基于地震危险性分析方法美国某高层建筑优化设计研究

Research on site-specific seismic hazard analysis of a high-rise building in downtown Seattle,USA

本文采用近年来美国地震灾害研究取得的最新进展,对美国西雅图市中心某拟建高层建筑地震危险性分析展开优化研究,以期达到在满足美国土木工程师协会抗震设计规范(ASCE 7-10)的前提下,合理降低建筑物抗震设计费用之目的。研究首先采用ASCE 7-10推荐的方法 2分析基于具体场地参数条件下的风险系数;对于地震动最大方向系数,采用最新的Shashi and Baker 2014模型进行优化;由于现有的卡斯卡迪亚俯冲带地震动衰减模型缺乏对盆地放大效应的考虑,研究采用基于2014 NGA West2的最新潜源地震动衰减模型盆地放大效应系数进行优化考虑。研究结果显示,优化后的地震反应谱在中短周期范围内与非优化的地震反应谱基本一致,但是在长周期范围内,进行优化后的反应谱值一般要比不优化的反应谱值小20%到30%。在建筑物的第一卓越周期7秒左右,这个差别是25%。可见采用优化后的地震反应谱将会达到安全合理节约建筑物抗震设计费用的目的。

The purpose of this study is to achieve an optimal design of the proposed high-rise building in Downtown Seattle with meeting satisfactory seismic safety design per the ASCE 7-10 code as well as saving related costs. Risk factors were computed using the Method 2 recommended by the ASCE 7-10 ; the latest Shashi and Baker 2014 mod- el was used to calculate period-dependent maximum direction factors; the current ground motion attenuation models for the Cascadia Subduetion Zone do not include effects of the basin amplification. As such, basin amplification factors derived from the NGA West2 ground motion attenuation models for the shallow crustal faults were adopted to consider basin amplification effects for ground motions. The result of the study revealed that the optimized response spectrum is in general in agreement with the non-optimized response spectrum for short and intermediate periods. However, the optimized response spectrum is about 20% to 30% less than the non-optimized response spectrum for long periods. In particular, the optimized response spectrum is about 25 % less for the periods of around 7 second which is the fundamental period of the proposed building.