基于风洞试验及大涡模拟的宽体扁平箱梁涡振特性研究与优化

基于1∶60节段模型风洞试验，研究了桥面附属构件对宽高比为12的宽体扁平箱梁涡激振动性能的影响。研究发现，成桥态主梁在正攻角(+5°，+3°)下发生了显著的竖弯和扭转涡振，而提高人行护栏透风率或内移检修车轨道均可同时降低两种涡振的振幅，且提高人行护栏透风率还可缩短两种涡振的风速锁定区范围。采用三维大涡模拟(3D LES)进行了施工态和成桥态的静态绕流计算，发现不合理附属构件将使箱梁上下表面均形成大范围流动分离，在迎风侧人行护栏、两道检修车轨道三处分离点产生的漩涡各自以不同频率向尾流脱落，从而诱发较强的涡振响应。

Investigation and optimization on VIV performances of wide flat box girders based on wind tunnel tests and large eddy simulations

In order to investigate the vortex-induced vibration performance of the long-span wide suspension bridge, a wide-body flat box girder with the width-to-height ratio 12, which was analyzed for the wind tunnel test at a scaling ratio of 1∶60, was selected as the study issue. A series of tests were carried out to investigate the influence of the type of pedestrian guardrails and track location of the maintenance vehicle. At attack angles of +5° and +3°, the results demonstrate that both vertical and torsional vortex-induced vibrations(VIV) are observed on the wide flat box girder. The pedestrian guardrails with larger ventilation rate or the maintenance vehicle track moving inward are found to improve both vertical and torsional VIV performances, and the pedestrian guardrails with larger ventilation rate could shorten the range of wind speed lock-in region at the same time. The static simulations of the bridge on under-construction and constructed states, based on 3D LES (large eddy simulation), were carried out. The results demonstrate that the unreasonable accessory structure will lead to the formation of a wide range of separation areas on the upper and lower surfaces of the wide-body flat box girder. The resulting vortices at the three separation points, i.e., the pedestrian guardrail and two rows of maintenance vehicle track on the windward side, shed downstream in different ways and cause strong vortex-induced response.