the effects of the asymmetric foot-rslabs on the aerodynamic characteristics of main girders, the aerostatic coefficients, the performance of vortex-rinduced vibration (VIV) and flutter of both an asymmetric П shaped girder and an asymmetric streamlined box girder were investigated via a section model a wind tunnel test in different flow directions. The test results show that the aerostatic coefficients in the 0° flow direction (the flow comes from the foot-slab direction) are larger than that in the 180° flow direction for two types of asymmetric girders under positive attack angles. The impact induced by asymmetric foot-slabs on the aerostatic coefficients of the П shaped girder is more significant than the streamlined box girder. The asymmetric property has a significant effect on the VIV performance of the П shaped girder, including the attack angle, the amplitude of VIV response, the vibration critical wind speed and the lock-in regime et al. From the perspective of bridge aerodynamics, the flow separates in advance, the reattachment positions change and the VIV forces decrease, which may be attributed to the existence of the foot-slab in the 0° flow direction. The VIV performance of main girder is thus improved in the 0° flow direction. The critical flutter wind speeds of two types of asymmetric girders in the 0° flow direction are higher than that in the 180° flow direction. The results of flutter derivatives show that the asymmetric foot-slabs and railings can provide a positive torsional aerodynamic damping. A high critical flutter wind speeds of main girder can thus be achieved in the 0° flow direction. © 2019, Editorial Office of Journal of Vibration and Shock. All right reserved.