In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(...In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.展开更多
反应谱是抗震设计的重要依据,传统数值方法的本构模型不能满足复杂场地和具有强不确定性土体动力过程的模拟,导致计算结果与实测反应谱之间差距较大。以一维场地反应分析为背景,从日本KiK-net强震台网搜集了2428组来自水平场地台站的基...反应谱是抗震设计的重要依据,传统数值方法的本构模型不能满足复杂场地和具有强不确定性土体动力过程的模拟,导致计算结果与实测反应谱之间差距较大。以一维场地反应分析为背景,从日本KiK-net强震台网搜集了2428组来自水平场地台站的基岩和地表地震动记录,将土层信息和基岩输入作为主要特征,使用场地类别引导的分层抽样训练策略,建立了BO-XGBoost-SS地表加速度反应谱预测模型。结果表明,构建的模型具有良好的预测性能,对地表加速度反应谱的决定系数R^(2)评价指标为0.87,各周期点的R^(2)均大于0.8,应用动态时间规整(dynamic time warping,DTW)的距离分析单条反应谱的预测匹配性,模型在各类场地表现稳定,克服了数值方法高频低估和长周期异常放大的不足。使用最新地震动记录作为外部数据集,进一步验证了模型的泛化能力。通过(shapley additive explanations,SHAP)解释分析特征对模型预测的贡献,揭示了影响反应谱预测的关键特征,各特征影响规律和现有研究成果一致。研究结果为场地反应预测模型的开发提供训练策略和评估指导,为机器学习在地震区划和工程结构抗震设计中的应用提供了新思路。展开更多
基金Project(2011CB013605)supported by the National Basic Research Development Program of China(973 Program)Projects(51178071,51008041)supported by the National Natural Science Foundation of ChinaProject(NCET-12-0751)supported by the New Century Excellent Talents Program in University of Ministry of Education of China
文摘In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures.
文摘反应谱是抗震设计的重要依据,传统数值方法的本构模型不能满足复杂场地和具有强不确定性土体动力过程的模拟,导致计算结果与实测反应谱之间差距较大。以一维场地反应分析为背景,从日本KiK-net强震台网搜集了2428组来自水平场地台站的基岩和地表地震动记录,将土层信息和基岩输入作为主要特征,使用场地类别引导的分层抽样训练策略,建立了BO-XGBoost-SS地表加速度反应谱预测模型。结果表明,构建的模型具有良好的预测性能,对地表加速度反应谱的决定系数R^(2)评价指标为0.87,各周期点的R^(2)均大于0.8,应用动态时间规整(dynamic time warping,DTW)的距离分析单条反应谱的预测匹配性,模型在各类场地表现稳定,克服了数值方法高频低估和长周期异常放大的不足。使用最新地震动记录作为外部数据集,进一步验证了模型的泛化能力。通过(shapley additive explanations,SHAP)解释分析特征对模型预测的贡献,揭示了影响反应谱预测的关键特征,各特征影响规律和现有研究成果一致。研究结果为场地反应预测模型的开发提供训练策略和评估指导,为机器学习在地震区划和工程结构抗震设计中的应用提供了新思路。
