地面运动离散性规律识别及其对长周期结构地震反应的影响

发布时间：2018-07-21 11:28

【摘要】：近年来，国内高层建筑抗震界组织的历次长周期结构研讨会中都讨论了有关长周期结构的抗震设计方法和地震反应预测方法的问题。加之，根据本团队参与指导高层、超高层建筑结构抗震设计工作中的累积，认识到关于我国当前预测结构地震反应的方法存在以下三个尤为值得关注的问题：1)当前我国规范设计反应谱中长周期段考虑到多方面因素而经过了人为调整[5]，不能代表该地区某个具有明确统计意义的地面运动强度，因此用拟合该段反应谱的方式选择出的地面运动记录不能代表具有明确统计意义的地面运动强度；2)通常一次地震发生，即使震级、距离和场地条件等参数相同，因地震波传播途径的多样性以及传播途径内地质构造的复杂性，所记录到的地面运动的频谱特性仍存在很大的离散性。而所输入地面运动的离散性必然会导致最终预测出的结构地震反应的离散性。然而，目前国内对于长周期结构性能的考察中都没有较为系统地考虑由地面运动的离散性而导致的结构反应的离散性。为得到真实可信的离散性规律，用来研究地震动离散性的地面运动记录必须在中长周期有足够的可信度；3)因结构所在场地周围地震环境的不同，加之每个结构的动力特征的不同，具体场地上的具体结构可能遭受的某个水准下的地震动类型也是不同的。要合理预测结构地震反应，应该体现该结构周围地震环境的影响。而依据我国结构设计规范选择的地面运动通常不能体现结构周围地震环境的影响。显然，这样预测出来的结构地震反应是不够准确和不够合理的。基于上述问题，本论文主要完成了以下工作： ①对地面运动长周期段进行了再考证，从地震动的量测仪器、地震动记录误差分析、地震动记录数据处理方法等方面讨论了地面运动长周期段的可信周期。 ②从美国太平洋地震研究中心（PEER）和新西兰FTP强地面运动数据库中收集了261组可信周期足够长、相当于中国抗震规范Ⅱ类场地条件的地面运动记录，并按震级、距离等参数分档，对各档地面运动记录加速度反应谱的长周期特性进行了研究，统计了地面运动的离散性分布规律。 ③主要针对现行地面运动记录选择方法中的不足之处，提出了能够体现结构周围地震环境影响及基于地面运动离散性、具有明确统计意义的拟合反应谱为目标谱的地面运动记录选择方法。 ④根据本论文提出的地面运动记录选择方法，选取了三个统计水准共计21组（每个统计水准各选择7组）地面运动记录，采用三维空间非线性分析程序PERFORM-3D对某个已完成设计及超限审查的212.3m超高层建筑结构算例进行罕遇地震下的非线性动力时程反应分析，对比不同水准统计意义的地面运动记录输入下的结构反应，考察由于地面运功的离散性而导致的结构反应的离散性，以达到合理预测长周期结构响应的目标。完成以上工作，得到的主要结论有： ①相比于早期使用的模拟式强震仪记录，基于新一代数字式强震仪记录到的地面运动记录可以提供更为准确的长周期分量，经过数据校正处理后的数字强震仪记录能够提供可靠的长周期信息，可以用来研究地震动的长周期特性。 ②震级大小是影响地面运动长周期分量大小的决定性因素，随着地震震级增大，当到发震断裂的距离不大时，所得的加速度反应谱的峰值段有周期范围加大的趋势，或形成第二个次高峰区。震级越大，近场地震动的动力放大系数β曲线在长周期区段的谱值也越大。特别是在M7.0以上的大地震时，近场与远场地震动的动力放大系数β曲线在长周期区段的谱值都较大。同一震级档的地面运动记录，随着距离的增大，其动力放大系数β曲线在长周期区段的谱值相差不太大，其衰减速率也相差不大，即“距离”对地面运动记录反应谱长周期段的影响不太明显。不论记录台站离发震断裂的距离大小，也不论地面运动记录对应的地震的震级大小，动力放大系数β的峰值多集中在2.5附近，变动范围为2.3~3.15。 ③建议的地面运动记录选择方法为：采用本论文得出的具有明确统计意义的拟合反应谱（统计平均反应谱、平均值+1倍标准差反应谱和平均值+2倍标准差反应谱）作为目标谱，并对地震危险性概率分析结果进行解聚处理，识别出对所考察结构地面运动危险性起控制作用的地震动类型，再选取震级和场点到震源之间的距离与解聚处理得出的地震动类型相协调的地面运动记录。然后求出选取的地面运动记录中的两个水平向分量各自的加速度反应谱及两个反应谱的几何平均谱，控制标定后的几何平均谱在0.2T1~1.5T1周期范围内的平均值不小于目标谱。 ④得到长周期结构在不同水准统计意义的地面运动记录输入下的结构反应离散性分布状态，，建议对于重要性一般的结构，依照传统设计控制水准，用本论文中具有明确统计意义且经过拟合的平均反应谱为目标谱选取的地面运动作为输入，并以此来考察结构的抗震性能是合适的；但是对于特别重要的结构，可能还需要考虑该结构在高于统计平均值某一特定水平，如平均值+σ或者平均值+2σ的地面运动强度下的反应状态，即采用本论文的平均值+σ拟合反应谱或者平均值+2σ拟合反应谱为目标谱来选取地面运动记录作为输入，考察结构的地震反应状态。如果此状态下不满足结构的性能目标，则可以考虑对结构设计方案进行调整，再重复以上步骤，直到满足结构的性能目标。
[Abstract]:In recent years, the long-period structure Symposium on the seismic boundary of high rise buildings in China has discussed the problems about the seismic design method and the seismic response prediction method of the long period structure. In addition, according to the team's participation in guiding the high-rise, the accumulation of the seismic design work of the super high rise building structure, we recognize the current forecast knot in our country. There are three particularly noteworthy problems in the method of seismic response: 1. In our country, the long period section of the standard design response spectrum of our country has been adjusted [5] by artificial adjustment, and can not represent a certain ground motion intensity with definite statistical significance in the region, so it is chosen by fitting the response spectrum of this section. Ground motion records do not represent ground motion intensity with definite statistical significance; 2) usually one earthquake occurs, even if the magnitude, distance and site conditions are the same, the spectral characteristics of the ground motion recorded are still very large because of the diversity of the seismic wave propagation paths and the complexity of the geological structure within the transmission path. The discreteness of the input ground motion inevitably leads to the discreteness of the final predicted structural seismic responses. However, the discreteness of structural reactions caused by the discreteness of the ground motion is not more systematically considered in the investigation of the long period structure and performance. Law, the ground motion records used to study seismic dynamic discreteness must have sufficient credibility in the medium and long period. 3) the type of ground motion under specific structures on the specific site may be different because of the different seismic environment around the site and the different dynamic characteristics of each structure. The prediction of structural seismic response should reflect the influence of the seismic environment around the structure, and the ground motion selected according to the structural design specification of our country usually can not reflect the influence of the seismic environment around the structure. Obviously, the predicted structural seismic response is not accurate and unreasonable.
Based on the above problems, this thesis has mainly completed the following tasks:
Firstly, the long period section of ground motion is re examined, and the credible period of the long period of ground motion is discussed from the measurement instrument of ground motion, the error analysis of ground motion record and the method of data processing of ground motion recording.
(2) from the American Pacific earthquake research center (PEER) and the New Zealand FTP strong ground motion database, 261 groups of credible cycles were collected, which were equivalent to the ground motion records of class II site conditions of China's seismic code, and were classified according to the magnitude and distance, and the long period characteristics of the acceleration response spectrum of the records of the ground motion were carried out. The discrete distribution law of ground motion is studied.
In view of the shortcomings of the current ground motion recording selection method, the ground motion recording selection method which can reflect the influence of the seismic environment around the structure and the discreteness of the ground motion based on the statistical significance of the fitting response spectrum as the target spectrum is proposed.
(4) according to the method of ground motion record selection proposed in this paper, three statistical levels, 21 groups (7 groups of each statistical level), are selected to record the ground motion, and the three dimensional space nonlinear analysis program PERFORM-3D is used for a 212.3m super high rise building structure with completed design and overlimit review to carry out a rare earthquake The linear dynamic time history response analysis is used to compare the structural responses under the ground motion records of different levels of statistical significance, and to investigate the discreteness of the structural response due to the discreteness of the ground work, so as to achieve the objective of a reasonable prediction of the response of the long period structure.
The main conclusions are as follows:
(1) compared with the early used analog strong seismograph, the record of the ground motion recorded on the new generation of digital strong seismograph can provide more accurate long period components, and the digital strong seismograph after the data correction can provide reliable long period information, which can be used to study the long period characteristics of the ground motion.
The magnitude of the magnitude of the earthquake is the decisive factor affecting the size of the long periodic component of the ground motion. With the increase of the earthquake magnitude, the peak segment of the acceleration response spectrum has a tendency to increase periodically, or second sub peak regions when the earthquake magnitude is not large. The greater the magnitude of the earthquake, the dynamic amplification factor beta curve near the ground motion is The spectral value of the long period section is also larger. Especially in the large earthquake above M7.0, the spectral value of the dynamic amplification factor beta curve of the near and far field vibration is larger in the long period section. The ground motion records of the same magnitude gear are not very different with the distance increasing, and the difference of the spectral values of the dynamic amplification factor beta line in the long period section is not too large. The rate of deceleration also has little difference, that is, the effect of "distance" on the long period of the response spectrum of ground motion records is not very obvious. No matter the distance of the seismic fault and the magnitude of the earthquake magnitude corresponding to the ground motion record, the peak value of the dynamic amplification factor beta is mostly near 2.5, and the variation range is 2.3~3.15..
3. The proposed method of selecting ground motion records is to use the fitting response spectrum (statistical mean response spectrum, mean value +1 times standard difference spectrum and mean value +2 times standard difference response spectrum) as target spectrum, and to dissolve the result of seismic hazard probability analysis and identify the test The type of ground motion that is controlled by the risk of structural ground motion, and then the ground motion records that coordinate the distance between the magnitude and the field to the source and the type of ground motion obtained by the depolymerization process. Then the acceleration response spectrum and the two response spectrum of the two horizontal components in the selected ground motion records are obtained. The mean value of the geometric mean spectrum in the 0.2T1~1.5T1 period is not less than the target spectrum after He Pingjun calibration.
(4) the discrete distribution state of the structural response under the input of the ground motion records with different levels of statistical significance is obtained. It is suggested that the ground motion selected in this paper, which has clear statistical significance and the average response spectrum is fitted, is selected as the target spectrum in accordance with the traditional design control level. It is appropriate to investigate the seismic performance of the structure, but for a particularly important structure, it is possible to consider the reaction state of the structure at a certain level above the statistical average, such as the mean value + Sigma or the average value of +2 sigma. The mean +2 sigma fitting response spectrum is used as the target spectrum to select the ground motion record as input to investigate the seismic response state of the structure. If this state does not meet the performance targets of the structure, the structural design scheme can be adjusted, and the above steps can be repeated until the structure's performance targets are met.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU311.3

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