摩擦制震壁之試驗與分析

Abstract

摩擦制震壁係以一種特殊合金鈑為消能材料之建築抗震裝置，藉由鋼鈑與合金夾鈑相對滑動過程中產生之摩擦機制消散地震能量。由於摩擦制震壁為壁式結構，與建築之空間相容性較佳，因此頗具發展潛力。本研究係有關摩擦制震壁之元件測試與耐震性能試驗，並針對制震壁三明治結構主體之鋼鈑進行非線性應力分析及參數研究。就工程實用性之觀點，摩擦制震壁的關鍵技術在於摩擦係數及正向力之精確掌握。率定試驗結果顯示，基本上螺栓的張力與扭力呈線性關係，其扭力係數為常數，與螺栓的直徑及材質無關，但會受到墊圈材質的影響，因此實際應用時須選擇適當之墊圈。元件測試結果顯示，摩擦制震壁之力學行為與擾動頻率無關，其遲滯迴圈相當飽滿穩定，呈現庫侖摩擦機制之特徵。特殊合金與鋼鈑間的摩擦係數高於習用之摩擦型阻尼器，可增加阻尼器之效能。耐震性能試驗結果顯示，摩擦阻尼器基本上可降低結構之加速度反應，尤其是均方根反應，減震效能隨地震強度之增加而提升。頻域分析結果顯示結構加裝摩擦阻尼器可大幅提升低頻振態之等效阻尼比，惟高頻反應則有放大情形，幸而高頻模態的參與係數較低，因此對於結構整體反應之負面影響並不顯著。非線性應力分析結果顯示，制震壁鋼芯鈑之極限強度隨高寬比之增加而降低，增加翼鈑則能有效提升其極限強度，參數研究的結果可供未來實務設計之參考。

The seismic friction wall consisting of a special alloy for energy dissipation is an earthquake-resistant device for building structures. The earthquake-induced energy is dissipated by the friction mechanism in between the steel plates and alloy via the relative sliding process. Being spatially compatible with the architecture, the friction wall in a panel-type is considered of great potential in the market. In this study, a series of component and seismic performance tests of the friction walls has been conducted, and a nonlinear stress analysis and parametric study on the core steel panel of the sandwich structure explored. From a practical point of view, the know-how of the friction wall is the ability to precisely control the desired frictional coefficient and normal force. Results from the calibration tests indicate that the tensile forces in the bolts basically are proportional to the torques with a constant torque-to-tension coefficient, regardless of the diameter and material of the bolt. However, the torque-to-tension coefficient may be affected by the material of the washer. Therefore an appropriate type of washers should be selected in practical application. Component tests indicate that the mechanical behavior of the friction walls is rate-independent, the hysteresis loops are rich and stable and exhibit characteristics of the Coulomb’s friction mechanism. The frictional coefficient (μ) between the special alloy and steel is higher than those for the existing friction dampers, therefore the capacity of the friction dampers can be substantially increased. Seismic performance tests show that, with the friction walls implemented, the floor acceleration responses of the structure can be reduced, in particular the Root-Mean-Square responses. The effectiveness of the frictional walls increases with the earthquake intensity. According to the frequency-domain analysis, the frictional walls significantly enhance the equivalent damping ratios of the structure in the lower modes while amplifying the high frequency responses. Fortunately, the overall structural responses are reduced as the participation factors for the higher modes are small, and the overall structure responses are not adversely affected. The nonlinear stress analysis indicates that the ultimate strength of the steel panel decreases with the increase of its aspect ratio. The ultimate strength of the steel panel can be effectively enhanced when reinforced with flanges. Results of the parametric study would be useful for practical design purposes.