中間樓層隔震建築物之試驗、設計與監測研究

Experiment, Design and Monitoring of Mid-Story Isolated Buildings

洪瑩真(Ying-Chen Hung)

指導教授 ： 張國鎮

國立臺灣大學/工學院/土木工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00542

摘要

隨著隔震技術漸趨成熟，除了基礎隔震建築物外，中間樓層隔震建築物之實務案例亦與日俱增，因其具有施工便捷、有效利用土地以及較易滿足建築上的特殊考量與功能需求等優點。所謂中間樓層隔震建築物即是將隔震層設置於基礎以上之樓層，國內最常見之中間樓層隔震設計是將隔震層設置於一樓頂。然而，中間樓層隔震建築物其動力行為相對於基礎隔震建築物更為複雜，可能因下部結構的存在而造成對於隔震設計非預期之影響。故本研究內容針對一組傳統基礎隔震結構以及兩組中間樓層隔震結構進行振動台試驗研究，隔震系統分別採用鉛心橡膠支承墊以及鉛心橡膠支承墊加裝線性黏性阻尼器之組合，藉由試驗結果比較隔震系統裝置於不同樓層以及隔震系統加裝線性黏性阻尼器之隔震效益，並探討中間樓層隔震結構之下部結構對其隔震效益的影響。
經由中間樓層隔震建築物之前導數值分析研究，以一簡化三自由度結構數值模型模擬一中間樓層隔震建築物，隔震系統之遲滯行為以一等效線性系統模擬，針對此一簡化三自由度結構模型之數值分析結果與實際振動台試驗研究結果比較，探討目前耐震設計規範中適用於基礎隔震設計之等效線性靜力分析程序，應用於中間樓層隔震設計之諸多不合宜處，並初步提出中間樓層隔震結構之初步設計構思。
最後以台灣大學土木系研究大樓進行中間樓層隔震結構之實例分析研究，將過去實際地震中所量測到的資料，進行結構動力特性識別以及受震反應分析，並藉此說明隔震元件數值分析模型與工址地震特性對於隔震設計之影響。

關鍵字

中間樓層隔震 ； 高模態 ； 等效線性靜力分析 ； 反應譜分析 ； 台灣大學土木系研究大樓 ； 地震監測

並列摘要

The mid-story seismic isolation design method, in which the isolation system is incorporated into the mid-story rather than the base of the building, is recently gaining popularity for the seismic protective design of buildings. In addition to be capable of satisfying some particular architectural concerns of aesthetics and functionality, the adoption of the mid-story isolation design, as an alternative to the base isolation design, can enhance the construction feasibility especially at highly populated areas. In the past, the dynamic behavior of mid-story isolated buildings has been numerically investigated using a simplified structural model in which three lumped masses are assigned at the substructure, super-floor above the isolation system and superstructure. It was disclosed that the dynamic characteristics and seismic responses of a mid-story isolated building are significantly affected by the mass and stiffness of the substructure.
In order to experimentally investigate the discrepancies of dynamic characteristics and seismic responses in base-isolated and mid-story isolated buildings, a series of shaking table tests on three seismically isolated structural models are performed in this dissertation. These three structural models are respectively isolated at the base of the superstructure, the top of an one-story substructure and the top of another two-story substructure. Therefore, the first specimen is a conventional based-isolated building while the other two are the so-called mid-story isolated buildings. In addition to the isolation system composed of four lead-rubber bearings (LRB), the implementation of two linear viscous dampers (VD) into the isolation system is adopted in the experimental study to demonstrate the seismic performance of the isolated superstructure. Furthermore, based on the comparison of test results of two mid-story isolated structural models with their isolation systems installed at different stories, the effect of substructure properties on the dynamic behavior of mid-story isolated buildings is thoroughly discussed.
It can be found from the analytical results and test results that the dynamic behavior of a mid-story isolated structure is not be identical to, or even becomes more complex than, that of a base-isolated structure. The contribution of higher modes to the seismic responses of mid-story isolated buildings should be paid more attention. Therefore, the assumption of a single degree of freedom system for the superstructure of a mid-story isolated building (i.e. the isolation system is the only lateral deformation system as the base isolation design) may not be conservative especially when the substructure is not stiff sufficiently. In this dissertation, the irrationalities of adopting the conventional equivalent lateral force procedure for the mid-story isolation design are discussed in detail. Furthermore, two modal response spectrum analysis procedures appropriately considering the contribution of higher modes are adopted to predict the peak seismic responses of the test structural models. Based on the comparison of test results and numerical predictions by these two analysis procedures, the feasibility of the modal response spectrum analysis procedures for the preliminary design of mid-story isolated buildings is also examined in this dissertation.
The Civil Engineering Research Building of the National Taiwan University (NTU) is a mid-story isolated structure with which several accelerometers and displacement transducers are equipped for the seismic monitoring. In this dissertation, the data recorded by these measurement instrumentations during the past major earthquake events are not only used for the structural system identification but also compared with the analytical results considering an appropriate numerical model for the seismic isolation bearings. It is disclosed that both the determination of the elastic stiffness of seismic isolation bearings and the earthquake characteristics around the site should be considered carefully for the seismic isolation design.

並列關鍵字

mid-story seismic isolation ； higher mode ； equivalent linear system ； equivalent lateral force procedure ； response spectrum analysis ； Civil Engineering Research Building of NTU ； seismic monitoring

參考文獻

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