面內撓曲式拱形阻尼器之材料力學理論與試驗

Abstract

本研究提出門形與拱形阻尼器等面內撓曲式阻尼器，目的在發展可增進材料利用效率之結構抗震消能裝置。本文根據材料力學之直梁與曲梁理論發展阻尼器之線彈性分析理論，並進行一系列足尺元件測試，結果顯示初始勁度之理論估算值與元件試驗結果相當吻合，其中以門形阻尼器的精度較佳，拱形阻尼器因幾何條件無可避免產生剪力作用導致剪切變形而違反材料力學之基本假設，因此誤差較大。元件測試所得之遲滯消能迴圈相當飽滿且穩定，與ANSYS分析結果也有很好的相關性。不管是韌性抑或極限強度，拱形阻尼器皆優於門形阻尼器，且因更易降伏可及早發揮遲滯消能作用，極具發展成為建築抗震裝置之潛力。拱形阻尼器之振動台耐震性能測試結果證明其具備相當優異之減震效能，加裝阻尼器後，結構各模態之等效阻尼比隨地震強度之增加而提升，符合非線性阻尼器之特性。

This study proposes two types of displacement-dependent metallic yielding dampers, namely the in-Plane Flexural Damper (i-PFD) and in-Plane Arched Damper (i-PAD), to be used as seismic energy-dissipative devices with improved efficiency on material utilization. Linear theories of the proposed dampers are developed based on mechanics of materials for straight or curved beams. Initial stiffness of the dampers predicted using the linear theory agrees very well with those obtained from the component tests. And the prediction is more accurate for i-PFD than i-PAD. The error is due to violation of the basic hypotheses of mechanics of materials with the introduction of shear deformation under inevitable shear forces produced in a curved geometry. Being stable in repeated cycles, the hysteresis obtained from the component tests exhibit characteristics of fullness and show good correlations with the ANSYS analysis. The i-PAD is experimentally proved superior not only in ductility but also in ultimate strength. Allowed to yield and dissipate energy in an early stage, the i-PAD turns out to be a potentially better device for building applications. Excellent performance of the i-PAD for seismic protection of structures has been achieved via the shaking table tests. With the dampers implemented, the effective modal damping ratios of the structure increase with the earthquake intensity.