摩擦型制震裝置之耐震性能試驗與分析

Abstract

本研究係以一種特殊合金材料為核心，發展摩擦阻尼斜撐及摩擦制震壁兩種建築抗震裝置，並進行一系列之元件測試與耐震性能試驗。元件測試結果顯示，摩擦阻尼斜撐與摩擦制震壁均具有相當飽滿而穩定之遲滯迴圈，其力學行為與擾動頻率（速度）無關，且符合庫侖摩擦機制之特徵，力學特性易於掌握。特殊合金與鋼材間具有高摩擦係數，若經適當設計，其摩擦係數甚至能超過1.0，高於習用之摩擦阻尼器，可大幅增加阻尼器之設計容量。就工程實用之觀點，成功應用摩擦型制震裝置之關鍵，在於對摩擦係數及介面正向力﹙螺栓軸力﹚之精確掌握。螺栓軸力與扭力呈線性關係，率定試驗結果顯示螺栓之扭力係數為一常數，而與直徑無關，此將有助於摩擦裝置在設計上之掌握。耐震性能試驗之結果顯示，摩擦阻尼斜撐能大幅提升結構低頻振態之等效阻尼比，但高頻反應則有放大情形。惟高頻模態參與係數較低，因此對於結構整體反應之影響並不顯著，故仍可達到減震之目的，其效能隨地震強度之增加而提升。模擬分析結果顯示， ETABS能有效模擬庫侖摩擦機制，結構地震反應之預測結果與試驗值雖有誤差，但仍有相當程度之契合。誤差來源應為分析模型忽略了斜撐的存在，在摩擦阻尼器處於未滑動狀態時高估結構之勁度所致。

In this study, both the frictional damping brace and seismic friction wall have been developed based on a special alloy. A series of component tests and seismic performance tests have been conducted. Component tests indicate that the proposed alloy-based friction dampers possess rate-independent stable and rich hysteresis loops with characteristics of the Coulomb’s friction mechanism. The frictional coefficient (μ) between the special alloy and steel is high. It may exceed 1.0 if properly designed, higher than those for the existing friction dampers. As a result, the capacity of the friction dampers can be substantially increased. From a practical point of view, the key to the success of friction-type damping devices is the ability to precisely manage the frictional coefficient and normal force (i.e. tensile force in the bolts). The tensile forces in the bolts are linearly related to the torques. Calibration tests indicate that the torque-to-tension ratio of the bolt is constant, regardless of the bolt diameters. This would be helpful in practical design of the friction devices. Seismic performance tests show that, the frictional damping braces significantly enhance the equivalent damping ratios of the structure in the lower vibration modes while amplify the high frequency responses. Fortunately, the overall structural responses are reduced as the participation factors for the higher modes are low. The effectiveness of the frictional damping braces increases with the earthquake intensity. Simulation results indicate that ETABS can sufficiently simulate the coulomb’s friction mechanism. The predicted seismic structural responses agree well with the test results, despite of the fact that discrepancy still exists. The source of errors possibly comes from neglecting the H-beam braces in the modeling, which results in over-estimation of the stiffness as the friction dampers are in non-sliding states.