ANALYTICAL STUDY ON BRIDGES WITH POLYNOMIAL FRICTION PENDULUM ISOLATORs

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Title:	ANALYTICAL STUDY ON BRIDGES WITH POLYNOMIAL FRICTION PENDULUM ISOLATORs
Authors:	潘葉桐;vy, pham duong uyen
Contributors:	土木工程學系
Keywords:	變動曲率;滑動隔震;三向地表運動;耦合效應
Date:	2018-10-30
Issue Date:	2019-04-02 14:06:46 (UTC+8)
Publisher:	國立中央大學
Abstract:	摘要傳統的隔震系統使用了固定頻率的隔震器，如摩擦單擺支承(FPS)，即是長週期的隔震系統。然而，此類隔震器具固定的週期與回復力之特性，在具長週期成分之震波下造成低頻似共振現象，進而降低隔震的效果。為了改善此現象，本文使用新的隔震器，即具變曲率面之多項式摩擦單擺支承(Polynomial Friction Pendulum Isolation, PFPI)，克服了原本的限制，並保留以往隔震器的優點。PFPI 的滑動位移隨著振動頻率下降而減少，而因回復力存在一上限值，使傳遞之結構的力不會超出限制。PFPI 由摩擦子與球窩支承和六次多項式函數所定義軸對稱之曲面所構成。目前常用之滑動隔震分析模型大多由適用於支承回復勁度為常數下為假設，而不考慮滑動曲面效應所引起的水平雙向耦合運動效應。此簡化模型若在極限地震力或近斷層地震力作用下將失去其精確度。此外，多數現有的分析模型並未考量軸壓對隔震器的影響。因此，為了解決類似問題，本文將分析考慮軸壓影響的支承，並研究水平雙向及水平垂直之耦合運動對隔震器隔震效果的影響。關鍵字: 變動曲率, 滑動隔震, 三向地表運動, 耦合效應;ABSTRACT A conventional isolation system with constant isolation frequency such as FPS is usually a long-period dynamic system. However, this system has limitation due to constant isolator period and restoring force characteristics. This lead its seismic response is likely to be amplified in the earthquake with long-period wave components. A new isolator called the polynomial friction pendulum isolator (PFPI) that overcomes these limitations while retaining all the advantages has been described in this thesis. The PFPI has oscillation frequency decreasing with sliding displacement, and the restoring force has an upper bound so that the force transmitted to the structure is limited. A PFPI consists of a slider and a concave and axially symmetrical sliding surface which is defined by a six-order polynomial function. Nowadays, the analytical models proposed for a SIVC isolator were usually derived by using static equilibrium condition. This kind of models (also called simplified model) is not able to account for dynamic coupling effects between each vibration direction as well as the curvature effect such as centrifugal force. As a result, these models will lose their accuracy when the isolators are subjected to extreme earthquakes that produce large velocity or displacement. In addition, most of the existing models did not consider the effect the vertical ground motion on the isolation performance. In order to solve that problem, this thesis establish another analytical for the bearing and consider the effect of vertical ground motions. In addition, it also investigates the dynamic coupling effects on the isolator performance. Keywords: Variable curvature, sliding isolation, tri-axial ground motion, coupling effect.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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