拉脹超材料之縮尺試驗及簡化模型研究

Abstract

全世界大部分的地震均發生於活躍的環太平洋地震帶，而坐落於上的臺灣每年平均發生約上萬次的地震，令抗震技術的研究與精進持續成為非常重要的議題。近年興起一種新抗震概念稱作地震超材料(Seismic metamaterials)，利用阻擋地震波之傳遞的方式避免災害，透過此概念有望達成在不改動既有建物的情況下保護整個目標區域之理想。 本研究持續先前對樁型拉脹地震超材料之探索，進行比例1/15之縮尺試驗證實樁型拉脹地震超材料符合試驗前數值掃頻分析得到之帶隙位置且在帶隙範圍內具波傳折減效果。另外進行排數試驗證實週期性排列確實為超材料展現波傳折減特性的基本假設，亦觀察針對此樁型拉脹地震超材料，為使帶隙效果開始明顯展現，所需之最小排列行數為三排。 另外，樁型拉脹地震超材料之設計帶隙範圍符合地震超材料之設計目標：具有低帶隙下界以及寬帶寬，因此本研究認為此設計單元晶格具未來進行更多延伸研究之可行性。基於樁型拉脹地震超材料的複雜結構，為使後續延伸模擬之可行性提升，本研究致力發展運用於此超材料之層疊排列拉脹結構等值模型，簡化原設計樁型拉脹地震超材料，目標使數值模擬過程簡單化並降低計算成本。

The majority of seismic events worldwide occurred within the Pacific Ring of Fire, also known as Circum- Pacific belt, where Taiwan is located in. Tens of thousands of earthquakes strikes Taiwan annually, making ongoing research and advancement in earthquake-resistant technology a crucial topic. In recent years, a new passive control technology, Seismic Metamaterials has aroused. These metamaterials aim to block seismic waves from passing, offering the potential to protect the entire target area without altering the current states of already- existing structures. This study extends the exploration of auxetic pile- type seismic metamaterials, conduct 1/ 15 scale- down experiments in order to validate that the range of band gap is actually the same as where previous studies have predicted by numerical analysis, and also observe whether the input waves are attenuated while the frequencies of the waves are within the designed band gap. On top of that, row tests are also carried out to prove that periodic arrangement is indeed a crucial precondition for wave attenuation characteristic of metamaterial to show, while the minimum rows of periodic arrangement of auxetic pile- type seismic metamaterials to exhibit band gap were observed to be three rows. In addition, since the designed band gap of auxetic pile- type seismic metamaterials actually fits the design goal quite well: possesses relatively low lower bound frequency and decent width of band gap, this study consider auxetic pile- type seismic metamaterials feasible for conducting extended research. Limited by the complicated structures of auxetic pile- type seismic metamaterial unit cell, in order to improve the feasibility of follow- up extended numerical analyses, this study aims to use equivalent model of this non-typical arrangement of auxetic structures for the development of simplified model, intent to simplify the process and modeling of numerical analyses and reduce the computation cost.