消能斜撐之設計與耐震性能試驗

Design and Seismic Performance Test of Energy-Dissipative Brace

於祐生(You-Sheng Yu)

指導教授 ： 王彥博

國立交通大學/工學院/土木工程系所/碩士(2019年)

摘要

結構加裝位移型阻尼器後會增加整體勁度，改變結構週期，進而影響結構所受之地震力，因此阻尼器之設計不能完全獨立於結構之外。有鑑於此，本研究擬建立一套整合結構系統在內的阻尼器設計流程，盼能提供實際工程應用之參考。
本文提出之阻尼器設計流程包括初步設計與細部設計兩階段。首先設定阻尼器之極限位移，以結構的層間變位角定義之，並由面內撓曲卵形阻尼器韌性比的經驗值推算阻尼器之降伏位移。由於結構一樓所受之剪力最大，通常阻尼器會最早發生降伏及破壞，故本文以裝設於一樓的阻尼器為設計標的。吾人將設計目標設定義為，結構在設計地震力作用下，阻尼器的極限位移與一樓層間變位達到一致。惟設計地震力與結構周期相關，周期又受結構與阻尼器之互制作用所影響，因此需先假設阻尼器之初始勁度，經迭代分析至阻尼器極限位移與層間變位趨於一致為止，以收斂時所對應之阻尼器初始勁度做為下一階段細部設計的依據。阻尼器之細部設計，則沿用交大團隊先前所發展之面內撓曲卵形阻尼器設計流程。此外，並以一座五層樓鋼構模型為對象，示範所提阻尼器設計方法之應用，同時規劃一系列的振動台試驗。
本文探討對應於不同極限位移之阻尼器的耐震性能表現，分別以EL Centro、Chi-Chi及Kobe等地震為輸入擾動，並考慮不同之震波強度。模擬分析結果顯示，阻尼器之耐震性能表現具有地震相依性，不同的設計地震可能有不同的最佳設計。綜合考量後，選擇對應於層間變位角1%的阻尼器為振動台試驗之控制元件，該控制元件係與H型鋼串連成消能斜撐與結構連結。振動台試驗結果顯示，加裝消能斜撐後，結構各樓層加速度反應峰值都有明顯折減，且減震程度隨震度增加而愈為顯著，這是因振動反應變大迫使阻尼器降伏範圍擴大，因而提升了減震效益。由各樓層之加速度均方根反應所呈現的減震效益則更為顯著，蓋因均方根值與振動能量成正比，能量消散是整個地震過程的累積，更能反映振動反應衰減的總體表現。數值模擬分析與試驗結果有極佳之相關性，證明本文所提阻尼器設計方法之合理，以及ETABS結構分析工具之可靠。

關鍵字

面內撓曲阻尼器 ； 阻尼器設計流程 ； 初步設計 ； 細部設計 ； 消能斜撐 ； 耐震性能試驗

並列摘要

Installation of displacement-dependent structural dampers will increase the stiffness of the entire structure, change its fundamental period and, as a consequence, affect the seismic design load. In light of the fact that design of seismic dampers cannot be independent of the structures, this study develops a damper design procedure that takes into account the structural system as a whole to serve as reference hopefully for practical application.
This thesis proposes a two-stage damper design procedure including the preliminary design and detail design. Firstly, the ultimate displacement of the damper is defined in terms of the story-drift ratio of the structure. The yielding displacement of the damper is then calculated by dividing the ultimate displacement with the ductility estimated empirically. Since the maximum story shear occurs always in the first story where the damper tends to yield and be damaged first, damper for the first story are chosen as the design object in this study. The design target is set to be the concurrence of the ultimate displacement of the damper and the story-drift under the seismic design load required by the code. As the seismic design load is related to the fundamental period of structure which in turn is affected by the interaction between the structure and dampers, the initial stiffness of the damper in the preliminary design stage cannot be determined directly. An iterative process therefore is required by first wild guessing an initial stiffness of the damper and updating it iteratively until convergence of the ultimate displacement of the damper to the story-drift of the structure. The corresponding initial stiffness of the damper so determined will be the basis for the detail design of the damper at the next stage. The detail design then is based on the process developed earlier for the in-plane oval damper by the NCTU research team. Moreover, application of the proposed methodology for damper design has been illustrated using a five-story steel modal structure as the object while a series of shake table tests has been conducted accordingly.
This thesis explores the seismic performance of the dampers corresponding to different ultimate displacements under El Centro, Chi-Chi and Kobe Earthquakes of various seismic intensities. Simulation results indicate that the seismic performance of the damper is earthquake-dependent that the optimal damper design may vary from one earthquake to another. Upon overall considerations, the ultimate displacement of the damper corresponding to 1% story-drift ratio is selected as the control device for the shaking table tests. The dampers are connected to the structure via H-beam in form of energy-dissipative braces. Results of shaking table tests indicate that, with dampers implemented, significant reductions in acceleration responses for all floors of the structure have been achieved. The control efficiency increases with the intensity of the input excitation as larger responses extend the yielded area of the steel plates and therefore enhance the control effect. The control effect is even more pronounced in terms of the root-mean-square responses (RMS) as the RMS acceleration is proportional to the vibrating energy which is accumulated over the entire earthquake process and reflects better the performance of overall response decay. Simulation analysis is well correlated with the test results, including the proposed damper design methodology is reasonable and the ETABS is reliable as a tool for structural assessment.

並列關鍵字

in-plane flexural damper ； damper design procedure ； preliminary design ； detail design ； energy-dissipative brace ； seismic performance test

參考文獻

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4. Yen-Po Wang, Di-Hong Chen and Chien-Liang Lee (2015),” An Experimental Study on in-Plane Arch-shaped Flexural Damper,” Implementing Innovative Ideas in Structural Engineering and Project Management, Proceedings of ISEC-8, Nov. 23~28, Parramatta, Australia, pp. 293-298.

5. J.H. Park & K. H. Lee (2012), “Cyclic Loading Tests of Steel Dampers Utilizing Flexure-Analogy Deformation” in Proceedings of the 15TH World Conference on Earthquake Engineering, Lisbon, Portugal, September 24~28, paper no. 1228.