Revisiting aerodynamic admittance functions of bridge decks

Abstract

A framework was proposed to identify a comprehensive set of aerodynamic admittance functions for bridge decks. The contributions of the cross-spectra between longitudinal and vertical wind velocity components and between turbulence components and gust-induced forces were embedded in the identification procedure. To facilitate application of the identified functions in engineering practice, the concept of an equivalent aerodynamic admittance function was introduced and numerically validated. The equivalent aerodynamic admittance functions of a set of streamlined and bluff cross sections were identified experimentally in a wind tunnel. Buffeting analysis of a bridge deck was carried out and the response predicted using the identified aerodynamic admittance functions compared well with the measured response. In addition, a sensitivity analysis was performed to delineate the influence of aerodynamic and structural parameters on the buffeting response, thereby demonstrating the significance of the proposed identification framework.

概要

目的

提出一种识别桥面气动导纳函数的理论框架并验 证其合理性。

方法

1. 提出一种考虑来流脉动风和气动力全部交叉分 量贡献的全分量导纳函数的识别算法。2. 利用风 洞试验与数值分析结合的方法,对一组流线型和 钝体断面的气动导纳进行验证。3. 对一桥梁断面 进行抖振响应分析,验证其等效气动导纳。

结论

1.通过数值计算,系统地验证了本文所提出的等 效气动导纳函数具有较高的保真度。2.风洞中流 线型断面的等效气动导纳函数的辨识结果与随 机子空间辨识方法的结果吻合良好。3.通过对一 组流线型和钝体断面进行气动导纳识别表明,某 些断面的气动导纳高于基于准定常理论的所得 值。4.根据准定常理论下的气动导纳函数、Sears 函数和实验验证的函数计算抖振响应并与风洞 试验结果进行比较发现,对于流线型断面,采用 Sears 函数或等效气动导纳函数都是合理的,而 用准定常理论得到的抖振响应则过于保守。5.灵 敏度分析表明,抖振响应对平均风速、气动导纳 函数、静风力系数及其导数和颤振导数等参数非 常敏感。