黏滯型隔震系統之隔震阻尼比最佳化設計公式 及雙向變曲率型摩擦隔震系統理論與實驗研究

Optimal Design Formulas for Isolation Systems with Viscous Dampers and Theoretical and Experimental Study of Bidirectional Sliding Isolators with Variable Curvature

范揚志(Yang-Chih Fan)

指導教授 ： 鍾立來

國立臺灣大學/工學院/土木工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10226

摘要

本文分為兩部分，第一部分為探討隔震系統之隔震阻尼比最佳化設計公式，第二部分為雙向變曲率摩擦隔震系統之理論與實驗研究。
第一部分旨在探討線性黏滯型隔震系統之最佳隔震阻尼比，首先由動力平衡方程式轉換成一階狀態方程式，以求得離散時間系統之狀態方程式來進行動力分析。再者，鑒於前人文獻在設計最佳化公式時，多以白雜訊為地表加速度輸入，但實例分析之效果無法反映地域之特性，故本文擬以177筆台灣之實際地表加速度作為輸入進行數值分析，並分別考慮結構為剛體與非剛體系統及變動多組結構參數情況下，使結構絕對加速度之均方最小化，以求取隔震系統之最佳阻尼比，並配合迴歸分析，從而建立設計公式。最後，以331地震分別為TAP097及CHY003兩個測站所得之地表加速度為輸入及台大土木研究大樓進行案例分析以驗證本文所提最佳化設計公式之可行性，由實例分析結果顯示本文之最佳化設計公式所得到之隔震效果與實際最佳情況相當接近，且整體效能優於由前人文獻所提出設計公式之結果。因此，本文所提之隔震阻尼比最佳化設計公式，實屬可行，可供工程師作隔震系統初步設計之用。
第二部分旨在探討雙向變曲率隔震系統在近遠域震波下之行為與預測。傳統滑動隔震支承對於近域震波易產生低頻似共振之現象，因而影響其隔震效能，為改善此問題本文使用多項式型摩擦單擺支承以進行實驗及理論之研究，此支承之滑動曲面係為多項式函數之軸對稱面，經由變化其函數之係數可將支承之回復力分為軟化段與硬化段兩種不同功能之區段，其中軟化段係用以降低結構加速度反應，硬化段則用以抑制支承位移。又目前對於變曲率隔震系統之理論模型多著墨於單一軸向，但實際地震卻為三維方向，故本文針對多項式型摩擦單擺支承進行水平雙向振動台實驗，並推導變曲率支承在水平雙向之回復力及摩擦力，從而建立隔震系統之數值模型，並進行相關之理論預測。由實驗及理論分析結果可知，本文提出之理論模型能夠有效預測實驗結果，證明雙向變曲率隔震系統之可預測性，且由理論模型驗證與傳統摩擦單擺支承(FPS系統)相比，變曲率支承在近域震波下能夠有效抑制支承位移，且當震波PGA越大抑制效果越明顯。

關鍵字

最佳化設計公式 ； 黏滯消能 ； 雙向隔震 ； 變曲率 ； 多項式函數 ； 近域震波 ； 摩擦隔震系統 ； 振動台實驗

並列摘要

In this paper, two parts of study were included. The first part was talking about optimal design formulas for isolation systems with viscous dampers. The next part was the theoretical and experimental study about bidirectional sliding isolator with variable curvature.
For the first part of this paper, the motion equilibrium equation was transformed to first-order state space equation. Then we could obtain the state space equation in discrete-time system for dynamics analysis. According to the previous literature in optimal design formulas, the system was usually subjected to white-noise excitation. But the case analysis in previous study was not doing well because the formulas could not retain the regional feature. Therefore, the numerical analysis intended to input several ground motion records in Taiwan. After that, considered the structure system in rigid and non-rigid system with variable structure parameters. And the mean square of absolute structural acceleration had been minimized for obtaining optimal isolation damping ratio. Repeating the optimal process with various structural parameters, the proposed simple design formula was developed by regression of those optimal isolation damping ratios from numerical simulations. Finally, we conducted the case analysis to verify the feasibility of proposed optimal design formulas.
For the second part, conventional sliding isolation systems might not be effectiveness when the isolated structures are subjected to near fault ground motions. In order to solve this problem, the polynomial friction pendulum isolator (PFPI) had been used. The restoring stiffness of this new type of isolators possessed a softening and a hardening section for reducing the structural acceleration and suppressing the isolator drift, respectively. Furthermore, previous studies of seismic isolation of variable curvature almost focused on single axes. Therefore, the shaking table test for PFPI isolator in two directions and its simulation model were conducted. According to the analysis results in shaking table test and simulation, the simulation model could predict the test results effectively for verifying the predictability of such isolation system.

並列關鍵字

optimal design formula ； viscous dissipation ； bidirectional isolation ； variable curvature ； polynomial function ； near-fault ； friction isolation ； shaking table

參考文獻

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