中文摘要：

文献[3]利用矩阵级数展开和特征值的谱迭加原理，将截断模态对响应的贡献用已知模态和系统矩阵来精确表达，本文在此基础上,利用特征值移位的方法，使计算载荷的频率提高，甚至接近于保留的模态频率，给出了实用的移位值，数值例子验证了本文方法的有效性。

英文摘要：

Fast and accurately evaluating the contribution due to the truncated modes to the response of harmonic excitation is put forward in reference \ without using the truncated modes. By using the series expansion of a matrix function and the theory of spectral representation of a matrix, the contribution due to the truncated modes to the response of a harmonic excitation is expressed exactly and explicitly, with the available low-frequency modes and the system matrices. The objective of this paper is to extend the method in reference \ by eigenvalue shift so that the frequency of the harmonic excitation can be near the higher natural frequency of the retained modes, and the practical shift value is put forward. The numerical examples are given to demonstrate the validity and the effectiveness of the present method.\;