應用週期性基礎結構之振動台試驗結果評估

Evaluation on Shaking Table Results of Structures with Periodic Foundations

劉德謙(Te-Chien Liou)

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(2019年)

https://doi.org/10.6342/NTU201901657

摘要

隔震系統為近年來蓬勃發展之耐震技術，傳統隔震系統已被證實其於水平向有優異的隔震效益，但於垂直向隔震尚有挑戰性。週期性材料為近年來研發中之概念性材料，藉由其頻散特性，可達到引導能量傳遞及濾波消能的效果。本文旨在探討一維週期性結構之振動台試驗結果，並對其做進一步的分析。
本文針對振動台試驗結果進行分析，探討試驗之設備對實驗結果的影響，利用公式計算及SAP2000軟體進行數值模型分析，得知振動台固定試體之螺栓側向勁度會影響水平向試驗，並分析一維週期性基礎與混凝土基礎之自然頻率差異對試驗結果的影響。另外，針對振動台試驗結果進行反應譜分析，得到一維週期性基礎自然頻率之譜加速度反應小於混凝土基礎的結果。
本文建立一維週期性結構之ABAQUS數值模型，利用接觸勁度模擬振動台螺栓側向勁度之影響，並考慮橡膠材料對於受拉及受壓之應力應變行為不同，採用壓力模數之計算方式提高橡膠材料垂直向的有效勁度，可成功以數值模型模擬實驗結果。並利用材料性質對週期性基礎帶隙頻率的影響，降低橡膠材料楊氏模數及增加其單位元件厚度，設計一參數分析模型，使其水平向帶隙頻率涵蓋1.5赫茲至50赫茲、垂直向帶隙頻率涵蓋5.3赫茲至50赫茲的區域。此參數分析模型進行地震歷時試驗，發現水平向試驗在帶隙頻率間之反應皆折減，但在帶隙頻率外之反應受到地震輸入頻率內涵的影響，較高頻的地震在帶隙頻率外之反應依然折減，較低頻的地震則在結構主頻的位置放大。垂直向之試驗在帶隙頻率區內的反應亦為折減，但在帶隙頻率外的反應皆在結構主頻位置放大，不受地震頻率內涵的影響。

關鍵字

週期性基礎結構 ； 振動台試驗 ； 隔震系統 ； 帶隙頻率 ； 參數分析 ； 地震超材料

並列摘要

The isolation system has flourished to equip with the structure in recent years. The traditional isolation system has been proven to enhance the horizontal seismic performance of many isolated structural system, but without the capability of isolating vertical earthquakes. Seismic metamaterials were known as conceptual materials in research and development field in recent years. Within the dispersion characteristics, seismic wave can be attenuated or controlled within acceptable range. This study aims to evaluate and analyze the shaking table test results of one-dimensional periodic structures.
In this thesis, the results of the shaking table test have been analyzed. The influences of the experimental equipments of the tests have been discussed. Calculation using formulas and numerical model analysis via SAP2000 software were carried out. The horizontal test results of the concrete foundation were found to be affected by the stiffness of the bolts. Also, the influences of the different natural frequency of the periodic foundation and concrete foundation on the test results have been analyzed. The response spectrum analysis has been carried out for the shaking table test results, and the spectral acceleration response of the one-dimensional periodic foundation is smaller than the concrete foundation.
In this study, ABAQUS numerical model of one-dimensional periodic structure has been established. The influences of the stiffness of the bolt were simulated by the contact stiffness. Since the stiffness of rubber under tension and compression were different, the vertical stiffness of the rubber was enhanced by calculating the compression modulus. Therefore, the numerical model can successfully simulate the experimental results. By utilizing the influences of the material properties on the periodic foundation band gap, a parametric analysis model was designed by reducing the Young’s modulus of the rubber and increasing the thickness of the foundation. The horizontal frequency band gap of the parametric model is 1.5Hz to 50Hz, the vertical frequency band gap is 5.3Hz to 50Hz. The results of parametric study with periodic foundation models show that both horizontal and vertical response are reduced within the frequency band gap. Beyond the frequency band gap, the horizontal responses were affected by the input earthquake frequency, responses reduced at the natural frequency of the model when subjected to high frequency earthquake but amplified when struck by low frequency earthquake. The vertical responses were not affected by the input earthquake frequency, responses always amplified at the natural frequency of the model.

並列關鍵字

Periodic Foundation Structure ； Shaking Table Tests ； Isolation system ； Frequency Band Gap ； Parametric Study ； Seismic metamaterial

參考文獻

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