抗震设计中多遇地震的问题和讨论  

Discussion on the problem of frequent earthquakes in seismic design

作　　者：石树中 沈建文[2] 

机构地区：[1]浙江省地震局,杭州310013 [2]上海市地震局,上海200062

出　　处：《地震学报》2012年第1期105-110,127,共6页Acta Seismologica Sinica

基　　金：浙江省重点科研社会发展项目(2005C23075)资助

摘　　要：指出作为截面抗震验算标准的"小震"混淆了两种明显不同的概念:其一是对应于50年超越概率63%的地震动参数(以下简称"多遇小震");其二是50年超越概率10%的地震动参数经过折算得到的参数(以下简称"折算小震").上述混淆导致抗震设计中实际上执行着不同的标准.文中讨论了中、小地震动参数之间关系的复杂性,包括从地震危险性分析得到的基岩面中、小地震峰值加速度的离散性,一致概率谱的差异,以及中、小地震由于土层反应非线性影响导致的场地相关谱的系统性差异.指出重大工程的抗震设计以"多遇小震"取代"折算小震"进行截面验算可能导致反应谱特征周期Tg明显低估的问题,并提出了相应建议.＂Small earthquakes＂ used as the standard of section seismic checking in seismic design confuses two significantly different concepts. One is the ground motion parameters corresponding to 63% exceeding probability in 50 years （hereinafter referred to as ＂frequent earthquakes＂）, and the other is the parameters received by reducing that corresponding to 10 % exceeding probability in 50 years （hereinafter referred to as ＂reduction small earthquakes＂）. Above confusion leads to a result that two different standards are actually followed in seismic design. Complexity of the relation of ground motion parameters corre sponding to medium and small earthquakes is discussed, such as dispersion of peak acceleration, differences of consistent probability spectra on the bedrock obtained from seismic hazard analysis, and systematic differences of site related response spectra between medium and small earthquakes by soil non-linear effect. Substitution frequent earthquakes for reduction small earthquakes in section seismic checking for major engineering projects may result in underestima tion of response spectrum characteristic period Tg. Some suggestions are put forward.

关 键 词：多遇地震 折算小震 设计地震动参数 峰值加速度 反应谱特征周期 

分 类 号：P315.9[天文地球—地震学]