橋梁直接基礎搖擺實驗

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題名:	橋梁直接基礎搖擺實驗
作者:	周煌鈞;Chou,Huang-chun
貢獻者:	土木工程學系
關鍵詞:	單跨度簡支橋梁;SAP2000;動力分析;直接基礎;搖擺效應;simply supported bridge;SAP2000;dynamic analysis;spread foundation;rocking mechanism
日期:	2015-05-18
上傳時間:	2015-07-30 15:52:03 (UTC+8)
出版者:	國立中央大學
摘要:	近年地震對台灣造成許多的災害，使耐震設計規範之設計地震力提高，導致部分補強和新建案例之直接基礎尺寸明顯過大。其主要原因乃設計地震力提高，穩定性檢核時基礎受壓面積仍須滿足原有規定，所以基礎尺寸必須擴大。依據過去地震經驗發現直接基礎之搖擺機制可降低傳遞至上部結構之地震力，並且透過搖擺機制產生振動週期延長降低地震力，也可藉由土壤於大地震下之塑性行為吸收地震能量。過去其研究對象均為直接基礎之單柱橋墩，並未有直接基礎單跨橋梁之搖擺效應研究。因此本研究以單跨度簡支橋梁為主要對象，先以商用軟體SAP2000建立分析數值模型進行動力分析，再進行一系列之振動台試驗，觀察橋面板質量、柱高、橋墩基礎面積、土壤強度對搖擺效應之影響。由實驗結果可得知當橋面板質量較重與橋柱柱高較高時，橋樑柱底應變隨之增大。另外橋墩基礎尺寸較小與土壤勁度較低，會有利於搖擺效應，降低柱底應變，延長試體自然震動週期，達隔震效果。搖擺行為時，試體結構系統自然振動頻率，會接近地震主要震頻。 ;In recent years, the earthquake caused many disasters in Taiwan, so seismic design specification to improve the design seismic forces. Therefore the spread foundation wide obviously is too large in some reinforcement and new cases. The main reason is improving the design seismic forces. And the foundation of pressured area have to satisfy the specification, therefore the size of foundation must be expanded. Based on the past experience, the rocking mechanism of spread foundation can reduce the seismic force of the main structure, besides it can extend the period of structure and decrease the seismic force. In addition, the soil will generate the plastic behavior and absorb the seismic energy under the extreme earthquake. In the past, the research subjects was single pier of spread foundation. There was not the research about the rocking mechanism of simply supported bridge. Therefore, the research of simply supported bridge is main subject. First, I build a numerical model in the commercial software SAP2000 and proceed the dynamic analysis. Next, we advance a series of shaking table tests to verify feasibility of spread foundation with linear numerical model. And then, we observe the deck quality, column height, the pier foundation area, the effect of soil strength to rocking. In the experiment, we can know that the stain of column base will be greater with heavy deck and high column height. On the other hand, the smaller footing size and lower rubber stiffness are facilitate to rocking effect. It can reduce the stain of column base and extend the nature period of the structure for isolation effect. When it is rocking, the nature frequency of the structure system will be close to major earthquake vibration frequency.
顯示於類別:	[土木工程研究所] 博碩士論文

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