In this paper the theory of dynamic analysis is proposed by adding again and again normal modes of vibration of rc (reinforced concrete) beams under the elastic loads, and an example is given.

研究钢筋混凝土梁的动刚度随外荷载的变化规律，对准确分析其动力响应有极其重要意义。采用振型叠加法，导得了弹性加载纯弯梁的动力分析理论，给出了确定梁动刚度的方法。

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