峡谷底斜拉桥抗风性能改善试验研究

采用节段模型风洞试验的方法对某峡谷底斜拉桥---西藏迫龙沟斜拉桥的抗风性能进行了改善研究。首先，借助于地形风洞试验结果获得了桥位处风攻角和风偏角大小，并确定了大桥颤振检验风速和颤振试验的风攻角范围；然后，考察了大桥原方案的颤振稳定性并通过气动措施改善了原方案的颤振性能；最后检验了施加气动措施前后大桥涡激共振特性。研究结果表明：峡谷底大跨度桥梁的设计基准高度可参照桥面高度确定，但有必要进行地形试验确定桥位处风攻角和风偏角的实际情况；迫龙沟大桥颤振稳定性出现了＆#177;3＆#176;和0＆#176;风攻角下满足要求而5＆#176;风攻角下不满足要求的现象，因此峡谷底大跨度桥梁颤振稳定性检验只进行《规范》建议的风攻角试验可能存在安全隐患；颤振性能改善措施选取时，应考虑斜风的不利影响，确保大桥有足够的颤振稳定性安全储备。

Experimental Investigation on Wind-resistant Performance Improvement of Cable-stayed Bridge at the bottom of Canyon

The wind-resistant performance of a cable-stayed bridge at the bottom of a canyon,Po-long canyon bridge in Tibet,was been improved via the sectional model wind tunnel test.Firstly,the flutter checking wind speed and the range of wind attack angles were confirmed on the basis of the topo-graphic experiment results.Then,the flutter stability was investigated by the wind tunnel test and im-proved by setting aerodynamic mitigation measures.Finally,the vortex-induced vibration performance of the girder before/after setting wind fair was checked by the sectional model wind tunnel test.The results show that,for the bridge at the bottom of the canyon,the design standard height can be calculated refer-ring to the elevation of the bridge deck but the wind attack and yaw angle should be measured by the top-ographic experiment.If the flutter stability is only checked under the attack angle range suggested by the specification,there may be some potential safety hazard,because it is possible that the flutter stability does not satisfy under the larger wind attack angle.The adverse effect of yaw wind should be taken into account for the choice of aerodynamic mitigation measures,and there should be enough security capacity for the flutter stability.