含變頻滑動支承不等高橋墩橋梁之最佳化設計

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Title:	含變頻滑動支承不等高橋墩橋梁之最佳化設計
Authors:	林宜泓;Lin, Yi-Hong
Contributors:	土木工程學系
Keywords:	變曲率隔震支承;變頻式隔震支承;摩擦單擺支承;不等高橋墩橋梁;PSO-SA混合式搜尋法;variable-curvature seismic isolator;various frequencies seismic isolator;friction pendulum isolator;bridge with unequal height piers;PSO-SA hybrid search algorithm
Date:	2022-01-25
Issue Date:	2022-07-13 16:53:34 (UTC+8)
Publisher:	國立中央大學
Abstract:	多項式摩擦單擺支承(Polynomial Friction Pendulum Isolator，PFPI) 為具變頻特性之新型摩擦單擺支承，相對於傳統滑動隔震支承，可預防近斷層震波產生的低頻共振現象。PFPI的曲面函數為六次方多項式，經由多項式參數設計，可使支承具變頻之隔震效果。支承位移不大時，可利用回復勁度遞減之軟化段減緩結構加速度反應，當位移過大時，再藉由回復勁度遞增之硬化段減低位移反應，過去研究已證實PFPI可發揮變頻特性防止低頻共振現象，於近域與遠域震波皆發揮良好隔震效果。以往研究主要討論之目標橋梁皆為規則性橋梁，橋墩高度均相同，但在不等高橋墩隔橋梁中，不同高度橋墩之勁度差異甚大，PFPI需利用不同參數組合之設計以達最佳之隔震效果，且前人所使用之數值分析法僅考量水平向與垂直向之雙向動力分析，而本研究多考慮側向與垂直向動力反應，其與軸向之反應行為會有著明顯差異。本研究針對PFPI不等高橋墩隔震橋，使用PSO-SA混合式演算法，針對不同震波，搜尋PFPI之最佳支承參數，同時在搜尋過程中限制PFPI參數使搜尋結果合理，並改善因限制PFPI參數，而降低之搜尋效率。最後透過觀察PSO-SA多目標函數中各目標權重比例與結構物反應之關係圖，選擇合適權重下之最佳參數做為設計結構物之參考。而從搜尋結果顯示來看，結構物反應皆能符合PSO-SA所設定之目標。 ;Polynomial Friction Pendulum Isolator is a new type of friction pendulum isolator with variable frequency characteristics. The feature can prevent low-frequency resonance from near-fault seismic waves. The function of PFPI is a hexagonal polynomial. By the design of the design of polynomial parameters, the bearing can have the vibration isolation effect of variable frequency. When the bearing displacement is small, isolator can reduce the acceleration of structure by the softening section which decreases restoring stiffness. When the bearing displacement is large, isolator can reduce the displacement of structure by the hardening section which increases restoring stiffness .The previous research has proved that PFPI can exert variable frequency characteristics to prevent low-frequency resonance, and it will have good effect of isolation. The target bridges discussed in previous studies are all regular bridges with the same height of piers. However, isolated bridges with unequal height piers, the stiffness has big difference. PFPI needs to design different combination of parameters to reach the best isolation effect. Moreover, previous research only considers the axial and vertical directions dynamic analysis. In this study, we discuss not only axial and vertical directions but also side and vertical directions dynamic responses, which are significantly different from the axial response behavior. In this study, we use the PSO-SA hybrid search algorithm to search for the best support parameters of PFPI for bridges which have unequal height piers in different seismic waves. In addition, by restricting PFPI parameters ,we get reasonable parameters of PFPI, and improve the search efficiency caused by restriction. Finally, through observing the relationship between the weight ratio of each target and the response of the structure in the PSO-SA multi-objective function, the optimal parameters under the appropriate weight are selected as the reference for designing the structure. From the search results, it can be seen that the structural dynamic reponses can meet the objective function set in PSO-SA.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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