交錨型雙核心自復位夾型挫屈束制斜撐發展及試驗驗證

Abstract

預力型自復位斜撐(SCB)是利用斜撐中的拉力構件束制斜撐中的鋼受壓構件，並在斜撐受軸拉與受軸壓下提供自復位能力，即在大變形下有回到零殘餘變形的能力。在拉力構件相同應變下，傳統雙核心自復位斜撐變形量可達兩倍傳統單核心自復位斜撐變形量(或是在相同斜撐變形量下，拉力構件額外應變減少一半)，有效降低拉力構件彈性應變需求。自復位斜撐使用摩擦板進行消能，經多組試驗後摩擦板耗損，消能效率降低。夾型挫屈束制斜撐(SBRB)是利用高強度螺栓將兩組獨立的圍束單元夾合核心消能構件，使得斜撐受軸壓下不會挫屈而產生十分飽滿的遲滯消能行為。本研究將挫屈束制系統消能機制取代摩擦消能機制，並結合挫屈束制系統及自復位系統，設計兩組不同配置方法的交錨型雙核心自復位夾型挫屈束制斜撐(長度7490 mm)，並說明交錨型雙核心自復位夾型挫屈束制斜撐力學理論及預測方法，兩組斜撐之拉力構件均使用D16 mm鋼鉸線。本研究目的在於探討兩組不同配置方法的交錨型雙核心自復位夾型挫屈束制斜撐耐震行為差異。試驗結果顯示交錨型雙核心自復位夾型挫屈束制斜撐之傳力機制與理論預測相符。第一階段試驗之層間側位移角2%時，兩組自復位斜撐仍有良好的自復位行為。兩組自復位斜撐的最大斜撐應變皆為1.1%，分別對應最大拉力構件應變為0.80%，兩組斜撐最大軸力分別為1648 kN與1705 kN。兩組斜撐之挫屈束制系統最大軸壓核心應變可達1.5%，累積韌性容量可達1090-1129，大於AISC(2010)耐震規範建議之200。

Self-Centering Brace (SCB) uses tendons to constrain steel compression member of the brace and provides self-centering properties under brace in tension and compression that is restored to zero residual deformation. Conventional dual-core SCB is two times brace deformation capacity than conventional single-core SCB under same strain of tendons (or reduce to half the additional strain of tendons under same brace deformation capacity) that effectively reduce the elastic strain demand of tendons.The Energy dissipating members experience serious wear, which reduces their energy dissipating efficiency and results in a need for replacement. Sandwiched Buckling-Restrained Brace (SBRB) uses two identical restraining members that sandwich the Energy Dissipative core with fully tensioned high-strength bolts to prevent core buckling and have stable hysteretic response. This study presents a cyclic behavior and self-centering behavior of Cross-Anchored Dual-Core Self-Centering Sandwiched Buckling- Restrained Brace (SC-SBRB). A SC-SBRB consists of a SBRB system, which provide energy dissipation, and self-centering system, which provide self-centering. The SC-SBRBs were Designed and tested two specimens (7490 mm long) with different member settings, tendons of two SC-SBRBs used same D16 mm steel strand. The objective was to compare the difference of seismic performance of SC-SBRBs. Test results indicate that the mechanism of SC-SBRBs is consistent with prediction. Under drift 2% of phase 1 test, two SC-SBRBs maintained good hysteretic response in self-centering behavior. Maximum brace strain of two SC-SBRBs were 1.1% corresponding to maximum tendons strain 0.80% and maximum load 1648 kN and 1705 kN, respectively. SBRB Systems can develop stable hysteretic responses up to a maximum core axial strain 1.5%, and cumulative plastic ductility 1090-1129 that is much higher than that specified the value of 200 in AISC seismic provisions (2010).