直接基礎搖擺反應於等高及不等高橋墩案例之橋梁與希爾伯特-黃之應用

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Title:	直接基礎搖擺反應於等高及不等高橋墩案例之橋梁與希爾伯特-黃之應用
Authors:	陳森杰;Chen, Sen-Chieh
Contributors:	土木工程學系
Keywords:	直接基礎;搖擺反應;不等高橋墩案例;週期延長;Spread foudation;Rocking Effect;Irregular-height bridge case;Period Prolongation
Date:	2019-01-21
Issue Date:	2019-04-02 14:07:59 (UTC+8)
Publisher:	國立中央大學
Abstract:	摘要世界上已發生多起因地震而導致許多橋梁損壞的案例，為有效減少地震所造成的災害，相關研究提出各種隔震方法，其中之一為直接基礎搖擺隔震，直接基礎搖擺可藉由延長結構週期降低傳遞至上部結構之地震力，雖會造成上部結構較大的位移，卻可使橋柱於地震中受到較輕微的損傷。本研究使用日本道路橋梁示方書之算例，探討不同震波作用下等高橋墩案例與不等高橋墩案例於考慮與不考慮直接搖擺反應，在柱頂反應及柱底受力情形之比較，直接基礎搖擺反應使用非線性土壤彈簧模擬基礎與土壤互制之關係，等高橋墩案例模型與不等高橋墩案例模型會以結構整體勁度比較。本研究亦使用適合處理非線性及非穩態訊號的希爾伯特-黃轉換(簡稱HHT)計算得到瞬時頻率，進一步得出能量-頻率-時間之分布情形，除了比較各模型於固定基礎與搖擺反應在HHT時頻譜中頻率分布及變化之情形，亦試圖找出搖擺反應效果顯著時，頻率下降之現象與柱頂反應及柱底受力的關係。關鍵字 : 直接基礎、搖擺反應、不等高橋墩案例、週期延長 ;Abstract There have been so many examples of bridge damage due to the earthquake throughout the world. One of the seismic isolation methods that have been proposed to effectively decrease the damage by the earthquake is rocking effect of the spread foundation. Although the rocking effect can cause larger displacement at the superstructure, it is capable of decreasing the seismic force from the ground to the superstructure by prolonging the period to keep the bottom of the structure from the major damage. This research shows that the comparison of the reaction at the superstructure and the substructure between the fixed behavior and the rocking effect. It also compares the results from a symmetrical model and two unsymmetrical models which are referred to Japan specification. Models with rocking effect use nonlinear soil springs to simulate the interaction between the foundation and the soil. In addition, the comparison between a symmetrical model and two unsymmetrical models depends on what entire stiffness the whole model is. This research also uses Hilbert-Huang Transform, which is capable of dealing with the nonlinear and non-steady state signals appropriately to get the instantaneous frequency that shows the energy-frequency-time relationship. Besides comparing the distribution and the change of the frequency between the fixed models and rocking effect models by using HHT, the relationship between the frequency descending proportion and either the reaction at the superstructure or the substructure would be shown when the rocking effect is applied on each of the model. Keywords : Spread foundation , Rocking effect , Irregular-height bridge case , Period prolongation
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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