The aerodynamic forces of the system were obtained based on a 3D aerodynamic model, and a dynamic analysis model of the train-bridge coupling system was established to compare the vibration responses of the train and bridge with and without a wind barrier to fully consider the wind shielding effect and train-induced wind effect on the vibration of a train-bridge system. The results show that the combined wind direction and the direction of the operating train are at an angle. Although the shape of the leading and trailing cars is the same, their wind load values are not the same due to the influence of the train wind. Because of the perforations, the vortex between the wind barrier and the train’s windward surface varies in a complicated fashion. The airflow traveling through the holes has a negative value because it circulates at the intersection of the windward surface and the top surface of the car body. The vehicles’ lateral wheel force, derailment factor, offload factor, and overturning factor are all lowered when the wind barrier is erected. The shielding effect of the wind barrier on the head car is more noticeable when it comes to lateral wheel force and derailment factor. With a wind barrier installed, the wind field surrounding the bridge is very complex, resulting in a modest decrease in vertical displacement.
In order to study the flutter of long-span pedestrian suspension bridge and its aerodynamic control, a 420m-span pedestrian suspension bridge is used as an engineering example, the wind-induced vibration of seven particular aerodynamic sections is studied by wind tunnel tests, and the soft flutter phenomenon of two kinds of aerodynamic sections is identified. The results show that the wind fairing and the wind-retaining plate measures are not necessarily effective measures to improve the wind-induced stability of long-span pedestrian suspension bridge, as these two measures may reduce the flutter stability: the wind fairing section in the positive angle of attack is prone to torsion-based soft flutter phenomenon, in which the vertical vibration spectrum contains multiple vibration frequencies, so the conventional formulation of the linearized self-excited forces is no longer satisfied; the wind-retaining plate section in the negative angle of attack is prone to soft flutter dominated by vertical vibration, and the beat vibration phenomenon is found in the torsional vibration time history of the wind-retaining section. Slotting in the center of the girder section can significantly change the flow state of the section, which is an effective measure to improve the flutter stability of the pedestrian suspension bridge.
In order to study the relationship between an aerostatic three-component coefficient (ATCC) and bridge flutter and to quickly evaluate the flutter performance of bridges, we proposed a method based on the empirical formula of the ATCC. The correlation between the flutter driving term and the critical flutter wind speed V of nine bridges (six types of girder sections) was analyzed, and its rationality was verified using wind tunnel test results. The results showed that the flutter stability of the X-term damping-driven type, i.e., the slotted box girder, was the best; the flutter stability of the X + D-term damping-driven type, i.e., the H-shape bridge deck, was the worst; the flutter stability of D-term damping-driven type was measured as being between these two values. The gray correlation analysis method was used to analyze the correlation between the ATCC and the critical flutter wind speed. As well as the relationship between the ATCC and aerodynamic damping, an empirical parameter, K, based on the ATCC, was proposed for use in determining the D-term damping-driven flutter. The flutter stability of three types of girder sections was analyzed using parameter K, and the results of the analysis were consistent with the wind tunnel test results. The results show that the ATCC obtained from the segmental model force test can be used to preliminarily realize the rapid comparison and selection of flutter aerodynamic measures for bridges.
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