軟木於樁型地震超材料應用之可行性研究

Abstract

台灣位於板塊交會地震頻繁處，避免地震造成災害之防震工程技術顯得尤為重要，現今廣泛應用之耐震與隔減震技術以保護單一建築物為目標，遂崛起以地震超材料(Seismic metamaterial)阻擋地震波傳，保護整區建築物安全之構想，比起建築物各自進行防震設計顯得更經濟、有效率。 本研究首先進行參數分析得到低帶隙下界頻率、寬帶隙頻率範圍樁型地震超材料設計目標之材料參數，軟木材料之材料性質能符合需求，遂探討軟木應用於樁型地震超材料之可行性。比較實心與空心單元晶格對於樁型地震超材料帶隙頻率範圍之影響，得知樁型地震超材料單元晶格內設計空心，能將其帶隙下界頻率降至更低。 數值模擬驗證實心樁型地震超材料、空心樁型地震超材料在有限元素分析軟體皆能於帶隙頻率範圍內產生衰減波傳效用。以鋼箱縮尺試驗證實軟木樁型地震超材料實務應用之可行性，比較實心樁型地震超材料及空心樁型地震超材料試驗結果，得知設計空心能較實心樁型地震超材料於較低頻率產生波傳折減效果。 本研究數值分析與縮尺試驗結果，皆得證軟木應用於樁型地震超材料確實可行。

Taiwan is situated at the convergence of three major tectonic plates, leading to frequent occurrences of earthquakes. Hence, seismic engineering technologies that can prevent the disasters caused by earthquakes are important. Nowadays, seismic resistance, vibration control, and seismic isolation technologies are designed for individual structures. Therefore, the concept of seismic metamaterials, which are used to block seismic wave transmission and protect the entire region of structures, is more economical and efficient than individual seismic design for structures. This study includes a parametric analysis to determine the material parameters for design objectives of pile-type seismic metamaterials, including a lower band gap frequency and a wider width of band gap. The material properties of cork fulfill the requirements for designing pile-type seismic metamaterials. Therefore, this study aims to investigate the feasibility of using cork in pile-type seismic metamaterials. The band gap frequency can be further lowered by the hollow unit cell when compared to the standard unit cell of pile-type seismic metamaterials. This study uses finite element software to verify that both the standard unit cell and the hollow unit cell of pile-type seismic metamaterials can exhibit wave attenuation within the band gaps. This study conducted a lab-scale test in a steel box to verify if cork pile-type seismic metamaterials can reduce the acceleration response in practical applications. The test results show that the hollow unit cell of pile-type seismic metamaterials attenuates the wave response at lower frequencies compared to the standard unit cell. The numerical analysis and test results in this study can validate the feasibility of cork application to pile-type seismic metamaterials.