Effects of Ground Motions on Seismic Response of Structures

地震动对结构地震响应的影响

• 批准号: RGPIN-2014-05726
• 负责人: Ventura, Carlos
• 金额: $ 2.48万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588582
• 关键词: Effects; Ground; Motions; Seismic; Response

Some of the lessons from recent significant earthquakes have shown the need for further research on design areas that have not been studied in detail. The subduction earthquakes in Sumatra, Indonesia (Mw 9.1) in 2004, Maule, Chile (Mw 8.8) in 2010, and Tohoku, Japan (Mw 9.0) in 2011 are some of the largest earthquakes ever recorded. The Cascadia subduction zone in Western Canada and the Pacific Northwest of the U.S. has the potential of generating very large earthquakes, as well. A recent study commissioned by the Insurance Bureau of Canada (Air Worldwide, 2013) estimate that the economic losses from a magnitude 9 in the region could be as high at 75 billion dollars, of which about 49 billion dollars would be due to ground shaking and the rest due to tsunami, fire-following, and liquefaction and landslides effects. So there is now strong motivation to reduce economic losses due to ground shaking. For several years, the applicant and his research team have been studying how the ground motions from different types of earthquakes affect the seismic response of structures. These studies included analytical studies, shake table and cyclic tests, and field testing and monitoring of instrumented structures. The proposed research will address three topics of significant relevance to the understanding of structural response during earthquakes. This, in turn, will contribute to the reduction of seismic risk in Canada: 1) Soil-foundation-structure interaction (SFSI) in buildings during earthquakes is characterized by several aspects including the variation between the free-field and foundation motions. The analytical studies conducted so far show that amplification occurs when the system period is close to the dominant period of the input motion. When these two periods are far apart, the motions at the slab are reduced with respect to the field. The basis of code recommendation should be re-examined in light of the fact that it appears in contradiction to the findings from field data and analytical results. 2) Pulse-like near fault ground motions can occur on sites in close proximity to a causative fault. In such cases consideration of flexibility of the foundation system is very important. The purpose of this research is to study the nonlinear response of structures to pulse-like near ground fault. 3) Subduction ground motions are important for Western Canada and their effects on the response of structures needs to be investigated in detail. This study is intended to provide a deep insight into subduction earthquakes by carrying out a comprehensive analysis of ground motions recorded during this type of event. The effects of duration and long period components of the ground motions on the linear and nonlinear response of structures will be investigated. To date, most of the research quantifying building and bridge response and safety has focused on crustal, California-type ground motions. The distinct geologic characteristics of subduction earthquake sources and attenuation, cause ground motions from subduction earthquakes to have different duration and frequency content when compared to crustal ground motions. The goal of this research is to quantify the impact of these ground motions on the response of buildings and bridges and to develop information that can be used by practicing engineers to design, or retrofit, structures that may be subjected to this type of ground shaking. Recommendations for incorporation of subduction ground motion effects on the National Building Code of Canada, and the Canadian Highway and Bridge Design Code will be developed.

最近重大地震的一些教训表明，有必要对尚未详细研究的设计领域进行进一步研究。2004年印度尼西亚苏门答腊岛(Mw 9.1)、2010年智利Maule(Mw 8.8)和2011年日本东北(Mw 9.0)发生的俯冲地震是有记录以来最大的地震。加拿大西部的卡斯卡迪亚俯冲带和美国西北部的太平洋也有可能发生非常大的地震。加拿大保险局(Air Worldwide，2013)最近委托进行的一项研究估计，该地区9级地震造成的经济损失可能高达750亿美元，其中约490亿美元是由于地面震动，其余的是由于海啸、火灾以及液化和山体滑坡的影响。因此，现在有强烈的动机来减少因地面震动造成的经济损失。几年来，申请人和他的研究团队一直在研究不同类型地震的地面运动如何影响结构的地震反应。这些研究包括分析研究、振动台试验和循环试验，以及现场试验和仪器结构监测。这项拟议的研究将涉及三个与理解地震期间的结构反应密切相关的主题。这反过来将有助于降低加拿大的地震风险：1)地震期间建筑物中的土-基础-结构相互作用(SFSI)具有几个方面的特征，包括自由场和基础运动之间的变化。到目前为止进行的分析研究表明，当系统周期接近输入运动的主导周期时，就会发生放大。当这两个周期相隔很远时，板上的运动相对于场是减小的。应重新审查代码建议的依据，因为它似乎与实地数据和分析结果的结论相矛盾。2)发震断层附近的场地可发生脉冲状的近断层地震动。在这种情况下，考虑基础体系的灵活性是非常重要的。本研究的目的是研究结构在脉冲状近地断层作用下的非线性响应。3)俯冲地震动对加拿大西部非常重要，其对结构响应的影响需要详细研究。这项研究旨在通过对俯冲地震期间记录的地面运动进行全面分析，对俯冲地震提供深入的见解。研究地震动的持续时间和长周期分量对结构线性和非线性反应的影响。到目前为止，大多数量化建筑和桥梁反应和安全性的研究都集中在加利福尼亚州地壳类型的地面运动上。俯冲地震震源和衰减的不同地质特征，导致俯冲地震的地震动与地壳地震运动相比具有不同的持续时间和频率含量。这项研究的目的是量化这些地面运动对建筑物和桥梁反应的影响，并开发出可供执业工程师设计或改造可能受到此类地面震动影响的结构的信息。将制定将俯冲地震动效应纳入加拿大国家建筑规范和加拿大公路与桥梁设计规范的建议。