具凸面導軌之雙向偏心滾動隔震系統機構開發與試驗驗證;Development and Experimental Verification of Bidirectional Eccentric Rolling Isolation System with Convex Guide

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题名:	具凸面導軌之雙向偏心滾動隔震系統機構開發與試驗驗證;Development and Experimental Verification of Bidirectional Eccentric Rolling Isolation System with Convex Guide
作者:	洪鎮韋;Hong, Zhen-Wei
贡献者:	土木工程學系
关键词:	隔震;非線性;滾動;凸面導軌;偏心;振動台試驗;摩擦消能;isolation;nonlinearity;rolling;eccentricity;shaking table test;frictional damping
日期:	2023-07-28
上传时间:	2024-09-19 14:42:26 (UTC+8)
出版者:	國立中央大學
摘要:	傳統隔震系統之回復力與位移呈現線性關係，因此其隔震頻率為定值。當地震力之頻率內涵與隔震頻率接近時，將會發生共振反應使隔震系統失去作用。因此，許多具有非線性回復力之隔震系統相關研究相繼產出。偏心滾動系統(Eccentric Rolling isolation System, ERIS)為其一，透過偏心設計使其具有非線性之回復力。前人之研究已證實相比於一般線性系統，ERIS於近斷層地震下有較低之加速度反應。此外，前人改進此數學模型，藉由加裝凸面導軌於ERIS下方使其成為(Eccentric Rolling isolation System with Convex guide, CERIS)，CERIS保有了ERIS之非線性回復力特性，並且增加其隔震效能。然而過去研究中CERIS只考慮結構隔震應用故忽略了圓形隔震器慣性之影響，並且於機構上只考慮了單向輸入之情況。對於設備隔震而言，由於設備物之質量與圓形隔震器相近，其慣性之作用將明顯影響隔震效能。此外真實地震應為雙軸向輸入，過去之數學模型不符合實際應用之考量。因此本研究基於偏心滾動系統加裝凸面導軌(Eccentric Rolling isolation System with Convex guide, CERIS)考量了隔震器慣性之影響，並且利用正交堆疊之方式將單向之機構拓展至雙向以符合實際運用。於實驗機構單一方向上，隔震平台以偏心梢接於圓形隔震器之偏心點上，隔震平台上裝置隔震目標物，凸面導軌在固定曲率半徑下加裝於機構下方。本研究採用能量法推導在考慮圓形隔震器質量下之運動方程式，同時採用庫倫摩擦模型模擬系統之消能行為。經參數敏感度分析，探討系統設計參數，包含偏心比、半徑比、圓形隔震器半徑與質量比對系統水平及垂直向動力行為之影響。於強迫振動之模擬，考慮數筆包含近斷層與遠域震波並與具有線性回復力之摩擦隔震系統進行比較，確認CERIS於何組參數組合下可發揮較佳之隔震效果。最終，以雙軸向之振動台試驗，透過兩組不同參數組合之隔震系統試體進行試驗。由試驗量測與數值擬合之結果，成功驗證以下三點。第一，數學模型之正確性。第二，考慮圓形隔震器質量之必要性。第三，由實驗結果驗證機構雙向之耦合影響為可忽略的，大幅提升實務應用之可行性。鍵字 : 隔震、非線性、滾動、凸面導軌、偏心、振動台試驗、摩擦消能;Conventional isolations exhibit a linear relationship between the restoring force and displacement, resulting in a fixed isolation frequency. However, when the dominant frequency of seismic excitation is close to the isolation frequency, the resonance will occur and the isolation system may be ineffective. To address this issue, numerous studies have been conducted on isolation systems with nonlinear restoring force. One such system is the eccentric rolling isolation system (ERIS), which possesses nonlinear restoring force by using the concept of eccentricity. Previous studies of ERIS have proven that ERIS exhibits a lower acceleration response compared to linear isolation systems during near-fault earthquakes. Furthermore, the eccentric rolling isolation system with the convex guide (CERIS) which is an improvement of ERIS by adding a convex guide beneath the ERIS has been proposed. CERIS retains the characteristic of nonlinear restoring force and also enhances the isolation performance. However, previous studies of CERIS focus on structural isolation applications, thus neglecting the influence of the inertial effects of circular isolators and the conceptual mechanism only effective for unidirectional input. For equipment isolation applications, the mass of the equipment is close to that of circular isolators, therefore the inertial effects significantly affect the isolation performance. Additionally, real earthquakes should be bidirectional inputs, which were not adequately considered in previous studies. Hence, this study proposes an investigation of the CERIS considering the influence of isolator inertia and extends the unidirectional mechanical system to a bidirectional one by using orthogonal stacking to satisfy the requirements of practical applications. In the unidirectional experimental setup, the isolation platform is eccentrically pin connected to the circular isolator, and the target object is mounted on the isolation platform. The convex guide with a fixed radius of curvature is assembled beneath each circular isolator. This study derives the equations of motion considering the mass of the circular isolator by the energy method and and the Coulomb friction model is used to simulate the energy dissipation of the system. Through parameter sensitivity analysis, the effects of system design parameters, including eccentricity ratio, radius ratio, circular isolator radius, and mass ratio on the horizontal and vertical dynamic behavior of the system. In the simulation of forced vibrations, several seismic waves including near-fault and far-field motions are considered and compared with linear isolation systems to perform the superior seismic performances of the CERIS with various design parameters. Finally, biaxial shaking table testing is conducted using two specific sets of parameters for the specimens. By numerical resimulation and experimental results, the accuracy of the mathematical model is validated, and the role of the mass of circular isolators is also investigated. Moreover, the coupling effect on the proposed bidirectional mechanism is also proved to be negligible, which further significantly enhanced the feasibility of practical applications. Keywords: isolation, nonlinearity, rolling, eccentricity, shaking table test, frictional damping
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