基于规范及实测风谱的苏通大桥抖振响应对比研究

Comparable study of the buffeting response of Sutong Bridge based on specification and measured wind power spectrum

复核结构设计是桥梁结构健康监测系统的主要功能之一。以世界第一大跨斜拉桥——苏通大桥为工程背景,采用实测风谱对大桥设计阶段基于规范谱所进行的抖振分析进行验证。首先采用非线性最小二乘法对桥址区实测强风紊流功率谱密度函数进行拟合,获得实测谱曲线,并分别以该实测拟合谱和规范谱为目标谱分别模拟桥址区三维脉动风场。然后采用上述两种风场,基于ANSYS对苏通大桥进行非线性时域抖振响应分析。两种分析结果的对比表明:与实测谱相比,基于规范谱所得的主梁抖振响应情况不一,但主塔抖振响应均偏于保守;两种抖振响应的PSD曲线整体趋势基本一致。分析结果可为该桥的风致抖振性能评价提供研究信息,同时对其他类型结构的抗风设计具有重要的参考价值。

Verifying the structural design is one of the major objectives of Structural Health Monitoring System （SHMS） of bridges. Sutong Bridge （ SB）, the longest cable-stayed bridge in the world is taken as an example, and the buffeting analysis results using the bridge design specifications is verified by using the measured wind turbulence power spectral density （PSD） function. The measured wind spectrum obtained from strong winds records of the SB site is fitted by using the nonlinear least-squares method, and the three-dimensional turbulence wind fields of the bridge site are simulated by using the measured and specification spectra, respectively. Then, nonlinear time-domain buffeting response analysis of SB is conducted using ANSYS. Comparison of the analysis results shows that, comparing with the one from using the measured spectrum, the buffeting response of the deck derived from the specification spectrum is variable, but the buffeting response of the main tower is inclined to be more conservative. The overall trends of the two types of buffeting response PSDs are basically similar.