基於挫屈及摩擦機制之位移型抗震阻尼器的試驗研究

Abstract

本文根據挫屈及摩擦機制分別發展出韌性斜撐與摩擦阻尼器兩種位移型結構抗震消能裝置。韌性斜撐係利用預彎拱鈑受軸向荷載時產生大幅側向變形而降伏之原理，於往復運動過程中產生遲滯消能行為。經由一系列的理論推導、參數研究與元件性能測試，已可充分掌握預彎拱鈑的力學特性與遲滯消能特性。預彎拱鈑之非線性彈性挫屈理論與試驗結果均顯示，預彎拱鈑受軸向荷載時呈現拉壓不對稱的力學特性。惟經適當的成對配置使其拉、壓互補，仍可得對稱的力學行為。元件測試所得之遲滯迴圈均相當飽滿且穩定，其消能特性與速度無關而與位移相依，具位移型阻尼器之特徵。本研究進一步將韌性斜撐以成對交叉配置型式安裝至結構模型，並以振動台進行耐震性能測試。試驗結果證實，本研究所提之韌性斜撐具有相當優異的減震效能。另一方面，本研究以某特殊合金材料為核心，發展摩擦阻尼斜撐及摩擦制震壁二種阻尼器，並分別進行一系列之元件測試，充分掌握摩擦阻尼器之力學特性。試驗結果顯示，以特殊合金為核心設計之摩擦阻尼斜撐與摩擦制震壁均具有相當穩定且飽滿的遲滯迴圈，其力學行為與庫侖摩擦機制相符，且與擾動頻率（速度）無關，特性容易掌握。此外，特殊合金所具有之高摩擦係數（ ），遠高於習用之摩擦阻尼器，可大幅增加阻尼器之設計容量。結構加裝摩擦阻尼器作為消能元件，因摩擦機制使整體結構成為高度非線性系統，本研究根據剪力平衡概念，求解結構系統之非線性動力反應。數值模擬結果顯示，結構加裝摩擦阻尼器確實可以有效降低結構的受震反應。本研究亦針對螺栓之扭力係數進行率定。試驗結果顯示，扭力係數與螺栓直徑有關，惟扭力與正向力之比值則為一定值。

Two types of displacement-dependent seismic damping devices, namely the ductile brace and friction damper based respectively on the buckling and friction mechanisms are proposed in this study. The ductile brace utilizes the yielding of pre-bent steel strips in geometrically large lateral deformation under axial loads to dissipate energy. The mechanical behavior and energy-dissipative characteristic of the pre-bent strips have been explored via a series of theoretical development, parametric study and component tests. Experimental results indicate a displacement-dependent but rate-independent energy-dissipative characteristic of the device. Encouraging seismic performance test results by shaking table tests suggest effectiveness and potential of the ductile braces as seismic structural dampers. On the other hand, the use of some special alloy as the core for both the friction damping brace and seismic friction wall has also been developed. The rate-independent energy-dissipative characteristics of the proposed friction dampers have been sufficiently realized via a series of component tests. Results indicate that the proposed alloy-based friction dampers possess stable and rich hysteresis loops with characteristics of the Coulomb’s friction mechanism. The special alloy presents high frictional coefficient of μ>0.7 that is much higher than those for the existing friction dampers. As a result, the capacity of the friction damper can be significantly enhanced. Moreover, the torque coefficient of the bolts has been calibrated experimentally. Results indicate that the torque coefficients of the bolts are diameter-dependent whereas the torque-to-normal force ratio remains constant, regardless of the bolt diameter.