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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。
Both theory and earthquake damage indicate that the turret damage caused by the whiplash effect at the top and bottom of the inlet and outlet towers of hydropower stations. The main force characteristics of the tower inlet tower are analyzed. The tower of the inlet tower and the opening / closing machine room on the inlet tower are simplified into two kinds of beam parameters with distributed parameters. The frequency equation is derived and solved by analytical method. According to the principle of equal bending stiffness, the column of the hoisting machine room on the tower is equivalent to the single-section emptying column, and the six models under different height-height ratio and stiffness and mass ratio are analyzed. Vibration amplitude ratio and frequency distribution, get the law of mutual influence. The analysis shows that the height of the upper part has a great influence on the amplitude ratio of the first-order mode of structure, while the stiffness ratio has a little effect, but the stiffness ratio has a significant effect on the amplitude ratio of the high-order mode. After comparison with the numerical analysis, the results of the analytical model are consistent with those of the numerical model. The correctness of the above process is validated, which shows that the proposed method is simple and effective in solving the fundamental mode shapes of such structures.