TLCD之高樓抗風設計與應用

Abstract

本研究針對水平及旋轉運動之變斷面調諧水柱消能系統(Variable Tuned Liquid Column Damper, VTLCD)系統進行動力特性試驗，參考並修正Wu’s formula 建立水頭損失係數之經驗公式，以供日後VTLCD系統工程實務設計之用。根據本文之理論推導結果，VTLCD系統之水頭損失係數與斷面比﹙β﹚成正比，此與斷面比β≧1之VTLCD試驗結果相符；本研究提出之modified Wu’s formula 水頭損失係數經驗公式中考慮了斷面比的影響，可將Wu’s formula分別針對斷面比β=1,2 及3等三組經驗公式統合為一。當VTLCD之斷面比β<1時，試驗結果所得之水頭損失係數並未呈現與斷面比﹙β﹚成正比之關係，應為尺寸效應。小尺寸VTLCD之流體運動行為受邊界層流影響較大，以經驗公式預估其落水頭損失係數會偏低。此外，本研究針對一座31層樓之細長結構進行VTLCD之抗風減振效能評估，證明其減振效能。針對本文分析案例之參數研究結果顯示， VTLCD對於結構位移及加速度反應之折減率，基本上隨阻塞率之增加而增加，當阻塞率為80%時達到最佳。

The horizontal and pitching motions of variable tuned liquid column damper (VTLCD) have been explored through a series of dynamic component tests in this study. An empirical formula of the headloss coefficient for practical engineering design of VTLCD has been proposed based on the Wu’s design formula. In accordance with the theoretical derivation results, the headloss coefficient of VTLCD is proportional to the cross-section area ratio (β), which is consistent with the experimental results of β≧1. The modified Wu’s empirical formula proposed in this study takes the cross-section area ratio into account and integrates the three empirical formulas as a single one for the cross-section area ratios of β=1,2 and 3,respectively. In the case of β<1, the experimental headloss coefficient is not proportional to the cross-section area ratio (β). This result may be due to the size effect of the scale-down VTLCD system. The liquid motion of the scale-down VTLCD is influenced by the boundary layer flow and the headloss coefficient predicted by the modified formula will be underestimated. Moreover, the feasibility of wind-induced vibration control of VTLCD system for a 31-story slender building structure has been confirmed through numerical simulations. The parametric study results indicate that the control effectiveness of structural displacement and acceleration increases with the blocking ratio and the optimal control performance is achieved as the blocking ratio is 80%.