非線性速度回饋控制於可變阻尼隔震結構之應用

Abstract

傳統式摩擦控制係利用改變正向力以增加摩擦控制力進行控制，在實務上難以達成。因此本研究引用已開發完成之半主動摩擦阻尼器，稱為槓桿式可控摩擦阻尼器(Leverage-type controllable friction damper，LCFD)。LCFD使用傳統被動型摩擦阻尼器與一可移動中央支點之槓桿，藉由即時控制槓桿支點之位置，以達到精準調控等效摩擦阻尼力。而半主動系統須具備適當之控制律即時因應震波特性與結構反應而達到良好的減震效果。本文選用先前研究之控制律之「比例位移控制律」為基礎，做進一步的改良其適用性與在真實結構應用上之舒適性，所研發之控制律稱之為「雙段速度控制律」。改良後之控制律延續比例位移控制律中僅需回授相對地表速度，不需複雜的數學運算之優點，故在應用上極為簡便且實用性高。而雙段控制更能在近斷層震波來臨時能大幅的抑制位移反應，而在地震加速度較小時放寬其位移束制，使加速度能降低。為驗證研發之控制律，本研究藉由數值分析計算控制結果，並以各類震波進行模擬驗證。經由分析結果顯示，LCFD的隔震系統加入考量雙段速度控制律後，確實能全面性的發揮隔絕近域地震大位移反應之特性，並且在小震盪時能降低結構之加速度；若與主動系統相比，半主動隔震系統所需之控制能量確實比主動隔震系統還低，解決了主動系統所需控制能量較大之問題。

A semi-active isolation system, which is used for seismic protection of structural systems and generally has better control performance than a passive damper, is proposed. Traditional systems adjust their friction resistance force by directly controlling the normal force applied on the friction interface. However, this is not easy to accomplish. In order to avoid problems associated with active and passive systems, a previously developed semi-active system named Leverage-type controllable friction damper (LCFD) is used in this research. LCFD system combines a traditional passive friction damper and a leverage mechanism that has a movable central pivot. By controlling the position of the pivot in real time, the equivalent friction force of the LCFD system can be accurately adjusted. Nevertheless, this system requires the application of an appropriate control law to effectively reduce structural response during an earthquake. In this study, Bi-gradation velocity control (BGVC), which is based on the control law of proportional displacement control (PDC), is applied in the LCFD system in order to determine the pivot position. Both control laws have the same advantages, as they merely require the related-to-the-ground displacement or velocity, are simple and can be easily implemented in practice. By adapting BGVC, the excessive isolator drift induced by a near-fault earthquake can be significantly suppressed, and less control force is used in slight excitations to mitigate the acceleration response. The results of numerical analysis demonstrate that the seismic response of a structure using the LCFD with the BGVC yields a lower response. It also show that the semi-active system requires lower control energy than the active system.