理论和震害均表明水电站进水塔顶部的启闭机房排架由于鞭梢效应更容易遭受地震破坏。分析塔式进水塔主要受力特点，将进水塔和其上的启闭机房排架简化为两种分布参数梁模型，采用解析方法推导和求解其频率方程。统计启闭机房排架与塔体高度范围，根据抗弯刚度相等原则将塔上启闭机房排架柱等效为单截面空腹柱，分析不同上下高度比和刚度、质量比情况下6种模型振型振动幅值比和频率分布情况，得到相互之间影响规律。分析表明上部高度对结构一阶振型幅值比影响较大，而刚度比影响较小，但刚度比对高阶振型幅值比影响显著。经过与数值分析对比，解析结果求得的结构振型和频率与数值结果较为一致，验证上述过程的正确性，表明本文方法对此类结构基本振型求解简单有效。

Theory and earthquake induced damage show that the hoist room frame on intake tower of hydroelectric power station are more vulnerable to earthquake damage due to the whiplash effect. In this paper, the intake tower and the hoist room frame were simplified into two distribution parameter beam models by analysis of the basic mechanical characteristics of intake tower, and then the frequency equation was derived using analytic methods. After statistics of hoist room frame and tower height range and according to the principle of equal bending stiffness, the hoist room frame column was equivalent to a single section of the tower fasting column, then the vibration amplitude ratio and frequency distribution of six kinds of models under conditions of different height ratios and different stiffness-mass ratios were analyzed to get the influence rules between each other. The analysis showed that the height of the upper structure had greater influence on the vibration amplitude ratio of first modal shape, and smaller influence on the stiffness ratio, but the stiffness ratio was more significance. Compared with numerical analysis, structural vibration type and frequency by analytic results was relatively consistent with numerical results, verifying the correctness of the above procedure, and indicating that the analytical method for solving such fundamental mode structure was simple and effective.

国家自然科学基金资助项目（51179154）