水平隔震結構裝設垂直向設備隔震系統之振動台試驗與分析

Experimental and Analytical Studies of Equipment using Vertical Isolation System on Base-Isolated Structures

蘇智偉(Chih-Wei Su)

指導教授 ： 黃尹男

國立臺灣大學/工學院/土木工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202003102

摘要

結構物的隔震設計，通常較著重於對抗水平向地震，因垂直向地震對結構元件的威脅相對上低於水平向地震，且三向隔震系統的設計難度較高。但在實務需求中，許多結構物設有昂貴或重要的設備，垂直向地震經結構物傳遞後加速度會被放大，進而增加了設備所需承受的地震力，垂直向隔震的價值也變得相當重要。本研究設計了一座垂直向的設備隔震系統，試圖降低設備的垂直向加速度以減少設備破壞的可能性。本研究將此設備隔震系統裝設於一雙向單跨的兩層抗彎鋼構架之頂樓進行振動台試驗，分別測試鋼構架底部1) 固接於振動台、2) 安裝有摩擦單擺支承墊以及3) 安裝有鉛心橡膠支承墊三種底部邊界條件，探討垂直向設備隔震系統搭配水平向結構隔震的可行性，本研究共選定30筆地震歷時，分別具有不同的頻率內涵，目的為觀察不同頻率內涵之地震對於垂直向設備隔震系統的影響。試驗結果顯示，垂直向加速度的放大與結構垂直向頻率和地震頻率內涵有關，而本研究設計之垂直向設備隔震系統能有效降低垂直向的加速度，但會產生搖擺效應(Rocking effect)的問題，需要針對垂直向隔震系統再做改善。水平隔震系統能有效降低結構與設備所承受之水平向地震力，且對於降低垂直向設備隔震系統的搖擺效應(Rocking effect)行為有顯著的效果。

關鍵字

振動台試驗 ； 設備隔震 ； 垂直向隔震 ； 水平向隔震 ； 搖擺效應

並列摘要

Seismic isolation systems mostly provide protection only against horizontal component of ground motion. However, vertical component of ground motion plays an important role when there is important equipment in the structure. The vertical ground motion is usually magnified by the slab vibration. Therefore, mitigating the vertical seismic load becomes an important issue and vertical isolation system is a feasible approach. In this study, a vertical isolation system for equipment was designed and tested on a shaking table. The system consists of linear coil spring, viscous damper and linear guideway installed on the roof of the two-story moment-resisting steel frame. The system was tested under three different frame base boundary condition: (1) fixed-end, (2) above friction pendulum bearing, and (3) above lead rubber bearing. This paper selects 30 ground motions and divides them into three group depending on the dominant vertical frequency of the ground motion. A series of shaking-table tests were conducted to investigate the effectiveness and feasibility of the base-isolated structure with vertical isolation system for equipment installed on it. The experiment results show that the vertical isolation system significantly reduces the vertical acceleration but also introduced rocking to the equipment. Rocking motion is affected by the magnitude of horizontal seismic load. Horizontal base-isolation system of the tested frame successfully reduced both horizontal acceleration demand and rocking motion of the equipment.

並列關鍵字

Shaking-table test ； equipment isolation ； vertical isolation ； horizontal isolation ； rocking effect

參考文獻

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