中文摘要：

为建立考虑界面滑移效应的组合梁自振频率实用计算方法，将静力折减刚度法与基于Euler梁模型的理论解析结果进行对比，揭示了静力折减刚度法计算组合梁自振频率的局限性。提出了组合梁自振频率计算的修正折减刚度法，拓展了静力折减刚度在动力计算中的适用范围，且有效统一了考虑滑移效应的组合梁静、动力分析中刚度的计算。基于4根跨度3．8m的简支钢-混凝土组合梁的模态试验结果，对修正折减刚度法进行了验证，结果表明：相比于静力折减刚度法，修正折减刚度法在组合梁自振频率计算中的适用范围更广，且计算精度更高；修正折减刚度法的计算精度与解析公式较为接近，且该方法是通过对广为接受的静力折减刚度法进行修正而得到，相比于解析方法更易被工程设计人员接受。

英文摘要：

In order to establish a practical calculation method for the natural frequencies of composite beams considering the effect of interfacial slippage, the static stiffness reduction method was compared with the exact analytical solution and the limitation of the static stiffness reduction method for calculating the natural frequency of composite beams was disclosed. Hence, a modified stiffness reduction method was proposed based on the comparison results, so that the application of static stiffness reduction method can be extended to the dynamic calculations, and the stiffness calculations of composite beams in static and dynamic analysis considering the effect of interfacial slippage can be effectibly unified. Furthermore, the proposed method was verified based on the modal test results of 4 simply supported steel-concrete composite beams with the span of 3.8m. The results show that compared to the static stiffness reduction method, the modified method has wider applications and should be more accurate in computations. The accuracy of the modified method is close to that of the exact analytical solution, and it should be accepted more readily by designers as it is modified from the widely accepted static stiffnes reduction method.