一种新的向量型地震动强度参数及其有效性评估

Validity assessment of a new vector-valued intensity parameter of earthquake ground motion

结构地震易损性分析中,地震动强度参数是影响分析结果的主要因素之一。为寻求一个合理有效的地震动强度参数,降低分析结果的离散性,提高计算效率,以结构第一周期反应谱加速度Sa(T1)为第一变量,地震动峰值加速度与其持时的乘积PGA*Td1/3为第二变量,构造向量型强度参数[Sa(T1),PGA*Td1/3]。以一栋20层的钢筋混凝土框架-核心筒结构为研究对象,选取10条地震动记录,分别采用3个标量型和5个向量型强度参数对该结构进行增量动力分析,而后以统计学的残差平方和RSS和拟合优度R2为评价指标,评估地震动强度参数的有效性。结果表明:向量型强度参数[Sa(T1),PGA*Td1/3]与其他强度参数相比具有较小的RSS和较大的R2值,分别为33.313、0.877,表明其有效性较好,而常用的标量型强度参数Sa(T1)的RSS和R2值分别为60.953、0.777,有效性较差。

Ground motion intensity parameter is one of the main factors that affect the results of seismic vulnerability structures.In order to find an efficient intensity parameter,which reduces the discreteness of analysis results and improves the computational efficiency,the vector intensity measure[Sa(T1),PGA*Td1/3]is formed based on response spectral acceleration at the fundamental period of the structure Sa(T1)as the first component and the product of Peek Ground Acceleration and time holding,PGA*Td1/3,as the second component.IDA of a 20-story high-rise reinforced concrete frame-core wall structure selected from 10 ground motion records is implemented to measure the efficiency of 3 scalar-valued and 5 vector-valued intensity parameters by the evaluation indicators of the Residual Sum of Squares(RSS)and coefficient of determination(R2)statistics.The results indicate that the vector[Sa(T1),PGA*Td1/3]formed is more efficient than the other intensity parameters,which has smaller RSS and larger R2 values,33.313 and 0.877 respectively.In addition,the efficiency of the scalar Sa(T1)is worse than the others, with the RSS and R2 values 60.953 and 0.777 respectively.