“建桥合一”铁路客站Rayleigh阻尼系数计算方法

Method for Calculating Rayleigh Damping Coefficients of Integrated Building-bridge Railway Station

在显著影响单自由度体系位移方差的激励频率范围内,采用最小二乘法拟合出水平向和竖向地震加速度互功率谱的线性修正表达式,并结合传统随机振动计算方法和规范加速度谱提出了多维激励多阶参考振型Rayleigh阻尼系数计算方法。以"建桥合一"铁路客站天津西站Ⅱ区为工程背景,基于应变能振型阻尼模型求得的结构响应值为标准,对分别基于二阶、单维激励多阶、多维激励多阶参考振型Rayleigh阻尼系数计算方法的结构响应值进行了比较。结果表明:多维激励多阶参考振型Rayleigh阻尼系数计算方法合理考虑了振型和地震激励的相关性,响应值偏差最小,更适合于类似铁路客站Rayleigh阻尼系数的计算。

The linear modified expression of cross power spectrum of seismic acceleration between horizontal and vertical direction was fitted by using least square method in the excitation frequency range that significantly affects the displacement of single freedom system.The calculation method of Rayleigh damping coefficients considering the influence of multidimensional excitations and multi-modes of vibration on behaviors of structure was deduced based on the acceleration spectrum of code,the linear modified expression and the traditional random vibration method.A case study of the Tianjin West Railway Station-Ⅱ,a typical example of integrated building-bridge railway station,was carried out,based on the structural response value obtained from the strain energy proportional damping model,to compare the structural response values based on the deduced method of Rayleigh damping coefficients,the method considering the influence of only two modes and the method considering the influence of singe direction excitation and multi-modes of vibration.The results show that the deviation of structural response value obtained from the deduced method of Rayleigh damping coefficients of multidimensional excitations and multi-modes of vibration is minimal for reasonably considering the correlation of the vibration modes and seismic excitation,and is more suitable for the calculation of Rayleigh damping coefficients of similar integrated building-bridge railway station.