长周期地震动强度指标与SDOF体系残余变形相关性分析

Correlation analysis between long-period ground motion intensity indices and residual deformation of SDOF system

为分析两类长周期地震动作用下如何选取合理的强度指标作为结构抗震设计的输入,从2011年东日本9.0级地震、2003年十胜冲8.0级地震和2016年熊本7.3级地震数据库中选取90条可靠的远场长周期地震动。从1994年美国北岭6.7级地震和1999年台湾集集7.6级地震数据库中选取60条近场长周期地震动,以SDOF体系为研究对象,讨论了阻尼比、屈服刚度折减系数和强度折减系数对残余变形与18个地震动强度指标的相关系数的影响,对比分析了两类长周期地震作用下相关系数之间的异同。研究结果表明:在考虑近场长周期地震动作用时,建议应根据结构周期的大小来选择合适的强度指标作为地震动的输入。远场长周期地震动作用下,以PGA、PGV和PGD为代表的强度指标与残余变形的相关程度均较高,PGV稳定性略好于PGA和PGD,建议PGV作为地震动输入的控制指标。残余变形相关系数受阻尼比、屈服刚度折减系数以及强度折减系数影响不大。

In order to select a reasonable intensity indice as the input of structural seismic design under the two types of long-period ground motions, 90 reliable far-field long-period ground motions were used as inputs, which were chosen from 2011＇ s East Japan earthquake （Mw9.0）, 2003＇ s Japan Tokachi-oki earthquake （Mw8.0） , and 2016＇ s Kumamoto earthquake （ Mw7.3 ） , 60 near-field long-period ground motions were used as inputs, which were chosen from 1999＇s Taiwan Chi-Chi earthquake （Mw7.6）, 1994＇s Northridge earthquake （Mw6.7）. Based on the SDOF system, the effects of damping ratio, post-yield stiffness and force reduction on correlation coefficient between residual deformation and 18 ground motion intensity indices are analyzed and that between the two types of long- period earthquake is compared. The results show that： it is suggested that the appropriate intensity indice should be selected as the input of ground motion according to the size of the structure period under near-field long-period ground motions. The intensity indices represented by PGA, PGV, PGD are highly correlated with the residual deformation, PGV is slightly better than PGA, PGD, under farfield long-period ground motions and PGV is suggested as a control indice for input of ground motion. The correlation coefficient of residual deformation is not affected by damping ratio, post-yield stiffness and force reduction.