| 引用本文: | 张琪,郑向远,李炜.海陆地震动的时频域工程特性对比[J].哈尔滨工业大学学报,2020,52(8):38.DOI:10.11918/201909194 |
| ZHANG Qi,ZHENG Xiangyuan,LI Wei.Comparison of temporal and spectral features of offshore and onshore ground motions[J].Journal of Harbin Institute of Technology,2020,52(8):38.DOI:10.11918/201909194 |
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| 摘要: |
| 海洋工程抗震几乎还沿用陆上土木工程的规范和成果,为了指出在海洋工程抗震设计和安全评估中使用海底地震动的重要性,选取多个地震事件,关注同一地震下震中距相似的海陆地震动记录.对比分析了传统地震动三要素,并且考虑到地震动属于非平稳信号,利用希尔伯特-黄谱分析了海陆地震动的能量在时频分布上的差异.结果表明:海底水平地震动加速度峰值比陆地的大很多,总体上其持时也较长,同时其加速度反应谱向中低频偏移,这些特征会对海洋结构动力响应造成更不利的影响；对于时频谱,海底地震动的主要能量所对应的频率比陆地的低,而其最大能量所对应的频率更接近峰-谷频率,而不是傅里叶谱上的卓越频率. |
| 关键词: 海洋工程 海底地震动 地震动三要素 希尔伯特-黄谱 峰-谷频率 |
| DOI：10.11918/201909194 |
| 分类号:P315.9 |
| 文献标识码:A |
| 基金项目:国家重点研发计划重点专项(2016YFC0303706)； 国家自然科学基金(51579227) |
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| Comparison of temporal and spectral features of offshore and onshore ground motions |
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ZHANG Qi1,2,ZHENG Xiangyuan2,LI Wei3
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(1.Department of Civil Engineering, Tsinghua University, Beijing 100084, China;2.Division of Ocean Science and Technology, Tsinghua University, Shenzhen International Graduate School, Shenzhen 518055, Guangdong, China; 3.POWERCHINA HUADONG Engineering Co. Ltd., Hangzhou 311122, China)
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| Abstract: |
| The seismic design of marine structures so far still relies on civil engineering design codes. The objective of this study was to point out the importance of using offshore ground motion for seismic design and safety assessment of marine engineering. Several earthquakes in history were selected, and the focus was on paired offshore and onshore accelerations with identical epicenter distances. Three key elements of seismic motions were discussed, and Hilbert-Huang spectrum was adopted to distinguish energy distributions in terms of temporal and spectral characteristics. Results show that the peak ground acceleration of offshore horizontal motion was larger than that of onshore horizontal motion. The duration was generally longer, and the response spectrum shifted to moderate and low frequencies. These features may have unfavorable effects on structural dynamic response. As revealed by the Hilbert-Huang spectral analysis, the frequency corresponding to the main energy of offshore ground motion was lower than that of onshore ground motion, and the frequency corresponding to the largest instantaneous energy was almost identical to peak-to-trough frequency rather than predominant frequency in Fourier spectrum. |
| Key words: marine engineering offshore ground motion three key elements of a seismic motion Hilbert-Huang spectrum peak-to-trough frequency |
