震级对近场地震动峰值加速度影响分析

Influence of Earthquake Magnitude to Peak Ground Acceleration on Near Field

利用273条震中距在0-30km范围内的美国地震真实记录,研究震级对近场峰值加速度(简称PGA)影响.研究结果表明随着震级增大水平向和竖直向PGA都增大,但不同类型场地增大幅度不同,Ⅲ类场地增长速度较快,Ⅰ类场地增幅较慢,比较平缓.从分析中得出Ⅰ类场地近场地震动饱和现象,但Ⅱ、Ⅲ类场地PGA值在近场变化却较大.

Influence of earthquake magnitude to peak ground acceleration（PGA） on near field was studied based on 273 earthquake records from American,with the epicenter ranges from 0 to 30 km.In the present study,the influence of earthquake magnitude on horizontal and vertical PGA is large,and the bigger the magnitude is,the larger the PGA.Nevertheless,increasing amplitude of PGA is different when site category is different.For example,PGA of Ⅲ site is large,but one of Ⅰ site is small.The result is observed that on Ⅰ site PGA shows ＂Saturated Phenomena＂ in near field.Therefore,on Ⅲ site the change of PGA is large.