挫屈型防震消能元件之研發

Abstract

挫屈原是一種不穩定的結構行為，若無適當支撐，將導致軸力構件側向不穩定之現象；若經適當設計將其變位控制在引導之方向與範圍內，則因其幾何大變形導致材料極易達到非線性，而在往復運動中產生遲滯消能行為，且在變形很小時即發揮消能作用，鋼製挫屈連桿可成為極佳之消能減震(振)元件。國內外目前尚無針對以挫屈連桿作為建築防震控制之相關研究，值得深入探討。本研究旨在建立挫屈連桿之基本力學原理，並透過一系列的元件測試探討其力學特性，掌握最佳之參數設計。試驗結果顯示，挫屈型消能元件之受力 - 位移關係成橢圓形之遲滯迴圈，類似黏滯阻尼，其迴圈路徑穩定而飽滿，具備阻尼器之優異性能。本研究並發展以挫屈連桿為核心之斜撐型抗震裝置，利用振動台完成耐震性能試驗，確認其用於提升結構抗震能力之可行性。最後，並以ANSYS進行挫屈型消能元件之非線性應力分析，以印證理論與假設之合理性，作為最佳鋼板切削模式之設計依據。

Buckling is an unstable structural behavior that may lead to lateral instability of axially loaded members if not properly supported. However, if a buckled steel member is deformed in a guided direction and range, it could become an excellent seismic energy dissipative device since its geometrically large deformation will easily lead to inelastic material behavior of the member and help in dissipating energy in cyclic loadings even at relatively small axial displacement. As of today, no such study as using buckled struts for seismic performance control of building structures has been explored. This topic deserves extensive investigation. The purpose of this study is to develop the fundamental principles of buckled strut and characterize its mechanical properties via component tests to serve as the basis for optimum design. Experimental results indicate that the force-displacement relationships of buckled struts are in the form of ellipses, similar to those for viscous fluid dampers. With steady and rich hysteretic loops, the buckled struts are considered of great potential as seismic dampers. In this study, a buckled-strut-based bracing-type seismic damper is further developed and a series of seismic performance tests by the shaking table is conducted to verify the feasibility of using buckled struts for seismic structural control. Finally, nonlinear analysis of the proposed buckling-type energy dissipative device by ANSYS is carried out to verify adequacy of the assumptions and principles made. The stress distribution pattern in the steel strut will be the basis for determining its optimum shape as a buckling-type damper.